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Evaluation of the Reliability of Cone-beam Computed Tomography Scanning and Electronic Apex Locator Measurements in Working Length Determination of Teeth with Large Periapical Lesions
Clinical Research
Evaluation of the Reliability of Cone-beam Computed Tomography Scanning and Electronic Apex Locator Measurements in Working Length Determination of Teeth with Large Periapical Lesions € un, DDS, PhD,* Tu Yakup Ust€ grul Aslan, DDS, PhD,* Ahmet Ercan S¸ekerci, DDS, PhD,† and Burak Sagsen, DDS, PhD* Abstract Introduction: This study evaluates the endodontic working-length measurements in teeth with large periapical lesions and persistent intracanal exudate by using preexisting cone-beam computed tomography (CBCT). It compares the measurements with clinical root canal lengths determined by using 2 electronic apex locators. Methods: All patients had undergone a CBCT scan independent of the present study and needed root canal treatment of at least 1 tooth visible in the field of view. Seventy-three teeth with single roots and canals were studied. An endodontist measured each root canal length with 2 different electronic apex locators. The measurements were repeated 3 times by using a digital caliper, and the mean was recorded. This mean was compared with the root canal length as measured on CBCT sections by an oral radiologist not involved in the endodontic treatment. The CBCT measurements were taken twice for analysis of intrarater reliability. The data were statistically analyzed. Results: There were no significant measurement differences between the methods used (P > .05). Conclusions: In teeth with large periapical lesions and persistent intracanal exudate, measurement of the root canal length by using CBCT was as reliable as measurements that used apex locators. (J Endod 2016;-:1–4)
Key Words Apex locator, cone-beam computed tomography, large periapical lesion, Propex Pixi, Raypex 6, root canal length measurement
T
he determination of Significance root canal preparation The present study investigated the reliabilities of length is one of the crucial root canal length measurements performed with factors that can affect the apex locators and cone-beam computed tomograoutcome of endodontic phy scans in teeth with large periapical lesion and treatment (1). Clinically, persistent intracanal exudate. conventional radiography and electronic apex locators (EALs) are usually used to determine the working length (WL). This method depends on a two-dimensional radiographic image and has some limitations, including superpositioning of anatomic structures, errors that are due to image magnification, distortions, and sensitivity of the technique (2). Radiographically, the WL is often measured 0.5–1.0 mm short of the radiographic apex. In addition, the major foramen does not always coincide with the anatomic apex; it may be laterally located (3). Determination of the WL of the canal in teeth with apical lesions and apical root resorption can be difficult by using conventional radiography (4). Electronic measurement of root canal length accurately determines the WL for root canal procedures (5), and this method has become indispensable in endodontics. Several studies have been performed to evaluate the accuracy of EALs (5–11), and EALs showed high accuracy rates, within 0.5 mm of the major apical foramen (8, 12). Several studies indicate that use of EALs reduces exposure of patients to radiation (13). Propex Pixi (Dentsply Maillefer, Ballaigues, Switzerland) and Raypex 6 (VDW, Munich, Germany) are recently introduced multi-frequency apex locators. Studies have assessed their accuracy for determining WL (8, 11, 14). Electric conductivity of intracanal liquids (irrigants, blood, pulp, exudate, etc), immature apex formation, periapical lesions, apical foramen size, and file size used to measure root canal length can compromise the accuracy of EALs (7, 15–18). Two different apex locators were evaluated under consistent intracanal exudate, and the EALs were found to be accurate (6). Cone-beam computed tomography (CBCT) has the advantage of a lower dose of radiation compared with computed tomography (19). Since its introduction in dentistry, CBCT has become an indispensable method for diagnosing root canal anatomy (20), root fracture (21), periapical pathology (14–17), and internal/external root resorption (22–24). CBCT is validated as a tool for exploring root canal morphology in
From the Departments of *Endodontics, and †Oral and Maxillofacial Radiology, Faculty of Dentistry, Erciyes University, Kayseri, Turkey. € €un, Department of Endodontics, Faculty of Dentistry, Erciyes University, Melikgazi, Kayseri 38039, Turkey. E-mail Address requests for reprints to Dr Yakup Ust address: [email protected] 0099-2399/$ - see front matter Copyright ª 2016 American Association of Endodontists. http://dx.doi.org/10.1016/j.joen.2016.06.010
JOE — Volume -, Number -, - 2016
CBCT in Endodontic Working Length Determination
1
Clinical Research 3 dimensions (25), and in some studies it was also used for estimating the WL (10, 26, 27). CBCT measurements in combination with EALs may also be useful for determining the WL (26, 27). The present study compared the accuracy of 2 EALs (Propex Pixi and Raypex 6) with a CBCT scan in determining apical foramen and WL in teeth with large periapical lesions and persistent intracanal exudate. The null hypothesis is that no differences exist between the measurement techniques.
