- Email: [email protected]
Effect of piezoelectric instruments on healing propensity of alveolar sockets following mandibular third molar extraction
Journal of Dental Sciences (2012) 7, 296e300
Available online at www.sciencedirect.com
journal homepage: www.e-jds.com
ORIGINAL ARTICLE
Effect of piezoelectric instruments on healing propensity of alveolar sockets following mandibular third molar extraction Shang-Jye Tsai a,b, Yen-Liang Chen b, Hao-Hueng Chang b,c, Yow-Chyun Shyu c*, Chun-Pin Lin b,c a
Cardinal Tien Hospital, Yung Ho Branch, New Taipei City, Taiwan, ROC School of Dentistry, National Taiwan University and National Taiwan University Hospital, Taipei, Taiwan, ROC c Department of Dentistry, National Taiwan University Hospital, Taipei, Taiwan, ROC b
Final revision received 30 August 2011; accepted 13 March 2012 Available online 24 August 2012
KEYWORDS attachment level; bone healing; piezoelectric instrument; pocket depth; third molar extraction
Abstract Background/purpose: The purpose of this study was to investigate whether the use of piezoelectric instruments affected the healing propensity of alveolar sockets after mandibular third molar extraction, compared with conventional rotary instruments. Materials and methods: Thirty patients with impacted bilateral symmetrical mandibular third molars participated in this investigation. We conducted a randomized, crossover study using conventional rotary instruments for extraction on one side and piezoelectric instruments on the other. We evaluated the healing of periodontium at the distal side of the mandibular second molar by probing depth and attachment level. All data including pocket depth and bone healing at the distal side of the mandibular second molar were evaluated with paired t tests for comparison. Results: Although the average pocket depth after extraction with piezoelectric instruments was slightly less than with conventional instruments, there was no statistically significant difference between the two groups. At one month after extraction, the attachment level at the distal side of the mandibular second molar was better where extraction was done with piezoelectric instruments than conventional instruments (P < 0.05), though no significant difference between the two extraction methods was observed at two months postoperation.
* Corresponding author. Department of Dentistry, National Taiwan University Hospital, Number 1 Chang Te Street, Taipei 10016, Taiwan, ROC. E-mail address: [email protected] (Y.-C. Shyu). 1991-7902/$36 Copyright ª 2012, Association for Dental Sciences of the Republic of China. Published by Elsevier Taiwan LLC. All rights reserved. http://dx.doi.org/10.1016/j.jds.2012.07.001
Piezoelectric instruments and healing after extraction
297
Conclusion: Peizoelectric instruments have potential to promote initial bone healing after molar extraction. Copyright ª 2012, Association for Dental Sciences of the Republic of China. Published by Elsevier Taiwan LLC. All rights reserved.
Introduction Surgical removal of an impacted mandibular third molar is commonly performed as a necessity for a variety of clinical reasons,1 and it high clinical demand promoted many different surgical techniques to be proposed over the years. In practice, two surgical methods have been widely adopted: the tooth division technique with rotary instruments and the distolingual alveolectomy with chisel and hammer (or split bone technique).1 Several exciting technological advances in extraction techniques and outpatient oral surgery have been developed.2 Jean and Marie Curie first introduced piezoelectric instrumentation, which utilizes ultrasound technology, in 1880.3 Its application to oral surgery was first proposed in the late 1970s by Horton et al,4e6 though a dedicated device for this purpose was developed only recently by Vercellotti et al.6e9 Piezoelectric instruments have become a promising alternative to rotatory drilling instruments for oral extraction.6,10,11 The advantage of piezosurgery is that it uses ultrasonic microvibrations to cut bone effectively with minimal damage to the surrounding soft tissue,3 which promotes rapid post operation wound healing. The device is generally useful in cases in which bone needs to be cut close to delicate soft tissues where mechanical or thermal injury must be avoided, such as nerves, vessels, Schneiderian membrane and dura mater. Though recognized as a safe alternative for extraction, other new indications are now being widely proposed for piezosurgical instruments. Researchers have evaluated its application to periodontal osseous surgery,9 germectomy,6 distraction of jaw,10 sinus grafting,7,9,12 cranial osteoplasty,13 hand surgery,14 rhinoplasty,15 orthognathic surgery,12,16 and head/neck oncological and reconstruction surgery.17,18 Although some had proposed advantages of piezosurgical instruments for tooth extraction, there were no clinical data to describe the effect of piezosurgical instruments on postoperative periodontal healing. This clinical study compared the healing propensity of alveolar sockets following mandibular third molar extraction when piezosurgical instruments were used to compare with conventional rotary instruments.
