AAE '09 Abstracts of Reasearch

Abstracts of Research To be Presented at the 2009 Annual Session of the American Association of Endodontists April 29 – May 2, at the Gaylord Palms Resort and Convention Center Abstracts appear as they were submitted by the presenters. The letters in the upper left corner represent the type of presentation: OR for Oral Research Presentation and PR for Poster Research Presentation. Please refer to the schedule below to determine when the abstracts will be presented. For example, OR 9 will be presented during the Resident Oral Research Presentations Endodontic Disinfection section, Thursday, April 30, between 11:45 a.m. – 1 p.m., in Room Sun 1.

Schedule of Presentations Resident Oral Research Presentations Thursday, April 30 Radiographic Techniques Sun 1 10:30 – 11:30 a.m. Abstracts 1-4 Regenerative Endodontics and MTA Sun 3 10:30 – 11:30 a.m. Abstracts 5-8 Endodontic Disinfection Sun 1 11:45 a.m. – 1 p.m. Abstracts 9-13 Prognosis Sun 3 11:45 a.m. – 1 p.m. Abstracts 14-18 Local Anesthetics/Pain Control Sun 1 1:30 – 3 p.m. Abstracts 19-24 Instruments, Instrumentation and Obturation I Sun 3 1:30 – 3 p.m. Abstracts 25-30

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Thursday, April 30, Continued

Friday, May 1, Continued

Instruments, Instrumentation and Obturation II Sun 1 3:30 – 5 p.m. Abstracts 31-36

Endodontic Irrigation, Instrumentation and Obturation Sun 3 10 – 11:30 a.m. Abstracts 58-63

Basic Science and Microbiology of Endodontics I Sun 3 3:30 – 5 p.m. Abstracts 37-42

Poster Research Presentations

Predoctoral Student, General Practitioner and Endodontist Oral Research Presentations Friday, May 1 Basic Science and Microbiology of Endodontics II Sun 1 8 – 9:30 a.m. Abstracts 43-48 Local Anesthesia Efficacy, Regenerative Endodontics and Prognosis Sun 3 8 – 9:30 a.m. Abstracts 49-51, 55 Properties of MTA and Rotary Instruments Sun 1 10 – 11:30 a.m. Abstracts 52-54, 56-57

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Friday, May 1 Resident Session Halls ABC 8 – 11:30 a.m. PR Abstracts 1-42

Saturday, May 2 Predoctoral Student, General Practitioner and Endodontist Sessions Halls ABC 9:15 a.m. – 12:30 p.m. PR Abstracts 43-70

Table Clinics (no abstracts) Friday, May 1 Resident Session Halls ABC 8 – 11:30 a.m.

Saturday, May 2 Predoctoral Student, General Practitioner and Endodontist Sessions Halls ABC 9:15 a.m. – 12:30 p.m.

OR 01 

OR 02 

Surgical endodontic procedures require precise knowledge of anatomical structures that might be traumatized. However, no study has used CBCT to evaluate whether gender or age alters the relative location of the inferior alveolar nerve (IAN) to the roots of the mandibular first molar. To address this gap in knowledge, we searched a database of 23,000 small-volume CBCT scans (J. Morita, Accuitomo 3DX) and evaluated the first 200 scans that met the following inclusion criteria: 1) age between 30-69; 2) known gender (n=25 males and 25 females for each 10-year age bin); and 3) scans containing the mandibular first molar and IAN. Exclusion criteria consisted of any pathosis that might alter the relationship of the first mandibular molar and the IAN. Anatomical measurements were made by two observers with mutual agreement of any discordant measures. Fourteen measurements (in mm) were taken at the level of the IAN and mesial and distal root apex. Data were analyzed by 2-way (Age, Sex) ANOVA with Bonferroni’s post-hoc test at p<0.05. The results indicate that regardless of age, females had significantly smaller vertical distances from the IAN to the mesial (p<0.01) and distal apices (p<0.01) and shorter horizontal distances for total width of mandibular bone at mesial (p<0.01) and distal apices (p<0.01). In addition, the overall width of the mandibular bone decreased in both genders from the 3rd - 6th decade of life (p<0.01). Collectively, these data indicate that both gender and age impact surgical endodontic anatomical relationships and should be considered in presurgical planning.

It has been suggested that Cone Beam-Computed Tomography (CBCT) may be comparable to histopathology in differentiating cysts from granulomas. To test this hypothesis, we examined: [1] agreement between pathologists as to whether a biopsy is a cyst or granuloma; [2] agreement between radiologists as to whether a CBCT image denoted a cyst or granuloma; then [3] determined accuracy of radiologists’ diagnostic assessments, using histopathology as the standard. Fifty-two endodontic patients scheduled for apical surgery were recruited and received a CBCT scan of the involved arch. Two standardized oral pathologists evaluated the surgical specimens and determined presence of either periapical cyst or granuloma. Two standardized oral and maxillofacial radiologists evaluated the CBCT images and categorized lesions into one of five choices: cyst, likely cyst, likely granuloma, granuloma or other. Results show that agreement between the two pathologists’ diagnoses is strong [kappa = 0.79] and statistically significantly different from no agreement [Z = 5.46; p < 0.0001]. However, there was no agreement between radiologists regarding diagnoses [weighted kappa = 0.14; p = ns]. Overall accuracy [true positive plus true negative outcomes] indicates that Radiologist 1 was more accurate that Radiologist 2 [63% vs. 51%] using the most stringent criterion for identifying cysts. Conclusion: Pathologists were in high agreement, radiologists were in low agreement, and radiologists differed in their sensitivity and specificity in identifying cysts or granulomas. Given the variability in radiologist’s assessments, the use of histopathology for differentiating periapical cysts from granulomas should remain the standard.

OR 03 

OR 04 

Evaluation of Gender- and age-Related Differences in the Position of the Inferior Alveolar Nerve Using Cone Beam CT J.D. Simonton*, B. Azevedo, W.G. Schindler, K.M. Hargreaves University of Texas Health Science Center Dental School, San Antonio, TX

An In Vitro Comparison of Working Length Accuracy Between a Digital System and Conventional Film When Vertical Angulations of the Object is Variable S.R. Christensen*, M.M. Vail, E.T. Parks, K.J. Spolnik, C.E. Brown, J.J. Legan Indiana University, Indianapolis, IN Comparisons of the working length accuracies between conventional and digital radiographs were examined. Twelve mounted teeth, in plaster with #15 K-type files in place, were radiographed at varying angles of the long axis to simulate the modified parallel imaging technique. The #15 K-type files were placed at a known, randomly selected distance from the apex either, 0.5mm, 1.0mm or 1.5mm. Thirteen variable angled images for each tooth, from parallel to +/- 30 degrees of inclination, were taken. Each angle-tooth combination was radiographed twice, using a Schick digital system and Kodak Ekta speed film. Standard exposure parameters were used to achieve ideal contrast and density of the rendered images. Four examiners evaluated the films, at random, measuring the distance from the radiographic apex to the apical extension of the file. The measurements for the conventional film and digital images were recorded to the nearest half millimeter. A mixed effects analysis of variance model was used to model the effect of image type and angle on the working length. Statistical analysis of the data confirmed that the working length measured for digital films was not significantly different from that of conventional film (mean difference of 0.02 mm (95% CI: -0.03, 0.06)). Furthermore, there was not a significant difference among the angles (p=0.246) nor in the interaction of image type with the angles (p=0.149). Hence, a digital image taken regardless of angle of exposure gives a working length similar to one taken with conventional film.

Key:

 denotes Resident

* denotes Presenter(s)

Evaluation of Pathologists (Histopathology) and Radiologists (Cone BeamComputed Tomography) Differentiating Periapical Cysts From Granulomas J. Frisbie*, J. Lee, K. Lee, G. Fisch, P.A. Rosenberg New York University, NY

An In Vitro Comparison of Working Length Determination Between a Digital System and Conventional Film P.J. Ley*, M.M. Vail, E.T. Parks, K.J. Spolnik, C.E. Brown, J.J. Legan Indiana University, Indianapolis, IN Accurate determination of working length during endodontic therapy is an essential step in achieving a predictable outcome. This is determined by the use of electronic apex locators, tactile perception and knowledge of average tooth lengths and/or dental radiography whether digital or conventional is utilized. This study determined if there was any difference between Schick digital radiography and Kodak Ektaspeed conventional film in accurately determining working lengths when modifying exposure time and source-film/sensor distance. Twelve teeth with #15 K-flex files at varying known lengths from the anatomical apex were mounted in a resin-plaster mix to simulate bone density. Each tooth was radiographed using a jig for standardization while varying the source-film/sensor distance and exposure time. Four dental professionals examined the images and films independently and measured the distance from the tip of the file to radiographic apex. The principal investigator recorded the measurements. Twenty images were selected at random and re-examined to determine each examiner’s repeatability. A mixed effects analysis of variance model was used to model the effect of image type and angle on the working length. Tooth type and examiner were included in the model as random effects. After adjusting for the effects of distance and exposure time, the working length from the digital image was significantly shorter (p<0.001) by 0.1 mm (95% CI: 0.06, 0.14) than working length from the film image. In conclusion, digital films read shorter than conventional films although not at a level of clinical significance.

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OR 05 

Effect of Inflammation on Pulp Stem Cell Potency D.J. Alongi*, A.F. Fouad, G.T.J. Huang University of Maryland, Baltimore, MD Human dental pulp stem cells (hDPSCs) possess multilineage potential. Whether inflammation affects their biological properties is not known. Objectives: To determine the difference in density of stem cell marker expression between normal and inflamed pulps and the effect of cytokines on the differentiation potential of hDPSCs. Methods: Normal pulps (NP, n=16) and inflamed pulps (IP, n=15) were collected from patients aged 14-22, and frozen-sectioned for immunohistochemical detection of stem cell markers STRO-1, CD90 and CD146. Staining foci on vascular/neural structures and single pulp cells were counted in 3 random 0.09 mm² areas, in a blinded manner. Three groups of cultured clonogenic hDPSCs were tested for their differentiation potentialities: i) from NP, ii) from IP and iii) from NP stimulated with TNFα + IL-1ß. Osteo/dentinogenic, adipogenic or neurogenic induction media were then added to cells except controls. Cell cultures were then subjected to chemical assays or RNA isolation for RT-PCR. Results: All three markers were detected in NP and IP. Their expression was associated with vascular or neurosheath structures and by scattered pulp fibroblasts. IP showed higher density of markers (p< .05) and more single cells expressing these markers (p<.05; except CD146, p>.05) than in NP. Based on chemical or RT-PCR analysis, osteo/dentinogenic and adipogenic gene expression was suppressed by cytokines whereas neurogenic gene expression was not affected. Conclusions: The pulp in IP cases has more scattered cells expressing stem cell markers. Cytokine stimulation appears to affect osteo/dentinogenic potential of hDPSCs but not neurogenic differentiation. Supported by AAE Foundation.

OR 07 

Dental Pulp Revascularization Potential of Stem Cells of Bone Marrow Origin in a Rat Model S.J. Welch*, V.B. Jensen, J.E. Bouquot, S. Cai University of Texas Health Science Center at Houston, TX Specifically identifying the progenitor cells involved in revascularization and elucidating the biological processes involved is critical to future therapies. Whether bone marrow derived stem cells form dental pulp and dentin in vivo is of interest. The purpose of this study was to 1) establish a rat model for dental pulp revascularization and 2) confirm that bone marrow derived cells participate in the revascularization of dental pulps. The apical segment and pulpal tissue of Wistar wild-type rat incisors were surgically removed using a novel retropulpectomy/ apicoectomy procedure. Revascularization therapy was performed two weeks later. Four weeks after revascularization therapy, histological evaluation showed new bone forming into the surgical crypt and granulation tissue with revascularization was noted proliferating into the root space with a few acute inflammatory cells. Fibroplasia was found along the dentinal walls where few inflammatory cells were located appearing contiguous with the dental lamina at the surgical site dentin/ enamel border. Adjacent zones contained more inflammatory cells or necrosis with edema and neutrophils. To determine the potential origin of the ingrowing cell population, bone marrow cells from transgenic green fluorescent protein (GFP) rats were transplanted into the apical bony crypt created by apicoectomy of NIH nude rat incisors. Revascularization was performed two weeks later. Four weeks after revascularization therapy, immunohistochemical staining detected GFP expressing cells in the apical areas and root canal space. Our preliminary results indicate that a rat model can be used to study revascularization and that cells of bone marrow origin participate in revascularization.

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JOE — Volume 35, Number 3, March 2009

OR 06 

Effects of Mineral Trioxide Aggregate on the Dental Pulp After Pulp Capping Procedures A. Paranjpe*, H. Zhang, M. Somerman, J.D. Johnson University of Washington, Seattle, WA Pulp capping techniques aim at preserving the vitality of pulp tissue, thus avoiding more invasive endodontic procedures. MTA (mineral trioxide aggregate) has been introduced as a potentially alternative dressing material that promotes the healing of pulp thus maintaining integrity and vitality of the pulp after pulp capping without having any cytotoxic effects. MTA has shown good results when used as a repair material in endodontics, for inducing bone, dentin, and cementum deposition. However, the exact mechanism by which MTA protects the pulp after pulp capping procedures is still not delineated. Therefore, it is hypothesized that the application of MTA to the pulp in pulp capping procedures may result in increased activation of the dental pulp cells which in turn protects them from cell death and leads to the formation of a dentinal bridge. The aim of this research is to delineate the mechanisms by which MTA protects the dental pulp and promotes healing. The results demonstrate that the dental pulp cells (DPCs) grown in contact with MTA secrete higher levels of VEGF (Vascular Endothelial Growth Factor), an angiogenic factor necessary for cell survival and function. MTA also upregulated the expression of key differentiation genes like ALP (Alkaline Phosphatase), OPN (Osteopontin) and OCN (Osteocalcin). Additionally MTA promotes increased proliferation of the pulp cells which contributes to the effectiveness of MTA. Overall, this study demonstrates the role of MTA on survival, proliferation and differentiation of DPCs which provides a safe and effective methodology for the protection of the pulpal cells after pulp capping procedures.

OR 08 

The Effect of Different Irrigation Solutions on the Survival of Stem Cells of the Apical Papilla (SCAP) in a PRP Scaffold in Human Root Tips E.G. Trevino*, M.A. Henry, A. Patwardhan, G.M. Perry, X. Sun, G. Helesic, E. Locke, K. Hargreaves University of Texas Health Science Center Dental School, San Antonio, TX Advancements in stem cell biology are leading to the development of new treatment approaches that are focused on the regeneration of human dental pulp. Stem cells from the apical papilla (SCAP) may be ideally suited for this task, yet many questions remain regarding what specific clinical protocol will allow this outcome. The aim of this study was to test the hypothesis that different root canal irrigation protocols alter stem cell survival in isolated human teeth. STRO-1 expressing SCAP were isolated from immature third molars using an immunomagnetic method, yielding >90% STRO-1 positive cells. Isolated human root tips (n=5/group) were instrumented to apical patency with a #130 LSX™ and irrigated with one of three protocols: 1) 17%EDTA, 2) 6%NaOCl+17%EDTA, and 3) 17%EDTA+2%CHX. The isolated STRO-1 stem cells were then mixed with platelet-rich-plasma (PRP), seeded into the root tips and grown for 21 days. Roots were then decalcified, sectioned, stained with the indirect immunofluorescence method with vimentin antibody and To-Pro-3 (nuclear stain) to identify viable cells, and images collected with confocal microscopy with Chi-Square test. Results showed that the Group 1 (EDTA irrigation only) protocol best supported cell survivability with 89% of cells displaying viability followed by Group 2 (74%). The 2% CHX protocol (Group 3) showed no viable cells. Irrigation with 6% NaOCl produced less cell survival than EDTA alone. The finding that irrigation protocols greatly affect stem cell survival should lead to future studies identifying an optimal irrigation treatment that permits both antimicrobial disinfection and stem cell survival.

OR 09 

An In Vitro Comparison of the Antimicrobial Effects From Mixtures of Chlorhexidine and Calcium Hydroxide as Compared to Chlorhexidine and Calcium Hydroxide Alone K. Mears*, J. Bahcall, J. Maki Marquette University, Milwaukee, WI

OR 10 

Evaluation of the Effectiveness of an Antimicrobial Decapeptide Versus Enterococcus Faecalis in Bovine (Bos taurus) Root Dentins L. Norby*1, J. McPherson1, A. Chuang1, S. Sidow1, K. McNally1, K. Leung2 1 U.S. Army Dental Activity, Fort Gordon, GA, 2USAIDR/WRAMC, Great Lakes, IL

The purpose of this in vitro investigation is to study the antimicrobial action of mixtures of various concentrations of chlorhexidine (CHX) with calcium hydroxide (Ca(OH)2) as compared to chlorhexidine and calcium hydroxide alone. Twentyeight Petri dishes of BHI agar were inoculated with E. faecalis. Each Petri dish had six saturated paper disks placed. Five of the disks were saturated with a different test solution, and the last paper disk served as a control and was saturated with sterile distilled water. Each of seven medicaments was tested twenty times. The following medicaments were tested: CHX gel (1%, 2%, 4%); aqueous Ca(OH)2; and CHX (2%, 4%, 8%) mixed with equal parts Ca(OH)2. The plates were randomly distributed into two groups. Group one (n=14) was incubated aerobically for 48 hours at 37ºC. Group two (n=14) was incubated anaerobically for 48 hours at 37ºC. The largest diameter of the zone of microbial inhibition was measured and recorded in millimeters for the control and each experimental group. Statistical analysis was performed with ANOVA and statistical significance was determined with the Tukey test. Ca(OH)2 inhibited E. faecalis only in direct contact; there were no measured zones of inhibition. CHX alone and CHX/Ca(OH)2 mixed inhibited significantly more E. faecalis than Ca(OH)2 alone (p<0.05). CHX alone for all concentrations inhibited significantly more E. faecalis than the mixtures of Ca(OH)2/CHX (p<0.05). The control showed no microbial inhibition.

The occurrence of a persistent root canal infection is a common clinical problem in endodontics. The presence of pathogenic bacteria in situ is essential for the development of periradicular disease, and bacterial infection is the major causative factor associated with endodontic treatment failure. KSL-W is a broad spectrum, positively charged, antimicrobial decapeptide with proven antifungal properties and is an effective antimicrobial agent against several oral bacteria. The purpose was to determine the susceptibility of intracanal E. faecalis to KSL-W in vitro. Twenty-four 5mm dentin disks were sectioned mid-root from extracted bovine incisors. The lumens were enlarged to 2.5mm, soaked and sonicated in 17% EDTA for 5 minutes followed by 6% NaOCl. Individual disks were secured with wax in two 12-well tissue culture plates then inoculated with E. faecalis (2.5x106 cfu in 25 μl) for 72 hrs. The dentin disks were rinsed with sterile saline to remove residual bacteria followed by enlarging the lumens with a 2.9mm bur to remove the biofilm. The disks were then subjected to KSL-W at concentrations of 100, 50, 25 and 12.5 μg/ml for 30 minutes. The disks were frozen, weighed, pulverized and suspended in 5mL PBS. Serial dilutions were plated on agar plates in triplicate and incubated at 37°C for 24 hours. KSL-W showed significant dose dependant reductions in E. faecalis counts compared to positive controls. There was no bacterial growth in the negative controls. These results suggest that KSL-W may be an effective irrigant in reducing E. faecalis from dentinal tubules.

OR 11 

OR 12 

The Antimicrobial Activity of Propolis Against Enterococcus Faecalis Biofilm at the Pulpal Dentinal Interface S. Markham*, C. Varella, C. Walker, L. Shaddox, R. Pileggi University of Florida, Gainesville, FL Enterococcus Faecalis is known as the main microorganism associated with failing root canal therapy. Therefore, the purpose of this study was to test propolis, a resinous hive product utilized in medicine as an anti-inflammatory and anti-microbial agent, as a potential anti-microbial agent against E. faecalis. Fifty-five single-rooted premolars were accessed and instrumented to a MAF 40. The smear layer was removed with 17% EDTA followed by 1.0 ml of 6.15% NaOCl and then saline. Roots were and 10ul of pure culture of E. faecalis was inoculated into each specimens and kept in a CO2 chamber for biofilm growth. Roots were then randomly assigned to each of the following intracanal medicaments: Propolis (20 roots), Calcium Hydroxide (Ca(OH)2=20 roots), Control (no medicament, 10 roots). Two roots were left with no biofilm and no treatment to check for bacterial contamination (negative control). Following treatment, samples were left in CO2 chamber for 7 days. At day 7, a larger file size #50 was rotated in the canal for biofilm detection at the dentinal-pulp layer interface. The dentinal layer was sonicated from the file in ringer’s for Colony Forming Units (CFU) counts, assessment of live/dead proportions by fluorescent assay and quantification of cells by optical density. Data were analyzed with a one-way ANOVA and post-hoc test. Propolis group showed a significant reduction in CFUs when compared to both Control and Ca(OH)2 groups (p<0.05). Negative control roots showed no growth. Propolis is an effective antimicrobial medicament against E. faecalis at the pulp-dentinal interface.

Key:

 denotes Resident

* denotes Presenter(s)

The Effect of Propolis as an Intracanal Medicament J. DeJongh*, C. Varella, C. Walker, L. Shaddox, R. Pileggi University of Florida, Gainesville, FL The most used and accepted intracanal medicament is calcium hydroxide. However, studies have questioned its effectiveness. The purpose of this study was to evaluate the effect of Propolis as an intracanal medicament against Enterococcus faecalis. Fifty-five single-rooted premolars were instrumented to a MAF 40/0.04. Smear layer was removed with 17% EDTA, followed by 1.0 ml of 6.15% NaOCl. Saline was used as a final rinse to remove residual NaOCl. Roots were sterilized and ten microliters of pure culture of E. faecalis was inoculated into each canals and kept in a CO2 chamber for biofilm growth. Roots were then randomly assigned to one of three intracanal medicaments: Propolis (20 roots), Calcium Hydroxide (20 roots), or Control (no medicament, 10 roots). Two roots were left with no biofilm and no treatment to check for bacterial contamination (negative control). Following treatment, samples were left in the CO2 chamber. At day 5, roots were split in half, and sonicated in ringer’s solution for bacterial counts (CFU), assessment of live/ dead proportions by fluorescent assay and quantification of cells by optical density. Two roots from each group were also evaluated by SEM. The results were analyzed with a one-way ANOVA and post-hoc test. Propolis group showed a significant reduction in CFUs when compared to both Control (p=0.01) and Ca(OH)2 groups (p=0.025). Both experimental groups showed reduced live/dead ratios and OD values when compared to the positive control (p<0.01 against Propolis and p<0.05 against Ca(OH)2). Propolis demonstrated very effective in reducing E faecalis biofilm.

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OR 13 

In Vivo Evaluation of the Antibacterial Efficacy of Ultrasonically Activated Chlorhexidine After Hand/Rotary Instrumentation in Human Mandibular Molars Z. Imperial*, J. Nusstein, M. Drum, A. Reader, M. Beck Ohio State University, Columbus, OH The purpose of this repeated-measures study was to evaluate the in vivo antibacterial efficacy of a hand/rotary/ultrasound technique in mesial root canals of necrotic mandibular molars utilizing 6.0% NaOCl and 2.0% chlorhexidine (CHX). The study group consisted of 35 mesial roots prepared with a hand/rotary technique followed by 1 minute of ultrasonic irrigation, per canal, utilizing an ultrasonic needle in a MiniEndo™ unit and 15 ml/min of 6.0% sodium hypochlorite followed by 30 seconds of ultrasonic irrigation using 2.0% CHX. Canals were sampled prior to instrumentation (S1), after hand/rotary instrumentation (S2), after 1 minute of NaOCl ultrasonic irrigation (S3) and after 30 seconds of CHX ultrasonic irrigation (S4). Samples were incubated anaerobically on reduced blood agar for 7 days at 37°C. Bacteria from each sample were then quantified and analyzed using nonparametric statistics. All pre-treatment samples were positive for growth. Reduction in median CFU counts occurred at each sampling (S1=3.4x105, S2=120, S3=40, S4=0). A reduction in the number of positive cultures was also identified (S1=35, S2=22, S3=18, S4=13). Analysis with the multiple Wilcoxon matched-pairs, signed ranks test showed significant reductions in CFU counts from S1 to S2, S3 and S4 (p=0.0005) A tendency toward significant reduction in CFU counts was seen from S2 to S3 (p=0.0892) and S3 to S4 (p=0.0664). In conclusion, the addition of 1 minute of ultrasonic irrigation with NaOCl and 30 seconds with CHX after hand/rotary instrumentation reduced median bacterial CFU counts and the number of positive bacterial cultures in the mesial roots of mandibular molars.

OR 15 

An Analysis of the Role of Coronal Restoration on Tooth Survival Following Nonsurgical Root Canal Therapy K. Roundy*, D. Pflum, M. Childers, J. Scheetz, J. Morelli, R. Caicedo, S. Clark University of Louisville, KY The purpose of this study was to evaluate the survival of teeth in relation to coronal restoration following non-surgical root canal therapy (NSRCT). Data were obtained from the Delta Dental of Kentucky database for 1) all patients who had initial NSRCT in 2002 or 2003 and 2) were continuously insured until 31 December 2007. 28,509 teeth had NSRCT performed by both endodontists and general dentists. 92.9% of all teeth with NSRCT (n=26,492) survived after a minimum of four years. Survival compared by tooth type ranged from a low of 92.4% for both maxillary premolars and mandibular molars to a high of 94.4% for maxillary anterior teeth. 45.4% of teeth (n=12932) had crowns placed following NSRCT. Using odds ratio of two binomial proportions, teeth with crowns placed after NSRCT survived at a statistically higher rate (96.2%, n=12443) than teeth that did not have crowns placed following NSRCT (90.2%, n=14049) (OR=0.36, CI [0.32, 0.40]). Teeth crowned after a core buildup (CB) had a survival rate of 96.7% (n=3787) compared to a rate of 96.1% (n=7773) for teeth crowned without a CB. The difference was not significantly different [OR=0.86, CI (0.70, 1.07)]. Teeth crowned without a post/core (PC) survived at a significantly greater rate, 96.7% (n=8193), than those crowned after placement of a prefabricated PC, 95.3% (n=2452) (OR=1.45, CI [1.16, 1.82]). The results of this study further demonstrate that placement of a crown following NSRCT significantly increases tooth retention.

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OR 14 

Short-Term Clinical Evaluation of the NobelReplace® Tapered Groovy Implant M. Pouresmail*, L.K. Bakland, R. Handysides, J.Y.K. Kan, J.S. Kim, J. Lozada Loma Linda University, CA The purpose of this clinical investigation was to make comparisons and to achieve estimates of the short-term implant success, marginal bone resorption, and soft tissue responses around the immediately loaded NobelReplace® Tapered groovy (with groove on rough collar portion) implant as compared to an implant without a groove on the collar (Replace® Select Tapered). This was a randomized controlled and prospective investigation in which subjects were consecutively included according to strict inclusion/exclusion criteria. Single stage procedures were used with immediate function. Seventeen subjects were recruited and randomly divided in two groups. Each group received the predetermined type of dental implant. The implants were provisionalized immediately after surgical placement. After subsequently placing the final restoration, the subjects were followed for 1 year. Drop-outs and withdrawals, as well as possible adverse events, were carefully monitored during the entire investigation period. The change in the level of distal papillae was significantly different between two groups (p=0.027), in favor of Replace® Select Tapered group. Statistical analysis showed no significant difference between the two groups in regards to other examined aspects. Supported in part by Nobel Biocare™, Yorba Linda, CA.