Materials and Methods The ethical board of the research foundation of Erciyes University of Medical Sciences in Kayseri, Turkey approved this investigation (Ethics Approval Number: 2016-249). The present investigation included 30 patients who were referred to the Erciyes University Faculty of Dentistry, Department of Oral and Maxillofacial Surgery for further diagnostics and comprehensive therapy of large lesions of the jaws. All patients were in good general health, and female subjects were not pregnant. All patients had received limited CBCT imaging as part of the diagnostics of a large periapical lesion (>10 mm). A total of 73 teeth with a single root and canal from 30 patients were included in this study. Molar teeth or premolar teeth with several canals or roots, teeth that were not entirely visible in the CBCT scan or that had undergone any modifications after the CBCT scan, and CBCT scans with additional artifacts were not included in the study. Roots with severe apical resorptive defects and teeth with metallic restorations were not included in the study. The treatment plan consisted of an initial biopsy and subsequent endodontic treatment of the non-vital teeth and of the teeth in close proximity to the large lesion before the definitive surgery. In addition, a planned root canal treatment in at least 1 tooth with a single canal and root represented in the scanned field of view was required.
Imaging Procedures and Evaluation of WL Measurements on the CBCT Images The CBCT images were obtained by using a NewTom 5G (QR, Verona, Italy) with a voxel size of 0.125 mm, positioned parallel to the horizontal axis of the alveolar bone. A single oral radiologist with 6 years of experience evaluated all CBCT images. Each CBCT image was evaluated twice, with a 7-day break between each evaluation. Only the first measurement was considered for the comparison with the EAL measurement. The CBCT images were analyzed in the NNT viewer, a simple version of the NNT software of the CBCT machine in a Dell Precision T5400 workstation (Dell, Round Rock, TX) and a 32-inch Dell LCD screen with a resolution of 1280 1024 pixels in a darkroom. The contrast and brightness of the images were adjusted by using the image-processing tool in the software to ensure optimal visualization. The CBCT slices were first reformatted to place the root canal of each analyzed tooth in a vertical position to visualize the incisal edge, pulp chamber, major foramen, and, if possible, the whole length of the canal in 1 single slice (Fig. 1). To ensure standardized measurements, the root canal length was established in the CBCT images as the distance between the most incisal (or the most cuspidal) tooth edge in the projected midline of the pulp cavity and the major foramen. Clinically Working Length Determination by Using EALs An expert endodontist completed all root canal treatment procedures. The endodontist was blinded to the results of the CBCT measurements. The clinical root canal length measurement was performed twice, once with each EAL according to the manufacturer’s instructions. The EAL reference points used to determine the WL were the same points used in the CBCT measurements. After the tooth was anesthetized, 2
€Ust€un et al.
Figure 1. WL measurements by using CBCT scans.
the access cavity was opened, and the pulp was removed with a barbed broach. Apical patency was controlled with #8 K-File (Dentsply Maillefer). A #15 or bigger size K-file (Dentsply Maillefer) attached to the EAL device was then introduced into the root canal, and the lip hook of the EAL device was put onto the lip of the patient. Working Length Determination with Propex Pixi. Measurements taken with Propex Pixi apex locator were determined following the manufacturer’s instructions. When the 0.0 signal was seen by the operator, the file was gently moved beyond the apex until the ‘‘beyond apex’’ signal appeared, at which point the file was quickly withdrawn and stopped at the 0.0 point. Simultaneously, the rubber stop of the file was maintained in continuous contact with the incisal reference point of the tooth and fixed with flowable light-cure composite to the shaft of the file (Nova Compo HF Flow; Imicryl, Konya, Turkey). The distance was recorded by using a digital caliper (Insize Mini digital caliper; I_stanbul, Turkey). Working Length Determination with Raypex 6. The Raypex 6 was used according to the manufacturer’s instructions. The measurements were taken with the ‘‘apex’’ mark as reference. The file was introduced to the major foramen (red ball point) and moved slightly beyond the apex. It was then retracted slightly to the zero point (red light), and the rubber stop of the file was then fixed to the incisal reference point of the tooth. The rubber stop was fixed to the shaft of the file, and the file was moved outward. The distance was recorded with a digital caliper. The measurements were repeated 3 times with each EAL, and the mean value was recorded. The measurements were not recorded until the reading remained stable for at least 5 seconds; unstable measurements were not considered for statistical evaluation. The teeth included in this study had intracanal exudate that leaked from periapical lesions. Therefore, endodontic treatments were performed until the leakage was depleted. Of the 73 teeth, 67 were obturated before the surgical operation, but the obturations of 6 teeth could not be perfomed during the treatment sessions. Those 6 teeth were obturated during the surgical operation. Most of the teeth included in this study were diagnosed as having pulp necrosis; those that were vital had root canal therapy because the subsequent surgery would devitalize them. All root canal preparations were performed by using Reciproc instruments (VDW) and an endodontic motor (VDW Silver; VDW). Root canals were irrigated with 1% NaOCl during instrumentation. After completion of the preparation, the canals were irrigated with 2 mL 17% ethylenediaminetetraacetic acid for 1 minute and subsequently rinsed with 2 mL distilled water. The root canals were then dried with paper points (Dentsply Maillefer). All root canal obturations were performed with gutta-percha and a resin-based root canal sealer by using a cold JOE — Volume -, Number -, - 2016
Clinical Research lateral compaction technique. After the root canal obturation was completed, a radiograph of each case was made for a final review of the teeth. All statistical analyses were performed with Sigmastat 3.1 (SigmaStat; Systat, San Jose, CA). The normality test of Shapiro-Wilk was applied to the data (a = 0.05). The sample failed the normality test (P < .05); consequently, the Friedman test was used (a = 0.05).