Materials and methods We selected a total of 30 consecutive healthy patients for inclusion in the trial (16 men and 14 women with an average age of 21.5 years, range from 18e28 years) following approval by the Institutional Review Board (IRB) of National Taiwan University Hospital. The main criteria for selection of patients were bilateral impacted third molars with symmetrical position and form. We assessed each patient clinically and radiographically (including panoramic and periapical radiography) in terms of depth of impaction, angulation, and root patterns. A certified operator at
National Taiwan University Hospital (NTUH) performed all extractions with rotary instrument employed on one side and piezosurgical instruments on the other. All patients received identical local anesthesia during extraction, postoperative drug regimens (analgesia and antibiotics) and instructions regarding postoperative care. After extraction, we monitored the healing status on each side distal to the mandibular second molar over a three-month period. All subjects completed the same postoperative protocol for both extractions. The protocol included antibiotic therapy (amoxicillin 50 mg/kg in two daily doses for six days) and analgesics (nimesulide 50 mg every eight hours) as necessary for pain control, associated with a chlorhexidine 0.2% mouthwash (three times daily for six days). All subjects were advised to use cold compresses immediately after extraction. We removed the stitches at the first follow-up visit seven days after the procedure. We determined the depth and position of the mandibular impacted third molar according to Pell and Gregory17 A, B, and C classifications (Table 1).
Surgical procedures Surgical procedures were similar to those used by Sivolella et al6 except for some modifications in the use of analgesics and instruments. We randomly selected the side for piezoelectric or conventional rotary extraction in each subject. First, we administered block anesthesia of the inferior alveolar nerve, followed by infiltration anesthesia of the buccal nerve with 2% lidocaine 3.6 ml. The incision was made from the base of the ascending ramus toward the distolingual line-angle of the second molar, then extended anteriorly along the gingival sulcus, terminating at the papilla between the first and second molars. Mucoperiosteal flaps were reflected on both the buccal and lingual aspects to expose the bone overlying the impacted tooth. After detaching the flap, we exposed the cortical bone, and performed an access to the impacted tooth. On the rotary side, we performed extraction with a surgical round bur fitted on a handpiece Table 1 Classification of impacted mandibular third molars according to Pell and Gregory A, B, and C.a Classification
Left
Right
Total
Position A Position B Position C Total
18 8 3 29
18 6 4 28
36 14 7 57
a Position A: The occlusal surface of the impacted tooth is level or nearly level with the occlusal plane of the second molar. Position B: The occlusal surface is between the occlusal plane and cervical line of the second molar. Position C: The occlusal surface of the impacted tooth is below the cervical line of the second molar.
298 using copious irrigation. The contralateral extraction was completed with the piezosurgical ablator (Mectron Piezosurgery, Medical Technology, Carasco, Italy) using the OP1 and OT2 inserts cooled with sterile physiologic solution. For both extractions, we performed tooth sectioning when necessary using a surgical bur attached to a handpiece. After loosening the crown of the impacted tooth and separating it from the roots, we delivered the exposed root masses projecting from the alveolus with elevators. After extraction, careful wound toilet was performed.
S.-J. Tsai et al Table 2 Pocket depth at the distal side of the mandibular second molar. Period
Piezoelectric instruments (mm)
Conventional instruments (mm)
7-days 1-month 2-month
4.4 (0.9)a 3.4 (0.7) 3.1 (0.7)
4.6 (1.0) 3.3 (0.8) 3.2 (0.9)
a b
t value
0.6 0.8 0.7
Pb
>0.05 >0.05 >0.05
Values are presented as mean (standard deviation). Determined by paired t test.
Periodontal assessment We followed the protocol that proposed by Chang et al’s1 method for periodontal assessment, with modification to the observation time points, evaluating periodontal healing around the distal aspects of the mandibular second molars at seven days, one month and two months after extraction. At each follow up, we assessed the periodontal condition using two major criteria: (1) periodontal pocket depth and (2) attachment level, as described by Osborne et al. In addition, a Marquis periodontal probe with the handle removed served as a marker on periapical radiographs, as described in Kugelberg et al.7 We used X-rays to check whether the probe was in the approximate location of the crevice base for accurate measurement of the periodontal pocket depth and attachment level. The X-rays were taken using a probe as a marker similar to the method employed by Kugelberg et al, in order to evaluate the healing of the bony socket around the distal aspect of the mandibular second molar.1,19,20 The radiographs were used as a quality check to ensure proper placement of the probes at the crevice base, as opposed to using them for specific calculations. We described the periodontal pocket depth at the distal aspect of the mandibular second molar (or the depth of the gingival crevice) by the average values of the depths at the distolingual, distobuccal and mid-distal areas. Attachment levels were determined by the average depth of the crevice to the distolingual cusp tip, the distobuccal cusp tip and the midpoint of the distal marginal ridge. We gave patients topical analgesics as needed to reduce discomfort during postoperation follow-ups. All data were recorded and analyzed using SAS 8.1 (SAS Institute, Cary, NC) for Windows 98 SE. We used paired t tests to compare the average values of the periodontal pocket depths and attachment levels for the two different surgical techniques. The level of significance for comparisons was set at P < 0.05.