OR 16 

Outcome Study of Gutta-Percha and ResilonTM Filled Root Canals: A Radiographic and Clinical Analysis A. Tehrany*1, E.M. Rivera1, F.B. Teixeira2, D.J. Caplan3 1 University of North Carolina, Chapel Hill, NC, 2University of Texas Health Science Center Dental School, San Antonio, TX, 3University of Iowa, Iowa City, IA The purpose of this study was to evaluate the clinical and radiographic outcome of teeth diagnosed as having Necrotic Pulp with Chronic Apical Periodontitis when root canal treated and filled with either gutta-percha or ResilonTM. It was hypothesized that endodontically treated teeth filled with gutta-percha or ResilonTM would have similar clinical and radiographic outcomes of success. Patients received standardized endodontic treatment by undergraduate dental students in a university setting; 61 teeth were recalled after a minimum of 12 months. A clinical assessment based on symptoms and diagnostic tests and a radiographic assessment comparing pre-operative and follow-up radiographs using the Periapical Index were performed blindly. The teeth were classified as healed, healing or not healed. Patients presenting with complaints of pain, the presence of swelling and/or sinus tract, sensitivity to percussion and/or palpation, attachment loss greater than 5mm, tooth mobility greater than +1 and/or a periapical radiolucency on the radiograph that was equal to or larger than the initial pre-operative image were classified as not healed. Patients who presented with none of the above and a decreased size of the periapical radiolucency were classified as healing and those with complete resolution of the periapical radiolucency were classified as healed. Initial findings indicate that endodontically treated teeth filled with ResilonTM have similar clinical and radiographic outcomes of success as those with filled gutta-percha. An additional finding indicated that teeth classified as not healed showed a tendency to be attributed to delay and/or lack of a permanent coronal restoration following root canal therapy.

OR 17 

The Effectiveness of Case Difficulty Assessment When Determining Endodontic Referral M.C. Curry*1, E.M. Rivera1, F. Teixeira2, D.J. Caplan3 1 University of North Carolina, Chapel Hill, NC, 2University of Texas Health Science Center Dental School, San Antonio, TX, 3University of Iowa, Iowa City, IA The purpose of this study was to address the effectiveness of the American Association of Endodontists (AAE) Case Difficulty Assessment Form to determine whether a dentist would treat or refer an endodontic case. Specifically, our aims were to: a. determine if the practicing dentists utilized the AAE Case Difficulty Assessment Form to rate the difficulty of each case, and b. provide the perceived importance of the conditions present on the AAE Case Difficulty Assessment Form. The null hypotheses were that there was no difference in the percentage of dentists who utilized the AAE Case Difficulty Assessment Form and those who did not utilize the form, and no difference between the number of conditions perceived to be important and the number of conditions perceived not to be important. A confidential, self-administered electronic survey was emailed to 30,000 dentists practicing in the USA and completed via a secure website. Each dentist was questioned on his/her field of dentistry, endodontic referral trends, usage of the AAE Case Assessment Difficulty Form, and perceived importance of certain conditions when determining if a case should be referred to the endodontic specialist. Statistical analysis was performed using a ratio estimate as a part of a survey data statistical package from StataCorp (College Station, TX). Preliminary results revealed that the majority of dentists did not utilize the form, and a difficult diagnosis, extreme curvature, and previous access with complications had high importance to the practicing dentists when deciding to treat or refer.

OR 18 

Prospective Study of the Outcome of Apical Surgery: The Toronto Study: Phases III-V C. Barone*, T.T. Dao, B.R. Basrani, N. Wang, S. Friedman University of Toronto, ON, Canada This prospective study assessed the 5-10 year outcome of apical surgery performed by graduate endodontics students during Phases 3-5 (1998-2003) of the “Toronto Study.” In total, 106 teeth were treated. With 45 teeth lost to follow-up (33 discontinuers, 12 dropouts) and 21 teeth extracted, 40 teeth were assessed for outcome by an independent examiner calibrated with the Periapical Index (PAI). Outcome was dichotomized as: “healed” (PAI score ≤2, absence of signs and symptoms) or “diseased” (PAI score ≥3, or presence of signs or symptoms). The Phases 3-5 sample was analyzed alone and pooled with Phases 1 and 2 (19931997), for a total of 134 teeth. The healed rate for the pooled Phases 1-5 was 74%. Bivariate analyses (Chi-square and Fisher’s Exact tests, p ≤0.05) of the pooled sample revealed significant healed rate differences associated with age (> 45 years - 84%; ≤ 45 years - 68%), preoperative root-filling length (inadequate - 84%; adequate - 68%), and intraoperative crypt size (≤ 10 mm - 80%; > 10 mm - 53%). Logistic regression analysis of the pooled sample revealed an increased risk of persistent disease associated with: subject age below 46 years (OR = 2.5; CI 1.016.00), adequate root-filling length (OR = 3.4; CI 1.34-8.76), and crypt size over 10 mm (OR = 1.9; CI 1.19-3.16). This prospective 5-10 year study reiterated the pre-operative root-filling length, identified in Phases 1-2, and suggested patient age and bony crypt size as outcome predictors of apical surgery.

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A number of studies have shown the superiority of articaine over lidocaine for buccal infiltration of the mandibular first molar. Whether articaine would provide effective supplemental infiltration anesthesia in patients with irreversible pulpitis has not been adequately studied. The purpose of this prospective study was to determine the anesthetic efficacy of the supplemental buccal infiltration injection of 4% articaine with 1:100,000 epinephrine in mandibular posterior teeth diagnosed with irreversible pulpitis. Fifty-five emergency patients, diagnosed with irreversible pulpitis of a mandibular posterior tooth, received an inferior alveolar nerve block and had anesthetic failure (moderate to severe pain) when endodontic access or initial instrumentation was performed. A buccal infiltration of 1.8 mL of 4% articaine with 1:100,000 epinephrine was administered next to the offending tooth. Patients were asked to rate their pain or no pain on a Heft-Parker visual analogue scale during endodontic access or initial instrumentation. Success was defined as none or mild pain upon endodontic access or instrumentation. The results of this study demonstrated that the infiltration injections were successful with a confidence interval of 95% for the following teeth: 1st molar - 58% (Lower Confidence Boundary 27 - Upper Confidence Boundary 69), 2nd molar - 48% (Lower Confidence Boundary 37- Upper Confidence Boundary 77). In conclusion, for molar teeth diagnosed with irreversible pulpitis, the supplemental buccal infiltration of 4% articaine with 1:100,000 epinephrine was 48% to 58% successful when the inferior alveolar nerve block failed.

Catechol-O-methyltransferase (COMT), an enzyme that metabolizes catecholamines, has been implicated in the modulation of pain. Previous studies have shown that human genetic variants coding for low COMT activity are correlated with increased experimental pain sensitivity and risk of developing persistent musculoskeletal pain conditions such as temporomandibular joint disorder. The present study extends this work by examining the potential contribution of COMT to acute endodontic pain perception. Eighty-five patients treated by endodontic residents at University of North Carolina School of Dentistry were enrolled into a prospective cohort study. Endodontic treatment was performed as indicated by their treatment plan. Participants recorded pain levels for five days following treatment and completed psychological questionnaires to quantify anxiety, depression and somatization disorders. Potential predictors of post-operative pain including patient age, gender, tooth type, pulpal and periapical diagnosis, and pretreatment pain intensity were collected. Additionally, all patients submitted saliva samples for genetic analysis. In this study, 65% of patients experienced at least mild pain after root canal therapy, and 50% reported using ibuprofen for pain control. Reported post-operative pain levels were analyzed for correlation with haplotype. While genetic analyses are ongoing, we hypothesize that an association exists between genetic variants of COMT and acute post-operative pain following endodontic treatment. An understanding to the genetic basis of endodontic pain perception will advance our pharmacologic management of post-operative pain.

Articaine for Supplemental Buccal Anesthesia in Patients With Irreversible Pulpitis R. Matthews*, M. Drum, A. Reader, J. Nusstein, M. Beck Ohio State University, Columbus, OH

Key:

 denotes Resident

* denotes Presenter(s)

Genetic Basis for Individual Variation in Pain Perception Among Endodontic Patients E.A. Applebaum*, J. Lambert, A.G. Nackley, E. Bair, L. Diatchenko, W. Maixner University of North Carolina, Chapel Hill, NC

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The purpose of this prospective, randomized, double-blind, placebo-controlled study was to evaluate the effect of 2 mg of morphine on postoperative pain in patients with symptomatic, necrotic teeth. Fifty-five adult patients presenting for emergency endodontic treatment with a maxillary or mandibular symptomatic necrotic tooth with a radiolucent area and moderate to severe pain participated in this study. The patients were randomly divided into two groups blinded to both the doctor and patient by random assignment and numerical coding. An emergency debridement of the tooth was completed with hand and rotary instrumentation. At the end of the appointment, the patients were injected with either 0.2 mL saline or 0.2 mL (2 mg) morphine via submucosal infiltration adjacent to the tooth being treated. Patients were given ibuprofen and Tylenol #3 for postoperative pain. Each subject received a 7-day diary to be completed the day of the appointment and every morning for six days. Subjects were asked to record pain and symptoms and the type and number of pain medications taken. There were no preoperative differences between the groups for age, gender, or jaw as determined by the randomization and Fisher’s exact tests (p>0.05). Postoperative data was analyzed by a factorial ANOVA. There were average decreases in pain levels and analgesic usage over time for both the placebo and morphine groups but this study did not provide evidence that morphine reduced postoperative pain in symptomatic, necrotic teeth when compared to the placebo.

A number of studies have shown the superiority of articaine over lidocaine for a primary buccal infiltration of the mandibular first molar. However, the duration of profound pulpal anesthesia with articaine decreases significantly around 25 minutes. The purpose of this prospective, randomized, singleblinded study was to determine the anesthetic efficacy of a repeated buccal infiltration of articaine given 25 minutes following a primary articaine infiltration in the mandibular first molar. Using a cross-over design, 86 adult subjects randomly received two sets of injections consisting of a primary buccal infiltration injection of 1.8 mL of 4% articaine (1:100,000 epinephrine) plus a repeated buccal infiltration injection 25 minutes later using either 1.8 mL of 4% articaine (1:100,000 epinephrine) or a mock infiltration injection, in two separate appointments spaced at least one week apart. The first molar was tested with an electric pulp tester every 3 minutes for 120 minutes. The initial success (two consecutive 80 readings with the pulp tester) was 69% and 64% for both buccal infiltrations. The repeated infiltration increased success to 80% and significantly (p<.05) increased the duration of pulpal anesthesia over the primary infiltration, as analyzed by Multiple-Exact McNemar tests. In conclusion, for the first molar, the repeated buccal, mandibular infiltration increased success and the duration of pulpal anesthesia.

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We examined pre-operative levels of anxiety to determine if they could be used as predictors of successful pulpal anesthesia during endodontic treatment. Pre-operative anxiety was measured using an anxiety virtual analog scale (AVAS). Successful pulpal anesthesia was defined as the absence of pain during removal of the pulp. The null hypothesis was that pre-operative anxiety level has no relationship to the success/failure of local anesthesia during endodontic treatment. Fifty patients were recruited for the study. Data regarding AVAS, tooth location, and number of injections [1-3] were obtained from each patient. Mean AVAS for the nopain group was 23.9, mean AVAS for the pain group was 39.9. The Mann-WhitneyWilcoxon [MWW] test revealed that ranked AVAS scores were significantly higher in the pain group [two-sided test; p < 0.03]. We also examined whether AVAS scores were related to tooth location. The MWW test revealed no statistically significant differences relating to tooth location. Finally, using ANOVA of ranks, we examined whether the number of injections were related to the AVAS score. Results show a statistically significant relationship between AVAS score and number of injections to eliminate pain [R² = 0.28; F = 9.03; p < 0.0005]. Therefore, we conclude that higher AVAS scores are correlated with a greater number of injections needed to eliminate pain, and that the higher the AVAS score, the less likely it is that pain will be eliminated during endodontic treatment.

Gram-negative bacteria are the predominant class of bacteria found in most chronic infections of root canal systems. Lipopolyssacharide (LPS) is an integral part of the cell wall of these bacteria and, after release, trigger host cells responses by activating its receptor, TLR4. This study evaluated the hypothesis that neuronal sensitization is produced by LPS binding to neuronal TLR4 via stimulation of the protein kinase C (PKC) signaling pathway. Primary cultures of trigeminal neurons from adult rats were used, and capsaicin was used to selectively activate the TRPV1-containing class of nociceptors. In the first experimental approach, we evaluated the sensitization of trigeminal nociceptors evoked by LPS as measured by inward currents using patch clamp electrophysiology. Next, we evaluated the effect of a TLR4 antagonist or a PKC inhibitor on the LPS sensitization of nociceptors as measured by the accumulation of i[Ca2+] using Fura-2 calcium imaging system. Data were analyzed with ANOVA/Bonferroni test. We found that LPS at concentrations ranging from 0.02-20μg/ml sensitized TRPV1 responses. LPS effects were selectively blocked by a TLR4 antagonist or a specific PKC inhibitor. Collectively, these data demonstrate that LPS in concentrations observed clinically in odontogenic infections, directly sensitizes TRPV1 responses in trigeminal nociceptors. Further, we demonstrated that this effect can be blocked at both the TLR4 receptor level and downstream intracellular signaling pathways. This novel finding has significant clinical and scientific implications since it represents the first report of a direct neuronal-microorganism communication with the potential to play a role in pain associated with odontogenic infections.

The Effects of Morphine on Postoperative Pain in Symptomatic, Necrotic Teeth A. Chandler*, M. Drum, A. Reader, J. Nusstein, M. Beck Ohio State University, Columbus, OH

Pre-operative Levels of Anxiety as a Predictor of Successful Local Anesthesia During Endodontic Treatment J.F. DiBernardo*, G. Fisch, P.A. Rosenberg New York University, NY

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Efficacy of Articaine for a Repeated Infiltration Following a Primary Infiltration L. Pabst*, J. Nusstein, M. Drum, A. Reader, M. Beck Ohio State University, Columbus, OH

A Mechanism for Abscess-Related Pain: How Bacteria Directly Sensitize Trigeminal Nociceptors A. Diogenes*, A.N. Akopian, M.A. Henry, G.M. Perry, K.M. Hargreaves University of Texas Health Science Center Dental School, San Antonio, TX

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Assessment of the Quality and the Learning Process of Different Root-Filling Techniques Performed by Novice Dental Students: MicroComputed Tomography Analysis M. Mirfendereski*1, K. Roth1, B. Fan2, A. Dubrowski1, H. Carnahan1, A. Azarpazhooh1, B. Basrani1, S. Friedman1 1 University of Toronto, ON, Canada, 2Wuhan University, China The limited endodontic experiences available in dental schools suggest the need for easy-to-learn techniques. Accordingly, two root-filling techniques were assessed for the volume of voids in fillings and for expediency, when performed by novice dental students. Two experienced operators uniformly shaped the root canals in acrylic tooth models and extracted single-rooted teeth with straight roots. Eight dental student volunteers with only pre-clinical endodontic experience attended structured didactic (45 min) and hands-on (90 min) sessions on root-filling with each of ProTaper® obturators (PTO) and System-B and Calamus™ backfill (SBC). After practice in 2 acrylic and 3 extracted teeth per technique, each student filled 2 extracted teeth per technique (N=32 teeth) in a random sequence, using pre-fitted obturators and master cones. Time to complete root-fillings was recorded, and students answered questionnaires on their experience with both techniques. Specimens were imaged with Skyscan 1172 μCT at 7 μm resolution to measure the void and total root-filling volumes in 1 mm increments. Data was analyzed using two-tailed, independent-sample T-test and Mann-Whitney U-test. The void volume in the apical 5mm of canals was significantly smaller (p<0.001) in the PTO group (0.001±0.002 mm3) than in the SBC group (0.019±0.048 mm3). The root-filling volume did not differ significantly between the groups. PTO required significantly (p<0.001) less time (1.63±0.619 min) than SBC (5.75±1.483 min), and the students rated PTO as less technique-sensitive. These results suggested that when used by novice dental students, the PTO technique resulted in more adequate root-fillings and was more expeditious than the SBC technique.

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Cyclic Fatigue Resistance of two Variable-Taper Rotary File Systems: ProTaper® and V-Taper™ S.J. Whipple*, T.C. Kirkpatrick, R.E. Rutledge Wilford Hall U.S.A.F. Medical Center, Lackland Air Force Base, TX The purpose of this study was to compare the cyclic fatigue resistance of ProTaper® and V-Taper™ files in a dynamic model. Seven file sizes in the ProTaper® system (S1, S2, F1, F2, F3, F4, F5), and six file sizes in the V-Taper™ system (15 V04, 20 V06, 25 V08, 30 V10, 35 V06, 40 V06) were tested (n=15 each; 195 total files). The files were rotated at 250 rpm with a continuous axial oscillation of 4 mm at 1 Hz along a 5mm radius curve resulting in 90° of maximum flexure. The number of cycles to failure was calculated and analyzed using univariate Analysis of Variance and the Tukey HSD post-hoc tests with results confirmed by nonparametric Kruskal-Wallis and Mann-Whitney U tests with a Bonferroni correction. The fracture faces of representative files were imaged with SEM to confirm cyclic fatigue as the mode of fracture. For the instruments tested, the ProTaper® files appeared to resist fracture better than the V-Taper™ files. At each tip size tested, the ProTaper® files either outperformed or were not statistically different than V-Taper™ files.

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Comparing Cyclic Fatigue of the new GT® Series X™ Files to the Original ProFile® GT® Rotary Instruments S. Osmond*, K.J. Replogle, A.M. Best Virginia Commonwealth University, Richmond, VA

Comparing Cyclic Fatigue of the New GT® Series X™ Files to the EndoSequence™ Brasseler Rotary Instruments N.S. Wayment*, K.J. Replogle, A.M. Best Virginia Commonwealth University, Richmond, VA

The purpose of this study was to test the number of rotations to fracture of the M-wire GT® Series X™ rotary files compared to the original ProFile® GT® rotary files in a simulated curve canal. Eighty GT® Series X™ files of 25mm length were divided into eight groups of 10, one for each of the new GT® Series XTM files. Eighty original ProFile® GT® files of 25mm length were divided into eight groups of the same tip and taper sizes consistent to the GT® Series X™ file groups. Files were rotated at 300 rpm. While the angle may have slightly changed due the flexure property of the file the angle was the same for each file of the same tip and taper. The time to fracture was recorded and rotations to fracture were calculated. The data collected was analyzed using a two-way ANOVA, followed by specific post-hoc contrasts comparing the two brands for each Tip/Taper combination. The results show the M-wire GT® Series X™ files were statistically significant to resistance of fracture by cyclic fatigue than the ProFile® GT® rotary instruments for the following tip and taper sizes: 20/.04, 30/.04, 30/.06, 30/.08, and 40/.08. The following tip and taper sizes: 20/.06, 40/.04, and 40/.06 were not statistically significant.

The purpose of this study was to examine the number of rotations to failure of two different rotary file systems, the EndoSequence™ Brasseler USA (Savannah, GA) and the GT® series X™. GT series X™ files (tip size 20, 30, & 40, taper 0.04 and 0.06 at 25 mm length) were compared to EndoSequence™ files (tip size 20, 30, & 40, taper 0.04 and 0.06 at 25 mm length). Like tips and tapers were compared between systems. Files were allocated into 12 groups of 10 files each. Files were mounted to an Instron universal testing machine at 70 degrees and rotated at 300 rpm until fracture occurred. The number of rotations to fracture was calculated. A two-way ANOVA proved that each of the 12 groups were significantly different (p < .0001). Analysis of the brand tip/taper interaction indicated that the differences between the brands varied by tip/taper combination (p < .0001). For all tip/taper combinations except the 40/0.04, the GT series X™ files demonstrated significantly higher rotations to failure than the EndoSequence™. The results suggested that the number of rotations to failure for GT series X™ files were greater than the EndoSequence™ file of the same tip and taper combination.

Key:

 denotes Resident

* denotes Presenter(s)

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Evaluation of Dislocation Resistance of Three Resin-Based Root Canal Sealers B.R. Babb*, R.J. Loushine, S. Roberts, R.N. Weller, F.R. Tay Medical College of Georgia, Augusta, GA New root canal sealers have been introduced that claim the ability to bond to radicular dentin. The purpose of this project was to examine the dislocation resistance of three root canal sealers from radicular dentin using a push-out test design that produced simulated canal spaces of uniform dimensions under identical cleaning and shaping conditions. Standardized simulated canal spaces were created using 0.04 taper Profile instruments along the coronal, middle and apical thirds of longitudinal tooth slabs. Following NaOCl/EDTA cleaning, the cavities were filled with RealSeal SE™, MetaSEAL™, or EndoREZ™. After setting, the cavities were tested with a fiber-optic illuminated push-out testing device. Failure modes were examined with stereomicroscopy, and the junctions between the sealer and radicular dentin were examined under TEM. Two-way ANOVA (Tukey Test) was used to determine whether differences in both sealer strength and dentin location were significant. The mean push-out strengths were 17.6, 14.0, and 8.5 MPa for MetaSEAL™, RealSeal SE™, and EndoREZ™, respectively. Differences among these strengths were statistically significant (p<0.05). When testing for differences among coronal, middle, and apical thirds of dentin, there were no statistically significant differences among the push-out strengths. Failure modes were mostly adhesive for both EndoREZ™ and RealSeal SE™, while MetaSEAL™ showed mostly mixed adhesive/cohesive failures. TEMs for all three sealers show a resin-infiltrated layer of demineralization at the dentin/sealer interface. In conclusion, these resinbased sealers show varying abilities to resist dislocation during push-out testing. MetaSEAL™ shows the greatest resistance, followed by RealSeal SE™ and EndoREZ™.

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Comparison of the Efficiency of Ultrasonic Tips to Remove Dentin Over Time C. Yelton*, K. Lawlor, J.C. Kulild, M.P. Walker University of Missouri at Kansas City, MO Locating root canal systems can be an endodontic challenge. Ultrasonics (US) are adjunctive instruments used in endodontics that can be used to uncover root canal system orifices. The purpose of this in vitro experiment was to compare the efficiency of four commonly used US tips to remove dentin from sectioned third molars. The four groups are as follows: ET-18D™ (Acteon Group), BUC-1™ (Obtura Spartan), TUFI-2™ (San Diego Swiss Machining Inc.), and P5™ (Plastic Endo). Five tips from each group were used in the P5 Newtron XS™ (Acteon Group) US unit. The US handpiece was mounted to the loading arm of a universal testing machine and a downward force of 15g was applied in cycles of 20 seconds for a total of 4 minutes of instrumentation time. The downward force was previously determined in a pilot study. Efficiency was measured by the change in the weight of the mounted third molar measured to the nearest 0.0001g after 2 and 4 minutes of instrumentation. A 2-factor ANOVA and Tukey’s post hoc (α= 0.05) indicated there was no significant difference in dentin removal between measurement times for any tip. In contrast, there was significant difference in dentin removal as a function of tip type (p = 0.0001) with the BUC-1™ tip removing significantly more dentin across time. Based on the results, the BUC-1™ tip removes dentin more efficiently than the other tips tested in this investigation. Future studies would be required to confirm whether this higher efficiency is maintained over longer instrumentation time.

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Contemporary Methacrylate Resin-Based Root Canal Sealers Exhibit Different Degrees of In Vitro Cytotoxicity When Cured in Their SelfCured Mode J.M. Ames*, R.J. Loushine, S. Roberts, R.N. Weller, F.R. Tay Medical College of Georgia, Augusta, GA Biocompatibility remains one of the main factors that influence the choice of sealers in root canal treatment. Obturation materials are generally designed to be contained within the canal confines, but sealers may be expressed into the periradicular tissues. The extrusion of foreign materials can result in tissue irritation and delayed healing. The purpose of this study was to evaluate the cytotoxicity of four methacrylate resin-based sealers (EndoREZ™, RealSeal™, MetaSEAL™ and RealSeal SE™) using cell mitochondrial function by estimating succinate dehydrogenase (SDH) activity using the MTT (3-(4,5-dimethylthiazoyl)-2,5-diphenyl-SH-tetrazolium bromide) assay. The sealers were polymerized in the self-cured mode to simulate the setting condition upon their extrusion into periradicular tissues. The four sealers served as individual experimental groups (1-4). Teflon and Pulp Canal Sealer™ (SybronEndo) were used as the respective negative and positive controls. After setting completely at 24 h, five-mm diameter disks prepared from the respective sealers and controls were placed in direct contact with ROS 17/2.8 cells and continuing for five succeeding weeks after the disks were immersed in simulated body fluid (SBF). The negative control showed active mitochondrial activity initially and throughout all 5 cycles. Based on the MTT assay all experimental sealers exhibited severe toxicity initially. EndoREZ™, RealSEAL™ and the positive control remained severely toxic after 5 cycles of SBF immersion. Conversely, the toxicity of the two self-etching resin-based sealers MetaSEAL™ and RealSeal SE™ decreased gradually over time. Transmission electron microscopy of cells exposed to RealSeal SE™ after different cycles of SBF immersion demonstrated variable degrees of cell injury.

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Dentin Removal Efficiency of the BUC-1™ Ultrasonic Tip Over Time K.L. Lawlor*, C. Yelton, J.C. Kulild, M.P. Walker University of Missouri at Kansas City, MO The BUC-1™ ultrasonic (US) tip (Obtura-Spartan) is often used during endodontic treatment to remove dentin in search of canal orifices. Limited data exists on the wear pattern of the BUC-1™ tip over multiple uses and whether this wear decreases the efficiency of dentin removal. The purpose of this in vitro study was to determine the loss of efficiency in dentin removal of the BUC-1™ tip (N=5) over time in dentin blocks. A Satelec P5 Newtron XS™ US unit (Acteon Group) was used throughout the experiment. The US handpiece was mounted to the loading arm of a universal testing machine and a downward force of 15 g was applied in 20-second cycles for a total of 30 min of instrumentation. The downward force was previously determined in a pilot study. Efficiency was measured by the change in weight of the dentin block to the nearest 0.0001 g after 2, 10, 20 and 30 min of instrumentation. A 1-factor ANOVA (α=0.05) indicated a significant difference in dentin removal across measurement times (p=0.001). The post hoc analysis revealed that dentin removal decreased significantly between 2 and 10 min of instrumentation with no further significant decrease after 20 or 30 min. The evidence suggests there is a significant decrease in dentin removal efficiency of the BUC-1™ tip after 10 min of instrumentation. Continued instrumentation for up to 30 min showed no further decrease in efficiency. Future studies with longer testing times and additional tip types are needed.