Results A total of 73 teeth from 30 patients (19 male and 11 female) were included in the present study; 11 patients received 1 root canal treatment, 9 patients received 2 root canal treatments, and 10 received 3 or more root canal treatments. Among the 73 teeth, 6 were premolars, and 67 were incisors and canines. CBCT images were evaluated by a single expert radiologist twice, and the intraoperator reliability for CBCT measurements was high (Pearson correlation coefficient, 0.96). The median values for CBCT, Raypex 6, and Propex Pixi measurements were 21.10, 21.36, and 21.55, respectively (Table 1). Statistical analysis showed no significant difference between the Raypex 6, Propex Pixi, and CBCT evaluations (P > .05).
Discussion CBCT scans have been popular in endodontics for both diagnosis and planning treatment (28). CBCT scans provide results comparable with EALs for the determination of the endodontic WL (10, 26, 27). In the preoperative CBCT scan of large jaw lesions, teeth whose roots are encompassed by the lesion that is to be removed could become devitalized by the surgery. Preoperative root canal treatment is indicated for these teeth, and the CBCT helps to determine whether this is necessary. In the present study, all CBCT scans were performed preoperatively, and a limited field of view was used. In accordance with the principle of as low as reasonably achievable, no additional preoperative radiography was taken, and CBCT images were evaluated in endodontic procedures. C¸alıs¸kan et al (6) evaluated the accuracy of 2 EALs (Apex Pointer and Propex) in persistent intracanal exudate and compared the actual length of teeth with the predetermined WL obtained with EALs. They concluded that EALs can be safely used to determine the WL of teeth with large periapical lesions. The results of the present study confirm this finding. The persistence of intracanal exudate caused no significant differences (P > .05) between the methods. C¸alıs¸kan et al compared the results of EALs with the WL measured during the surgical operation. In the present study, most patients had 2 or more teeth that required root canal treatments. Attempting to measure the actual length visually and the performance of the obturation of root canals during the surgical operation might have jeopardized the outcome of both the endodontic (by unintentional extrusion of the irrigants, debris, and obturation materials) and surgical treatments (by contamination of surgical operation site). The cessation of intracanal exudate could not be achieved during multiple treatment sessions in 6 teeth. Root canal obturations of those 6 teeth were therefore performed during the surgical operation.
Different apical landmarks, such as cemento-dentinal junction and major foramen, are acceptable as reference points when evaluating the performance of EALs (8, 10, 16). However, in CBCT scans it is impossible to detect cemento-dentinal junction even when the major foramen is easily seen. Therefore, in the present study, the major foramen (apical foramen seen on CBCT scan) was used as the apical reference point for WL measurements. The apical root canal structure may be altered in teeth with necrotic pulp and periapical lesions or inflammatory apical root resorption (29). This could affect the performance of EALs when detecting the major foramen (30). Inaccurate results can occur in teeth with a large apical foramen (31, 32). Also, the previous studies compared the EAL measurements with actual length that was performed visually by aid of a file visible at apical foramen (6, 29–32). CBCT measurements were accurate as the real WL (33). In the present study, root canal length measurements were performed by using 2 different EALs and compared with measurements from preexisting CBCT scans. All teeth had large periapical lesions, and according to the results, there were no significant differences between the measurements. The results of the EAL measurements in our study were not affected by any existing periapical inflammation. Both EALs used in the study were operated by using the multiple frequency system for taking measurements. Therefore, the results may be related to the novel technologies of the EALs used in this study. In an in vitro test model, Raypex 6 was found to be more accurate in determining the apical foramen (10). In the present study, although the median CBCT measurement (21.10 mm) was shorter than the medians of the 2 EAL measurements (21.36 for Raypex 6 and 21.55 for Propex Pixi), there were no significant differences between the systems (Fig. 2). The best scan showing the whole root canal and apical foramen was used for the CBCT scan measurements. A limitation of CBCT imaging occurs when a canal exits laterally or prematurely from the visual apex; it may not be imaged correctly in a single CBCT scan. Therefore, only teeth with straight roots were included in this study. In addition, the resolution of CBCT scans (voxel size) can affect WL measurements taken from scan images. CBCT systems with different voxel sizes should be evaluated in further studies. The results of the present study showed that CBCT scans can be used as an alternative method for ascertaining the WL. If a patient has a preexisting CBCT scan, the clinician should take advantage of this technique as an alternative, reliable method for determining the WL. EAL
TABLE 1. Medians, Quartiles, and Maximum and Minimum Values of Groups Groups
N Median 25%
CBCT 73 Raypex 6 73 Propex Pixi 73
21.10 21.36 21.55
75% Maximum Minimum
19.0 23.82 19.93 23.60 19.83 23.78
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27.70 29.15 30.36
15.1 15.5 15.5
Figure 2. Box plot graphic of the endodontic WL measurements obtained by using CBCT and EALs (Raypex 6, Propex Pixi). Bold lines show median of each group.