statistically significant difference between the two groups (Table 2). Attachment levels at the distal side of the mandibular second molar showed better wound recovery on the piezoelectric side than on the side treated with conventional rotary methods at one month postoperation (P < 0.05) (Table 3). This difference was no statistically significant at two months postoperation.
Discussion When surgically removing impacted mandibular third molars, it is important to preserve the integrity of the adjacent mandibular second molar, and unwise to use a surgical method that might lead to exposure of roots, pulpal necrosis, apical periodontitis of neighboring teeth, or the formation of residual cysts.1 Therefore, it is essential to select surgical techniques or instruments that conform to anatomic structures and are soundly based on physiological principles. Many authors had discussed distal periodontal healing and injuries to the mandibular second molars after removal of impacted mandibular third molars as an indicator of successful treatment.19e21 This study used the same parameters to evaluate treatment outcomes of mandibular third molar extractions employing different surgical instruments on young, healthy, and highly cooperative individuals who served as their own controls in crossover trials. Since the variation of clinical parameters was greater between subjects than within the same subject, the crossover methodology efficiently increased the power of our statistical tests, and also minimized the effect of important factors such as patients’ different healing capacity and operator proficiency. A variety of new instruments and
Results
Table 3 Attachment level at the distal side of the mandibular second molar.
The average pocket depths and attachment levels distal to mandibular second molars at seven days, one month, and two months after extraction are shown in Tables 2 and 3. We found no difference in pocket depth and attachment level between the two groups at seven days post operation. To minimize measurement error due to discomfort, topical analgesics were applied as needed during examinations. Although the average pocket depth where extraction was performed with piezoelectric instruments was slightly less compared with conventional instruments, there was no
Period
Piezoelectric instruments (mm)
Conventional instruments (mm)
7-days 1-month 2-month
7.6 (0.9)a 6.4 (0.8) 6.2 (0.7)
7.5 (1.0) 7.1 (0.7) 6.3 (0.9)
t value
1 3.78* 0.8
*P < 0.05 is statistically significant. a Values are presented as mean (standard deviation). b Determined by pair t test.
Pb
>0.05 <0.05 >0.05
Piezoelectric instruments and healing after extraction techniques are revolutionizing the fields of oral and maxillofacial surgery and dentistry, and piezosurgery may be the most important of these, given its precision for cutting hard tissue while sparing soft tissue. The number of situations where piezosurgery is indicated in oral and maxillofacial surgery and other fields such as otorhinolaryngology, neurosurgery, ophthalmology, traumatology and orthopedics, is increasing.22 According to this study at one month after extraction, the attachment level at the distal side of the mandibular second molar, which may be taken as indication of bone healing, was better on the side receiving piezoelectric extraction than on the side given conventional rotary treatment (P < 0.05) (Table 2, Fig. 1). However, at two months post extraction the degree of bone healing using both piezoelectric devices and conventional drilling instruments were similar (Tables 2 and 3). It seems that piezoelectric surgical instruments may promote faster wound healing compared to rotary instruments over a short-term observation period. Other studies had also addressed the benefits of piezoelectric surgical instruments. Blus and Szmukler-Moncler22 concluded that piezoelectric surgery is a new, relevant and predictable method for atraumatic tooth extraction
299 and subsequent implant site preparation, based on their removal of 40 noninfected teeth or roots in 23 patients followed by immediate implantations.22 Furthermore, histological and histomorphometric evidence of wound healing and bone formation in experimental animal models supports such observations of effectiveness in clinical settings.8,23,24 Stacchi et al found a limited decrease of Implant Stability Quotient (ISQ) values with piezoelectric methods that increased stability patterns compared with traditional drilling techniques. Not only does the piezoelectric method improve short-term wound healing, other studies have also indicated that it provides the benefit of significantly reduced pain following mastoidectomy. These results, in combination with ours, highlight the unique benefits of piezoelectric devices as safe and minimally invasive tools,25 which provide a more favorable tissue repair response compared with conventional bone-cutting techniques, such as diamond or carbide rotary instruments. Though speculative, there were several reasons why piezosurgical instruments could promote wound healing. A study conducted by Berengo et al23 compared approximately nine bone harvesting methods. Their results showed that the best methods to harvest vital bone are: gouge shaped bone chisel, back-action, en bloc harvesting, rongeur pliers and piezosurgery, although the latter left some empty gaps in the tissue. The bone harvested with a round bur on low-speed hand-piece, a bur on high-speed handpiece, a spiral implant bur, or safe scraper, was not suitable for grafting as indicated by the absence of osteocytes and the predominance of non-vital bone.23 On the other hand, some authors argued that piezoelectric methods should be contraindicated. For example, Rashad et al showed that piezoelectric implant site preparation was more time consuming and generated higher bone temperatures than conventional drilling.26 These differing results could be accounted for by different modes of application and treatment targets, and should not be taken at face value. Despite other considerations regarding the use of piezoelectric methods for oral surgery, in our study, they promoted initial wound recovery and bone healing compared with conventional rotary instruments.