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The Effect of Various Solvents on Endodontic Sealers J.I. Hwang*1, A.H. Chuang2, S. Sidow1, K. McNally1, J. McPherson2 1 U.S. Army Dental Activity, Fort Gordon, GA, 2Eisenhower Army Medical Center, Fort Gordon, GA

The Effect of High Altitude on Interradicular Dentin due to Spacing Between Post Placement and Gutta-Percha J.M. Michel*1, S. Sidow1, K. McNally1, R. Topolski2, J. McPherson1 1 U.S. Army Dental Activity, Fort Gordon, Fort Gordon, GA, 2Augusta State University, GA

Successful retreatment of the root canal is dependent upon the complete irradication of bacteria and complete removal of contaminated root canal material from the canal. The aim of this study is to investigate the effectiveness of various endodontic solvents in the removal of endodontic sealers (Roth’s 801™, AH Plus™, and MetaSEAL™). One-hundred sixty capillary tubes, 21 mm x 3 mm were filled with Roth’s 801™, AH Plus™, and MetaSEAL™; thermaplastized gutta-percha served as the positive control. Samples were stored at 37°C and 75% relative humidity for 14 days to allow the sealers to set. Each sample was exposed to the respective solvents: chloroform, xylene, EndoSolv R™, EndoSolv E™, and no solvent (negative control) to provide initial softening of material. Protaper D3 Universal Retreatment File™ was used to penetrate the samples. The amount of time for the rotary file to reach the length of the tube was recorded and statistically analyzed. Roth’s 801™ was not tested because it failed to set within the test period. Penetration time was 3.4, 4.8, 5.7, 4.5, and 10.6 sec for tubes filled with gutta-percha and corresponding solvents: chloroform, xylene, EndoSolv R™, EndoSolv E™, and no solvent, respectively. AH Plus™ took 56.8 to 81.5 sec. MetaSEAL™ took 97.2 to >180 sec. These results suggest: 1) EndoSolv E™ is the most effective solvent for removal of AH Plus™; 2) There is no significant difference among the solvents for removal of MetaSEAL™; 3) Significantly more time is needed to remove MetaSEAL™ than AH Plus™.

Vertical root fractures generally result in a poor prognosis for long term survivability of a tooth. Many endodontically treated teeth require placement of a post, to retain its function. This study examined the effects of high altitude on dentin adjacent to the space created between a post and gutta-percha. To test the hypothesis that air expansion due to high altitude would cause fractures, 9 experimental groups and 3 control groups were created. Fifty-three teeth were decoronated at the CEJ and instrumented with K3 rotary files. Teeth were obturated with AH-Plus® and K3 gutta-percha using continuous wave of condensation. Post space was created using the ParaPost Fiber Lux #4 drill. The #4 ParaPosts were cemented using Ketac™ Cem Aplicap™ cement. Gap spaces tested were 1mm, 2mm, and 3mm. Samples were divided into groups by the number of exposures to high altitude (40,000 feet), 0, 1, 3, and 5 times respectively. The final division of samples was broken down to gap space/number of exposures. Teeth were sectioned at the radicular surface adjacent to the gap. The samples were evaluated via SEM. Data was subjected to two-way ANOVAs, with number of exposures and gap size serving as independent variables. The interradicular surface revealed that number of cracks increased with the number of exposures (p<.001). There was no significant difference in number of cracks for gap size and number of exposures. The frequency of exposure to high altitude caused an increase in the number of cracks found on the interradicular surface.

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The first and arguably most important step in endodontic therapy is making an accurate diagnosis. One of the most relied on sensitivity tests is the application of a cold source to the tooth or restored surface and subsequent evaluation of the patient’s response. If a dental restorative material has sufficient insulating capacity, it could lead to a false negative response and ultimately an inaccurate diagnosis. The aim of this project was to determine if varying thickness of different restorative materials can insulate the conductance of cold during sensitivity testing. Three samples at thicknesses of 0.5mm, 1.0mm, 1.5mm, 2.0mm, 2.5mm, and 3.0mm for each of the following materials were fabricated: resin-based composite, bis-acrylic, polymethylmethacrylate, porcelain fused to metal, porcelain fused to zirconia, and all porcelain. Nine enamel samples were created from extracted teeth and used as positive controls. All samples were fabricated to a dimension of 7.0mm x 7.0mm. A thermocouple was placed on the internal surface of each sample and readings were recorded for maximum temperature, minimum temperature, time to minimum temperature, and minimum slope (Temperature/Time). CO2 snow and 1,1,1,2-tetrafluoroethane (TFE) were used as the cold source. The effect of thickness on change in temperature showed a statistically significant difference for both TFE and CO2 (ANOVA p<0.01). There was no statistically significant difference between types of restorative materials. None of the tested materials are efficient insulators even at a thickness of 3.0mm.

The purpose of this study was to compare the resistance to fracture by the twisting of two nickel-titanium (NiTi) rotary file systems. The Profile GT™ (GT) and the GT Series X™ (GTX) files were tested to analyze the maximum torque and angular deflection at the separation of the file. The GT and GTX files in sizes 20, 30, and 40 with 0.04, 0.06, and 0.08 taper were divided into eight groups. Files were mounted to a Maillefer Torsiometer machine, which records maximum torque and rotations to fracture by clamping each end of the file and twisting at 2 rotations per minute. A two-way ANOVA revealed significant differences after comparing the size and type of file. An increase in size and taper resulted in an increase in maximum torque and a decrease in rotations to fracture in all file groups. GT files required significantly more torque to separate than GTX files in all groups tested except the GTX file size 20/0.06, which showed significantly more maximum torque than the GT file, and there was no significant difference between the GT and GTX file size 30/0.04. GT files were significantly more resistant to angular deformation than GTX files at sizes 30/0.04 and 40/0.08. The GTX file was more resistant at size 30/0.08. There was no significant difference between the other groups. In summary, the GT files required significantly more torque to fracture and angular deflection compared to the GTX files.

The Insulating Capability of Various Restorative Dental Materials During Tooth Vitality Testing K. Kjar*, S. Sidow, K. McNally, J.C. McPherson U.S. Army Dental Activity, Fort Gordon, GA

Key:

 denotes Resident

* denotes Presenter(s)

A Comparative Analysis of Torsional Strength Between Profile GT™ and GT Series X™ Nickel-Titanium Rotary Instruments J. Reynolds*, K.J. Replogle, A.M. Best Virginia Commonwealth University, Richmond, VA

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The Effects of Electro-Magnetic Wave on Bacterial Viability and Osteoblastic Cell Proliferation T. Tominaga*, T. Sumotomo, H. Yumoto, T. Matsuo Tominaga Dental Clinic, Naruto, Japan Objectives: Disinfection within the root canal system is the important point for endodontic treatment. We reported that the electron-magnetic radiation has bactericidal effects. The aim of this work was to clarify the effects of ElectroMagnetic wave on bone as well as bacteria and provide a new concept for “Electro-Magnetic-based Endodontic therapy” which leads to the periapical tissue regeneration as non-surgical treatment. Methods: Gram-negative bacteria (F. nucleatum, P. gingivalis) and Gram-positive bacteria (S. intermedius, S. mutans, E. faecalis) were radiated by the electro-magnetic-wave apparatus at different frequencies. After radiation, the bacterial viability was determined by ATP assay and the bacterial growth was monitored by measuring OD at various time points. MC3T3-E1 cells (murine osteoblastic cell line) were also stimulated by same apparatus. After stimulation, the osteoblastic cell proliferation activity was determined. Results: By comparison with unradiation group, the high-frequency radiation completely reduced the growth of Gram-negative bacteria and significantly decreased that of Gram-positive bacteria (P<0.01). In contrast, this radiation has prominent activity to activate the osteoblastic cell proliferation (P<0.001). Conclusion: These results demonstrated that the electro-magnetic-wave radiation has clear activating effect on the osteoblastic cells as well as antibacterial effect and suggest that this radiation might be suitable for clinical application to refractory periapical periodontitis as non-surgical technique.

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New Bacterial Diversity in Primary Endodontic Infections Revealed by High-Throughput Deep Coverage Pyrosequencing Technology L. Li*1, W. Hsiao2, R. Nandakumar1, S. Barbuto3, E. Mongodin2, B. Paster3, C. Fraser-Liggett2, A. Fouad1 1 University of Maryland, Baltimore, MD, 2Institute for Genome Sciences, University of Maryland, Baltimore, MD, 3Forsyth Institute, Boston, MA Culture-independent techniques using Sanger sequencing of 16S ribosomal RNA (rRNA) genes have revealed previously unrecognized microbial diversity in the human oral cavity. In the present study, we surveyed the bacterial diversity in primary endodontic infections through 16S rRNA gene sequencing using the new Roche 454 pyrosequencing technology, and compared the results with that of Sanger sequencing approach. DNA was extracted from the teeth of seven patients with primary endodontic infections. 16S rRNA genes were amplified by PCR using universal bacterial 16S rRNA primers. The resulting PCR products were either sequenced after cloning by using the Sanger capillary technique, or sequenced directly in parallel by using the 454 pyrosequencing technique. On average, 40 vs. 28,590 sequences were obtained per specimen using Sanger or 454 sequencing, respectively, representing a 700-fold difference in depth coverage. Sequence data were then analyzed using the Ribosomal Database Project version 10.2. A total of 13 bacterial phyla and 179 known genera were identified in the 454 sequencing dataset. A comparison of the mean number of taxa per specimen revealed a 6.5-fold difference. The predominant bacterial phylotypes coincided between these 2 sequencing datasets, confirming the validity of both approaches with different depth of coverage. These results demonstrate that the bacterial communities in endodontic infections are more diverse than recently revealed by the culture-independent molecular approaches. Our study also highlighted the use of high-throughput deep coverage pyrosequencing technology as a powerful tool to unravel the true microbial composition in endodontic infections. Supported by grant DE015320-01-A1 from NIDCR.

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Porphyromonas gingivalis (P. ging) complex lipids (PGLP) have been shown to stimulate osteoclastogenesis. The present study examined the effects of PGLP on the osteoblastic differentiation and mineralization using either primary bone marrow stromal cell culture (MSC) or mouse calvarial osteoblast culture (mCOB) established from pOBCol2.3GFP transgenic mice. PGLP were extracted from P. ging ATTC strain 33277 and were shown to be free of lipid A by electrospray-MS. MSC from 8-week-old and mCOB cultures from 5-7-day-old mice were generated. Cells were exposed to vehicle, 156, 313, 625, 1250 or 2500 ng/ml PGLP at day 3 of culture. At day 7, differentiation was induced with 50 µg/ml ascorbic acid and 4 mM β-glycerophosphate. Medium was changed every 2 days until day 21. Osteoblastic differentiation and mineralization were monitored by GFP visual marker scanning, von Kossa staining and by assessing mRNA bone markers using quantitative realtime RT-PCR analysis. In the vehicle group (control), Col2.3GFP activity in mCOB was detected on day 10 and increased thereafter. Most cells within the mineralizing nodules expressed Col2.3GFP by day 21. In lipid treated groups, Col2.3GFP expression and von Kossa positive colonies were inhibited with increasing doses of PGLP such that almost complete inhibition occurred with 2500 ng/ml PGLP. RT-PCR analysis of mRNA extracted from mCOB and MSC demonstrated that PGLP treatment inhibited bone sialoprotein, alkaline phosphatase, type I collagen, osteocalcin and dentine matrix protein-1 expression. This study demonstrates that PGLP inhibit osteoblastic differentiation and mineralization and suggests that these lipids are important inhibitors of bone formation.

Porphyromonas endodontalis (P. endo) is recognized as a pathogen associated with apical periodontitis. The purpose of this study was to characterize the major lipids of P. endo (PELP), and compare their biological activities with those exhibited by P. gingivalis (P. ging) including the total lipid extract (PGLP), phosphoethanolamine dihydroceramides (PEDHC), and phosphoglycerol dihydroceramides (PGDHC). PELP and PGLP were extracted, fractionated by HPLC and analyzed by electrospray-MS. To study the effects of lipids on osteoclastogenesis, RAW 264.7 cells were stimulated with either vehicle, 3.75, 7.5 or 15 µg/ml of PELP, PGLP, PGDHC, and PEDHC. At day 5 of culture, cells were stained for TRAP and RNA was extracted and analyzed by real-time quantitative RT-PCR for osteoclast-specific markers. To study the effects of lipids on osteoblast differentiation, mouse calvarial osteoblast cultures (mCOB) were treated with vehicle or 1.25 µg/ml PELP, PGLP, PGDHC or PEDHC, and were assessed by alkaline phosphatase and von Kossa staining. P. ging synthesizes both PGDHC and PEDHC while P. endo only synthesizes PEDHC. The total lipids (PELP and PGLP) and fractions stimulated TRAP-positive multinucleated cell formation dosedependently (PGDHC>PGLP>PELP>PEDHC). Real-time RT-PCR analysis confirmed upregulation of TRAP and Cathepsin K gene expression, which was independent of NFATc1 activation. The total lipids and fractions inhibited alkaline phosphatase activity and von Kossa positive mineralization nodule formation. P. endo total lipids and PEDHC stimulate osteoclast formation and inhibit osteoblastic differentiation and mineralization. The catabolic effects of these lipids on bone remodeling may be important in the development of apical periodontitis.

Porphyromonas Gingivalis Lipids Inhibit Osteoblastic Differentiation and Transgene Col2.3GFP Expressions A.Z. AlAnezi*, Q. Zhu, Y. Wang, K. Safavi, F.C. Nichols, J. Jiang University of Connecticut, Farmington, CT

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Characterization of Structure and Biological Activity of Novel Lipids From Porphyromonas Endodontalis C.S. Mirucki*, J. Jiang, Q. Zhu, Y. Wang, K. Safavi, F.C. Nichols University of Connecticut, Farmington, CT

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Peripheral Inflammation Leads to an Upregulation in the Expression of the Beta 1 Adrenergic Receptor in Human Dental Pulp Neurons J.D. Vela*1, G. Perry2, M. Henry2, K.M. Hargreaves2 1 University of Iowa, Iowa City, IA, 2University of Texas Health Science Center Dental School, San Antonio, TX Dental pulp is a unique tissue since application of physiologic stimuli triggers an intense sensation of pain. During inflammation, sensory neurons innervating this tissue undergo substantial plasticity by axonal sprouting and altered expression of receptors and neuropeptides. Pharmacological studies have demonstrated the presence of α2AR and β2AR in modulating capsaicin-sensitive nociceptive neurons in dental pulp. However, no study has evaluated the presence of the β1AR subtype in human dental pulp, the cell type(s) expressing this receptor, or whether clinical inflammation alters its expression. Therefore, this study evaluated the expression of the β1AR in neurons and non-neuronal cells in normal and inflamed human dental pulp tissue. The expression pattern of the β1AR in normal pulpal tissues removed from extracted non-painful molars was compared to the expression pattern found in inflamed pulpal tissues removed from extracted painful molars with a clinical diagnosis of irreversible pulpitis. Samples were processed identically using the indirect immunofluorescence method and images were obtained with confocal microscopy. The immunofluorescence intensity and area occupied by the β1AR within N52/CGRP-identified nerve fibers and within non-neuronal tissues were both quantified. Results demonstrated the presence of the β1AR in neuronal and non-neuronal structures and revealed a 2-3 fold increase in β1AR expression in axons innervating the irreversibly inflamed pulpal samples compared to the normal samples (p<0.001). These data demonstrate that the β1AR expression on dental pulp axons is dynamically increased during inflammation and suggests that this receptor is poised to modulate the function of peripheral sensory nociceptors during inflammatory pain in humans.

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Association Between Dental Health, Oral Infections and Acute Myocardial Infarction B.S. Willershausen*, B. Briseño, A. Kasaj, I. Willershausen, T. Münzel Johannes Gutenberg University, Mainz, Germany In patients with cardiovascular diseases many risk factors such as high blood pressure, diabetes, smoking, genetic disposition or chronic inflammation are considered. The present study’s aim is to establish a correlation between dental focal infections and the presence of an acute myocardial infarction. A total of 130 patients having suffered from a myocardial infarction (mean age: 63 years), participated in this study. 130 healthy individuals of matching ages served as comparison. The dental examination was carried out following the consent of the ethics committee and the National Board for Radiation Protection. The oral inspection included the number of teeth, endodontically treated teeth, apical lesions, AL, probing depth, inflammation markers as well as radiographs. The medical examination included blood glucose values, CRP serum levels, LDL cholesterol and leukocyte number. The study demonstrated that patients with acute myocardial infarction showed an unfavorable dental state of health. They had a significantly higher number of missing teeth (p=0.001), less teeth with root canal fillings (p=0.062), a higher number of radiological apical lesions (p=0.021) and more teeth with higher AL values (p=0.001) compared to probands without myocardial patient history. The medical data showed a weak correlation between CRP and the number of radiological apical lesions; however, this was not significant. There was no correlation between the dental findings, blood glucose, BMI, LDL and CK values. This study documents that patients after myocardial infarction show an unfavorable dental state of health in comparison to healthy probands. It suggests an association between chronic oral infections and myocardial infarction.

Key:

 denotes Resident

* denotes Presenter(s)

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The Impact of PTH and Flt-3L on Cells of the Hematopoietic Lineage: An Ex Vivo Study E.S. Ghaname*, F. Pirih, J. Berry, L.K. McCauley University of Michigan, Ann Arbor, MI Parathyroid hormone (PTH) is known for its anabolic actions in bone and is under investigation to restore localized osseous defects. The oral cavity presents a unique environment for regeneration in sites of inflammatory-mediated bone loss as occurs in endodontic lesions. Despite great promise, the mechanisms of PTH action are not completely understood. Our laboratory reported that PTH acts in conjunction with FMS-like tyrosine kinase-3 receptor ligand (Flt-3L) to expand hematopoietic cells. The aim of this study was to evaluate the PTH impact on cell proliferation and apoptosis. Murine bone marrow was isolated and cells plated with Flt-3L (100ng/ ml), PTH (10nM), a combination of both, or vehicle for 2, 4, 6, and 8d. Western blots for cyclin D1, Poly(ADP-ribose) polymerase (PARP) and Caspase 3 (C3), and FACS analysis for Annexin V and Propidium Iodide (PI) were performed. Flt-3L significantly increased non-adherent bone marrow cell numbers after 8d. PTH alone did not alter cell numbers, but significantly augmented the Flt-3L response. In nonadherent cells, PTH combined with Flt-3L increased cyclin D1, total PARP, and C3 levels at all times and decreased cell apoptosis observed as a decrease in percentage of Annexin V and PI stained cells at d8. In summary, PTH acts in conjunction with a hematopoietic stem cell factor to expand cells in the bone marrow through a decrease in apoptosis and an increase in proliferation. These data suggest that PTH may play a novel role in modifying and augmenting the healing response in osseous defects in the oral cavity.

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Impact of Dental Devices on Neurostimulators S. Roberts*1, J. Vender1, M. Causey1, J.R. Roberts2, N. Weller1, R. Loushine1, S. Looney1 1 Medical College of Georgia, Augusta, GA, 2Walter Reed Army Medical Center, Washington, DC Spinal cord stimulation has been a therapeutic option for chronic pain for over 40 years. The nuerostimulator (NS) is a device consisting of an insulated wire, a mini computer, and a transceiver/antenna or a battery that is implanted into the epidural space of patients. It sends electric signals to the brain, altering the patient’s sensation of pain into parasthesia. The purpose of this study was to investigate whether electromagnetic interference of the NS occurs during the operation of the apex locator, the electric pulp tester or the electrocautery unit. A NS was implanted into the epidural space on a human cadaver. The dental devices were used intraorally, and the implant’s circuitry was tested after each trial. Using the exact method of determining confidence intervals, the probability of damage to the NS by any of the devices was negligible.

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Evaluation of Radiographs, Clinical Signs and Symptoms Associated With Pulp Canal Obliteration A.O. Oginni*, C.A. Adekoya-Sofowora, K.E. Kolawole Obafemi Awolowo University, Ile-Ife, Osun State, Nigeria

Biologic and Clinical Evaluation of 6.5% Paraformaldehyde (PF) in Endodontics R.M. Block*1, P. Supan2, K. Langeland1 1 University of Connecticut, Farmington, CT, 2Leesburg, VA

Pulp canal obliteration (PCO) is a sequela of tooth trauma. The endodontist faced with this condition in its active state has to make a difficult decision. This study was to evaluate the clinical signs and symptoms associated with teeth with PCO and to assess the status of the periapical tissues using the periapical index (PAI) as an aid in making treatment decision. The study included teeth diagnosed with PCO in patients with histories of traumatic injuries to the involved teeth. Histories of pain, swelling, and drainage from a sinus tract, were elicited. Data recorded included tooth color, sensibility, mobility and percussion tenderness. 276 teeth had PCO. 157 (56.9%) and 119 (43.1%) demonstrated partial and total PCO, respectively. Yellow discoloration presented most frequently, occurring in 186 teeth. Sixty-two (33.3%) of these had developed periapical lesions and reacted negatively to sensibility testing. Seventy-one (38.2%) teeth presented radiographically with normal periapical contour and reacted normally to sensibility testing, whereas 53 (28.5%) presented with small changes in the periapical bone pattern and reacted in the high normal range to sensibility testing. Teeth with PAI scores of 2 or lower presented with occasional spontaneous pain. Teeth with PAI scores of 3 or higher presented with clinical symptoms and signs ranging from pain on percussion to spontaneous pain, and slight swelling to sinus tract drainage. Based on the findings of this study, endodontic therapy should be initiated in teeth with tenderness to percussion, PAI scores of 3 or higher and a negative response to sensibility testing.

At our recent joint symposium, Pedodontists were still advocating Formocresol Pulpotomies. The purpose of this study was to evaluate the immunologic, radioisotopic and histopathologic response to 6.5% paraformaldehyde (PF). Methods: 10 dogs were used. Immunologic responses were analyzed for antibody and cell mediated immunity. Immunization occurred via 20 pulpotomies over a 28 day period in 5 dogs. In 5 other dogs PF pulpotomies were performed in 5 teeth/dog using C-14 labeled 6.5% paraformaldehyde. In each animal, the radioactivity was measured over 1 hr., 1, 7,14,21, and 28 days in the blood, submandibular lymph nodes, kidney and liver. At 28 days the animals were sacrificed. The teeth, bone and surrounding tissues were processed for light microscopy using standard procedures. Semiserial 5-8 micron sections stained with H&E were examined in diffuse and polarized light. Sections were examined for acute, chronic, foreign body inflammatory cells, extravasated erythrocytes, brown pigment, vessel, cell and tissue destruction. Results: Pulp altered by 6.5% PF produced specific antibody and cell mediated responses. 2) C-14 labeled PF was detected in the blood, lymph node, kidney and liver over 28 days. 3) Histopathologic evaluation demonstrated tissue, cell, vessel destruction and inflammation adjacent to the PF PO. Bone and periapical damage was also present. Conclusions: Paraformaldehyde containing products should not be used in Endodontics. This presentation is a tribute to the late Dr. Kaare Langeland who passed away this year.

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Quantitative Analysis of Biofilm Growth on Different Splints R. Pileggi*, C. Varella, C. Walker, L. Shaddox University of Florida, Gainesville, FL The incidence of traumatic injuries has increased in the past decade. Following teeth injury, when there is mobility involved, stabilization of the teeth is fundamental for the success of treatment. Several materials and techniques have been introduced in the past few years. These materials have been analyzed in their capacity to induce periapical healing and maintain proper stabilization. Since the presence of bacteria is of paramount importance for the success and retention of these teeth, the purpose of this study was to analyze biofilm growth on different types of splints. Four different splint materials were utilized in this study. A total of 6 splints per group of 3 extracted anterior teeth were splinted with the four different materials: Ribbond (R), Orthodontic-wire (OW), Fishing-line (FL) or Titanium Trauma Splint (TTS). Supragingival biofilm was collected and used to inoculate TSB broth containing each of the groups of teeth. The groups were maintained in CO2 chamber for cultivation of bacteria for 7 days. The biofilm was quantified by Optical Density Values (OD) and Colony Forming Units counts (CFU). Results: Results were analyzed with an ANOVA and Tukey’s post-hoc test. The TTS splint demonstrated the least amount of cell growth with both Optical Density values and CFU (p<0.05). The optical density mean values were as follows: TTS (0.05), FL(1.27),Ribbond (1.5) and OW(1.45). The new TTS splint system retains much less biofilm as compared to the other splints.

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Assessment of Results Obtained by Bacterial Leakage and Fluid Filtration Methodologies Applied to the Same Specimens E. Farmakis*, E.G. Kontakiotis, A. Kotsovili, A. Tseleni-Kotsovili, V.G. Tsatsas University of Athens, Greece Microleakage methodologies have been applied in order to evaluate the quality of obturated root canals with conflicting results. This study aimed to assess the results of fluid filtration (FFM) and bacterial leakage models(BLM) on the same specimens. 90 extracted single-rooted teeth were prepared and assigned in 3 experimental groups of 20; the rest served as positive, negative and sterility controls. Each experimental group was obturated by cold lateral condensation of gutta-percha using as sealer EndoRez™, TopSeal™ or RSA™. After setting, specimens were exposed to 0.3atm pressure for 3 hours; leakage was expressed in μL/3hours, classified as “no leakage”(Flux=0μL/3h-NL), “slight leakage”(020μL/3h-GL) and recorded. Following, specimens were γ-radiation-sterilized, mounted horizontally and challenged over 60 days by P.vulgaris (108CFU/ml) placed coronally. Sampling was performed daily from the sterile saline-filled apical reservoir. Results were recorded as “sterile” or “bacterial positive”(BP). EndoRez showed 6SL (1BP) and 2GL(2BP)-mean bacterial penetration time 31 days; TopSeal 7SL (4BP)-26days, and RSA 9SL (0BP). Controls behaved as expected. Under FFM, sealers performed almost equally (Fisher’s exact p> 0.1). As for BLM, P.vulgaris penetrated some but not all of the FFM-leaking specimens, and not in an equal fashion regarding the different sealers with no statistically significant difference (Log-rank test for equality of survivor functions p>0.1). No correlation was established between the time needed for total bacterial penetration and FFM recordings (Wilcoxon matched pairs signed ranks test p>0.05). Under these experimental conditions, results by FFM and BLM were not comparable. The differences in adhesion of P.vulgaris on these sealers could provide an explanation.

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The purpose of this retrospective study was to determine the anesthetic success of the inferior alveolar nerve block by tooth type in patients with irreversible pulpitis. Two-hundred and thirty-nine patients in moderate to severe pain presenting for emergency treatment of a mandibular posterior tooth diagnosed with irreversible pulpitis participated in this study. The patients were given 1.8 to 3.6 mL of 2% lidocaine with 1:100,000 epinephrine by inferior alveolar nerve block. After confirming lip numbness patients were asked to rate any pain experienced during endodontic treatment on a 170 mm Heft-Parker visual analogue scale (VAS). If moderate-to-severe pain was felt during treatment (> 54 mm on the VAS), the operator stopped and administered supplemental anesthesia. Anesthetic success of the inferior alveolar nerve block was determined based on the need for supplemental anesthesia. Success was assessed with exact binominal 95% lower and upper confidence limits (LCL and UCL). The success rates for the premolars, first molars, and second molars were 41% (25% LCL, 59% UCL), 36% (27% LCL, 45% UCL) and 28% (18% LCL, 39% UCL), respectively. All tooth types had low success rates but the second molar had the lowest success. This study found clinically unacceptable pulpal anesthesia success rates in all three tooth types when irreversible pulpitis was present. Therefore, supplemental anesthetic techniques must be investigated to address the low clinical success rates in all mandibular posterior teeth (premolars, 1st and 2nd molars).