CBCT in Endodontic Working Length Determination
3
Clinical Research measurements can provide inconsistent results in teeth with metallic restorations because of electrical short circuiting (5). In such cases, CBCT images could be helpful in obtaining more precise evaluation of the WL and could increase the success rates for endodontic treatment (10, 27). In conclusion, in teeth with a large periapical lesion with intracanal exudate, CBCT images with a voxel size of 0.125 mm show comparable results with measurements made with the Raypex 6 and Propex Pixi devices. Therefore, if a preoperative CBCT scan is available, it could be an alternative or additional method for determining the endodontic WL of teeth with single canals.
Acknowledgments The authors deny any conflicts of interests related to this study.
References 1. Sjogren U, Hagglund B, Sundqvist G, Wing K. Factors affecting the long-term results of endodontic treatment. J Endod 1990;16:498–504. 2. Real DG, Davidowicz H, Moura-Netto C, et al. Accuracy of working length determination using 3 electronic apex locators and direct digital radiography. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2011;111:44–9. 3. ElAyouti A, Weiger R, Lost C. The ability of root ZX apex locator to reduce the frequency of overestimated radiographic working length. J Endod 2002;28:116–9. 4. Goldberg F, De Silvio AC, Manfre S, Nastri N. In vitro measurement accuracy of an electronic apex locator in teeth with simulated apical root resorption. J Endod 2002;28:461–3. 5. ElAyouti A, Dima E, Ohmer J, et al. Consistency of apex locator function: a clinical study. J Endod 2009;35:179–81. 6. Caliskan MK, Kaval ME, Tekin U. Clinical accuracy of two electronic apex locators in teeth with large periapical lesions. Int Endod J 2014;47:920–5. 7. Frank AL, Torabinejad M. An in vivo evaluation of Endex electronic apex locator. J Endod 1993;19:177–9. 8. Marigo L, Gervasi GL, Somma F, et al. Comparison of two electronic apex locators on human cadavers. Clin Oral Investig 2015 [Epub ahead of print]. 9. Marroquin BB, Fernandez CC, Schmidtmann I, et al. Accuracy of electronic apex locators to detect root canal perforations with inserted metallic posts: an ex vivo study. Head Face Med 2014;10:57. 10. Lucena C, Lopez JM, Martin JA, et al. Accuracy of working length measurement: electronic apex locator versus cone-beam computed tomography. Int Endod J 2014;47: 246–56. 11. Moscoso S, Pineda K, Basilio J, et al. Evaluation of Dentaport ZX and Raypex 6 electronic apex locators: an in vivo study. Med Oral Patol Oral Cir Bucal 2014;19: 202–5. 12. Pagavino G, Pace R, Baccetti T. A SEM study of in vivo accuracy of the Root ZX electronic apex locator. J Endod 1998;24:438–41.