Acknowledgments This research was supported by the Southern Taiwan Science Park Administration (STSPA), Taiwan, R.O.C. under contract AZ-09-10-25-98.
References
Figure 1 Bone healing at the distal side of the mandibular second molar after extraction done with piezoelectric instruments (A) and with conventional instruments (B) one month following extraction. Bone healing on the piezoelectric side is better than that on the conventional side (black arrow).
1. Chang HH, Lee JJ, Kok SH, Yang PJ. Periodontal healing after mandibular third molar surgeryea comparison of distolingual alveolectomy and tooth division techniques. Int J Oral Maxillofac Surg 2004;33:32e7. 2. Weiss A, Stern A, Dym H. Technological advances in extraction techniques and outpatient oral surgery. Dent Clin North Am 2011;55:501e13. 3. Pavlikova G, Foltan R, Horka M, Hanzelka T, Borunska H, Sedy J. Piezosurgery in oral and maxillofacial surgery. Int J Oral Maxillofac Surg 2011;40:451e7.
300 4. Horton JE, Tarpley Jr TM, Wood LD. The healing of surgical defects in alveolar bone produced with ultrasonic instrumentation, chisel, and rotary bur. Oral Surg Oral Med Oral Pathol 1975;39:536e46. 5. Horton JE, Tarpley Jr TM, Jacoway JR. Clinical applications of ultrasonic instrumentation in the surgical removal of bone. Oral Surg Oral Med Oral Pathol 1981;51:236e42. 6. Sivolella S, Berengo M, Bressan E, Di Fiore A, Stellini E. Osteotomy for lower third molar germectomy: randomized prospective crossover clinical study comparing piezosurgery and conventional rotatory osteotomy. J Oral Maxillofac Surg 2011;69:e15e23. 7. Vercellotti T, De Paoli S, Nevins M. The piezoelectric bony window osteotomy and sinus membrane elevation: introduction of a new technique for simplification of the sinus augmentation procedure. Int J Periodontics Restorative Dent 2001;21:561e7. 8. Vercellotti T, Nevins ML, Kim DM, et al. Osseous response following resective therapy with piezosurgery. Int J Periodontics Restorative Dent 2005;25:543e9. 9. Vercellotti T, Pollack AS. A new bone surgery device: sinus grafting and periodontal surgery. Compend Contin Educ Dent 2006;27:319e25. 10. Heiland M, Blessmann M, Pohlenz P, Li L, Schmelzle R, Blake F. Intraoral osteotomies using piezosurgery for distraction in an infant with Pierre-Robin sequence. Clin Oral Investig 2007;11: 303e6. 11. Stubinger S, Kuttenberger J, Filippi A, Sader R, Zeilhofer HF. Intraoral piezosurgery: preliminary results of a new technique. J Oral Maxillofac Surg 2005;63:1283e7. 12. Munoz-Guerra MF, Naval-Gias L, Capote-Moreno A. Le Fort I osteotomy, bilateral sinus lift, and inlay bone-grafting for reconstruction in the severely atrophic maxilla: a new vision of the sandwich technique, using bone scrapers and piezosurgery. J Oral Maxillofac Surg 2009;67:613e8. 13. Kotrikova B, Wirtz R, Krempien R, et al. Piezosurgeryea new safe technique in cranial osteoplasty? Int J Oral Maxillofac Surg 2006;35:461e5. 14. Hoigne DJ, Stubinger S, Von Kaenel O, Shamdasani S, Hasenboehler P. Piezoelectric osteotomy in hand surgery: first experiences with a new technique. BMC Musculoskelet Disord 2006;7:36.