The purpose of this research was to conduct an ultrastructural analysis of stem cell attachment within tissue-engineered dental pulp constructs. Stem cells from human exfoliated deciduous teeth (SHED) were grown to confluence and seeded on 3-dimensional tissue engineering scaffolds (BD Biosciences, Franklin Lakes, NJ). The pulp tissue constructs (n=30) were created by seeding SHED on two types of scaffolds; a rat-tail collagen scaffold (CS, Serva, Heidelberg, Germany), or a CS coated with hydroxyapetite (CS+HA, Bioland, Toulouse, France). The negative control was an absence of treatment. As a positive control, the scaffolds were seeded with L929 cells. The constructs were submerged in Dulbecco’s Minimal Essential Media containing 10% fetal calf serum and antibiotics, maintained at 30oC in a 5% CO2 atmosphere for 4, 8, and 24 hours. The specimens were fixed in formalin, dehydrated and processed for visualization in a scanning electron microscope (SEM). SHED attachment within the dental pulp constructs was viewed in SEM micrographs at x2000 magnification. Data was analyzed by analysis of variance statistical tests (P values) at a significance of 95%. SHED attachment was similar in both the CS and CS+HA dental pulp constructs (P>0.05). These ultrastructural results suggest that coating CS with HA does not promote increased SHED attachment. Further research is needed to identify coatings which optimize the effectiveness of scaffolds to be used as part of future regenerative endodontic therapy. Supported by NSU Health Professions Division.

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Anesthetic Success by Tooth Type for the Inferior Alveolar Nerve Block in Patients With Irreversible Pulpitis M. Drum*, A. Reader, J. Nusstein, M. Beck Ohio State University, Columbus, OH

An Ultrastructural Investigation of Tissue-Engineered Pulp Constructs T.C. Sayin*1, P.E. Murray1, H.M. Aydin2, K.N. Namerow1 1 Nova Southeastern University, Fort Lauderdale, FL, 2Hacettepe University, Ankara, Turkey

Incidence of Endodontic-Implantitis and Implant-Endodontitis Occurring With Single-Tooth Implants: A Retrospective Study F.M. Alsalleeh* University of Nebraska, Lincoln, NE

Particle Length, Width, Perimeter, and Aspect Ratio of Gray and White ProRoot® Mineral Trioxide Aggregate Using Flow Particle Image Analyzer T. Komabayashi*1, R.N. D’souza1, P.C. Dechow1, K.E. Safavi2, L.S.W. Spångberg2 1 Baylor College of Dentistry, Dallas, TX, 2University of Connecticut, Farmington, CT

The purposes were to determine success and survival rates for implants and teeth adjacent to implants; and the incidence of Endodontic-Implantitis (E-I) (endodontic involvement in adjacent teeth causing implant failure) and of Implant-Endodontitis (I-E) (implant placement causing endodontic failure). The data were from 233 single-tooth implants placed in 116 subjects by postgraduate periodontal students with recall radiographs taken ≥ 9 months after implant placement. Three groups were analyzed; Group A - implants with no adjacent teeth (n=90), Group B - implants with non-endodontically treated adjacent teeth (n=123), and Group C - implants with endodontically treated adjacent teeth (n=20). The success and survival rates for implants were both 92.2% in Group A, 98.4% and 99.2% for Group B, and 85% and 95% for Group C, respectively. For adjacent teeth they were both 99.4% in Group B compared to 75% and 90% in Group C. However, after case review, none of the implants or adjacent teeth in Group B were considered to have E-I or I-E, and one (5%) of the implants in Group C had E-I and two (10%) of the adjacent teeth may have had I-E. The results of the present study agree with previous research, which suggests that endodontically treated teeth adjacent to singletooth implants are usually successful and should be maintained.

Gray and White ProRoot® Mineral Trioxide Aggregate (GMTA, WMTA) are widely used in Endodontics and the possible penetration of its particles into dentin tubules is known. While WMTA contains a lower percentage of tetra-calcium aluminoferrite than GMTA for preventing tooth discoloration, the precise difference in particle physical properties between GMTA and WMTA is unknown. The aim of this study was to observe particle length, width, perimeter, and aspect ratio of finer fractions of GMTA and WMTA using flow particle image analyzer. Five sample groups each with 10mg sample were mixed with 10mL of alcohol and sonicated. Samples were run using a High Power Field mode at an effective size range of 0.5-40μm. Digital images of particle samples were taken. One-way ANOVA tests were conducted to see if there are any significant differences in length(μm), width(μm), perimeter(μm), and aspect ratio among five sample groups for GMTA and WMTA, respectively. Student’s t-test was made to identify if there is significant difference in length, width, perimeter, and aspect ratio between material groups GMTA and WMTA. For GMTA group, overall average±S.D among five groups were 1.938±1.645, 1.429±1.188, 5.608±4.265, and 0.761±0.139 for length, width, perimeter, and aspect ratio, respectively. For WMTA group, overall average±S.D. among five groups were 2.043±1.865, 1.493±1.332, 5.880±4.806, and 0.757±0.142, respectively. No significant differences in length, width, perimeter, and aspect ratio were observed among five sample groups for GMTA and WMTA, respectively. However, there were significant differences in length, width, perimeter, and aspect ratio between GMTA and WMTA (all p-values<0.0001). Acknowledgement: Hosokawa-Micron/MalvernInstrument. NIH-KL2-RR024983(TK)/UL1-RR024982.

Key:

 denotes Resident

* denotes Presenter(s)

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How to Prepare Oval-Shaped Root Canals With Modern Rotary NiTi Instruments? A Microcomputed Tomography Analysis F. Paqué*1, M. Balmer1, T. Attin1, O.A. Peters2 1 University of Zürich Dental School, Switzerland, 2University of the Pacific, San Francisco, CA

MTA Preparations From Different Origins May Vary in Their Antimicrobial Activity K. Al-Hezaimi*1, T. Al-Shalan1, J. Naghshbandi2, J. Simon3, I. Rotstein3 1 King Saud University, Riyadh, Saudi Arabia, 2Phoenix, AZ, 3University of Southern California, Los Angeles, CA

This study evaluated the prepared surface areas of oval-shaped root canals using different instrumentation techniques. Mandibular molars were pre-scanned and reconstructed using microcomputed tomography (µCT) at low resolution (68µm). Forty-eight molars with ribbon-shaped/oval distal root canals were selected and randomly assigned to 4 groups. Distal canals (n=12 each) were instrumented as follows: circumferential filing using K-files to apical size #40 (group 1); ProTaper® to F4 considering the distal canal as one canal (group 2); ProTaper to F4 considering buccal and oral aspects of the distal canal as two individual canals (group 3); ProTaper to F4 in a circumferential filing motion (group 4). Before and after shaping, teeth were evaluated employing µCT at 34µm resolution. The percentage of prepared surface was assessed for the full canal length and the apical 4mm. Statistical analysis utilized ANOVA and Bonferroni/Dunn multiple comparisons. Preoperatively, canal anatomy was statistically similar among the groups (p=0.56). Mean (±SD) untreated areas ranged from 56.9% (±15.5, group 3) to 74.8% (±12.0, group 2) regarding overall canal length and 52.9% (±13.5, group 4) to 61.3% (±16.2, group 3) regarding the apical canal portion, respectively. Canals in group 2 had greater untreated surface areas (p<0.01) than groups 3 and 4. Among the groups, treated surface was statistically similar in the apical 4mm. In conclusion, preparations of oval-shaped root canals in mandibular molars left a high percentage of surface unprepared, regardless of the instrumentation technique used. However, considering such canals as two separate entities during preparation seemed to be beneficial.

Purpose: The antimicrobial effects of 4 Mineral Trioxide Aggregate (MTA) preparations, 2 white-colored (WMTA-1, WMTA-2) and 2 gray-colored (GMTA1, GMTA-2) against C. albicans, and E. faecalis were assessed in vitro. Methodology: Minimal inhibitory concentration (MIC) for each preparation was determined using the tube dilution test and Sabouraud agar media for C. albicans and brain heart infusion media for E. faecalis. Medium plates were prepared and divided into experimental (11 plates each) and control (5 plates each) groups. Aliquots of each of the tested microorganisms were taken from a stock culture and added to each experimental and positive control group. All groups were incubated at 37°C and evaluated for turbidity at 24, 48 and 72hour time periods. Results: MIC of MTA against the two microorganisms tested varied among the four preparations tested. WMTA-1 and WMTA-2 inhibited C. albicans growth at concentrations of 3.125 mg/ml and 25 mg/ml respectively. Statistically significant differences were found between WMTA-1 and WMTA-2 (p<0.001). Both GMTA-1 and GMTA-2 inhibited C. albicans growth at concentrations of 3.125 mg/ml. WMTA-1 and WMTA-2 inhibited E. faecalis growth at concentrations of 12.5 mg/ml and 50 mg/ml respectively. Statistically significant differences were found between WMTA-1 and WMTA-2 (p<0.001). GMTA-1 and GMTA-2 inhibited E. faecalis growth at concentrations of 12.5 mg/ml and 3.125 mg/ml respectively (P<0.02). Conclusion: The origin of MTA as well as the type of preparation may affect its antimicrobial characteristics. Clinicians should be aware of variations that may exist among such MTA preparations.

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Perspectives on Usage Parameters of Nickel-Titanium Rotary Root Canal Instruments: A Survey D.C. Bird*, O.A. Peters University of the Pacific, San Francisco, CA Best practices and perspectives of U.S. endodontists regarding rotary root canal instruments are not well documented. Therefore, the aim of this study was to retrieve data from a representative sample of endodontists regarding contemporary usage of rotary instruments. A questionnaire addressing nickel-titanium (NiTi) rotary instrument usage and expectations for future designs was constructed. A total of 954 online surveys were e-mailed to endodontists in California (n=148), Iowa (n=9), Massachusetts (n=35), Minnesota (n=28), New York (n=61), Texas (n=61), and Wisconsin (n=17). Data was collected from respondents utilizing the Survey Monkey interface over a four-month period. Valid responses were received from 359 endodontists, representing a 38% response rate. Chi-square tests and correlation coefficients were used to analyze the data; the level of significance was set at 0.05. Reported practices varied by region, graduation date and type of practice. Recent graduates were more likely to use NiTi rotary instruments for every treatment (p=0.007), multiple NiTi systems (p=0.002), torque control motors (p=0.03), and Gates Glidden instruments (p=0.001) than older endodontists. Over 50% of respondents used NiTi rotary instruments in several patients before discarding and 57% reported cleaning the instruments with a combination of ultrasonics and sterilization. Crown down was the most frequently used preparation strategy; overall, there were little differences regarding geographic regions. Over 70% of respondents expect similar but improved files in the next 10 years. In conclusion, differences exist among U.S. endodontists regarding current NiTi instrument use and expectations for future development may be correlated with level of exposure and training.

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JOE — Volume 35, Number 3, March 2009

Rat Connective Tissue Reaction to White and Gray Mineral Trioxide Aggregates Mixed With Distilled Water and 0.12% Chlorhexidine Gluconate S. Shahi*, H. Yavari Tabriz University of Medical Sciences, Iran The purpose of this study was to evaluate subcutaneous connective tissue reaction to white and gray mineral trioxide aggregate mixed with 0.12% chlorhexidine gluconate and distilled water in subcutaneous connective tissue of rats. Freshly mixed WMTA and GMTA with 0.12% chlorhexidine gluconate or distilled water were placed in polyethylene tubes and implanted into the dorsal subcutaneous connective tissue of 50 Wistar Albino rats, tissue biopsies were collected and histologically examined 7,15,30, 60 and 90 days after the implantation procedure. Scores were defined as follows: Grade I, few inflammatory cells without edema; Grade II, <25 inflammatory cells, wavy collagen fibril deposition and fibrosis; Grade III, 25-125 inflammatory cells, edema and vascular congestion; Grade IV, 125 inflammatory cells, edema and vascular congestion and fibrin deposition. Data was analyzed by one-way and multiple-way ANOVA and post hoc Tukey test. All the materials tested were completely biocompatible after 90 days except for WMTA+CHX, which had a significantly higher mean of inflammation grade. According to the results of this study, it seems that chlorhexidine gluconate is a suitable substitute for distilled water in combination with MTA; however further research is necessary to support this finding.

OR 57

OR 58

Purpose: Qualitatively assess the wear of new Twisted Files (TF™, SybronEndo) and GT Series-X (GTX™, DENTSPLY Tulsa Dental Specialties) nickel-titanium rotary instruments in as-received condition and after simulated clinical use. Methods: ISO sizes #25 TF™ and #30 GTX™ of 04, 06 and 08 tapers were employed to prepare MB canals in extracted molars using a standardized protocol. After ultrasonication and sterilization, each instrument was examined at various sites with a SEM (Hitachi, TM-1000) over a range of magnifications in the as-received condition and after one, three and six simulated clinical uses. Sites evaluated were the cutting edges, radial lands and flute regions at D1, D3 and D6. Results: As-received surfaces of TF™ instruments had minimal machining marks and metal rollover, and were smoother compared to GTX™ instruments. Both TF™ and GTX™ instruments varied in cutting surface design, with the former having sharper radial lands and the latter with broader radial lands. After one-three uses, clinically insignificant wear was observed along the cutting edges of both TF™ and GTX™ instruments. After six simulated uses, cutting edges appeared blunt and burnished for both instruments. Dentinal debris in the flute regions was greatest at D3 for both instruments. Conclusions: SEM observations showed that TF™ instruments have a highquality surface suggestive of some proprietary treatment during manufacturing. Insignificant wear was observed at the tip and cutting edge regions for up to 3 uses, but notable wear existed at 6 uses for both rotary instruments. Adherence of dentinal debris can be related to instrument geometry and manufacturing technique.

The loss of hard tooth structure following endodontic procedures has not been measured previously. The aim of this study was to compare the volume of hard tooth structure lost due to caries removal, access cavity preparation, root canal preparation, and fiber post space preparation in human premolar teeth presenting with mesial or distal carious lesions penetrating into the pulp chamber. The null hypothesis tested was that there is no difference between the volumes of hard tooth structure lost expressed as a percentage of the pre-operative hard tooth volume, after each operative procedure. 12 extracted human premolars with mesial or distal carious cavities penetrating into the pulp chamber were selected. Teeth were scanned using a GE Locus microCT scanner (GE Pre-clinical Imaging, London, Ontario, Canada). After performing each operative procedure the loss of hard tooth tissue volume was measured. The data was statistically analyzed using one way analysis of variance and Fisher’s PLSD test with statistical significance set at α=0.01. The percentages of hard tooth volume lost after caries removal, access cavity preparation, root canal preparation and fiber post space preparation were 8,3±5,83, 12,7±6,7, 13,7±6,7 and 15,1±6,3 respectively. Each procedure performed after caries removal significantly increased (p<0.01) the amount of hard tissue volume lost with the exception of the root canal preparation. Access cavity and post space preparation are the endodontic procedures that cause the biggest loss of hard tooth tissue structure. This needs to be taken into account in planning root canal treatments and restorations of root filled teeth.

OR 59

OR 60

This study aimed to compare the efficacy of ultrasonic, sonic and syringe irrigation, and to determine the influence of frequency, tip size and irrigant on the effectiveness of a recently-developed sonic device, EndoActivator® to remove artificially placed dentin debris. Each of eighteen ex-vivo models with a standard straight root and a standard groove in the apical portion of one canal wall filled with dentin debris was tested repeatedly by different irrigation regimens. After each irrigation procedure, the amount of dentin debris in the groove was evaluated by taking pictures. Group 1 (n=18) received ultrasonic irrigation. Group 2 (n=18) received sonic irrigation with the #15/.02 tip and sodium hypochlorite under highest frequency; Group 3 (n=18) the same as group 2, except the #25/.04 Activator tip was used; Group 4 (n=18) the same as group 2, except the frequency was the lowest; Group 5 (n=18) the same as group 2, except the irrigant was replaced by water. Group 6 (n=18) received only syringe irrigation. Images of grooves were imported into AxioVision™ (Axio Cam, Carl Zeiss) for scoring that ranged from 0 (no debris) to 3 (all covered by debris). Nonparametric analysis showed significant differences between the ultrasonic, sonic and syringe irrigation (K-W test, P<0.005). There was no significant difference within sonic groups (M-W test, P>0.05). Irrigant activation by sonic or ultrasonic energy is more effective than syringe irrigation to remove apical dentin debris, and ultrasonic irrigation is the most effective. File size and irrigant had little influence on the efficacy of EndoActivator®.

The purpose of this study was to compare the in vitro effectiveness of sodium hypochlorite (NaOCl) in a gel form with sodium hypochlorite (NaOCl) in a liquid form in removing the debris and smear layers from the canal walls of endodontically treated teeth. Sixty anterior teeth with a curvature of 15-25 degrees were accessed and all canals were instrumented using the crown-down technique. Teeth were divided into six experimental groups according to the size of their master apical file and type of irrigation used [group 1 (#10G), group 2 (#20G), group 3 (#30G), group 4 (#10L), group 5 (#20L), group 6 (#30L)]. Root canals in groups 1, 2 and 3 were irrigated with 5ml of 2.25% NaOCl in gel form using a 30 gauge needle. Groups 3, 4 and 5 were irrigated using 2.25% NaOCl in liquid form following same protocol. Each canal in the control group was enlarged at the working length to a #40 K-file without using any irrigation. Evaluation of debris, smear layer, and the visibility of open tubules at the coronal, middle and apical third of root canals were determined under a scanning electron microscope. Data was analyzed using Kruskal-Wallis and Mann-Whitney tests. Based on the results there was no statistical significant difference between both irrigants for all canals sizes at all levels. Conclusively as NaOCl gel exhibits the same effectiveness as NaOCl liquid it can be recommended as intracanal irrigation agent.

SEM Evaluation of TF™ and GTX™ Rotary Instruments in AsReceived and After Simulated Clinical Use M.E. Levitan*, J. Assad, S. Alapati Medical University of South Carolina, Charleston, SC

Cleaning Efficacy in Apical Dentin Debris Removal With or Without Irrigant Activation L.M. Jiang*, L.W.M. van der Sluis Academic Centre Dentistry Amsterdam, Amsterdam, Netherlands

Key:

 denotes Resident

* denotes Presenter(s)

The Loss of Hard Tissue Volume Following Root Canal Preparation and Fiber Post Space Preparation: A Microcomputed Tomography Investigation O.H. Ikram*, S. Sauro, F. Mannocci Kings College, London, United Kingdom

Evaluation of Sodium Hypochlorite (NaOCl) Gel as an Endodontic Irrigant D.I.M. Al-Sudani* King Saud University, Riyadh, Saudi Arabia

JOE — Volume 35, Number 3, March 2009

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Potential Use of Grapefruit Extract as Endodontic Irrigant: Antibacterial Study D. Al-Sudani1, A.A. Hashem*2, A.A. El-Sayed2 1 King Saud University, Riyadh, Saudi Arabia, 2Ain Shams University, Cairo, Egypt Grapefruit extract, a natural non-toxic solution derived from the seeds and pulp of grapefruit, has been shown to have antibacterial action. It disrupts the bacterial cell membrane and liberates cytoplasmic contents suggesting its potential to be used as endodontic irrigant. The antibacterial effect of grapefruit extract against three common endodontic pathogenic microorganisms (E. faecalis, S. aureus, and C. albicans) has been investigated and compared to two common endodontic irrigants (NaOCl 5.25% and CHX 2%). Self-made ethanolic extract (33% m/V) of commercially available grapefruit was prepared. Two in vitro antimicrobial sensitivity tests (standard dilution susceptibility test and agar assay) were used. Ninety samples were studied per test. They were divided into 3 groups (n=30) according to the irrigant solution. Every group was further subdivided into 3 subgroups (n=10) according to the type of bacteria tested. NaOCl 5.25% and CHX 2% proved to be effective at lower concentrations than grapefruit extract (p≤0.05) in standard dilution test. However, grapefruit extract has shown definite cidal effects against the three tested microorganisms. In an agar assay test, grapefruit extract produced inhibition zones of 17.8±1.7mm, 14.3±2.4mm, and 14.6±3.2mm for E. faecalis, S. aureus, and C. albicans respectively. CHX showed the highest inhibition zones with E. faecalis and S. aureus while was insignificant from NaOCl 5.25% with C. albicans (p≤0.05). Despite that grapefruit extract had lower data than NaOCl 5.25% and CHX 2%, further research regarding its effect on intracanal bacterial reduction is needed.

OR 63 

Are we Getting Gutta-Percha to Move? B. Briseño Marroquín*, D. Schürger, B. Willershausen University of Mainz, Germany Thermoplastic filling methods are supposed to improve the adaptation of the filling material to the root canal walls. The aim of this investigation was to determine the heat absorption and transportation potential of gutta-percha. Methods: Heat was applied at room temperature (28/±2°C) by means of a heat-plugger size .10 (M) (SybronEndo, Orange CA, USA) to gutta-percha points (n=15) for 2s (±0.5s) sizes 30/.06 and .04 (Roeko/Coltène/Whaledent, Langenau, Germany). The maximum temperature (°C) of the heat-plugger tip and edge of the gutta-percha point at 5 and 1mm from their tip were measured by means of a ThermaCAM SC640 infrared camera (Flir Systems/Frankfurt, Germany). The results were statistically analyzed and showed that the mean temperatures applied and reached by the gutta-percha points sizes 30/.06 and .04 5mm from the tip were 302.62 (applied; ±32.05); 156.02 (reached; ±17.14) and 266.51 (applied; ±32.64); 136.16 (reached; ±26.47) respectively. The mean temperatures 1mm “apical” from this point were 302.62 (applied; ±32.05); 47.38 (reached; ±3.59) and 266.51 (applied; ±32.64); 75.38 (reached; ±8.10) respectively. The mean temperatures applied and reached by the gutta-percha points sizes 30/.06 and .04 1mm from the tip were 360.76 (applied; ±49.21); 133.32 (reached; ±41.15) and 288.26 (applied; ±91.04); 169.56 (reached; ±48.38) respectively. Discussion: the mean differences between the applied, reached and between 5 and 4mm temperatures demonstrated that gutta-percha has an extremely low heat transportation potential; thus, caution should be taken to place the heat-pluggers at the point were gutta-percha should plasticize to facilitate an accurate compaction of the material.

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OR 62 

Fluid Dynamic Aspects of Root Canal Cleaning Using Laser-Activated Irrigation B. Verhaagen*1, S.D. De Groot2, L.W.M. Van der Sluis2, M. Versluis1 1 University of Twente, Enschede, Netherlands, 2Academic Centre Dentistry Amsterdam, Netherlands An important procedure of a root canal treatment is irrigation. Hand irrigation is the standard procedure but unfortunately, hand irrigation is not effective in the apical part of the root canal and in the cleaning of isthmuses or oval extensions. Therefore it is important to activate the irrigant in the root canal in order to achieve an improved flow of the irrigant through the root canal system and a better cleaning efficiency in oval extensions and isthmuses. Laseractivated irrigation (LAI) has been introduced as a powerful method for root canal irrigation. We activate the irrigant directly by guiding the output of an Er: YAG laser into the root canal. The absorbed energy of the laser radiation pulse is converted into heat and a vapor bubble is produced, which rapidly expands followed by an inertial violent collapse of the bubble. In this study we evaluate the removal of artificially placed dentine debris in standardized root canals by laser-activated irrigation. The removal efficiency was compared to that of hand irrigation and passive ultrasonic irrigation (PUI). Laser-activated irrigation was also visualized in vitro using high-speed imaging at a timescale relevant to the cleaning process, which was at the order of several tens of microseconds. It was found that LAI is significantly more effective in removing debris from a root canal than PUI or hand irrigation when the irrigant was activated for 20 seconds. The in vitro recordings suggest that streaming, caused by cavitation, is the main cleaning mechanism.

PR 01 

Comparing the Accuracy of Detecting and Measuring Predetermined Artificially Simulated Lesions Using Cone Beam-Computed Tomography, Direct Digital Radiography, and Conventional Radiography O. Alhalasa*, A. Mickel, S. Chogle, J. Jones Case Western Reserve University, Cleveland, OH The radiographic detection of a bony rarefaction in the periradicular area is considered to be one of the diagnostic signs for the presence of a periradicular pathosis. On the other hand, in 1961 Bender and Seltzer have demonstrated that artificial lesions cannot be detected by conventional radiography unless erosion of the inner and/or outer cortical plates has occurred. The purpose of this study was to compare the precision of detecting and measuring predetermined artificially simulated lesions in human cadaver mandibles using Cone Beam-Computed Tomography (CBCT), Direct Digital Radiography (DDR), and Conventional Radiography (CR). We hypothesize that CBCT will be able to detect and measure the simulated lesions more accurately compared to DDR, and CR. Three mandibles were sectioned yielding six posterior segments, teeth extracted, segments sectioned in a sagital and axial plans exposing the periapical areas, six lesional states were artificially created using burs, radiographic images were obtained using the above mentioned radiographic imaging systems. Three blinded observers independently viewed the images at two different time periods. Sensitivity, Specificity, and Pairwise kappa index were calculated. Overall sensitivity was 100%, 81.67%, and 76.47% for CBCT, DDR, CR respectively. Specificity was 100% for all systems. Pairwise Kappa index for the agreement between observers was 1.0, 0.714, 0.673 respectively for CBCT, DDR, CR. There was no significant difference between observers in reporting the size of the lesion for both CBCT and CR. A significant difference between two observers was noted in the DDR. P (0.05) We concluded that CBCT was more accurate in reporting the presence and size of the lesions compared to DDR and CR.

PR 03 

Identification and Role of Regulatory T-Cells in Periapical Bone Lesions E. AlShwaimi*1, P. Purcell2, H. Sasaki2, T. Kawai2, K. Ouhara2, S. Kashino2, A. Campos-Neto2, P. Stashenko2 1 Harvard School of Dental Medicine, Boston, MA, 2The Forsyth Institute, Boston, MA T regulatory (Treg; CD4+FOXP3+) cells constitute a unique subpopulation of CD4+ T cells that inhibit T cell responses and prevent disease development/ exacerbation in models of autoimmunity. We hypothesized that Treg cells are induced in periapical lesions, and function as inhibitors of periapical bone destruction. To test this hypothesis, infection was induced in mouse first molar teeth by pulp exposure and inoculation with the oral pathogen Porphyromonas gingivalis (Pg). In situ hybridization (ISH) and FACS were used to identify Treg cells in lesions. GFP/FOXP3 knock-in transgenic mice were used to isolate Treg by FACS from Pg-immunized and non-immune mice for cell transfer experiments. Six groups (n=8) of mice were used: Group I: no pulp infection, negative control; Groups II-VI, pulpal infection. Infected groups received the following: Group II: no cell transfer, positive control; Group III: FOXP3+ immune Treg (5 x 105 cells/mouse, i.v.); Group IV: FOXP3+ naive Treg; Group V: Immune FOXP3- T cells; Group VI: Naive FOXP3- T cells. After 21 days, mice were sacrificed, and Treg, bone destruction and cytokine expression were quantified. ISH showed the presence of FOXP3+ cells at the periphery of periapical lesions (PAL). FACS of cells isolated from PAL of Group II showed elevated numbers of Treg compared to Group I uninfected controls (1.3% vs. 0.2%). Mice infused with Pg-sensitized Treg (Group III) had the least bone destruction (p<0.05 vs. positive control). Groups IV and V showed similar results. We conclude that Treg cells are induced by pulpal infection and suppress periapical bone destruction.