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13. Martins JN, Marques D, Mata A, Carames J. Clinical efficacy of electronic apex locators: systematic review. J Endod 2014;40:759–77. 14. Kolanu SK, Bolla N, Varri S, et al. Evaluation of correlation between apical diameter and file size using Propex Pixi apex locator. J Clin Diagn Res 2014;8:18–20. 15. McDonald NJ. The electronic determination of working length. Dent Clin North Am 1992;36:293–307. 16. Shabahang S, Goon WW, Gluskin AH. An in vivo evaluation of Root ZX electronic apex locator. J Endod 1996;22:616–8. 17. Mayeda DL, Simon JH, Aimar DF, Finley K. In vivo measurement accuracy in vital and necrotic canals with the Endex apex locator. J Endod 1993;19:545–8. 18. Herrera M, Abalos C, Lucena C, et al. Critical diameter of apical foramen and of file size using the Root ZX apex locator: an in vitro study. J Endod 2011;37:1306–9. 19. Suomalainen A, Kiljunen T, Kaser Y, et al. Dosimetry and image quality of four dental cone beam computed tomography scanners compared with multislice computed tomography scanners. Dentomaxillofac Radiol 2009;38:367–78. 20. Demirbuga S, Sekerci AE, Dincer AN, et al. Use of cone-beam computed tomography to evaluate root and canal morphology of mandibular first and second molars in Turkish individuals. Med Oral Patol Oral Cir Bucal 2013;18:737–44. 21. Ozer SY. Detection of vertical root fractures of different thicknesses in endodontically enlarged teeth by cone beam computed tomography versus digital radiography. J Endod 2010;36:1245–9. 22. Kamburoglu K. Evaluating root resorption lesions with CBCT. Am J Orthod Dentofacial Orthop 2011;140:453. 23. Kamburoglu K, Kursun S, Yuksel S, Oztas B. Observer ability to detect ex vivo simulated internal or external cervical root resorption. J Endod 2011;37:168–75. 24. Patel S, Dawood A, Wilson R, et al. The detection and management of root resorption lesions using intraoral radiography and cone beam computed tomography: an in vivo investigation. Int Endod J 2009;42:831–8. 25. Michetti J, Maret D, Mallet JP, Diemer F. Validation of cone beam computed tomography as a tool to explore root canal anatomy. J Endod 2010;36:1187–90. 26. Janner SF, Jeger FB, Lussi A, Bornstein MM. Precision of endodontic working length measurements: a pilot investigation comparing cone-beam computed tomography scanning with standard measurement techniques. J Endod 2011;37:1046–51. 27. Jeger FB, Janner SF, Bornstein MM, Lussi A. Endodontic working length measurement with preexisting cone-beam computed tomography scanning: a prospective, controlled clinical study. J Endod 2012;38:884–8. 28. Patel S, Horner K. The use of cone beam computed tomography in endodontics. Int Endod J 2009;42:755–6. 29. Lomcali G, Sen BH, Cankaya H. Scanning electron microscopic observations of apical root surfaces of teeth with apical periodontitis. Endod Dent Traumatol 1996;12: 70–6. 30. Aydin U, Karataslioglu E, Aksoy F, Yildirim C. In vitro evaluation of Root ZX and Raypex 6 in teeth with different apical diameters. J Conserv Dent 2015;18:66–9. 31. Ebrahim AK, Wadachi R, Suda H. Ex vivo evaluation of the ability of four different electronic apex locators to determine the working length in teeth with various foramen diameters. Aust Dent J 2006;51:258–62. 32. Ebrahim AK, Yoshioka T, Kobayashi C, Suda H. The effects of file size, sodium hypochlorite and blood on the accuracy of Root ZX apex locator in enlarged root canals: an in vitro study. Aust Dent J 2006;51:153–7. 33. Connert T, Hulber JM, Godt A, et al. Accuracy of endodontic working length determination using cone beam computed tomography. Int Endod J 2014;47: 698–703.
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Evaluation of the Reliability of Cone-beam Computed Tomography Scanning and Electronic Apex Locator Measurements in Working Length Determination of Teeth with Large Periapical Lesions € un, DDS, PhD,* Tu Yakup Ust€ grul Aslan, DDS, PhD,* Ahmet Ercan S¸ekerci, DDS, PhD,† and Burak Sagsen, DDS, PhD* Abstract Introduction: This study evaluates the endodontic working-length measurements in teeth with large periapical lesions and persistent intracanal exudate by using preexisting cone-beam computed tomography (CBCT). It compares the measurements with clinical root canal lengths determined by using 2 electronic apex locators. Methods: All patients had undergone a CBCT scan independent of the present study and needed root canal treatment of at least 1 tooth visible in the field of view. Seventy-three teeth with single roots and canals were studied. An endodontist measured each root canal length with 2 different electronic apex locators. The measurements were repeated 3 times by using a digital caliper, and the mean was recorded. This mean was compared with the root canal length as measured on CBCT sections by an oral radiologist not involved in the endodontic treatment. The CBCT measurements were taken twice for analysis of intrarater reliability. The data were statistically analyzed. Results: There were no significant measurement differences between the methods used (P > .05). Conclusions: In teeth with large periapical lesions and persistent intracanal exudate, measurement of the root canal length by using CBCT was as reliable as measurements that used apex locators. (J Endod 2016;-:1–4)