S.-J. Tsai et al 15. Robiony M, Toro C, Costa F, Sembronio S, Polini F, Politi M. Piezosurgery: a new method for osteotomies in rhinoplasty. J Craniofac Surg 2007;18:1098e100. 16. Geha HJ, Gleizal AM, Nimeskern NJ, Beziat JL. Sensitivity of the inferior lip and chin following mandibular bilateral sagittal split osteotomy using Piezosurgery. Plast Reconstr Surg 2006; 118:1598e607. 17. Pell GJ, Gregory G. Report on a ten year study of a tooth division technique for the removal of impacted teeth. Am J Orthod Oral Surg 1942;28:660. 18. Crosetti E, Battiston B, Succo G. Piezosurgery in head and neck oncological and reconstructive surgery: personal experience on 127 cases. Acta Otorhinolaryngol Ital 2009;29:1e9. 19. Kugelberg CF, Ahlstrom U, Ericson S, Hugoson A. Periodontal healing after impacted lower third molar surgery. A retrospective study. Int J Oral Surg 1985;14:29e40. 20. Kugelberg CF, Ahlstrom U, Ericson S, Hugoson A, Kvint S. Periodontal healing after impacted lower third molar surgery in adolescents and adults. A prospective study. Int J Oral Maxillofac Surg 1991;20:18e24. 21. Kugelberg CF, Ahlstrom U, Ericson S, Hugoson A, Thilander H. The influence of anatomical, pathophysiological and other factors on periodontal healing after impacted lower third molar surgery. A multiple regression analysis. J Clin Periodontol 1991;18:37e43. 22. Blus C, Szmukler-Moncler S. Atraumatic tooth extraction and immediate implant placement with Piezosurgery: evaluation of 40 sites after at least 1 year of loading. Int J Periodontics Restorative Dent 2010;30:355e63. 23. Berengo M, Bacci C, Sartori M, Perini A, Della Barbera M, Valente M. Histomorphometric evaluation of bone grafts harvested by different methods. Minerva Stomatol 2006;55:189e98. 24. Chiriac G, Herten M, Schwarz F, Rothamel D, Becker J. Autogenous bone chips: influence of a new piezoelectric device (Piezosurgery) on chip morphology, cell viability and differentiation. J Clinl Periodontol 2005;32:994e9. 25. Crippa B, Salzano FA, Mora R, Dellepiane M, Salami A, Guastini L. Comparison of postoperative pain: piezoelectric device versus microdrill. Eur Arch Otorhinolaryngol 2011;268:1279e82. 26. Rashad A, Kaiser A, Prochnow N, Schmitz I, Hoffmann E, Maurer P. Heat production during different ultrasonic and conventional osteotomy preparations for dental implants. Clin Oral Implants Res 2011;22(12):1361e5.
Available online at www.sciencedirect.com
journal homepage: www.e-jds.com
ORIGINAL ARTICLE
Effect of piezoelectric instruments on healing propensity of alveolar sockets following mandibular third molar extraction Shang-Jye Tsai a,b, Yen-Liang Chen b, Hao-Hueng Chang b,c, Yow-Chyun Shyu c*, Chun-Pin Lin b,c a
Cardinal Tien Hospital, Yung Ho Branch, New Taipei City, Taiwan, ROC School of Dentistry, National Taiwan University and National Taiwan University Hospital, Taipei, Taiwan, ROC c Department of Dentistry, National Taiwan University Hospital, Taipei, Taiwan, ROC b
Final revision received 30 August 2011; accepted 13 March 2012 Available online 24 August 2012
KEYWORDS attachment level; bone healing; piezoelectric instrument; pocket depth; third molar extraction
Abstract Background/purpose: The purpose of this study was to investigate whether the use of piezoelectric instruments affected the healing propensity of alveolar sockets after mandibular third molar extraction, compared with conventional rotary instruments. Materials and methods: Thirty patients with impacted bilateral symmetrical mandibular third molars participated in this investigation. We conducted a randomized, crossover study using conventional rotary instruments for extraction on one side and piezoelectric instruments on the other. We evaluated the healing of periodontium at the distal side of the mandibular second molar by probing depth and attachment level. All data including pocket depth and bone healing at the distal side of the mandibular second molar were evaluated with paired t tests for comparison. Results: Although the average pocket depth after extraction with piezoelectric instruments was slightly less than with conventional instruments, there was no statistically significant difference between the two groups. At one month after extraction, the attachment level at the distal side of the mandibular second molar was better where extraction was done with piezoelectric instruments than conventional instruments (P < 0.05), though no significant difference between the two extraction methods was observed at two months postoperation.