Key:

 denotes Resident

* denotes Presenter(s)

PR 02 

Perforation Repair Utilizing Dental Pulp Stem Cells and Dentin Matrix Protein 1 Following Subcutaneous Teeth Transplantation in Mice R.A. Alsanea*, M.I. Fayad, B.R. Johnson, C.S. Wenckus, A. George University of Illinois at Chicago, IL Perforations due to iatrogenic mishaps compromise the prognosis of root canal treatment. Regenerative endodontics can be utilized in perforation repair to replace damaged dentin and pulp with new healthy tissues. Until now, there is no ideal material to repair a perforation site. This study was conducted to evaluate the ability of Dental Pulp Stem Cells (DPSCs) and Dentin Matrix Protein 1 (DMP1) impregnated within a collagen scaffold to induce dentin formation in a furcal perforation site within 3 months duration. 6 animal groups were compared, with 3 immunocompromised mice in each. Perforations were created in 18 dentin wafers made from freshly extracted human molars. The following groups were designed: 1: Empty wafers, 2: Wafers containing MTA, 3: Wafers containing collagen scaffold, 4: Wafers containing collagen scaffold impregnated with DMP1, 5: Wafers containing collagen scaffold impregnated with DPSCs, 6: Wafers containing collagen scaffold impregnated with DPSCs and DMP1. One sample was placed subcutaneously in each mouse. Radiographs were taken at 10 days, 6 weeks, and 12 weeks intervals to detect mineralization within the perforation site. At the end of the 12 weeks, the mice were sacrificed and the samples were subjected to radiographic, histological and histochemical evaluations. The results showed that DPSCs impregnated within a collagen scaffold differentiated into odontoblast-like cells forming a highly cellular, vascular and mineralized matrix, in the presence of DMP1. Under the conditions of this study, it may be concluded that repairing perforations with a triad of a collagen scaffold, DPSCs and DMP1 promotes dentin regeneration.

PR 04 

A New Device for Cyclic Load Fatigue of Endodontic Post Systems R.C. Bell*, S.M. Bertch, A. Paine, J. Partridge, S.N. White University of California at Los Angeles, CA Introduction: Limited clinically relevant in vitro studies exist in the evaluation of restored endodontically treated teeth. Cyclic loading simulates in vivo function, fatigue, and failure. However, servo-hydraulic fatigue equipment is extremely expensive to buy and to operate. The aim of this investigation was to develop and validate a simple device that can measure failure over time with great precision during cyclic fatigue loading. Materials and Methods: An electric motor based device was designed and fabricated to deliver a specific load (2-20kg) at a uniform and defined frequency (0.75Hz) to teeth in vitro. Two sensors comprised of strain gauges were designed and incorporated to measure load applied throughout each cycle, and deflection or failure of an endodontically treated tooth, post, core, cement and crown system throughout each load cycle. Results: The system has been validated: The load arm sensor accurately measured the amount (grams ±1g) and frequency (±0.125Hz) of applied load (~haversine), while the deflection sensor detected linear movement of crown deflection (±25.4µm) and sent the information into data acquisition hardware (System 5000,Vishay Intertechnology) where the analog signals are amplified and digitized for display on a computer monitor through the use of data acquisition software (StrainSmart V3.1, Vishay Intertechnology), and recorded. Conclusion: A novel inexpensive device has been developed that will enable in vitro cyclic load fatigue testing of restored endodontically treated teeth. It is believed that the use of such devices will generate clinically relevant data on the mechanical performance of various commonly used endodontic posts, cores, cements, and crowns.

JOE — Volume 35, Number 3, March 2009

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PR 05 

Microbial Changes in Endodontic Infections Following Treatment Procedures I.G. Bennett*1, R. Nandakumar1, S.M. Barbuto2, B.J. Paster2, A.F. Fouad1 1 University of Maryland, Baltimore, MD, 2The Forsyth Institute, Boston, MA The purpose of this study was to show, using sensitive molecular techniques, how treatment procedures may change the composition of microorganisms identified in endodontic infections. Specimens were obtained immediately following access preparation in 42 teeth with primary or persistent endodontic infections, and at the second appointment following intracanal Ca (OH)2 medication for 1-2 weeks (CHM). For 25 teeth, an additional specimen was obtained at the first appointment, following chemomechanical instrumentation (CMI). PCR with broad range 16S rDNA bacterial primers was performed, and the products were cloned into the vector pCR 2.1-TOPO TA and transformed into E. coli One-Shot TOP10. 16S rRNA cloned inserts were purified and sequenced. Phylogenetic analysis was performed to determine final identity. A total of 3655 clones from 320 phylotypes were identified. No bacteria could be identified in 44% of specimens following CMI and 36% percent of specimens following CHM (Chi-square; p>0.05). When bacteria were detected, 85% of the phylotypes present prior to treatment were not detected after CMI, and 91% of them were not detected after CHM. One-hundred and one phylotypes not detected preoperatively were found after CMI, 88% of which were not detected after CHM. However, 11.9% of the 101 new phylotypes present after CMI were still detected after CHM. 209 phylotypes not detected preoperatively were found after CHM. Phylotypes that persisted following CHM included Enterococcus casseliflavus/flavescens/gallinarum (67%), E. italicus/saccharominimus (67%), Lactococcus lactis (60%), and Mogibacterium timidum (33%). In conclusion, these molecular methods allowed the identification of novel endodontic microflora that survived endodontic techniques.

PR 07 

Comparison of Ex Vivo Human Dental Pulp Responses to Scaffolds S. Chandrahasa*, P. Murray, K. Namerow, S. Kuttler, F. Garcia-Godoy Nova Southeastern University, Fort Lauderdale, FL The purpose of this study was to measure and compare the adherence and growth of human dental pulp (DP) tissues in three-types of tissue-engineering scaffolds. Following IRB approval and patient consent, freshly-extracted teeth were collected immediately following extraction for routine dental treatment reasons. The teeth (n=15) were cut into 1mm thick longitudinal tooth slices (n=45) using a diamond-blade rotary saw (Buehler, Lake Bluff, IL) and placed in submerged in Dulbecco’s Minimal Essential Media containing 10% fetal calf serum and antibiotics, maintained at 37oC in a 5% CO2 atmosphere for 7, 14, and 21 days. Neutral red dye (0.0016%) was added to the culture media to stain metabolically active cells. During culture, three-types of tissue-engineering scaffolds; polymer, collagen, and calcium phosphate (BD Biosciences, Franklin Lakes, NJ) were placed in direct contact with the DP of the tooth slices. The specimens were fixed in formalin, dehydrated and processed for histology. The numbers of DP cells were counted per light microscope field (x200 magnification) according to ISO criteria. Data was analyzed by analysis of variance (ANOVA) statistical tests (P values) at a significance of 95%. The greatest numbers of dental pulp DP cells were observed in the collagen and polymer scaffolds, compared to the calcium phosphate scaffolds (P<0.05) especially over longer time periods (P<0.05). These ex vivo results suggest that polymer and collagen scaffolds have the potential to be used as part of dental pulp regenerate therapies. Supported by an AAE Foundation Grant and NSU Health Professions Division.

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JOE — Volume 35, Number 3, March 2009

PR 06 

Magnification’s Effect on Endodontic Fine Motor Skills D.J. Bowers*1, 2, G. Glickman2, E.S. Solomon2, J. He2 1 Keesler Air Force Base, Dallas, TX, 2Baylor College of Dentistry, Dallas, TX The purpose of this study was to quantitatively investigate the effect of magnification on fine motor skills used in endodontics. This study utilized a novel, precision manual dexterity (PMD) test performed with and without magnification. The PMD test consisted of accurately penetrating a series of fine targets printed on a test sheet of paper with a #10 C-file. The test sheet, attached to a foam backing, was made up of 4 target fields containing 10 circular 0.3mm targets and 4 fields containing 10 circular 0.35mm targets. Blinded accuracy scores were provided for each test sheet ranging from least accurate (0) to most accurate (3). Forty subjects, 20 with microscope experience and 20 without, participated in the study. Each subject performed 3 identical PMD tests using unaided vision, dental loupes with 2.5X magnification, and the operating microscope (OM) with 8X magnification. Statistical analysis was performed using one-way ANOVA and posthoc Student-Newman-Keuls test (p< 0.05). Accuracy scores increased overall 17.5% with 2.5X loupes and 57.7% with the 8X OM compared to unaided vision. The average time required to complete the unaided vision test was 240.08 seconds, increasing to 440.55 seconds with the OM; however, the increase in time was not significant among subjects with more than 3 years of microscope experience. OM magnification significantly increased fine motor skill accuracy, independent of microscope experience. Additionally, this increased accuracy did not significantly increase required working time for experienced (>3 yrs) practitioners.

PR 08 

Nanoparticle-Based Endodontic Antimicrobial Photochemotherapy J. Chen*1, C.R. Fontana2, K. Ruggiero2, F. Foschi2, X. Song2, J. Dunham2, T.C. Pagonis1, H. Devalapally2, M.M. Amiji2, Z. Skobe2, R. Kent2, A.C.R. Tanner2, N.S. Soukos2 1 Harvard School of Dental Medicine, Boston, MA, 2The Forsyth Institute, Boston, MA We studied the effects of poly(lactic-co-glycolic acid) (PLGA) nanoparticles loaded with the photosensitizer methylene blue (MB) and light against Enterococcus faecalis, a pathogen associated with failures of endodontic treatment, in vitro. MB-loaded PLGA nanoparticles were prepared and characterized. The uptake and distribution in E. faecalis was investigated by transmission electron microscopy (TEM) after incubation with PLGA complexed with colloidal gold particles for 2.5, 5 and 10 min. A large fraction (>99%) of nanoparticles were found to be concentrated onto the cell walls of microorganisms at all three time points. Sensitization of E. faecalis species in planktonic phase with MB-loaded nanoparticles (final concentration: 6.25 μg/ml equivalent to MB) for 10 minutes followed by exposure to red light at 665 nm with an irradiance of 100 mW/cm2 and energy fluence of 60 J/cm2 led to approximately 2 log10 reduction of colony-forming units. Nanoparticles loaded with MB reduced bacterial survival by 34% in the absence of light. Methylene blue-loaded nanoparticles in combination with red light eliminated approximately 1 log10 of E. faecalis biofilm bacteria in experimentally infected root canals of human extracted teeth. The data suggest that PLGA nanoparticles encapsulated with photoactive drugs may have an application in antimicrobial endodontic therapy.

PR 09 

PR 10 

The aim of this study was to compare the shaping ability of two prototype rotary nickel-titanium instruments using x-ray micro-focus computed tomography. The mesial roots of 20 human mandibular molars, with independent orifices and apical openings, were scanned non-destructively at a spatial resolution of 100 µm before and after canal preparation. Canal preparation was accomplished using either a K-blade instrument with four blades (R3-30/.06, DENTSPLY Tulsa Dental Specialties, Tulsa, Okla.) used in a reciprocating fashion (220º CW, 80º CCW at 400 RPM) or a swaggering file that is cut circling around a central core such that the envelope of motion of any point on the asymmetric file circumscribes an arc around the midpoint (X3-30/.06, DENTSPLY Maillefer, Ballaigues, Switzerland) used at 300 RPM as a standard nickel-titanium rotary instrument. The mesiobuccal or mesiolingual canal was randomly assigned and instrumented to a final apical matrix size of #30. Qualitative and quantitative analyses were performed on changes in canal volume, remaining dentin thickness and instrument centering ability using image analysis software (VG Studio Max 2.0, Volume Graphics GmbH, Germany). Data were analyzed with ANOVA, Wilcoxon and t-tests. The results indicated that both rotary instruments altered the morphology of the root canals (P < 0.05). More research is needed to optimize the effectiveness of rotary instruments to minimize changes in root canal morphology. Supported by NSU Health Professions Division.

The purpose of this study is to evaluate the efficiency of root canal preparation using two canal preparation techniques and assess the canal geometry by microcomputed tomography and three-dimensional reconstruction. The mesial roots of 20 mandibular molars (Weine Type III) were randomly shaped by either a prototype swaggering rotary instrument (X3, DENTSPLY Maillefer, Ballaigues, Switzerland), manufactured as an asymmetric file design or an EndoSequence 25/.06 (Brasseler USA, Savannah, Ga.) rotary instrument. The teeth were scanned prior to any canal preparation and subsequent to canal preparation at a spatial resolution of 100 µm. Time taken to prepare using each system was recorded to an accuracy of 1 s. Analyses of the centering ability, change in total canal volume and linear dentin removal were performed on the three-dimensionally reconstructed teeth. Factorial ANOVA and Student t-test were used to assess variations in time and canal alteration when prepared using the X3 and Sequence 25/.06 instruments. The results indicated changes in canal volume (P < 0.05) and linear dentin removal (P < 0.05) with both rotary instruments. Further research is needed to optimize the ability of rotary instruments to maintain original root canal morphology and to minimize changes in linear dentin removal towards the furcation danger zone. Supported by NSU Health Professions Division.

PR 11 

PR 12 

Single Instrument Root Canal Preparation Using a Reciprocating Four-Bladed Nickel-Titanium File vs. a Swaggering Rotary Prototype Instrument Assessed by Micro-CT S. Cherian*, A. Lloyd, K.N. Namerow Nova Southeastern University, Fort Lauderdale, FL

Endo-Antral Syndrome: Are Bisphosphonates to Blame? N.C. Dewsnup*, M.R. Edlund, R. Heydrich, U. Nair University of Florida, Gainesville, FL Endo-antral syndrome (EAS) has been described as a spread of pulpal infection beyond the confines of the tooth and into the maxillary sinus. EAS typically involves teeth that do not heal satisfactorily after initial root canal therapy and can be difficult to diagnose and treat due to variations in symptoms and clinical findings. Selden named five features commonly associated with EAS. (1) pulpal infection in a tooth which is close to the sinus, (2) PA radiolucency on pulpally involved tooth, (3) loss of lamina dura defining the inferior border of the sinus over the pulpally involved tooth, (4) a radiopaque mass bulging into the sinus above the involved tooth, (5) varying degrees of radiopacity in the involved sinus. It is now well recognized that a history of bisphosphonate use can lead to compromised healing in sites of previous dental treatment and induce osteonecrosis of the jaws. Whether or not bisphosphonates can contribute to failure of endodontic treatment and subsequent EAS remains an important question. The purpose of this poster is to present a diagnostically challenging case of EAS in a patient with a history of oral bisphosphonate use. Further, one approach to effective management of this condition is described which may prove useful in diagnosing and treating similar cases.

Key:

 denotes Resident

* denotes Presenter(s)

Root Canal Instrumentation Using a Prototype File and EndoSequence™ 25/.06: Efficiency and Canal Geometry Assessment Using Microcomputed Tomography R. Desir*, A. Lloyd, K.N. Namerow Nova Southeastern University, Fort Lauderdale, FL

Ex Vivo Radiographic Assessment and Size Determination of Simulated External Root Resorptions of Maxillary Anterior Teeth T.N. Drake*, R.E. Walton, W.T. Johnson, A. Ruprecht University of Iowa, Iowa City, IA Introduction: The purpose of this study was to quantify the size at which simulated external root resorptions of maxillary anterior teeth are detectable. Analog and digital radiographs were also compared. Material and Methods: One cadaver maxilla with all anterior teeth and superimposing soft tissues present (nose, lips, cheeks, etc.) was harvested en bloc. Teeth were extracted. Resorptive-type cavities were made at the anatomical apex and along the proximal radicular surfaces of each tooth beginning with a size ¼ round bur. Teeth were then replanted. Analog and digital radiographs were made using a custom fabricated positioning stint for each tooth. This process was repeated and radiographs were made for progressively larger cavities (sizes ½, 1, 1½, 2, 3, and 4 round burs.) Blinded evaluators indicated presence or absence and location of resorptive cavities. Pre-extraction radiographs of teeth without resorptive cavities served as negative controls. Size 4 round cavities were positive controls. Results: Preliminary data showed the volumetric threshold for cavity detection was .6 mm3, or the size of a 1½ round bur. Nearly all cavities with a volume of 2.3 mm3 (size 4 round bur) were detected. No differences were noted between analog and digital radiographs or between cavities at various proximal levels. The volumetric threshold for cavity detection was larger for canines than for central or lateral incisors. Conclusions: Very small resorptive cavities (<.6mm3) were often not detected with either analog or digital radiographs.

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PR 13 

Evaluation of Volumetric Contraction in Nanocomposite Enhanced Retrofill Polymer R. Duval*, S. Potluri, A.K. Mickel, S. Chogle, J. Jones Case Western Reserve University, Cleveland, OH Nanocomposites (NC) are a new class of polymeric materials containing well dispersed clay platelets. When dispersed in a polymer matrix at a nano-scale the Nanocomposites offer tremendous improvement in dimensional stability, stiffness, mechanical and thermal properties (Venhoven). For the properties to be observed, the nanoparticles must be evenly distributed through the PolymerMonomer Matrix (PMM) and without uniform distribution of nanoparticles, the material can undergo Polymerization Shrinkage (PS) (Antonucci, Stansbury). We hypothesize that nanocomposites with optimum concentrations of Nanoparticles will result in reduction of volumetric contraction of the Nanocomposite Enhanced Retrofill Polymer (NERP). The objective of this study was to determine optimal concentration of an organoclay nanoparticle (C18) in NERP and assess its effect on volumetric contraction. The NERP groups included: 1 PMM only; 2 PMM+1% C18; 3 PMM+1% C18+2% Chlorhexidine (CHX); 4 PMM+2% C18; 5 PMM+2% C18+2% CHX. These were compared to Geristore™ and TPH (light-cured hybrid composite). The PMM and initiator concentration held at constant levels, volumetric contraction was measured by computer controlled mercury dilatometer at NIST facility in Gaithersburg, MD. Statistical analysis Pairwise Comparison between groups 1 and 3 (p=0.16). The overall shrinkage due to polymerization calculated based on the known mass of polymer. Mean volumetric shrinkage for group 2 was the least among the NERP, Geristore showed the least shrinkage of all groups tested. In the present study we found that NERP with 1% C18 demonstrated the least volumetric shrinkage within the NERP groups. Further studies are underway to evaluate the efficacy of NERP as a retrofill material in endodontics.

PR 15 

Association of TNF-Beta Polymorphism to the Clinical Presentation of Periradicular Disease J.J. Ferrari*, S. Bolden, A. Mickel, S. Chogle, J. Jones Case Western Reserve University, Cleveland, OH Multiple factors contribute to pathogenesis of periradicular bone resorption including microbes, immune response, osteoclastogenesis, and cytokines. Cytokines are proteins that regulate immune response, being pro/anti-inflammatory. Altered expression of some cytokines resulting from gene polymorphism can potentiate inflammatory response leading to apical periodontitis. Tumor Necrosis Factor (TNF) is a potent proinflammatory cytokine that is able to induce tissue destruction and bone resorption. The purpose of this study was to investigate the relation between TNF-Beta gene polymorphism and susceptibility to a patient presenting with CAP (Chronic Apical Periodontitis=CAP). We hypothesized that gene polymorphism of TNF-Beta could modulate host responses and enhance inflammatory reactions leading to CAP. A case-control study was conducted on subjects who presented to the Graduate Endodontic Department for root canal treatment. 135 subjects who presented with either chronic apical abscess, chronic apical periodontitis or acute apical abscess were used for this study. Thirty-seven patients with no history of caries or periradicular disease served as controls. Buccal swabs were collected for DNA isolation and analysis. Genomic DNA was amplified using polymerase chain reaction followed by dye termination to distinguish the alleles of TNF-β gene polymorphism. Multivariate logistic regression was done for each diagnosis classification to obtain the adjusted odds ratios. The polymorphism in TNF-β showed significant differences between cases and controls and between CAP and CAA. Subjects that carried the heterozygous polymorphic variant for TNF-β were 3.7 times more likely to present with chronic apical periodontitis than subjects who express the homozygous polymorphic G/G allele of TNF-β.

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PR 14 

The Opinions of Diplomates Towards Regenerative Endodontics I.E. Epelman*, P. Murray, K. Namerow, S. Kuttler, F. Garcia-Godoy Nova Southeastern University, Fort Lauderdale, FL The success of regenerative procedures requires endodontic practitioner acceptance, but little or no evidence is available. The purpose of this study was to survey the opinions of 56 attendees of the 2008 College of Diplomates Summer Conference on the issue of regenerative endodontic procedures (REP). Following NSU IRB approval, one-hundred copies of a 40-question survey was circulated at the Conference, and 56 completed surveys were returned anonymously. The survey found that 96% thought that more regenerative therapies should be incorporated into treatments. Although only 14% had used umbilical cord or stem cell banking for themselves or a relative, 63% thought that stem cell banking would be useful to regenerate dental tissues. 89% of the respondents would be willing to save teeth and dental tissues for stem cell banking. A fear of the risks of stem cell therapy was expressed by 31% of respondents; however 90% would be willing to receive training in REPs. Most of the respondents (58%) thought that the greatest obstacle to the introduction of REPs was their higher cost. Almost half the respondents (49%) thought that REPs would be more successful than implants. Almost two-thirds (62%) of respondents thought that that dental professional associations should regulate the use of stem cell and regenerative dentistry. These results suggest that Diplomates are optimistic about the future use of REPs. The authors gratefully acknowledge the assistance of the College of Diplomates of the American Board of Endodontics. Supported by an AAE Foundation Grant and NSU Health Profession Division.

PR 16 

Fusobacterium Nucleatum in Endodontic Infections D.S. Fife*, C.W. Kaplan, S.K. Haake University of California at Los Angeles, CA Fusobacterium nucleatum (Fn) is an important human and endodontic pathogen. Limited data exist on Fn subspecies distribution relative to health and disease, as well as expression of virulence determinants. The aims of this study are to use molecular approaches to classify the subspecies of Fn isolates from endodontic infections and adjacent healthy periodontal sites, compare the distribution of subspecies from these sites, and determine the expression of specific fusobacterial outer membrane proteins (FOMPs) implicated in virulence properties. In this study, the samples of necrotic root canals and adjacent healthy periodontal pockets were taken on human subjects using conventional anaerobic cultivation techniques. Fn strains have been isolated from 75% of the samples on selective media, with mean CFUs of 1.39 X 103 and 9.32 X 104 for the endodontic and periodontal isolates respectively. The strains are subspeciated by sequence analysis of 16S rDNA and the beta subunit of the DNA gyrase gene gyrB. The high molecular weight FOMPs expressed in these strains is determined by SDS-PAGE and the identity of selected FOMPs by mass spectroscopic analyses. The results of this study demonstrate that there was a higher prevalence of Fn in the periodontal sites than in the endodontic sites. Additional studies will clarify the subspecies and FOMP distribution among the strains and may shed light on virulence properties of significance to endodontic infections.

PR 17 

An In Vitro Comparison of Profile GT™ and GTX™ NiTi Rotary Instruments in Apical Transportation and Length Control in Mandibular Molars S. Floratos*, Y. Hsu, S. Mahajan, B. Karabucak, M.K. Iqbal University of Pennsylvania, Philadelphia, PA In a recent design change, DENTSPLY Tulsa Dental Specialties (Tulsa, OK USA) has introduced the M-Wire nickel-titanium technology. According to the manufacturers, this new alloy significantly increases resistance to cyclic fatigue and file separation and provides faster cutting and canal shaping efficiency. In this study, a double-digital radiographic technique was used to compare apical transportation (AT) and length control (LC) between Profile GT™ rotary files and the new GTX™ rotary files. The mesiobuccal canals of forty extracted first and second mandibular molars were instrumented by each rotary system, according to the manufacturers’ instructions. Digital radiography and AutoCAD 2009 were used to determine the central axes of files at size15K hand file and 30/04 rotary file. By superimposition of central axes with a baseline at size 15, the degree of AT was measured at 1 and 3 mm from working length (WL). The distance from file tips to set WL indicated any change in LC. ANOVA test showed no significant differences between groups in the amount of AT. The mean change in WL for the GTX™ group was -0.25 +/- 0.42. For the Profile GT™ group, the change in WL was 0.17 +/- 0.30. This difference was statistically significant at p<0.001. However, this difference in LC may not be clinically significant. The results indicate that the newly designed GTX™ rotary instruments maintain the same effectiveness regarding AT as that of the current Profile GT™ instruments. However, further research is required to assess any difference in cutting efficiency and cyclic fatigue.

PR 18 

A Comparison of Apical Transportation and Length Control Between EndoSequence™ and Guidance™ Rotary Instruments A.J. Gatan*, C. Hsiao, B. Karabucak, M. Iqbal University of Pennsylvania, Philadelphia, PA The prognosis of root canal treatment depends on the ability to eliminate bacteria and hermetically seal the canal. It has been shown that transportation leaves walls of the canal untouched, leaving bacteria behind. Therefore, the aim of this study was to evaluate and compare the apical transportation and length control between EndoSequence™ (Brasseler, Georgia) and Guidance™ (Guidance Endo, NM) rotary files. Fifty canals, mesio-buccal or mesial-lingual, from extracted mandibular first and second molars were instrumented using EndoSequence™ or Guidance™ NiTi rotary files. The manufacturer’s instructions were followed strictly for both systems. Group 1 consisted of 25 canals instrumented to a 25/.06 EndoSequence™ file by a crown down technique following pre-coronal flare with Gates Glidden burs. Group 2 consisted of 25 canals instrumented to size a 25/.08 Guidance™ file by a crown down technique following pre-coronal flare with the 30/.10 file. The double digital radiographic technique along with AutoCad 2009 was used to determine central axes at the maximum curvature pre-instrumentation (size 10K file) and post-instrumentation (EndoSequence™ 25/.06, Guidance™ 25/.06). Loss of working length and apical transportation were measured at 0, 1, and 3 mm from the working length. Results were analyzed using repeated measure ANOVA. Results indicated that there was no statistically significant difference in loss of working length or transportation at any level between EndoSequence™ and Guidance™ rotary files.

PR 19 

PR 20 

Epstein-Barr virus (EBV) has emerged as a putative periapical pathogen. The pathogenesis of EBV within pulp tissue is relatively unknown. This pilot study was undertaken to determine the EBV status, the presence of selected bacteria and the relationship of each of these pathogens to inflammatory responses within irreversible pulpitis. Ten patients who presented with spontaneous pain and were diagnosed with irreversible pulpitis were recruited to the study (UNC IRB, study # 08-0229). Teeth were accessed after rubber-dam isolation and disinfection with 2% Chlorohexadine. Pulp tissue was collected using sterilized barbed broaches and stored in RNAlater (Qiagen) in -80°C. Nucleic acids were isolated from pulp tissue using DNeasy and RNeasy kits (Qiagen). Quantitative PCR was employed to assess EBV viral load and total bacterial load along with loads for Streptococcus sp., Lactobacillus sp., Actinomyces sp., Fusobacterium sp. and Enterococcus faecalis (E. faecalis). The mRNA expression levels for inflammatory genes including IL-6, IL-10, TNF-α, and TNF-β were also evaluated in these same samples using real-time RT-PCR. EBV was detected in all samples. E. faecalis was not detected in any of the samples; all other bacterial species were detected in all samples. Significant correlations (Correlation coefficient>0.90, P<0.01) were detected between IL-6, IL-10, TNF-α and TNF-β expression levels. Regression analysis did not indicate a linear relationship between the inflammatory gene expression levels, EBV load, or bacterial load. In this study, we detected a high prevalence of EBV in diseased pulp tissue. Further study is needed to evaluate EBV’s potential role in endodontic diseases.