Key Words Apex locator, cone-beam computed tomography, large periapical lesion, Propex Pixi, Raypex 6, root canal length measurement
T
he determination of Significance root canal preparation The present study investigated the reliabilities of length is one of the crucial root canal length measurements performed with factors that can affect the apex locators and cone-beam computed tomograoutcome of endodontic phy scans in teeth with large periapical lesion and treatment (1). Clinically, persistent intracanal exudate. conventional radiography and electronic apex locators (EALs) are usually used to determine the working length (WL). This method depends on a two-dimensional radiographic image and has some limitations, including superpositioning of anatomic structures, errors that are due to image magnification, distortions, and sensitivity of the technique (2). Radiographically, the WL is often measured 0.5–1.0 mm short of the radiographic apex. In addition, the major foramen does not always coincide with the anatomic apex; it may be laterally located (3). Determination of the WL of the canal in teeth with apical lesions and apical root resorption can be difficult by using conventional radiography (4). Electronic measurement of root canal length accurately determines the WL for root canal procedures (5), and this method has become indispensable in endodontics. Several studies have been performed to evaluate the accuracy of EALs (5–11), and EALs showed high accuracy rates, within 0.5 mm of the major apical foramen (8, 12). Several studies indicate that use of EALs reduces exposure of patients to radiation (13). Propex Pixi (Dentsply Maillefer, Ballaigues, Switzerland) and Raypex 6 (VDW, Munich, Germany) are recently introduced multi-frequency apex locators. Studies have assessed their accuracy for determining WL (8, 11, 14). Electric conductivity of intracanal liquids (irrigants, blood, pulp, exudate, etc), immature apex formation, periapical lesions, apical foramen size, and file size used to measure root canal length can compromise the accuracy of EALs (7, 15–18). Two different apex locators were evaluated under consistent intracanal exudate, and the EALs were found to be accurate (6). Cone-beam computed tomography (CBCT) has the advantage of a lower dose of radiation compared with computed tomography (19). Since its introduction in dentistry, CBCT has become an indispensable method for diagnosing root canal anatomy (20), root fracture (21), periapical pathology (14–17), and internal/external root resorption (22–24). CBCT is validated as a tool for exploring root canal morphology in
From the Departments of *Endodontics, and †Oral and Maxillofacial Radiology, Faculty of Dentistry, Erciyes University, Kayseri, Turkey. € €un, Department of Endodontics, Faculty of Dentistry, Erciyes University, Melikgazi, Kayseri 38039, Turkey. E-mail Address requests for reprints to Dr Yakup Ust address: [email protected] 0099-2399/$ - see front matter Copyright ª 2016 American Association of Endodontists. http://dx.doi.org/10.1016/j.joen.2016.06.010
JOE — Volume -, Number -, - 2016
CBCT in Endodontic Working Length Determination
1
Clinical Research 3 dimensions (25), and in some studies it was also used for estimating the WL (10, 26, 27). CBCT measurements in combination with EALs may also be useful for determining the WL (26, 27). The present study compared the accuracy of 2 EALs (Propex Pixi and Raypex 6) with a CBCT scan in determining apical foramen and WL in teeth with large periapical lesions and persistent intracanal exudate. The null hypothesis is that no differences exist between the measurement techniques.
Materials and Methods The ethical board of the research foundation of Erciyes University of Medical Sciences in Kayseri, Turkey approved this investigation (Ethics Approval Number: 2016-249). The present investigation included 30 patients who were referred to the Erciyes University Faculty of Dentistry, Department of Oral and Maxillofacial Surgery for further diagnostics and comprehensive therapy of large lesions of the jaws. All patients were in good general health, and female subjects were not pregnant. All patients had received limited CBCT imaging as part of the diagnostics of a large periapical lesion (>10 mm). A total of 73 teeth with a single root and canal from 30 patients were included in this study. Molar teeth or premolar teeth with several canals or roots, teeth that were not entirely visible in the CBCT scan or that had undergone any modifications after the CBCT scan, and CBCT scans with additional artifacts were not included in the study. Roots with severe apical resorptive defects and teeth with metallic restorations were not included in the study. The treatment plan consisted of an initial biopsy and subsequent endodontic treatment of the non-vital teeth and of the teeth in close proximity to the large lesion before the definitive surgery. In addition, a planned root canal treatment in at least 1 tooth with a single canal and root represented in the scanned field of view was required.