* Corresponding author. Department of Dentistry, National Taiwan University Hospital, Number 1 Chang Te Street, Taipei 10016, Taiwan, ROC. E-mail address: [email protected] (Y.-C. Shyu). 1991-7902/$36 Copyright ª 2012, Association for Dental Sciences of the Republic of China. Published by Elsevier Taiwan LLC. All rights reserved. http://dx.doi.org/10.1016/j.jds.2012.07.001
Piezoelectric instruments and healing after extraction
297
Conclusion: Peizoelectric instruments have potential to promote initial bone healing after molar extraction. Copyright ª 2012, Association for Dental Sciences of the Republic of China. Published by Elsevier Taiwan LLC. All rights reserved.
Introduction Surgical removal of an impacted mandibular third molar is commonly performed as a necessity for a variety of clinical reasons,1 and it high clinical demand promoted many different surgical techniques to be proposed over the years. In practice, two surgical methods have been widely adopted: the tooth division technique with rotary instruments and the distolingual alveolectomy with chisel and hammer (or split bone technique).1 Several exciting technological advances in extraction techniques and outpatient oral surgery have been developed.2 Jean and Marie Curie first introduced piezoelectric instrumentation, which utilizes ultrasound technology, in 1880.3 Its application to oral surgery was first proposed in the late 1970s by Horton et al,4e6 though a dedicated device for this purpose was developed only recently by Vercellotti et al.6e9 Piezoelectric instruments have become a promising alternative to rotatory drilling instruments for oral extraction.6,10,11 The advantage of piezosurgery is that it uses ultrasonic microvibrations to cut bone effectively with minimal damage to the surrounding soft tissue,3 which promotes rapid post operation wound healing. The device is generally useful in cases in which bone needs to be cut close to delicate soft tissues where mechanical or thermal injury must be avoided, such as nerves, vessels, Schneiderian membrane and dura mater. Though recognized as a safe alternative for extraction, other new indications are now being widely proposed for piezosurgical instruments. Researchers have evaluated its application to periodontal osseous surgery,9 germectomy,6 distraction of jaw,10 sinus grafting,7,9,12 cranial osteoplasty,13 hand surgery,14 rhinoplasty,15 orthognathic surgery,12,16 and head/neck oncological and reconstruction surgery.17,18 Although some had proposed advantages of piezosurgical instruments for tooth extraction, there were no clinical data to describe the effect of piezosurgical instruments on postoperative periodontal healing. This clinical study compared the healing propensity of alveolar sockets following mandibular third molar extraction when piezosurgical instruments were used to compare with conventional rotary instruments.
Materials and methods We selected a total of 30 consecutive healthy patients for inclusion in the trial (16 men and 14 women with an average age of 21.5 years, range from 18e28 years) following approval by the Institutional Review Board (IRB) of National Taiwan University Hospital. The main criteria for selection of patients were bilateral impacted third molars with symmetrical position and form. We assessed each patient clinically and radiographically (including panoramic and periapical radiography) in terms of depth of impaction, angulation, and root patterns. A certified operator at
National Taiwan University Hospital (NTUH) performed all extractions with rotary instrument employed on one side and piezosurgical instruments on the other. All patients received identical local anesthesia during extraction, postoperative drug regimens (analgesia and antibiotics) and instructions regarding postoperative care. After extraction, we monitored the healing status on each side distal to the mandibular second molar over a three-month period. All subjects completed the same postoperative protocol for both extractions. The protocol included antibiotic therapy (amoxicillin 50 mg/kg in two daily doses for six days) and analgesics (nimesulide 50 mg every eight hours) as necessary for pain control, associated with a chlorhexidine 0.2% mouthwash (three times daily for six days). All subjects were advised to use cold compresses immediately after extraction. We removed the stitches at the first follow-up visit seven days after the procedure. We determined the depth and position of the mandibular impacted third molar according to Pell and Gregory17 A, B, and C classifications (Table 1).