Periapical pathology is a multifactorial disease representing an interaction between a microbial challenge and immune response, which results in cytokine production and ultimately bone resorption. The host defensive reaction against irritants from the infected root canal induces inflammatory mediators from a variety of cells. These cells stimulate the production of cytokines, several displaying inflammatory and others anti-inflammatory properties. IL-1β, IL-6 and tumor necrosis factor are cytokines that stimulate bone resorption. The purpose of this study was to investigate if functional gene polymorphisms affect periradicular diagnosis. It was hypothesized that the polymorphisms IL-1β, IL-6, IL-10 and TNF-β would affect the way a subject responds to infection. A case-control study was conducted. Forty-six patients with chronic apical abscess(CAA), fifty-nine with chronic apical periodontitis(CAP) and thirty-one with acute apical abscess(AAA) were included. Thirty-seven patients with no history of caries or periradicular disease served as controls. Buccal swabs were collected for DNA analysis. DNA was amplified using polymerase chain reaction and dye termination to distinguish alleles of IL-1β, IL-6, IL-10 and TNF-β. Statistical analysis, including multivariate logistic regression was performed. No association was found between any diagnosis with IL-1β, IL-6 or IL-10 polymorphism. There were significant differences between AAA, CAA and CAP subjects in TNFβ polymorphism. Subjects with the wild type (normal) A/A are 17 times more likely than the homozygous polymorphic variant G/G to present with CAA. When comparing AAA to CAP, the wild type A/A are 11 times more likely to present with AAA compared to the homozygous polymorphic G/G genotype.

Assessment of Virus, Bacteria and Inflammation in Pulp Tissue With Irreversible Pulpitis F. Gu*, E.M. Rivera, J. Webster-Cyriaque University of North Carolina, Chapel Hill, NC

Key:

 denotes Resident

* denotes Presenter(s)

A Possible Influence of IL-1β, IL-6, IL-10 and TNF-β Polymorphisms on Periradicular Diagnosis K.M. Hopkins*, S. Bolden, A. Mickel, S. Chogle, J. Jones Case Western Reserve University, Cleveland, OH

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PR 21 

PR 22 

When endodontic therapy fails, in terms of development or persistence of periradicular pathosis or symptoms, treatment options include retreatment or surgical therapy. While guidelines are in place, the treatment route is left to the discretion of the clinician and the patient. A retrospective study was conducted that examined the treatment trends at the New Jersey Dental School Postgraduate Endodontic Program. Chart entries and radiographs were reviewed from onethousand randomly selected charts treated over the past five years (2002-2008). The results indicate that first time retreatment accounted for 19% of patient care. Approximately 3% of the retreated cases required subsequent apical surgery. Mandibular molars (23%) were the most commonly retreated teeth; however, overall there were twice as many maxillary teeth retreated compared to mandibular. The most frequently cited reasons for retreatment were faulty/leaky restorations followed by obturation short of the apex (defined as greater than 2 mm from the radiographic apex). With regards to the surgical trends, 7% of the total reviewed cases had apicoectomies. Of these teeth, 10% had previous surgical treatment preformed. There were twice as many surgeries performed in maxillary (66%) versus mandibular teeth (33%). However, there were an equal number of maxillary molars (17%) as mandibular molars (16%). A future look at outcomes of these two procedures could lend itself to a more evidence based approach in determining treatment approaches for failing endodontic cases. Examining the trends over the past 5 years provides greater insight into the allocation of surgical versus retreatment cases.

Purpose: The purpose of this prospective randomized double-blinded study was to compare the anesthetic efficacy of 1.8 ml 4% articaine with 1:100,000 epinephrine and 1.8 ml of 2% lidocaine with 1:100,000 epinephrine in mandibular molars with irreversible pulpitis. Material/Method: Thirty-one emergency patients received either: (Group 1) articaine block and articaine infiltration, (Group 2) lidocaine block and lidocaine infiltration, or (Group 3) lidocaine block and articaine infiltration. Patients that reported inadequate lip and tongue numbness and/or painful response to Endo Ice were excluded from the study. Anesthetic success was defined as the ability to access and instrument the root canal without pain (VAS score of zero). Data was analyzed using statistics for binomial and categorical outcomes to explore association of interests. Results: Only twenty subjects that responded negative to Endo Ice after mandibular block and buccal infiltration were retained in the study. One out of 8 (12.5%) was successful in Group 1, 0 out of 4 (0%)was successful in Group 2, and 3 out of 8 (37.5%) was successful in Group 3. Lidocaine was more effective in blocking response to cold at 10 minutes interval compared to articaine when used as a mandibular block (p=.007). However, articaine was statistically more significant yielding a negative response to cold when used for infiltration (p=.038). Preliminary results indicate that conventional mandibular blocks and buccal infiltrations may not be sufficient for anesthetizing irreversibly inflamed pulps.

PR 23 

PR 24 

Retrospective Analysis of Treatment Trends for Failing Endodontically Treated Teeth S. Hubbi*, V. Tawadros, G.R. Hartwell University of Medicine & Dentistry of New Jersey, Newark, NJ

Current use and Views of Carrier-Based Obturation: Report of a Survey G.P. Kaban*1, 2, G.N. Glickman2, E.S. Solomon2, J. He2, J.L. Schweitzer2 1 Keesler Air Force Base, Dallas, TX, 2Baylor College of Dentistry, Dallas, TX The purpose of this study was to conduct surveys to determine current usage and views of carrier-based obturation among two groups: Board-Certified Endodontists and dental school educators within the United States and Canada. Two separate surveys regarding current practice habits, teaching preferences, and perceptions related to carrier-based obturation, were mailed to 966 Diplomates of the American Board of Endodontics and 62 dental school pre-doctoral directors of endodontics, respectively. A total of 648 Diplomates (66%) responded. 96.4% (618/648) indicated they do not currently use a carrier-based obturation system in their practice. The 3.6% (23/648) that do practice carrier-based obturation cited support from the literature as their primary reason for using this technique. Regarding retreatment of carrier-based obturation cases, 96.1% (597/621) of respondent Diplomates attributed inadequate cleaning and shaping as the reason for failure. Forty (64%) dental school pre-doctoral directors responded to the second survey. 80% (32/40) of these respondents indicated they currently do not teach carrier-based obturation to their students. Reasons for not teaching carrierbased obturation included: “difficult to remove, difficult to make post space, and not predictable.” Six schools that do teach the technique use Thermafil™ and cited “predictable results” as their primary reason for using this product. Although these surveys suggest that carrier-based obturation is neither practiced nor taught in great numbers by the respondents, only 35% feel that carrier-based obturation is below the standard of care. Both surveys demonstrate that carrier-based obturation is still a controversial issue within the endodontic community.

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Comparison of Anesthetic Efficacy of Articaine and Lidocaine for Inferior Alveolar Nerve Blocks With Buccal Infiltrations in Patients With Irreversible Pulpitis M.K. Iqbal, B.D. Greenberg*, D. Wang, E.V. Hersh, A. Pinto University of Pennsylvania, Philadelphia, PA

An In Vitro Study Comparing the Torsional Profiles of New and Used 20/.06 GT® and GT® Series X™ Rotary Endodontic Files T.M. Kell*1, A. Azarpazhooh1, O.A. Peters2, O. El-Mowafy1, B. Tompson1, B. Basrani1 1 University of Toronto, ON, Canada, 2University of the Pacific, San Francisco, CA M-Wire™ is reportedly created by altering alloy temperatures during the manufacturing process of GT® series X™ files. Currently, there are few published studies looking at torsional profiles of this alloy. The purpose of this study was to evaluate and compare the torsional profiles of new and used 20/0.06 GT® and GT® series X™ (GTX) rotary files. Of the 240 files used in this study, 30 were randomly allocated to one of 8 groups to be used 2, 6, or 10 times in simulated canals or remain as unused controls. Canal preparation was conducted in a crown down manner with 5.25% NaOCl and sterilization cycles between uses. Testing of torque (TF) and angle (AF) at fracture was conducted in accordance with ANSI/ADA Specifications No. 28, by using a digital torque meter and ‘ENDOTEST’ software. The statistical power of this study is 88%. Data analyses were performed using one- and two-way ANOVA with HSD post hoc comparison, with alpha=0.05. Overall results indicate a significant reduction in TF with increased use of GT (p<0.004) in contrast to the GTX which had a significant initial increase in TF with 2 and 6 uses which eventually dropped (p<0.001). Both the GT and GTX showed a significant decrease in AF in all groups except the GT 2 use group (p<0.021). M-Wire™ proved to have a slightly higher resistance to torsional fracture after use as compared to traditional nickel titanium.

PR 25 

In Vitro Comparisons of Debris Removal of the EndoActivator™ System, the F™ File, Ultrasonic Irrigation and NaOCl Irrigation Alone Following Hand-Rotary Instrumentation in Human Mandibular Molars S.L. Klyn*, T.C. Kirkpatrick, R.E. Rutledge Wilford Hall U.S.A.F. Medical Center, Lackland Air Force Base, TX The purpose of this in vitro study was to compare the debris removal efficacy of the EndoActivator™ system, the F™ file, ultrasonic irrigation and 6% NaOCl irrigation alone in human mandibular molars after hand-rotary instrumentation. A custom brass cube (K-Kube) was used to create a sealed canal system allowing each tooth to serve as its own control. Forty extracted mandibular molars were randomly divided into 4 equal experimental groups. Each tooth was mounted, sectioned at 1, 3, and 5 mm from the working length, then reassembled into the K-cube and the mesial roots were similarly prepared using hand-rotary instrumentation. Final debridement: Group 1: F™ file for 30 seconds; Group 2: EndoActivator™ system for 30 seconds; Group 3: Ultrasonic irrigation for 30 seconds; Group 4: Irrigation with 6% NaOCl within 1 mm of working length. All groups received a final irrigation with 2 ml of 6% NaOCl in each canal. Specimens were evaluated at 1, 3, and 5 mm from the working length for cleanliness by capturing a digital image using a stereomicroscope. All specimens had the percent cleanliness for each canal and isthmus calculated both before and after final debridement. Statistical analysis was completed using a repeated measures ANOVA with Tukey’s posthoc tests. The results showed no statistically significant difference in canal or isthmus cleanliness among the 4 groups, but there was a statistically significant difference (p<0.001) in canal cleanliness between the 1 mm level versus the 3 and 5 mm levels for all of the groups.

PR 26 

An In Vitro Comparison of Torsional Stress and Cyclic Fatigue Resistance of ProFile GT® and ProFile GT® Series X™ Rotary Nickel-Titanium Files T.R. Kramkowski*, J.K. Bahcall Marquette University, Milwaukee, WI The purpose of this in vitro study was to compare the torsional stress and cyclic fatigue characteristics of ProFile GT® and ProFile GT® Series X™. Files of 0.04 and 0.06 taper; 25 mm in length; and ISO sizes of 20 and 30 tips were compared (n=25 per test group). Torque stress resistance was evaluated by measuring the torque (GM-N) and angle of deflection (degrees of rotation) required for instrument separation with use of a torsiometer instrument. Cyclic fatigue was determined by recording the time until breakage of a file rotating in a cyclical axial motion in a simulated canal with an applied 45o or 60o curve with a 5-mm radius. T-Test analysis revealed no statistical difference (p>0.05) when comparing the torque (GM-N) required to induce a torsional failure of GT® and GT® Series X™ files of identical file sizes. Angle of deflection (degrees of rotation) of GT® was significantly greater (p≤.001) prior to separation than GT® Series X™ for all file sizes tested except 20/.04 (p>0.05). There was no statistical difference (p>0.05) in cyclic fatigue failure for GT® and GT® Series X in a canal with a curvature of 45o. In the 60o canal curvature, GT® was found to be significantly more resistant to fracture due to cyclic fatigue than GT® Series X™ for file sizes 20/.06 (p≤.001), 30/.04 (p≤.001), and 30/.06 (p=.005). There was no difference in cyclic fatigue resistance in the 60o canal for GT® and GT® Series X™ for file size 20/.04 (p>0.05).

PR 27 

PR 28 

Toothaches are a frequent and common pain complaint in the general population. Non-surgical root canal treatment is a predictable and relatively successful treatment option for pain of odontogenic origin. However, in certain cases, even though the endodontic treatment appears to be both clinically and radiographically successful, the individual may continue to complain of persistent pain. These individuals may be experiencing a type of pain referred to as “neuropathic pain.” The aim of this study was to quantify, utilizing a self-reported validated postal survey, the number of subjects, characteristics, location and severity of neuropathic pain present in an adult population who received non-surgical endodontic treatment in a university based postgraduate endodontic clinic. A modified version of the Self-Administered Leeds Assessment of Neuropathic Symptoms and Signs (S-LANSS) survey and consent form with a pre-stamped return envelope was mailed to 1,838 subjects who received single tooth non-surgical endodontic treatment between November 1, 2004 and October 31, 2007. A response rate of 10.3% (N=189) was established. Of the subjects who returned the questionnaire, 67.2% (N=127) fully answered all the questions and were therefore included in the final analysis. Approximately 15% (N=19) received a positive score predictive of neuropathic pain. Of the 19 subjects who scored positively for neuropathic pain, 12 were female and 13 of the 19 teeth were present in the mandibular arch. In this study population, the prevalence of persistent pain possibly of neuropathic origin after non-surgical root-canal treatment was 15% and occurred more commonly in the mandibular arch with a female predilection.

The creation of dental pulp constructs in the laboratory for regenerative root canal therapy requires the seeding of dental pulp stem cells (DPSCs) on tissue engineering scaffolds. The objective of this study was to measure and compare the survival of DPSC on three types of rigid scaffolds; polymer, collagen, and calcium phosphate (BD Biosciences, Franklin Lakes, NJ) and three types of injectable bone augmentation scaffolds; DBX demineralized bone, Pepgen P-15 putty, and Puramatrix™ pep hydrogel (DENTSPLY Tulsa Dental Specialties, Tulsa, OK). A total of 90 tissue constructs were created by seeding the scaffolds with 106 cells with the aid of a sterile micro-syringe. A further three scaffolds were not seeded with cells as a negative control. All the specimens were maintained in Dulbecco’s Minimal Essential Media containing 10% fetal calf serum and antibiotics, at 37oC in a 5% CO2 atmosphere for between 7 and 21 days. Neutral red dye (0.0016%) was added to the culture media to stain metabolically active cells. The cell survival within the constructs was measured using histologic criteria and the numbers of cells were counted per light microscope field of view. The data was analyzed using the analysis of variance (P value) statistics. The survival of DPSCs was more optimal in the rigid scaffolds, compared to the injectable bone augmentation scaffolds (P<0.05). These in vitro results suggest that rigid scaffolds provide the most optimal environment to deliver DPSCs for regenerative root canal therapy. Supported by an AAE Foundation Grant and NSU Health Professions Division.

A Survey of the Prevalence of Persistent Pain After Non-surgical Endodontic Treatment A.M. Kugelmann*, G.D. Klasser, B.R. Johnson University of Illinois at Chicago, IL

Key:

 denotes Resident

* denotes Presenter(s)

Cell Survival Within Delivery Scaffolds for Regenerative Root Canal Therapy G. Llavona*, P. Murray, K. Namerow, S. Kuttler, F. Garcia-Godoy Nova Southeastern University, Fort Lauderdale, FL

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449

PR 29 

Bacterial Leakage of Temporary Endodontic Restorative Materials C. Loucks*, B. Reavley, G.R. Hartwell University of Medicine & Dentistry of New Jersey, Newark, NJ An ideal temporary material for endodontics should seal the access cavity avoiding re-infection, be resistant to mechanical forces and thermal changes, be nontoxic, and not affect future bonding to the tooth structure. Previous studies have investigated whether new temporary endodontic materials seal better than IRM. Findings indicate that all popularly utilized endodontic temporary material are superior to IRM. The aim of this study is to investigate how long the most popularly utilized temporary endodontic restorative materials can resist bacterial leakage. Decoronated molars were randomly assigned to each group. In addition to positive and negative controls, temporary materials were placed (Cavit, Ketac-Silver, DuoTemp, and a dual seal Cavit and Ketac-Silver). S. mutans was introduced from the coronal aspect, and sterile BHI broth was sealed beneath the apparatus. Each sample was inspected for bacterial contamination, as indicated by turbidity of the BHI broth. Bacterial leakage results were identified as follows: positive controls, then Ketac-Silver. Dual seal Cavit and Ketac, Cavit, and DuoTemp were not statistically significantly different. Lastly, negative controls did not leak.

PR 31 

Diagnostic Accuracy of Cone Beam-Computed Tomography for Evaluation of Canal Lumina C. Maupin*, N. Chugal, D. Elashoff, T. Chang, G. Longhurst, M. Kang, S. White, S. Tetradis University of California at Los Angeles, CA Cone Beam-Computed Tomography (CBCT) utility and relevance to the practice of endodontics is reported with increasing frequency. Studies are needed to evaluate diagnostic efficacy of CBCT for endodontic applications. Objective: The purpose of this study was to compare CBCT and conventional radiography for their ability to detect root canal lumen, localize lumen origin and determine lumen diameter. Methods: Forty-three teeth/roots (n=43) were selected from an existing collection of extracted teeth. Two imaging systems were compared: CBCT images and periapical radiographs. The test teeth were mounted in a dry sagittally-sectioned mandible and CBCT scans and periapical radiographs were taken. The teeth were examined by MicroCT and scored for presence of canal lumen and lumen diameter. These scores served as the gold standard. The CBCT and periapical radiographs were evaluated by five evaluators. The CBCT images were evaluated dynamically in the axial, sagittal and coronal planes. Results: The prevalence of canal lumina as identified by MicroCT as standard reference was 100%. The percent agreement between MicroCT and CBCT in identifying canal lumina was 98.6%. Root canal lumina were detected in an average of 98% of the roots using CBCT and 64% of roots using periapical radiographs, a difference of 34% (p<0.05). The detection of canal lumen origin relative to a reference point was significantly more accurate in CBCT scans compared to periapical radiographs (p<0.05). Conclusion: The ability of CBCT images to detect and localize canal lumen and to aid in determination of canal diameter is superior to conventional periapical radiographs.

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JOE — Volume 35, Number 3, March 2009

PR 30 

Bactericidal Activity of Stabilized Chlorine Dioxide as an Endodontic Irrigant in a Polymicrobial Biofilm Tooth Model System J.R. Lundstrom*, A.L. Villhauer, A.E. Williamson, D.R. Drake University of Iowa, Iowa City, IA The polymicrobial nature of infected root canals makes their biofilm particularly resistant to chemical debridement. Rowpar Pharmaceuticals, Phoenix, Arizona, has introduced a product, CloSYSIITM, which in the concentrated form (0.4% stabilized chlorine dioxide), has proven effective against polymicrobial biofilms. The purpose of this study was to determine bactericidal efficacy of CloSYSII, 3% sodium hypochlorite, 2% chlorhexidine gluconate and sterile distilled water in a tooth polymicrobial biofilm model. Twenty primary bovine incisors were instrumented to identical length and preparation size in order to standardize volume. After coating canals overnight with mucin, teeth were inoculated with standardized suspensions of Streptococcus sanguinis, Actinomyces viscosus, Fusobacterium nucleatum, and Peptostreptococcus micros, and incubated anaerobically for fourteen days. Teeth were randomly divided into four groups (n=5) and rinsed for 2 minutes with 10ml irrigant. Canals were rinsed for 1 minute with 5ml of Neutralizing Broth, and biofilms were harvested and spiral-plated on selective and non-selective media. Numbers of bacteria in the harvested biofilms was then determined via standard spiral-plating methodology. Raw bacterial counts were log10 transformed. Data were analyzed by a 2-way ANOVA with post-tests. NaOCl and then CHX showed the highest levels of activity against all of the bacteria within the biofilms (p<0.05) although complete kill was only achieved with A. viscosus. Chlorine dioxide exhibited strong bactericidal activity against the anaerobic bacteria comparable to NaOCl (p<0.001), but significant decreases in S. sanguinis and A. viscosus were not achieved. Our data show that chlorine dioxide demonstrates strong bactericidal activity against anaerobic bacteria, but not facultative organisms.

PR 32 

Ten-Month In Vitro Leakage Study of a Single-Cone Obturation System (Activ GP™) A.J. McKissock*, P. Mines, M. Sweet U.S. Army Dental Activity, Fort Bragg, Fayetteville, NC The purpose of this study was to compare the in vitro sealing ability of a warm vertical compaction technique using gutta-percha to the sealing ability of the Activ GP™ Precision Endodontic and Obturation Systems (Brasseler, Savannah, GA, USA) in single canal teeth over a ten-month period of time. Fifty maxillary anterior teeth were randomly divided into 2 test groups (20 canals each) and two control groups (5 positive and 5 negative). Group 1 (GP) received canal preparation with Profile™ rotary instruments (DENTSPLY Tulsa Dental Specialties, Tulsa, OK, USA) and obturation with gutta-percha and AH Plus™ sealer (DENTSPLY Maillefer, Tulsa, OK, USA). Group 2 (Activ) was prepared and obturated with the EndoSequence™ File System (Brasseler, Savannah, GA, USA) and the heatless, single cone glass ionomer based Activ GP™ Precision Obturation System. The canal orifices were sealed with amalgam and stored for 10 months in 100% humidity at 37°F. Amalgam was removed and leakage was evaluated by fluid filtration at 10 psi. Average leakage for Group 1 (GP) was 1.13 mm, SD= ± 1.98. The leakage results of fourteen of the twenty teeth in Group 2 (Activ) were immeasurably high using the current fluid filtration system. The six teeth which registered measurable levels averaged 19.81 mm, SD = ± 23.71. Using a fluid filtration system, the Activ GP™ single-cone technique demonstrated significantly higher leakage rates than a warm vertical compaction and gutta-percha technique.

PR 33 

Bupivacaine Increases PGE2 Expression In Vitro A.V. Mischenko*, N. Letwin, K. Wills, A.F. Fouad, S.M. Gordon, L.M. Hicks University of Maryland at Baltimore, MD Surgical endodontic treatment often results in post-operative pain and inflammation. Pre-emptive and/or post-treatment administration of long-acting local anesthetics, such as bupivacaine, may inhibit central sensitization leading to diminution of post-operative pain. However, recent clinical studies of bupivacaine have shown a pro-inflammatory effect, resulting in up-regulation of COX-2 expression, increased PGE2 and increase in post-operative pain. The purpose of this study was to examine in vitro inflammatory mechanisms of two commonly used local anesthetics—lidocaine and bupivacaine. Whole blood from healthy volunteers was stimulated with physiologic concentrations of 0.5% bupivacaine/epinephrine 1:200,000 or 2% lidocaine/epinephrine 1:200,000, with positive (LPS) and negative (PBS) controls, and incubated at 37ºC for 24 hrs. PGE2 was measured using ELISA. PGE2 concentrations significantly increased following bupivacaine stimulation as compared to PBS and lidocaine (p< 0.001). PBS and lidocaine were similar to each other. The difference between bupivacaine and LPS was not significant (p>0.001). These results suggest that bupivacaine plays a role in the up-regulation of inflammation through the COX pathway.

PR 35 

Effect of VEGF on the Revascularization of Severed Human Dental Pulps E.M. Mullane*, C.M. Sedgley, J.C.C. Hu, T.M. Botero, G.R. Holland, J.E. Nör University of Michigan, Ann Arbor, MI Tooth avulsion is a common type of trauma in children and young adults. Replantation is the treatment of choice, but complications such as ankylosis, pulpal necrosis, external root resorption make the long-term prognosis of avulsed teeth questionable. Recently, it was shown that vascular endothelial growth factor (VEGF) is capable of inducing an angiogenic response in dental pulps in vitro. We do not know if VEGF induces revascularization of severed dental pulps in vivo. The purpose of this study was to evaluate the effect of VEGF on the revascularization of human pulp tissue of tooth slices implanted subcutaneously in severe combined immunodeficient (SCID) mice. Noncarious human third molars were sliced with a sterile diamond saw cross-sectionally at the CEJ to produce 1 mm thick slices. Slices were treated ex vivo in culture media supplemented with 50 ng/ml rhVEGF165 or in control culture medium. After 1 hour, tooth slices were implanted subcutaneously in SCID mice. After 14 days, mice were euthanized, tooth slices retrieved, and dental pulp microvessel density was quantified by counting the number of Factor VIII positive blood vessels in four high powered fields per pulp slice (6 tooth slices per condition). Independent experiments were carried out to verify data reproducibility. Statistical analyses (Kruskal-Wallis One Way Analysis of Variance on Ranks and Tukey Test) were performed using Sigmastat 2.0. We conclude that VEGF enhances neovascularization of severed human dental pulps in vivo. These results may have implications on the treatment of avulsed immature teeth ex vivo, prior to replantation.

Key:

 denotes Resident

* denotes Presenter(s)

PR 34 

Evaluation of Brain Cortical Activity Following Injection of Anesthetic Solutions in Human Subjects Using Electroencephalography M. Modareszadeh*, A. Mickel, S. Chogle, J. Jones Case Western Reserve University, Cleveland, OH Anticipation of pain before and during injection of anesthetic solutions, the pain resulting from entering the needle into the tissues and pharmacochemical effect of anesthetic material itself can cause some changes in the human brain cortical activity shown in electroencphalogram (EEG). We hypothesized that because these stimuli can cause different perceptions by the individual, EEG responses would be different from what we can see as the base line. We conducted a pilot study on 5 human subjects which consisted of acquiring surface EEG from frontal sites a few minutes before injection and continued till the subjects reported complete numbness confirmed by pulp test. A visual analog scale (VAS) was obtained after injection. A hand-held, portable EEG device capable of real-time EEG analysis and display was utilized for this study. The acquired EEG was also post processed in time and frequency domains. In particular short-term Fourier transforms and wavelength analysis were utilized to characterize the EEG dynamics around the time of injection. Specifically, the dynamic spectral powers in those frequency bands shown previously to be associated with pain perception were analyzed. These included the alpha (8-12 Hz), the beta (20-35 Hz), and the gamma band (38-42 Hz). The results show that the absolute and relative powers of EEG in these bands demonstrate statistically significant changes from their background in response to pain sensations invoked during injection. Several minutes after injection, the EEG-based indices moved back toward their pre-injection levels.