Imaging Procedures and Evaluation of WL Measurements on the CBCT Images The CBCT images were obtained by using a NewTom 5G (QR, Verona, Italy) with a voxel size of 0.125 mm, positioned parallel to the horizontal axis of the alveolar bone. A single oral radiologist with 6 years of experience evaluated all CBCT images. Each CBCT image was evaluated twice, with a 7-day break between each evaluation. Only the first measurement was considered for the comparison with the EAL measurement. The CBCT images were analyzed in the NNT viewer, a simple version of the NNT software of the CBCT machine in a Dell Precision T5400 workstation (Dell, Round Rock, TX) and a 32-inch Dell LCD screen with a resolution of 1280 1024 pixels in a darkroom. The contrast and brightness of the images were adjusted by using the image-processing tool in the software to ensure optimal visualization. The CBCT slices were first reformatted to place the root canal of each analyzed tooth in a vertical position to visualize the incisal edge, pulp chamber, major foramen, and, if possible, the whole length of the canal in 1 single slice (Fig. 1). To ensure standardized measurements, the root canal length was established in the CBCT images as the distance between the most incisal (or the most cuspidal) tooth edge in the projected midline of the pulp cavity and the major foramen. Clinically Working Length Determination by Using EALs An expert endodontist completed all root canal treatment procedures. The endodontist was blinded to the results of the CBCT measurements. The clinical root canal length measurement was performed twice, once with each EAL according to the manufacturer’s instructions. The EAL reference points used to determine the WL were the same points used in the CBCT measurements. After the tooth was anesthetized, 2
€Ust€un et al.
Figure 1. WL measurements by using CBCT scans.
the access cavity was opened, and the pulp was removed with a barbed broach. Apical patency was controlled with #8 K-File (Dentsply Maillefer). A #15 or bigger size K-file (Dentsply Maillefer) attached to the EAL device was then introduced into the root canal, and the lip hook of the EAL device was put onto the lip of the patient. Working Length Determination with Propex Pixi. Measurements taken with Propex Pixi apex locator were determined following the manufacturer’s instructions. When the 0.0 signal was seen by the operator, the file was gently moved beyond the apex until the ‘‘beyond apex’’ signal appeared, at which point the file was quickly withdrawn and stopped at the 0.0 point. Simultaneously, the rubber stop of the file was maintained in continuous contact with the incisal reference point of the tooth and fixed with flowable light-cure composite to the shaft of the file (Nova Compo HF Flow; Imicryl, Konya, Turkey). The distance was recorded by using a digital caliper (Insize Mini digital caliper; I_stanbul, Turkey). Working Length Determination with Raypex 6. The Raypex 6 was used according to the manufacturer’s instructions. The measurements were taken with the ‘‘apex’’ mark as reference. The file was introduced to the major foramen (red ball point) and moved slightly beyond the apex. It was then retracted slightly to the zero point (red light), and the rubber stop of the file was then fixed to the incisal reference point of the tooth. The rubber stop was fixed to the shaft of the file, and the file was moved outward. The distance was recorded with a digital caliper. The measurements were repeated 3 times with each EAL, and the mean value was recorded. The measurements were not recorded until the reading remained stable for at least 5 seconds; unstable measurements were not considered for statistical evaluation. The teeth included in this study had intracanal exudate that leaked from periapical lesions. Therefore, endodontic treatments were performed until the leakage was depleted. Of the 73 teeth, 67 were obturated before the surgical operation, but the obturations of 6 teeth could not be perfomed during the treatment sessions. Those 6 teeth were obturated during the surgical operation. Most of the teeth included in this study were diagnosed as having pulp necrosis; those that were vital had root canal therapy because the subsequent surgery would devitalize them. All root canal preparations were performed by using Reciproc instruments (VDW) and an endodontic motor (VDW Silver; VDW). Root canals were irrigated with 1% NaOCl during instrumentation. After completion of the preparation, the canals were irrigated with 2 mL 17% ethylenediaminetetraacetic acid for 1 minute and subsequently rinsed with 2 mL distilled water. The root canals were then dried with paper points (Dentsply Maillefer). All root canal obturations were performed with gutta-percha and a resin-based root canal sealer by using a cold JOE — Volume -, Number -, - 2016
Clinical Research lateral compaction technique. After the root canal obturation was completed, a radiograph of each case was made for a final review of the teeth. All statistical analyses were performed with Sigmastat 3.1 (SigmaStat; Systat, San Jose, CA). The normality test of Shapiro-Wilk was applied to the data (a = 0.05). The sample failed the normality test (P < .05); consequently, the Friedman test was used (a = 0.05).
Results A total of 73 teeth from 30 patients (19 male and 11 female) were included in the present study; 11 patients received 1 root canal treatment, 9 patients received 2 root canal treatments, and 10 received 3 or more root canal treatments. Among the 73 teeth, 6 were premolars, and 67 were incisors and canines. CBCT images were evaluated by a single expert radiologist twice, and the intraoperator reliability for CBCT measurements was high (Pearson correlation coefficient, 0.96). The median values for CBCT, Raypex 6, and Propex Pixi measurements were 21.10, 21.36, and 21.55, respectively (Table 1). Statistical analysis showed no significant difference between the Raypex 6, Propex Pixi, and CBCT evaluations (P > .05).