Surgical procedures Surgical procedures were similar to those used by Sivolella et al6 except for some modifications in the use of analgesics and instruments. We randomly selected the side for piezoelectric or conventional rotary extraction in each subject. First, we administered block anesthesia of the inferior alveolar nerve, followed by infiltration anesthesia of the buccal nerve with 2% lidocaine 3.6 ml. The incision was made from the base of the ascending ramus toward the distolingual line-angle of the second molar, then extended anteriorly along the gingival sulcus, terminating at the papilla between the first and second molars. Mucoperiosteal flaps were reflected on both the buccal and lingual aspects to expose the bone overlying the impacted tooth. After detaching the flap, we exposed the cortical bone, and performed an access to the impacted tooth. On the rotary side, we performed extraction with a surgical round bur fitted on a handpiece Table 1 Classification of impacted mandibular third molars according to Pell and Gregory A, B, and C.a Classification
Left
Right
Total
Position A Position B Position C Total
18 8 3 29
18 6 4 28
36 14 7 57
a Position A: The occlusal surface of the impacted tooth is level or nearly level with the occlusal plane of the second molar. Position B: The occlusal surface is between the occlusal plane and cervical line of the second molar. Position C: The occlusal surface of the impacted tooth is below the cervical line of the second molar.
298 using copious irrigation. The contralateral extraction was completed with the piezosurgical ablator (Mectron Piezosurgery, Medical Technology, Carasco, Italy) using the OP1 and OT2 inserts cooled with sterile physiologic solution. For both extractions, we performed tooth sectioning when necessary using a surgical bur attached to a handpiece. After loosening the crown of the impacted tooth and separating it from the roots, we delivered the exposed root masses projecting from the alveolus with elevators. After extraction, careful wound toilet was performed.
S.-J. Tsai et al Table 2 Pocket depth at the distal side of the mandibular second molar. Period
Piezoelectric instruments (mm)
Conventional instruments (mm)
7-days 1-month 2-month
4.4 (0.9)a 3.4 (0.7) 3.1 (0.7)
4.6 (1.0) 3.3 (0.8) 3.2 (0.9)
a b
t value
0.6 0.8 0.7
Pb
>0.05 >0.05 >0.05
Values are presented as mean (standard deviation). Determined by paired t test.
Periodontal assessment We followed the protocol that proposed by Chang et al’s1 method for periodontal assessment, with modification to the observation time points, evaluating periodontal healing around the distal aspects of the mandibular second molars at seven days, one month and two months after extraction. At each follow up, we assessed the periodontal condition using two major criteria: (1) periodontal pocket depth and (2) attachment level, as described by Osborne et al. In addition, a Marquis periodontal probe with the handle removed served as a marker on periapical radiographs, as described in Kugelberg et al.7 We used X-rays to check whether the probe was in the approximate location of the crevice base for accurate measurement of the periodontal pocket depth and attachment level. The X-rays were taken using a probe as a marker similar to the method employed by Kugelberg et al, in order to evaluate the healing of the bony socket around the distal aspect of the mandibular second molar.1,19,20 The radiographs were used as a quality check to ensure proper placement of the probes at the crevice base, as opposed to using them for specific calculations. We described the periodontal pocket depth at the distal aspect of the mandibular second molar (or the depth of the gingival crevice) by the average values of the depths at the distolingual, distobuccal and mid-distal areas. Attachment levels were determined by the average depth of the crevice to the distolingual cusp tip, the distobuccal cusp tip and the midpoint of the distal marginal ridge. We gave patients topical analgesics as needed to reduce discomfort during postoperation follow-ups. All data were recorded and analyzed using SAS 8.1 (SAS Institute, Cary, NC) for Windows 98 SE. We used paired t tests to compare the average values of the periodontal pocket depths and attachment levels for the two different surgical techniques. The level of significance for comparisons was set at P < 0.05.
statistically significant difference between the two groups (Table 2). Attachment levels at the distal side of the mandibular second molar showed better wound recovery on the piezoelectric side than on the side treated with conventional rotary methods at one month postoperation (P < 0.05) (Table 3). This difference was no statistically significant at two months postoperation.
Discussion When surgically removing impacted mandibular third molars, it is important to preserve the integrity of the adjacent mandibular second molar, and unwise to use a surgical method that might lead to exposure of roots, pulpal necrosis, apical periodontitis of neighboring teeth, or the formation of residual cysts.1 Therefore, it is essential to select surgical techniques or instruments that conform to anatomic structures and are soundly based on physiological principles. Many authors had discussed distal periodontal healing and injuries to the mandibular second molars after removal of impacted mandibular third molars as an indicator of successful treatment.19e21 This study used the same parameters to evaluate treatment outcomes of mandibular third molar extractions employing different surgical instruments on young, healthy, and highly cooperative individuals who served as their own controls in crossover trials. Since the variation of clinical parameters was greater between subjects than within the same subject, the crossover methodology efficiently increased the power of our statistical tests, and also minimized the effect of important factors such as patients’ different healing capacity and operator proficiency. A variety of new instruments and
Results
Table 3 Attachment level at the distal side of the mandibular second molar.