PR 36 

Endodontic Treatment Outcomes: An Epidemiologic Comparison of Survival of Teeth Following Non-surgical Root Canal Treatment Performed by Endodontists or General Dentists/Non-Endodontic Specialists D.P. Pflum*, K. Roundy, M.A. Childers, J. Scheetz, J. Morelli, R. Caicedo, S.J. Clark University of Louisville, KY Tooth survival after non-surgical root canal therapy (NSRCT) was compared after treatment by endodontists (ENDO) or by general dentists (GP) using data obtained from the Delta Dental of Kentucky database. Patients included (1) had root canal therapy completed in 2002 or 2003 and (2) remained insured from the date of NSRCT through 12/31/07, allowing a minimum follow up time of 4 years. Data collected included tooth number, provider classification (ENDO or GP), date of treatment, and all subsequent restorative, endodontic, and surgical procedures performed on the treated tooth. 28,509 teeth received NSRCT with a survival rate of 92.9%. 25,939 (91%) of the NSRCT were performed by GP, while 2,570 (9%) were performed by ENDO. Survival rates for tooth types treated by GPs ranged from 94.4% for maxillary anteriors to 92.2% for mandibular molars; those treated by ENDO ranged from 96.4% for maxillary anteriors to 92.9% for mandibular anteriors. 93.7% of teeth treated by ENDO and 92.9% of those treated by GP survived through 2007. Using odds ratio, there was no significant difference between survival rates for the total group of teeth treated by GP or ENDO. However in teeth restored with crowns following NSRCT, the survival rate for teeth treated by ENDO (98%, n=1073) was significantly higher (p < .001) than the survival rate of those treated by GP (96.1%, n=11370). The results of this study support previous research that NSRCT is very predictable with a high rate of tooth retention.

JOE — Volume 35, Number 3, March 2009

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PR 37 

An In Vitro Assessment of Antibacterial Activity of Nanocomposite Enhanced Retrofill Polymer Using a Polymicrobial Marker S. Potluri*, S. Chogle, A. Mickel, J. Jones Case Western Reserve University, Cleveland, OH Nanocomposites(NC) are a new class of polymeric materials which when dispersed in a polymer matrix can offer improvement in drug elution characteristics (Cypes) and dimensional stability (Petkov). The primary function of the retrofill is to improve the seal of the root canal system following apicoectomy and gradual release of medicament into the crypt would be most ideal. In pilot studies done at school of dental medicine analyzed a NC-retrofill material and demonstrated that an optimum polymer-monomer-matrix(PMM) combination will behave synergistically with NC, reducing apical bacterial leakage and exhibit sustained drug elution characteristics. We hypothesized that Nanocomposite-Enhanced-Retrofill polymer(NERP) in optimum concentrations would display antimicrobial activity and demonstrate sustained drug release. The purpose of the study was to assess antibacterial activity of NERP by direct contact method using polymicrobial marker. The groups of five samples each included in 1. PMM1%NC2%Chlorhexidine(CH X); 2. PMM1%NC1%CHX; 3. PMM1%CHX; 4. PMM2%CHX; 5. PMM1%NC only. Antimicrobial activity was assessed by colonizing test polymers in polymicrobe suspension containing S. mutans, S. mitis, E. faecalis in Schaedler broth(107 CFU/ml). The pellets were rinsed with PBS and inserted in minimal medium (PBS with 0.25% glucose, 0.2% (NH4)2SO4 and 1% sterile trypticase soy broth) for incubation at 37°C for 24 hrs. Proliferations of microbes were read with a UV Spectrophotometer. Results were statistically analyzed using ANOVA. Groups 1-4 with CHX displayed significant antibacterial activity compared to Group 5 (p≤0.0001). In the present study NERP with CHX shows promise as a retrofill material to provide for antibacterial activity. Further studies are underway to assess effect of NERP on antibacterial activity.

PR 39 

PR 38 

Should Endodontists Place Dental Implants? A Survey of Endodontists K.S. Potter*, A.E. Williamson, P.C. Damiano, F. Qian, M.R. McQuistan University of Iowa, Iowa City, IA Background: As implant therapy has become routine within dentistry, there has been discussion regarding whether endodontists should place implants. Purpose: The purpose of this study was to: 1) assess endodontists’ opinions regarding whether implant placement is within the scope of the specialty of endodontics, and 2) to identify the predictor variables associated with endodontists who favor implant placement. Methods: A written survey was developed and mailed to 1505 practicing endodontists within the United States concerning their attitudes about endodontists placing implants. Univariate, bivariate, and logistic regression analyses were performed. Results: The response rate was 45.6%. 57.0% of respondents believed that endodontists should place implants. Regression analyses identified the following variables as being positively associated with endodontists placing implants: graduation from an endodontic training program ≥10 years ago; interest in personally placing implants in the future; the belief that implant placement should be incorporated into the endodontic residency curriculum; the belief that general dentists in the community would support endodontists placing implants; and the desire to continue the rapport with a referred patient by personally placing an implant if the patient’s tooth is deemed non-restorable with endodontic treatment. Conclusion: The majority of responding endodontists believe that endodontists should place dental implants. Governing bodies of the specialty of endodontics and endodontic training programs should consider discussing whether formal implant training should be incorporated into future curricula.

PR 40 

The Outcomes of Single-Tooth Implant as Compared to Non-Surgically and Surgically Endodontically Retreated Teeth H. Kim, M.K. Soliman*, M. Iqbal University of Pennsylvania, Philadelphia, PA

Distortion and Breakage of Liberator™, EndoSequence™, and ProFile™ Systems in Severely Curved Roots of Molars J.T. Stewart*, S.M. Lafkowitz, G.R. Hartwell, K.S. Appelbaum University of Medicine & Dentistry of New Jersey, Newark, NJ

Purpose: The clinical question this review aimed to answer was “What are the differences in outcome of single tooth implants (STI) compared to non-surgical root canal retreatment (NSRCR) and surgical root canal retreatment (SRCR)?” Therefore the aim of this systematic review to compare the functionality of endodontically retreated teeth with the success of STI. Materials and Methods: Medline, Embase and PubMed databases were searched to identify studies related to outcome of STI, NSRCR and SRCR. Inclusion criteria for STI and endodontically retreated teeth included a minimum 2-year study, and primary publication in English language. Implant studies that used Albrektsson’s criteria for success and endodontic studies that allowed estimation of tooth functionality were included. Two steps screening procedure was used to identify articles that met the inclusion/ exclusion criteria. Wilson score method was utilized to establish 95% confidence intervals (CI) for each of the population. Results: Following the search criteria and independent analysis by two reviewers, four articles were identified in implant literature (κ=0.80), two in NSRCR (κ=1) and two in SRCR (κ=1). Pooled success of STI at 66 months interval was 94.85% (CI: 91.5%-94.3%), while NSRCR at 48 months and SRCR at 78 months exhibited functionality value of 93.50% (CI: 88.9%95.6%) and 90.0% (CI: 88.5%-96.1%) respectively. Conclusion: The results did not suggest any statistically significant difference in the outcomes among STI, NSRCR and SRCR. Furthermore, the literature search failed to identify any articles that directly compared survival or success of STI with endodontically retreated teeth.

The purpose of this study was to investigate the incidence of endodontic file distortion and breakage when the Liberator™ (Miltex), EndoSequence™ (Brasseler), and ProFile™ (DENTSPLY Tulsa Dental Specialties) systems were used to instrument severely curved root canals of extracted human molars. 80 roots of maxillary and mandibular molars, all with curvatures measuring between 40 and 80 degrees, were utilized in this study. Group 1 (n=20) was instrumented with the ProFile™ (.04 Taper) system. Group 2 (n=20) was instrumented with the EndoSequence™ (.04 Taper) system. Group 3 (n=20) was instrumented with the Liberator™ (.04 Taper) system, and Group 4 (n=20) was instrumented using the Liberator™ (.02 Taper) system. The percentage of files that were distorted was 19.4% for the ProFile™ group, 10% for the Sequence™ group, 44.4% for the Liberator™ .04 group, and 59.1% for the Liberator™ .02 group. There was a statistically significant difference between the ProFile™ and Liberator™ .04 groups (p=0.0323), the ProFile™ and Liberator™ .02 groups (p=0.0021), the Sequence™ and Liberator™ .04 groups (p=0.0032), and the Sequence™ and Liberator™ .02 groups (p=0.00015). The percentage of broken files was 2.8% for the ProFile™ group and 7.4% for the Liberator™ .04 taper group. The Sequence™ and Liberator™ .02 taper groups did not result in any broken files. No statistically significant differences were found among the four groups (p=0.2793) with regard to breakage. It can be concluded that great care should be taken when instrumenting teeth with severely curved roots with any of these four rotary file systems.

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JOE — Volume 35, Number 3, March 2009

PR 41 

PR 42 

The purpose of this study was to examine the morphology, with respect to number of canals, in mandibular first molars in vivo. The patient logs from 17 past and current residents of the U.S. Army Endodontic Residency Program, Fort Bragg, North Carolina, were examined. A total of 1519 cases of mandibular first molars were compiled and examined for number of canals obturated during non-surgical endodontic therapy. The percentages of 1, 2, 3, 4 and 5 canals obturated were calculated for each resident and totaled. Results of this study found that 55.0% of mandibular first molars presented with four canals. This study showed a greater percentage of four canals than previous in vivo retrospective mandibular molar morphology studies. The majority of previous morphology studies showed the incidence of canals in mandibular molars prior to the popular use of operating microscopes among endodontists. The results of this study suggest a higher incidence of 4 canals in mandibular first molars than previously reported.

We investigated the effects of methylene blue (MB)-encapsulated nanoparticles of poly(lactic-co-glycolic acid) (PLGA) with negative and positive surface charge and light against Enterococcus faecalis, a pathogen associated with failures of endodontic treatment, in vitro. MB-loaded PLGA nanoparticles were prepared and characterized. The uptake and distribution in E. faecalis was investigated by transmission electron microscopy (TEM) after incubation with PLGA complexed with colloidal gold particles for 5 and 10 min. A large fraction of nanoparticles were found to be concentrated onto the cell walls of microorganisms at both time points. Sensitization of E. faecalis species in planktonic phase with MB-loaded nanoparticles (final concentration: 12.5 μg/ml equivalent to MB) for 5 and 10 minutes followed by exposure to red light at 665 nm with an irradiance of 100 mW/cm2 and energy fluence of 30 J/cm2 led to approximately 2 and 1 log10 reduction of colony-forming units for the positively- and negatively-charged nanoparticles, respectively. Cationic nanoparticles loaded with MB reduced bacterial survival by 94% in the absence of light, whereas anionic nanoparticles by 19%. The in vitro release of MB in simulated environment showed that the “percent release” of MB in cationic nanoparticles was greater than that in anionic nanoparticles. This may explain the greater dark toxicity of cationic nanoparticles. The data suggest that PLGA nanoparticles loaded with photoactive drugs may have an application in antimicrobial therapy. Supported by the NIDCR grant RO1-DE-16922.

PR 43

PR 44

A Retrospective In Vivo Study of Mandibular First Molar Root Canal Morphology M. Vagnetti*, P. Mines, M. Sweet, J. Libbesmeier U.S. Army Dental Activity, Fort Bragg, Fayetteville, NC

Qualitative Assessment of a Nanocomposite-Dentin Interface Using Scanning Electron Microscopy J.T. Beacham*, S.M.A. Chogle, S. Shaikh, J. Phark, A. Mickel, J. Graves, S. Qutubuddin, S. Potluri, S. Duarte Case Western Reserve University, Cleveland, OH Polymer nanocomposites (PNC) are a new class of materials consisting of nanoparticles dispersed within a monomer matrix (MM). Nanoparticles may be an important area of endodontic research because of their drugeluting capabilities and ability to improve MM and yield better adaptability and decrease microleakage when used as a retrofill material. The purpose of this study was to qualitatively assess the dentin-material interface of root canals filled with PNCs using SEM as compared to Mineral Trioxide Aggregate (MTA™) and Geristore™. Thirty-two single-rooted extracted teeth were decoronated and biomechanically prepared. The apical 3mm of each tooth was resected and the remaining canal space was filled with MM, MM+1% nanoparticle (C18), MM+2%C18, MM+1%C18+1% chlorhexidine (CHX), MM+2%C18+2%CHX, MTA™, or Geristore™. The MM consisted of BisGMA+TEGDMA+HEMA monomers. The filled canals were sectioned into three 2.0mm sections using the Isomet 1000 Precision Saw™. Apical sections were then prepared and analyzed using the Philips XL30 SEM™ (middle and coronal sections were used for parallel studies). The results showed that although tubule occlusion at the interface was found using MTA™ and Geristore™, tubule penetration (>50%) was more prevalent in the samples filled with MM alone and MM+1% or 2% C18. Smear layer removal increased penetration as well, but adding CHX to the mixture reduced tubule penetration (<50%) compared to groups without CHX. These results indicate the possibility of using a C18 enhanced PNC material for further investigation as an endodontic retrofill material because of the high penetration of the tubules.

Key:

 denotes Resident

* denotes Presenter(s)

Photodynamic Effects of Methylene-Blue Loaded Polymeric Nanoparticles In Vitro H. Youm* Harvard School of Dental Medicine, Boston, MA

Desire for Endodontic Therapy in an Appalachian Community R.J. Crout*1, D. McNeil1, G. Casto1, R.J. Weyant 2, M. Marazita 2 1 West Virginia University, Morgantown, WV, 2University of Pittsburgh, PA West Virginia leads the country with the highest rate nationally of edentulism in seniors over age 65 while those adults under 35 lose at least 6 teeth. Little research, however, has explored to what degree this Appalachian population would utilize treatment that would help retain teeth, and what factors may affect such choices. The objective of this study was to evaluate interest in preserving teeth, endodontic therapy, and reasons for their decision. Methods including participation by 1,089 adults from two rural counties in West Virginia and Pennsylvania who were part of a larger oral health in family study in Appalachia. Participants were presented with two questions, the first asking about treatment choices if a tooth was painful. The second involved a hypothetical question choosing between endodontic therapy versus extraction, with follow-up inquiries about reasons for their choices. Results revealed that if a tooth was painful, only 53.2% (with a 95% confidence interval of ±3.0) would prefer to have it “filled” while 43.1% (±2.9) preferred to “take it out” and 3.8% (±1.0) chose to “leave it alone.” There were 27.3% (±2.7) who would choose extraction rather than endodontic therapy; reasons included too expensive (39.8% ±2.1), fear (14.6% ±1.5) and lack of insurance (15.7% ±1.5). In conclusion, over 40% of this group would have a tooth extracted rather than restored and almost 30% would choose extraction over endodontic treatment. Culturally sensitive interventions are necessary to help increase retention of teeth in this Appalachian population. Support by NIH Grant: RO1-DEO14889.

JOE — Volume 35, Number 3, March 2009

453

PR 45

Ex Vivo Comparison of Three Electronic Apex Locators in Locating the Apical Constriction—A Preliminary Report F.L.C. D’Assunção*, D.S. de Albuquerque, J.R. Salazar-Silva, V.C. Dos Santos, J.C.N. Sousa Federal University of Paraiba, João Pessoa, Brazil The ideal apical endpoint of root canal treatment is the apical constriction. Electronic apex locators (EAL) are advocated for root canal length measurement. However, the accuracy of these devices is still controversial. This study evaluated the accuracy of the Root ZX-II™, Mini Apex Locator™ and Novapex™ in locating the apical constriction. 31 extracted human teeth were used for the study. The electronic length (EL) measurements were obtained with the three devices with an aid of K-type files and a mounting model that made use of a digital micrometer. After the last electronic measurement, the file was cemented in place and the 4mm of each root canal was exposed. Photographic slides of each root canal were projected in a computer screen and the file position in relation to the apical constriction was determined by one calibrated investigator by using the Image Tool system v. 1.28. The results obtained with each EAL were compared with the corresponding actual length (AL). The electronic measurement means were inferior to ± 0.08mm for each device, taking to account the distance among the tip of the file and the apical constriction. According to the Student’s t-test, there was no statistical difference among the three devices and the actual length position (p>0.05). The electronic apex locators tested were accurate to detect the apical constriction and these devices will lead to a safety working length obtainment.

PR 46

In Vitro Comparison of Three Root Canal Irrigation Systems in Reducing Intracanal Microorganisms P. Desai*, V. Himel, J. Babu University of Tennessee, Memphis, TN Chemical debridement plays an important role reducing intracanal microorganisms, the primary cause of root canal infections. The objective of this study was to evaluate the flushing efficiency of intracanal irrigation systems, EndoVac® and EndoActivator™ in reducing intracanal microorganisms using saline and compare it to needle irrigation. Sixty-six (n=66) single canal, mature teeth were selected and cross sectioned coronally to a canal length of fifteen (15) mm. Teeth were instrumented to a Master Apical File size of #45 with 4% taper and were mounted in a test tube using PVS impression material. Teeth were randomly divided in three experimental groups (n=20) and one control group (n=6). A precision syringe pump was used to deliver saline at the rate of 6ml/min. A 24-hour culture of Streptococcus Mutans (C4) (5x105 cells) was used for infecting the sterilized root canals and incubated for 72 hours. The numbers of bacterial colonies were determined before (S1) and immediately after (S2) the experiment by plating the samples on agar plates. Fresh culture media was added to each root canal, and incubated for another 72 hours. The numbers of re-colonized bacteria (S3) were determined. Scheffe’s analysis of variance was used for statistical analysis (p< 0.0001). There was a statistical significant difference between all groups in their effectiveness in reducing bacterial counts. EndoVac® and EndoActivator™ reduced bacterial load by >99% compared to control. EndoVac® and EndoActivator™ have a highly significant better flushing efficiency than needle irrigation. EndoVac® flushed out statistically significant more microorganisms than the EndoActivator™ system.

PR 47

PR 48

Objective: Angiogenesis and vasodilatation are established mechanisms in pulpitis. Their key regulator is vascular endothelial growth factor (VEGF). VEGF expression has been qualitatively demonstrated by immunohistochemistry but there has been no quantification of expression with ideal controls or sample size. The purpose is to quantify VEGF expression in normal dental pulps as compared to dental pulps with shallow or deep caries lesions. Methods: Thirty healthy patients (24-60y) scheduled for multiple extractions were selected and one sound tooth and one carious vital tooth were collected. 60 total samples were classified: 30 sound controls, 22 deep-caries and 8 shallow-caries. Teeth were cut and pulps were sectioned longitudinally in half. One-half was used for ELISA to analyze protein and the other half was used for mRNA analysis by RT-PCR. Results: ELISA data showed in deep caries samples 67% increase (14/22 cases) and 33% decrease (8/22 cases) of VEGF expression. While the shallow caries samples showed only 12.5% increase (1/8 cases) and 88.5% decrease(7/8 cases). Semi-quantitative RT-PCR showed consistent correlation to increase or decrease as shown in protein levels in 19 cases. Samples were analyzed as compared to the sound tooth from each patient. Conclusion: At this point these results showed that there is an increase (67%) on VEGF expression in deep caries teeth as compared with shallow. Further study should be done to increase the sample size by caries type and future mRNA quantification by RT-PCR. VEGF and its signaling molecules could be a therapeutic target to prevent progression of pulpitis to necrosis. Supported by AAE Foundation.

The bending properties of NiTi files are closely related to the transformation behavior, and it is noted that the behavior is induced by heat treatment. The purpose of this investigation was to evaluate the bending properties of NiTi instruments processed by heat treatment. K3 (SybronEndo, CA) files that had a 0.30 mm tip diameter size and 0.06 taper were used in this study. After dividing them into four groups randomly, they were heated in a nitrate bath for 30 minutes at 400 (Group 400), 450 (Group 450), and 500 degrees centigrade (Group 500). Then, they were quenched in water. Files as received were served as control. A cantilever bending test was performed with the maximum deflection of 3.0 mm. The distance between the clamp edge and the file tip was 9.5 mm, and the initial loading point was 3.0 mm distant from the file tip. The bending load was measured at 0.5 mm deflection which corresponds to elastic area and 2.0 mm deflection to super-elastic area. The data were statistically analyzed by Tukey-Kramer test (p=0.05). At 0.5 mm deflection, load values of control group and Group 500 were higher than those of groups 400 and 450 (p< 0.05). At 2.0 mm deflection, the bending load values of the control group showed the highest value among all groups (p< 0.05). It was suggested that heat treatment of NiTi files might be effective for the improvement of flexibility that was an important factor for preparation of curved root canals.

Dental Caries Progression Correlates With VEGF Up-Regulation in Patients A.L. Doering*, D. Vodopyanov, J.E. Nor, T.M. Botero University of Michigan, Ann Arbor, MI

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JOE — Volume 35, Number 3, March 2009

Effect of Heat Treatment for NiTi Rotary Endodontic Instruments: Change of Bending Properties A. Ebihara*, Y. Yahata, K. Nakano, Y. Hayashi, H. Suda Tokyo Medical and Dental University, Japan

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Evaluation of Bond Strength of New Nano-Clay Enhanced Retrofill Polymer Material in Endodontics J.R. Graves*, S.M.A. Chogle, S. Shaikh, J. Phark, J.T. Beacham, A.K. Mickel, S. Qutubuddin, S. Potluri Case Western Reserve University, Cleveland, OH Success in periradicular surgery depends on a number of factors including the nature of the retrofill material. The ideal retrofill should be biologically compatible, prevent bacterial leakage, and inhibit microbial growth. Polymer nanocomposites (PNCs) are a new class of materials containing organoclay nanoparticles (OC) dispersed within polymer matrix (PM), which substantially enhance physical properties and drug-elution characteristics. Current studies are investigating the properties of novel nano-enhanced polymers used in retrofill materials. The objective of this study was to evaluate push-out bond strength (PBS) of PNCs to dentin and characterize the mode of failure at the PNC/dentin-interface. Analyzed groups of PNCs included: PM+1%OC, PM+1%OC+2%Chlorohexidine (CHX), PM+2%OC, PM+2%OC+2%CHX. These were compared to MTATM and Geristore®. Eighty extracted single-rooted teeth were decoronated, endodontically prepared, apically resected, and sub-grouped based on smear layer removal. Roots were filled with one of the materials and sectioned into 2 mm sections with 26 samples per group. PBS testing was performed using a universal testing device (Instron) and failure method was analyzed using light microscopy and a scanning electron microscope (SEM). Microscopic examination of the samples showed adhesive failure occurred in nearly every sample. Analysis of variance (ANOVA) test results (alpha=0.05) on push-out samples showed significant differences in recorded failure stress values (p=0.024) between materials. Pairwise t-testing showed PM+2%OC+2%CHX and PM+2%OC required significantly larger (p<0.05) stress values to push out the material than MTATM and Geristore®. In the current study, the bond strength of PNC groups was shown to be higher than MTATM and Geristore®.

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Phase Transformation Behavior and Bending Properties of GT® Series X™ Rotary Endodontic File Y. Hayashi*, Y. Yahata, A. Ebihara, H. Doi, H. Suda Tokyo Medical and Dental University, Japan Many types of nickel-titanium rotary endodontic files have been applied in these years. Each nickel-titanium rotary endodontic file has special features, including cross-sectional shapes, pitches, and various tapers. However, there are a few reports that focused on their nickel-titanium alloy properties. Recently GT® series X™ (GTX; DENTSPLY Tulsa Dental Specialties, USA), newly designed nickel-titanium rotary endodontic files, has become available. The aim of this study was to evaluate the phase transformation behavior and bending properties of GTX rotary endodontic file that has a special nickeltitanium alloy feature. Phase transformation temperatures were calculated using diagrams obtained from differential scanning calorimetry (DSC), and bending load values of the instruments were measured by cantilever bending test. System GT® file (GTO; DENTSPLY Maillefer, Switzerland) and ProFile™ (PF; DENTSPLY Maillefer) were used as reference. In all groups, files with size 30 and .06 taper were used. Data were analyzed by Fisher’s post-hoc test. As to the Ms, Mf, and Af points of phase transformation temperature, significant differences were recognized between GTX and GTO groups (p<0.05). In the bending test, no significant difference was found between GTX and PF groups (p>0.05). The average of bending load value of GTX was lower than that of GTO. We concluded that features of alloy including heat-treatment may be one of the most important factors affecting mechanical properties, especially bending properties of nickel-titanium rotary endodontic files.

Key:

 denotes Resident

* denotes Presenter(s)

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The Apical Shaping Ability Using GT-XTM System in Simulated Double Curved Canal G. Hata*, I. Nishikawa Osaka Dental University, Japan The purpose of this study was to evaluate the shaping ability of the GT-X™ file system in the simulated double curved canals. Forty simulated canals with double curvatures were randomly divided into 4 groups and each group was prepared with a different NiTi rotary system: namely, GT-X™ in group 1, ProTaper™ in group 2, a combination of rotary GT-X™ and ProTaper™ in group 3, and a hybrid technique by rotary ProTaper™ and manual instrumentation using K-file in group 4.The root canal preparation of group 1 and 2 was completed by using GT-X™ .06 #30, #F3 for group 3, and #30 hand K-file for group 4. All canals were scanned pre- and postoperatively, and then each prepared canal image was superimposed with the preoperative one in a computer. The amount of material removed from the preoperative inner and outer curved walls after the use of each instrument was measured at seven levels in the apical 6mm of the canal. Statistical analysis was performed by using an analysis of variance test at α= 0.05. Although most of the root canals prepared up to the final apical file were straightened, the original canal shape was maintained with some transportation after the use of .06/20 in group 1 and group 3.The original canal shape was maintained in group 2 and 4 with the use of shaping files (#S1 & S2); however, the root canal prepared with ProTaper™ finishing file #F1 or hand file #25 was straightened progressively and remarkable transportation was created.

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Hard Tissue Barrier Formation in Pulpotomized Teeth Capped With Trichloracetic Acid (TCA), Mineral Trioxide Aggregate and Formocresol B. Karami*1, A. Khayat1, F. Moazami1, S. Pardis1, P. Abbott2, E. Amirhakimi1 1 Shiraz University of Medical Sciences, Iran, 2University of Western Australia, Perth, Australia One outcome used to indicate a successful pulpotomy is the presence of a dentin bridge at the site of pulp amputation. The study aimed to compare dentin bridge formation in 162 premolar roots of eight dogs when TCA, MTA, formocresol and zinc oxide eugenol (ZOE) were used as pulpotomy agents. The teeth in each dog were divided into four groups and after pulpotomy procedures they were restored with amalgam. The dogs were sacrificed at 48h, 2, 4 and 8 weeks (two dogs per interval). Histological evaluation indicated no cases with pulp necrosis. After 2 weeks, bridge formation was only seen in 58.3% of MTA cases while after 4 weeks, it was seen in both MTA (75%) and TCA (42.9%) samples and after 8 weeks in 20%, 50%, and 91.7% of formocresol, TCA and MTA cases respectively. Bridges were not observed at any period with ZOE. ANOVA analysis indicated a significant difference between TCA (F=8.2,Sig.=0.0001) and MTA (F=13.8,Sig.=0.0001) bridge formation at four observation periods. The t-test results indicated that at 4 weeks, MTA had a higher (χ=0.75) mean bridge formation than TCA(χ=0.43) but this was not significant (t=-1.68, d.f.=14, Sig.=0.106). LSD test at 8 weeks revealed that MTA had a significantly higher mean bridge formation (χ=0.92) than the other materials. TCA was the second best after 8 weeks (χ=0.5). MTA was superior to formocresol and TCA; however, bridge formation was seen in 50% of TCA cases after 8 weeks which is a desirable finding in pulpotomy procedures. Supported by Shiraz University of Medical Sciences.