Discussion CBCT scans have been popular in endodontics for both diagnosis and planning treatment (28). CBCT scans provide results comparable with EALs for the determination of the endodontic WL (10, 26, 27). In the preoperative CBCT scan of large jaw lesions, teeth whose roots are encompassed by the lesion that is to be removed could become devitalized by the surgery. Preoperative root canal treatment is indicated for these teeth, and the CBCT helps to determine whether this is necessary. In the present study, all CBCT scans were performed preoperatively, and a limited field of view was used. In accordance with the principle of as low as reasonably achievable, no additional preoperative radiography was taken, and CBCT images were evaluated in endodontic procedures. C¸alıs¸kan et al (6) evaluated the accuracy of 2 EALs (Apex Pointer and Propex) in persistent intracanal exudate and compared the actual length of teeth with the predetermined WL obtained with EALs. They concluded that EALs can be safely used to determine the WL of teeth with large periapical lesions. The results of the present study confirm this finding. The persistence of intracanal exudate caused no significant differences (P > .05) between the methods. C¸alıs¸kan et al compared the results of EALs with the WL measured during the surgical operation. In the present study, most patients had 2 or more teeth that required root canal treatments. Attempting to measure the actual length visually and the performance of the obturation of root canals during the surgical operation might have jeopardized the outcome of both the endodontic (by unintentional extrusion of the irrigants, debris, and obturation materials) and surgical treatments (by contamination of surgical operation site). The cessation of intracanal exudate could not be achieved during multiple treatment sessions in 6 teeth. Root canal obturations of those 6 teeth were therefore performed during the surgical operation.
Different apical landmarks, such as cemento-dentinal junction and major foramen, are acceptable as reference points when evaluating the performance of EALs (8, 10, 16). However, in CBCT scans it is impossible to detect cemento-dentinal junction even when the major foramen is easily seen. Therefore, in the present study, the major foramen (apical foramen seen on CBCT scan) was used as the apical reference point for WL measurements. The apical root canal structure may be altered in teeth with necrotic pulp and periapical lesions or inflammatory apical root resorption (29). This could affect the performance of EALs when detecting the major foramen (30). Inaccurate results can occur in teeth with a large apical foramen (31, 32). Also, the previous studies compared the EAL measurements with actual length that was performed visually by aid of a file visible at apical foramen (6, 29–32). CBCT measurements were accurate as the real WL (33). In the present study, root canal length measurements were performed by using 2 different EALs and compared with measurements from preexisting CBCT scans. All teeth had large periapical lesions, and according to the results, there were no significant differences between the measurements. The results of the EAL measurements in our study were not affected by any existing periapical inflammation. Both EALs used in the study were operated by using the multiple frequency system for taking measurements. Therefore, the results may be related to the novel technologies of the EALs used in this study. In an in vitro test model, Raypex 6 was found to be more accurate in determining the apical foramen (10). In the present study, although the median CBCT measurement (21.10 mm) was shorter than the medians of the 2 EAL measurements (21.36 for Raypex 6 and 21.55 for Propex Pixi), there were no significant differences between the systems (Fig. 2). The best scan showing the whole root canal and apical foramen was used for the CBCT scan measurements. A limitation of CBCT imaging occurs when a canal exits laterally or prematurely from the visual apex; it may not be imaged correctly in a single CBCT scan. Therefore, only teeth with straight roots were included in this study. In addition, the resolution of CBCT scans (voxel size) can affect WL measurements taken from scan images. CBCT systems with different voxel sizes should be evaluated in further studies. The results of the present study showed that CBCT scans can be used as an alternative method for ascertaining the WL. If a patient has a preexisting CBCT scan, the clinician should take advantage of this technique as an alternative, reliable method for determining the WL. EAL
TABLE 1. Medians, Quartiles, and Maximum and Minimum Values of Groups Groups
N Median 25%
CBCT 73 Raypex 6 73 Propex Pixi 73
21.10 21.36 21.55
75% Maximum Minimum
19.0 23.82 19.93 23.60 19.83 23.78
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27.70 29.15 30.36
15.1 15.5 15.5
Figure 2. Box plot graphic of the endodontic WL measurements obtained by using CBCT and EALs (Raypex 6, Propex Pixi). Bold lines show median of each group.
CBCT in Endodontic Working Length Determination
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Clinical Research measurements can provide inconsistent results in teeth with metallic restorations because of electrical short circuiting (5). In such cases, CBCT images could be helpful in obtaining more precise evaluation of the WL and could increase the success rates for endodontic treatment (10, 27). In conclusion, in teeth with a large periapical lesion with intracanal exudate, CBCT images with a voxel size of 0.125 mm show comparable results with measurements made with the Raypex 6 and Propex Pixi devices. Therefore, if a preoperative CBCT scan is available, it could be an alternative or additional method for determining the endodontic WL of teeth with single canals.
Acknowledgments The authors deny any conflicts of interests related to this study.
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