The average pocket depths and attachment levels distal to mandibular second molars at seven days, one month, and two months after extraction are shown in Tables 2 and 3. We found no difference in pocket depth and attachment level between the two groups at seven days post operation. To minimize measurement error due to discomfort, topical analgesics were applied as needed during examinations. Although the average pocket depth where extraction was performed with piezoelectric instruments was slightly less compared with conventional instruments, there was no
Period
Piezoelectric instruments (mm)
Conventional instruments (mm)
7-days 1-month 2-month
7.6 (0.9)a 6.4 (0.8) 6.2 (0.7)
7.5 (1.0) 7.1 (0.7) 6.3 (0.9)
t value
1 3.78* 0.8
*P < 0.05 is statistically significant. a Values are presented as mean (standard deviation). b Determined by pair t test.
Pb
>0.05 <0.05 >0.05
Piezoelectric instruments and healing after extraction techniques are revolutionizing the fields of oral and maxillofacial surgery and dentistry, and piezosurgery may be the most important of these, given its precision for cutting hard tissue while sparing soft tissue. The number of situations where piezosurgery is indicated in oral and maxillofacial surgery and other fields such as otorhinolaryngology, neurosurgery, ophthalmology, traumatology and orthopedics, is increasing.22 According to this study at one month after extraction, the attachment level at the distal side of the mandibular second molar, which may be taken as indication of bone healing, was better on the side receiving piezoelectric extraction than on the side given conventional rotary treatment (P < 0.05) (Table 2, Fig. 1). However, at two months post extraction the degree of bone healing using both piezoelectric devices and conventional drilling instruments were similar (Tables 2 and 3). It seems that piezoelectric surgical instruments may promote faster wound healing compared to rotary instruments over a short-term observation period. Other studies had also addressed the benefits of piezoelectric surgical instruments. Blus and Szmukler-Moncler22 concluded that piezoelectric surgery is a new, relevant and predictable method for atraumatic tooth extraction
299 and subsequent implant site preparation, based on their removal of 40 noninfected teeth or roots in 23 patients followed by immediate implantations.22 Furthermore, histological and histomorphometric evidence of wound healing and bone formation in experimental animal models supports such observations of effectiveness in clinical settings.8,23,24 Stacchi et al found a limited decrease of Implant Stability Quotient (ISQ) values with piezoelectric methods that increased stability patterns compared with traditional drilling techniques. Not only does the piezoelectric method improve short-term wound healing, other studies have also indicated that it provides the benefit of significantly reduced pain following mastoidectomy. These results, in combination with ours, highlight the unique benefits of piezoelectric devices as safe and minimally invasive tools,25 which provide a more favorable tissue repair response compared with conventional bone-cutting techniques, such as diamond or carbide rotary instruments. Though speculative, there were several reasons why piezosurgical instruments could promote wound healing. A study conducted by Berengo et al23 compared approximately nine bone harvesting methods. Their results showed that the best methods to harvest vital bone are: gouge shaped bone chisel, back-action, en bloc harvesting, rongeur pliers and piezosurgery, although the latter left some empty gaps in the tissue. The bone harvested with a round bur on low-speed hand-piece, a bur on high-speed handpiece, a spiral implant bur, or safe scraper, was not suitable for grafting as indicated by the absence of osteocytes and the predominance of non-vital bone.23 On the other hand, some authors argued that piezoelectric methods should be contraindicated. For example, Rashad et al showed that piezoelectric implant site preparation was more time consuming and generated higher bone temperatures than conventional drilling.26 These differing results could be accounted for by different modes of application and treatment targets, and should not be taken at face value. Despite other considerations regarding the use of piezoelectric methods for oral surgery, in our study, they promoted initial wound recovery and bone healing compared with conventional rotary instruments.
Acknowledgments This research was supported by the Southern Taiwan Science Park Administration (STSPA), Taiwan, R.O.C. under contract AZ-09-10-25-98.
References
Figure 1 Bone healing at the distal side of the mandibular second molar after extraction done with piezoelectric instruments (A) and with conventional instruments (B) one month following extraction. Bone healing on the piezoelectric side is better than that on the conventional side (black arrow).
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