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Objectives: The study investigated the indications for surgical and non-surgical endodontic retreatment in 914 cases completed at University of Pennsylvania graduate endodontic clinic. Methods: A multiple regression model was constructed with surgical root canal revision (SRCR) vs. nonsurgical root canal retreatment (NSRCR) being the outcome assessed. The independent variables were biological or technical reasons for retreatment, presence of respected or altered root canal morphology, type of coronal/intra-coronal restoration, and presence or absence of periapical radiolucency. The odds for the independent variables were obtained with the help of an SPSS statistical package (p<0.05). Results: 304 of the cases were SRCRs and 610 were NSRCRs. Anterior teeth were 19 times more likely to undergo SRCR for biological reasons. This likelihood dropped to 8 times when both biological and technical reasons coexisted. Premolars and molars were 24 and 4 times respectively more likely to undergo SRCR if the quality of the crown was satisfactory. In the absence of a post, premolars were 14 times less likely to undergo SRCR. Molars with altered root canal morphology were 14 times more likely to undergo SRCR. Molars with good obturation length were 81 times more likely to undergo SRCR. Conclusions: The variables that significantly effected the decision making process were biological or technical reasons, quality of crown, presence of the post, altered root canal morphology, and length of root canal obturation. The presence of periapical pathology did not affect the decision making process.

Various materials have been attempted to reduce the setting time of MTA cement. In this study, we evaluated in vitro microleakage of MTA powder with Superbond C&B® cement as a retrograde filling material by using methylene blue dye method. Fifty-two single rooted, extracted teeth were instrumented and obturated with gutta-percha and AH Plus sealer. The apical 3mm of each root was resected and 3mm deep ultrasonic root end preparation was done. External surface of roots was coated with nail varnish. Prepared teeth were randomly divided into five groups; Group 1 (negative control: completely covered with nail varnish); Group 2 (positive control: coated with nail varnish except for apical foramen); Group 3 (retrofilled with Portland cement); Group 4 (retrofilled with MTA); Group 5 (retrofilled with MTA powder mixed with Superbond C&B® polymer and monomer). Immediately after completion of root-end filling, all specimens were submerged in methylene blue dye for 72 hours at 37°C incubator. The roots were longitudinally sectioned and measured for extent of dye penetration by three different examiners under microscope(x10). The results were statistically analyzed using one way ANOVA and Tukey’s HSD test. No leakage was evident in group 1 and complete leakage in group 2. Group 5 showed significantly less leakage than group 3 and 4 (p<0.01). There was no significant difference between group 3 and 4 (p>0.01). It was concluded that MTA powder with Superbond C&B® cement was excellent in reducing initial apical microleakage.

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A Database Study of Variables Involved in the Decision-Making Process of Endodontic Retreatment: Surgical or Non-Surgical N. Karney, J.H. Tran*, A. Gatan, M.K. Iqbal University of Pennsylvania, Philadelphia, PA

Differential Scanning Calorimetric Studies of Endodontic Nickel-Titanium Rotary Instruments After Sterilization U. Li*1, J. Liou2, C. Lin1 1 National Taiwan University, Taipei, Taiwan, 2Dental Department at Mackay Memorial Hospital, Taipei, Taiwan Differential scanning calorimetry (DSC) is highly convenient for investigating the bulk metallurgical structure of nickel-titanium (NiTi) endodontic instruments. Especially repeated autoclaving processes often cause the surface of NiTi instruments blunt and reduce their cutting properties. The purpose of this study was to utilize DSC to study the variation in NiTi phases with temperature for ProFile™ NiTi rotary instruments after three different types of sterilization. A total of 40 ProFile™ NiTi rotary instruments were randomly divided into four groups: one control group in as-received condition and the other three experimental groups were doing sterilization cycles with steam autoclave, dry heat, and fast cassette autoclave procedures. DSC analyses were performed between -90° and 100°C on specimens in as-received and post-treated conditions. The specimens for analysis were cut into segments with a water-cooled, slow-speed diamond saw to minimize mechanical stresses that might change the proportions of the austenitic and martensitic NiTi phases. Plots were analyzed by computer software to obtain temperatures for phase transformations and enthalpy changes associated with these processes. DSC plots showed that the as-received ProFile™ instruments had the previously observed superelastic NiTi property, with an austenite-finish temperature of approximately 37.5°C. Temperature ranges for phase transformations for the experimental specimens were similar to those of control group specimens. The resulting enthalpy changes of experimental groups decreased that compared to those of control group specimens. In conclusion, the sterilization process does not alter the metallurgical phases in the NiTi rotary instruments or their superelastic character.

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Apical Microleakage of MTA With Superbond C&B® Cement as a RootEnd Filling Material J. Kim*, W. Yang, H. Ko, M. Kim Ulsan University Asan Medical Center, Seoul, Korea

Influence of Cleaning Reagents to Cutting Aspect of Canal With Rotary Instruments M. Maeda*, Y. Ogura, I. Katsuumi Nippon Dental University, Tokyo, Japan The purpose of this investigation was to compare the lubricating effects of cleaning reagents on the torque generated during canal preparation by using engine-driven rotary instruments. The stainless steel files of .06 taper size No.40 (ERT file, Mani, Japan) and the standardized straight canal models were used. A computer-controlled torque testing-device was specially designed for this investigation. A root canal orifice was enlarged in advance by using an instrument with taper of .12 taper ERT file. The following substances were used as cleaning reagents: paste-type 10% sodium hypochlorite (Canal cleaner, BEE BRAND MEDICO DENTAL, Japan), paste-type EDTA (Glyde, DENTSPLY Maillefer, Switzerland), distilled water, and no reagent (control). Each reagent was injected in adequate quantity into the root canal every 30 seconds from the starting of the preparation. And rotary files of .06 taper were inserted to a depth of 8 mm into the root canal. The torque generated under each experimental condition was recorded. Five root canal models were used for each condition. The cutting efficacy is analyzed according to the torqueinsertion distance and to the calculation of the variation in torque (ΔT). The cutting torque used at the time of canal preparation was increased as the file was inserted to the direction of root apex under each of the experimental conditions. The value of ΔT was significantly influenced by the difference of the reagents, and the value decreased in the order of: control > Glyde > Canal cleaner > distilled water (P<0.05).

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The aim of the present study was to assess cyclic fatigue resistance of NiTi Twisted File instruments (TF; SybronEndo, Orange, CA) and Profile instruments (PF; DENTSPLY Tulsa Dental Specialties, Tulsa, OK). Ten instruments of each group were tested. Tests were performed using an Instron machine and a slowspeed motor rotating the instruments on a polished metal block at a 45-degree angle. The number of cycles to failure of each rotary instrument was recorded. Data were subjected to a student t-test and mean values were found to be significantly different at a (P) level of <0.001. Results indicated that 0.04 taper size 25 PF instruments demonstrated a higher number of revolutions than 0.04 taper size 25 TF instruments. In conclusion, within the parameters of this study, it was found that the twisting of NiTi wires (TF) does not result in higher resistance to cyclic fatigue than that using a grinding process (PF).

The purpose of this study was to assess the impact of final irrigation regimens on sealer penetration into the dentinal tubules by using confocal laser scanning microscopy (CLSM). Eighteen roots of extracted maxillary and mandibular molars with root curvature of more than 20 degrees were used. After instrumentation, the samples were divided into three groups and subjected to final irrigation as follows: Group 1, irrigated only with 3.5% NaOCl (3 mL) for 2 min; Group 2, 17% EDTA (3 mL) for 1 min; Group 3, 17% EDTA (3 mL) for 1 min, followed by 3.5% NaOCl (3 mL) for 2 min. All teeth were obturated with gutta-percha and AH PlusTM sealer labeled with fluorescent Rhodamine Bisothiocyanate. 500 μm sections cut at 2 and 5 mm from the root apex were viewed using CLSM and the percentage and depth of sealer penetration were determined. At 2 mm level, the data showed no significant difference of percentage and depth of penetration between the groups. At 5 mm level, group 2 showed deeper sealer penetration than group 1 (Mann-Whitney tests, p < 0.05). The Kruskal-Wallis test found significantly higher percentage and depth of penetration at 5 mm level than 2 mm level in group 2 and 3 (p < 0.05). The use of EDTA as a final irrigant showed greater depth of sealer penetration than the use of NaOCl alone at the 5 mm level from apex. However, complete debridement still seems to be a challenge in apical portion of curved canals.

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Many types of NiTi rotary instruments have been developed and widely used. Mechanical properties of NiTi alloy are strongly affected by heat treatment. The aim of study was to evaluate the shaping ability of heat-treated NiTi files. K3® (SybronEndo, CA) was used in this study. The heat treatment temperature was set at 400 (Group400), 450 (Group450) and 500 degrees centigrade (Group500), and commercial K3® was used as control. Standardized plastic curved root canal models (Endo Training Block, DENTSPLY Maillefer, Switzerland) were prepared using the crown-down method, and at the apex terminus enlarged to a size #35 in each group (n=10). Images of each sample before and after instrumentation were taken by a digital microscope (VH8000, Keyence, Japan) and evaluated at three levels in the apical 6 mm of the canal. Time required for canal preparation was also recorded. As to working time, there were no significant differences among all groups (p>0.05). In the control group, root canals at the apex were transported to the outer side of the curvature after preparation compared to all heat treated groups (p<0.05). As to deformation and fracture, in Group 450, there was no plastic deformation or fracture of files. In Groups 400 and 500, there were one and three plastic deformations, and one and one fracture of files, respectively. On the other hand, there were one plastic deformation and five fractures of files in the control group. Our results suggest that heat treatment for the K3® might be effective for the prevention of fracture.

The purpose of this investigation was to continue the analysis of an ongoing patient database in an endodontic practice, and specifically examine areas of interest in nonsurgical retreatment therapy (RETX). Patient data, excluding identifiers, were entered into a Microsoft Excel® spreadsheet. Eighty-eight items were available for each patient entry. These were grouped under Patient History, Clinical Examination, Radiological Examination, Diagnosis, and Treatment. Chi-Square was used for statistical analysis. 2871 consecutive patient visits recorded in the database were analyzed. RETX procedures represented 15% of the total number of treatment procedures (190 actual patients) with nonsurgical root canal treatment comprising 77%, periradicular surgery 2%, and less common procedures 6%. The age range for RETX was 13 to 90 years with 70% of patients between the ages 30 and 60. Patients over 60 years of age represented 17% of the group. Females presented significantly more often than males for RETX (63% vs. 38%; p<.05). Maxillary and mandibular first molars represented over half of the teeth retreated in this study (54%) with tooth #19 the most frequently retreated (16%). Asymptomatic apical periodontitis was the most common apical diagnosis (32%) followed by symptomatic apical periodontitis (29%). At the time of the initial retreatment visit, 22% of patients reported taking an analgesic and 20% reported taking an antibiotic. The results of this study provide a demographic profile of patients who presented for endodontic retreatment therapy by using a database. Utilization of a database has the potential to promote better care to endodontic patients.

Comparison of Cyclic Fatigue Resistance of Profile™ and Twisted File™ Endodontic Rotary Instruments S. Mazareei*, J. Williams, N. Nguyen Oregon Health & Science University, Portland, OR

Effect of Heat Treatment for NiTi Rotary Endodontic Instruments: Evaluation of Root Canal Preparation K. Nakano*, A. Ebihara, Y. Yahata, Y. Hayashi, H. Suda Tokyo Medical and Dental University, Japan

Key:

 denotes Resident

* denotes Presenter(s)

Effect of Final Irrigation Regimens on Root Canal Sealer Penetration in Curved Root Canals Y. Moon*, W. Shon, W. Lee Seoul National University, Seoul, Korea

Database Analysis of Nonsurgical Retreatment Therapy in an Endodontic Practice E.A. Nelson*, S.R. Nelson Leawood Commons Endodontics, Leawood, KS

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Influence of Conditioning Agents for a Resin-Based Sealer on the Root Canal Wall Y. Ogura*, M. Maeda, K. Oshima, I. Katsuumi Nippon Dental University, Tokyo, Japan The purpose of this study was to investigate the property changes in the root canal wall treatment with conditioning agents used for resin-based sealer. Four singlerooted extracted human teeth were used. The root canals were prepared to apical size 80, and were cut into several pieces, these were to yield 25 fan-shaped pieces final test specimens. All specimens were coated with nail polish except for a 0.5 mm width of root canal wall, and divided into 5 groups. The dentin conditioning agents were applied for 60 minutes each: ethanol (group 1), 10% citric acid (group 2), 14.3% EDTA (group 3), 3% EDTA (group 4) and 10% NaOCl (group 5). After the nail polish was removed, the root canal surfaces were observed under a digital microscope and SEM. In Group 2, the surfaces were recessed in comparison with the untreated portion. Pigment of the agent, also had permeated to a depth of 50 μm from the surface. In Group 3 and 4, dentinal tubules were opened, and the shape of the tubules was changed on that portion to a depth of about 30 μm from the surface. In Group 1 and 5, no significant differences in surface property were noted. These results suggested that 10% citric acid has strong solubility into the root canal wall dentin. It concerns that agent remaining in the root canal may lead to weakening of the canal wall. Sufficient irrigation with distilled water after application of conditioning agents is therefore a very important procedure.

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Patients’ Perception of the Informed Consent for Endodontic Treatment M.T.L. Rezende*, B. Xavier Universidade Federal de Goias, Goiânia, Goias, Brazil BACKGROUND: Root canal treatment only should be performed after having an informed consent signed-up by the patient. In Brazil, the informed consent process is not routinely used in endodontic practice. It is generally believed that previous information about treatment risks could generate more fear and, therefore, patients would decline treatment. However, there is no controlled study evaluating patients’ perception of the informed consent form. AIM: The objective of this study was to evaluate patients’ perception of an informed consent form for endodontic treatment. METHOD: A descriptive study was performed at an outpatient university clinic and in a private practice office. After an informed consent form was read and signed, a structured questionnaire was applied, evaluating: socio-demographic variables; previous knowledge of the risks of endodontic treatment; the patient satisfaction of being informed; and if the patient would recommend the use of the informed consent form. Descriptive statistical analysis was used. RESULTS: 340 consecutive patients were eligible for the study. Of those, 7 (2%) refused to participate. 333 (98%) patients answered the questionnaire: 302 (90.7%) were pleased of being informed; 92.5% would recommend the use of the informed consent form prior to endodontic treatment; 59% have no previous knowledge of the risks of endodontic treatment. Previous knowledge was independent of age, gender or social condition. 3.3% considered giving up endodontic treatment after being informed about the risks of such procedures. CONCLUSIONS: These results showed that, in a Brazilian population, the use of the informed consent for endodontic treatment was well accepted by the patients.

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Detection of Epstein-Barr Virus and Human Cytomegalovirus in Periapical Lesions Using Quantitative Real-Time Polymerase Chain Reaction S. Park*, K. Bae, S. Park, S. Yang, S. Baek Seoul National University, Seoul, Korea Recent studies have shown the presence of herpesviruses, especially EpsteinBarr virus (EBV) and Human cytomegalovirus (HCMV) in periapical lesions. The purpose of the present study was to investigate the presence of EBV and HCMV in persistent periapical lesions. Periapical samples of persistent periapical lesions were obtained from 17 teeth (11 symptomatic and 6 asymptomatic teeth) in conjunction with periapical surgery. DNA of the samples was extracted with QIAamp DNA Mini Kit (Qiagen Inc., Valencia, CA). Real-time polymerase chain reaction (PCR) was used to identify and quantify genomic copies of EBV and HCMV. A total 13 of 17 (76.5%) patients revealed EBV in the periapical lesions. EBV was detected in 9 of the 11 (81.8%) symptomatic teeth and 4 of the 6 (66.7%) asymptomatic teeth. The mean level of EBV in symptomatic lesions (14.62 copies/ml) was higher than that of asymptomatic lesions (5.67 copies/ml). The difference was not significant (p > 0.1). HCMV was not detected in any samples. The Real-Time PCR technique represents an attractive method for measuring viral load in periapical lesions. This study showed the presence of EBV in a significant proportion of persistent periapical lesions. However, the role of herpesviruses in the etiopathogenesis of periapical pathosis remains to be elucidated.

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Transient Hypoxia Enhanced Osteogenic Characteristics in Post-Natal Human Dental Pulp Cells J.B. Sakdee*1, R.R. White2, P.V. Hauschka3 1 Srinakharinwirot University, Bangkok, Thailand, 2Harvard School of Dental Medicine, Boston, MA, 3Children’s Hospital Boston, MA The purpose of this study is to examine osteogenic differentiation of human dental pulp cells (DPC) in normoxia and transient hypoxia. DPC were divided into 2 groups cultured in α-MEM culture medium with 10% fetal bovine serum in normoxic and hypoxic conditions. After 14 days, osteogenic medium was added for both groups. DPC were incubated for 21 days in normoxic condition. DPC cultured in regular medium were used as a control group. Osteogenic differentiation was assessed by alkaline phosphatase activity, Von Kossa staining, and quantitative RealTime PCR of osteoblast markers, Runx2 and Osteocalcin (OCN). Transient hypoxia enlarged the number of DPC by a 2-fold. DPC in osteogenic medium cultured for 7 days after transient hypoxic treatment offered the highest alkaline phosphatase activity (2.548, S.D. ± 0.13) per well. The activity of the normoxic group was 1.788 (S.D. ± 0.04) per well, and the control group was 0.177 (S.D. ± 0.026) per well. The difference was also statistically significant (p < 0.0001) for all groups. Alkaline phosphatase staining from transient hypoxic group demonstrated stronger positive staining result than the normoxic group. Both groups displayed positive Von Kossa staining. The level of expression of Runx2 in DPC cultured in transient hypoxia was 16.6-fold higher than in normoxia (S.D. ± 1.2). Though the level of expression of OCN in transient hypoxic group was also higher, 9.6-fold (S.D. ± 2.4), the difference was not statistically significant. Transient hypoxia increased the number of osteoprogenitor cells from DPC population and amplified their osteogenic characteristics.

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Histomorphometric Biological Compatibility Evaluation of EDTA, EDTA-T and Citric Acid in Rats’ Lower Jaws M.F.Z. Scelza* Fluminese Federal University, Niterói, Rio de Janeiro, Brazil This study was conducted to evaluate the biological compatibility of 17% EDTA, 17% EDTA-T and 10% citric acid in 80 adult Wistar rats (Rattus novergicus albinus). Transosseous defects were created bilaterally on rat’s lower jaw. One side received only Fibrinol® (control), while the opposite side received it soaked with each substance and was kept in place for 1, 7, 14 and 28 days (n=5). Hemi-jaws were prepared for light microscopy and samples were stained with hematoxylin-eosin. To evaluate the number of inflammatory cells in the samples, five randomly selected fields around each surgical compartment were captured by PlanApo 40X and 10X magnification. The images with 680 x 512 pixels corresponding to an area 321.8 x 430.1 μm2 were recorded in TIFF. The inflammatory cells were morphologically identified and counted using the software - NIH ImageJ. The difference between the control and experimental groups was statistically analyzed by Kruskal-Wallis and Mann-Whitney tests considering significant the differences when P<0.05. For all time points, 10% citric acid and 17% EDTA-T showed, respectively, the lowest and highest number of inflammatory cells per area. All tested substances and also controls showed the highest inflammatory cell response at 14 days. Statistical significance for comparison among the tested substances was observed for the lowest inflammatory reaction presented by 10% citric acid at the 1-day and 14-day periods, even when compared with the control samples (p< 0.05). Among the tested substances, 10% citric acid revealed a significant biocompatibility potential in terms of inflammatory reaction. Supported by FAPERJ E-26/171.984/2000.

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Subcutaneous Facial Emphysema due to the use of Pressurized air During Radicular Perforation Repair J.M. Sullivan*, R. Pileggi, C.H. Varella University of Florida, Gainesville, FL Subcutaneous emphysema secondary to dental treatment is generally associated with the use of air-driven hand pieces during surgical procedures. However, the use of pressurized air syringes during orthograde root canal therapy has also been associated with serious complications. These complications can range from a moderate swelling, which resolves spontaneously within 5 to 10 days, to death. Although there have been reports of subcutaneous facial emphysema in the literature, its occurrence as a result of air driven through a root perforation has been documented to a lesser extent. It is important for the clinician to be able to identify this condition and differentiate it from secondary infection. The clinical presentation of subcutaneous emphysema is characterized by a sudden onset of a swelling with crepitation while lacking the typical symptoms of infection—erythema, tenderness, and local and systemic temperature elevation. The purpose of this presentation is to bring awareness to the potential complications associated with the use of pressurized air during root canal therapy by presenting of a case report of a 35 year-old healthy female who developed a subcutaneous facial emphysema secondary to radicular perforation repair. The preventive measures, differential diagnosis, recommended treatment, and potential complications will be presented.

Key:

 denotes Resident

* denotes Presenter(s)

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Patient Perception and Satisfaction With Endodontic Microsurgery S. Shin*, S. Lee, C. Song, E. Kim Yonsei University, Seoul, Korea Although endodontic microsurgery is already a well-established procedure, it may not have been familiar to the general population when compared with dental implant. To deliver endodontic microsurgery to future patients as well as general dentists effectively, it is valuable to assess endodontic microsurgery by the patients who experienced the procedure. The purpose of this study was to investigate patient perception and satisfaction with endodontic microsurgery. A questionnaire study was performed among patients who were recalled for a minimum of 3 monthroutine check-ups after an apicoectomy in the department of conservative dentistry, Yonsei University in 2007. Our questionnaire contained 6 questions—the main reason to decide surgery, general satisfaction with surgical procedures and so on. One-hundred and nine (41 male and 68 female) patients participated in the survey. The average patients’ age was 41.4. Contingency table and correlation analysis were used to analyze whether any correlations existed between age/sex and patients’ responses (p=0.05). About 60% of respondents answered they had never heard about surgical endodontic procedures before. 63.3% of respondents chose the surgical option because they wanted to keep their natural teeth instead of extraction. If him (her) self needs the same procedure on another tooth later, 100 out of 109 respondents answered they would choose microsurgery instead of extraction. Most of the patients (82.57%) appeared to be satisfied with a surgical procedure. There was no statistically significant correlation found among variables. We concluded that endodontic surgical procedure appeared to be a satisfactory and valuable treatment choice for candidates who will need endodontic surgery.

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Dentin Strain Caused by Removal of Root Canal Obturation With Er:YAG Laser Irradiation S. Watanabe*, C. Kokuzawa, B. Gomb, H. Saegusa, T. Anjo, A. Ebihara, C. Kobayashi, H. Suda Tokyo Medical and Dental University, Japan Root fractures in endodontically treated teeth are considered a critical clinical issue. They occur due to loss of root dentin, excessive pressure during chemomechanical preparation, lateral condensation, and preparation of a post space. Strain in dentin seems to be a possible cause of root fractures. Laser applications in endodontics have been made practicable. From its cutting mechanism of hard tissue, Er:YAG laser irradiation may cause low strain to the dentin. The purpose of this study was to investigate dentin strain caused by the removal of root canal obturation materials with Er:YAG laser. Fifteen roots of extracted human anterior teeth were prepared and filled with laterally condensed Gutta-percha (Zipperer, OK)(GP) and Sealapex sealer (SybronEndo, CA). The strain in dentin was measured using strain gauges fixed on the coronal third of the buccal root surface. Teeth were divided into three groups: GP removal using Er:YAG laser (Erwin Adverl, Morita, Japan) (140mJ 10pps) under water cooling; GP removal using ultrasonic device (PiezoMaster400, Shofu, Japan); GP removal using NiTi rotary instruments (Orifice Shaper #4, Maillefer, Switzerland). Er:YAG laser generated smaller increase in the dentin strain than those with the ultrasonic device and NiTi rotary instruments groups (p<0.05). Strain in dentin may be caused by heat and force. Removal of gutta-percha using Er:YAG laser may cause lower heat and force than those using an ultrasonic device and NiTi rotary instruments. These results suggest that the strain induced by Er:YAG laser irradiation in dentin may be minimal for removing root canal obturation materials.

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Fatigue fracture of NiTi rotary instruments is a major problem in the practice of endodontics. Radius of curvature might be one of the most important factors that affect fatigue fracture. However, the relation between radius of curvature and load is not clarified. The aim of this study was to evaluate the influence of radius of curvature and load on fatigue fracture of rotary NiTi instruments using a newly designed cyclic fatigue testing machine. ProFile (size 30, 0.06 taper, DENTSPLY Maillefer, Switzerland) was subjected to cyclic fatigue testing. A newly designed cyclic fatigue testing machine which can define radius of curvature by three cylindrical stainless steel pins and measure applied load was used. Radius of curvature was set at 4, 5, 6, 7 and 8 mm. Instruments were rotated at 250 rpm until fracture occurred. Load-time curves were obtained from the fatigue test. The number of cycles before fracture (NCF) and mean load were obtained and analyzed by Tukey-Kramer test (p=0.05). Lower NCF and higher mean load of 4, 5 and 6 mm in radius were obtained when compared with those of 7 and 8 mm in radius (p<0.05). Super-elastic deformation occurred in 4, 5 and 6 mm in radius. In conclusion, it was suggested that radius of curvature and load were related closely, and that the phase transformation might be another important factor for the fatigue fracture of NiTi rotary instruments.

The repair process after direct pulp capping requires dentin bridge formation on exposed pulp surfaces. Calcium hydroxide (Dycal) poses problems by causing persistent inflammation of the dental pulp and forming porous dentin bridges. On the other hand, the application of adhesive resin cements such as Superbond C&B® (SB) has been attempted. Mineral trioxide aggregate (MTA) is a relatively new material that has a wide range of applications, including pulp capping, root perforation repair, and root-end filling. Direct pulp capping experiments have reported that MTA induced the formation of dentin bridges with little or no inflammation The aim of this study was to investigate the effect of MTA on cell viability and mineralization ability of rat dental pulp cells. The pulp capping materials, such as MTA, Dycal, and SB were placed on transwell inserts and cultured with rat dental pulp cells. MTA and SB exhibited no cytotoxicity, whereas almost all cells had died after 72 h of culture with Dycal. MTA significantly stimulated mineralization by 60% compared with the control. MTA and Dycal significantly up-regulated by 2-fold the level of bone morphogenetic protein (BMP)-2 mRNA expression compared with the control. Furthermore, MTA increased BMP-2 protein production by about 40%, whereas Dycal significantly reduced it. While MTA and Dycal increased the concentration of extracellular calcium by about 0.4 mM, SB had no effect. These results suggest that BMP-2 may play a pivotal role in mineralization stimulated by MTA.

Influence of Radius of Curvature and Load on Fatigue Fracture of NickelTitanium Rotary Instruments Y. Yahata*, Y. Hayashi, A. Ebihara, C. Kobayashi, H. Suda Tokyo Medical and Dental University, Japan

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JOE — Volume 35, Number 3, March 2009

Mineral Trioxide Aggregate Increases Bone Morphogenetic Protein-2 Expression in Dental Pulp Cells Y. Yasuda* Health Sciences University of Hokkaido, Hokkaido, Japan