Risk factors of inferior alveolar nerve and vessels injury in the mandibular third molar extractions: the contact and positional relation between root and inferior alveolar canal

Abstract

Abstract: PURPOSE : To suggest a risk degree and classification according to the contact and positional relation between root and inferior alveolar canal (IAC) for prognosis estimation and surgery design. METHODS : Consecutive cases with complicated mandibular third molars underwent extraction using piezosurgery were reviewed. Those teeth contacted IAC in panoramic radiographs were included, and classified into degree Ⅰ (contact), Ⅱ (compress), Ⅲ (penetrate) according to the contact relation between root and IAC in both panoramic radiographs and cone-beam CT (CBCT). Kappa test and youden index were used to compare two imaging RESULTS. The included teeth were categorized into class I (root on the buccal side), Ⅱ (above IAC), Ⅲ (on the lingual side), Ⅳ (surrounding IAC) according to the positional relation. Inferior alveolar nerve and vessels injury rates of teeth in different degrees and categories were recorded. Fisher’s exact probability was used to analyze the difference of injury rates in teeth of different degrees and categories. Statistical analysis was performed using SAS 8.2 software package. RESULTS : 79.31% (92/116) of complicated mandibular third molars had inferior alveolar nerve and vessels injury risk (33.70%, 28.26%, 38.04% in risk degree Ⅰ, Ⅱ, Ⅲ according to the evaluation of panoramic radiographs, 36.96%, 33.70%, 29.35% in risk degree Ⅰ, Ⅱ, Ⅲ according to CBCT). The concordance of two images RESULTS was better on Kappa test (Kappa=0.8699). Teeth in risk degree Ⅰ, Ⅱ were occasionally mistaken for Ⅲ in panoramic radiographs. The percentages of teeth in class Ⅰ, Ⅱ, Ⅲ and Ⅳ were 31.52%, 55.43%, 11.96% and 1.09%. 7.61% (7/92) of teeth developing inferior alveolar nerve and vessels injuries during extractions (3 in degree Ⅲ class Ⅲ, and 2 in degree Ⅲ class Ⅱ, 2 in degree Ⅱ class Ⅱ). Teeth in higher risk degrees had higher percentage to injure inferior alveolar nerve and vessels (P<0.05). The injury rate was highest in teeth whose roots were on the buccal side of IAC (P<0.05). CONCLUSIONS : Panoramic radiographs could evaluate the contact relation between root and IAC. CBCT can overcome the limitation of overlapping structures and provide positional relation. Extractions of teeth in degree Ⅱ or Ⅲ and class Ⅱ or Ⅲ are easier to cause inferior alveolar nerve and vessels injuries. Direct force should be avoided during extraction.

Key words: Complicated mandibular third molar extraction, Inferior alveolar nerve and vessels injury, Panoramic radiography, Cone-beam CT

CLC Number:

R782.1

YE Zhou-xi, YANG Chi. Risk factors of inferior alveolar nerve and vessels injury in the mandibular third molar extractions: the contact and positional relation between root and inferior alveolar canal[J]. China Journal of Oral and Maxillofacial Surgery, 2016, 14(1): 51-56.

References

[1] Marciani RD. Complications of third molar surgery and their management[J]. Atlas Oral Maxillofac Surg Clin,2012,20(2):233-251.
[2] Guerrero ME, Nackaerts O, Beinsberger J, et al. Inferior alveolar nerve sensory disturbance after impacted mandibular third molar evaluation using cone beam computed tomography and panoramic radiography: a pilot study[J]. J Oral Maxillofac Surg,2012,70(10): 2264-2270.
[3] Renton T, Yilmaz Z, Gaballah K. Evaluation of trigeminal nerve injuries in relation to third molar surgery in a prospective patient cohort. Recommendations for prevention [J]. Int J Oral Maxillofac Surg, 2012, 41(12): 1509-1518.
[4] Renton T, Hankins M, Sproate C, et al. A randomised controlled clinical trial to compare the incidence of injury to the inferior alveolar nerve as a result of coronectomy and removal of mandibular third molars[J]. Br J Oral Maxillofac Surg,2005,43(4):7-12.
[5] Alhassani AA, AlGhamdi AS. Inferior alveolar nerve injury in implant dentistry: diagnosis, causes, prevention, and management [J]. J Oral Implantol, 2010, 36(5): 401-407.
[6] Roy TS, Sarkar AK, Panicker HK. Variation in the origin of the inferior alveolar nerve [J]. Clin Anat, 2002, 15(2):143-147.
[7] Kim JW, Cha IH, Kim SJ, et al. Which risk factors are associated with neurosensory deficits of inferior alveolar nerve after mandibular third molar extraction? [J]. J Oral Maxillofac Surg, 2012, 70(11): 2508-2514.
[8] Ueda M, Nakamori K, Shiratori K, et al. Clinical significance of computed tomographic assessment and anatomic features of the inferior alveolar canal as risk factors for injury of the inferior alveolar nerve at third molar surgery [J]. J Oral Maxillofac Surg, 2012, 70(3): 514-520.
[9] Blondeau F, Daniel NG. Extraction of impacted mandibular third molars: postoperative complications and their risk factors [J]. J Can Dent Assoc, 2007, 73(4): 325.
[10] Rood JP, Shehab BA. The radiological prediction of inferior alveolar nerve injury during third molar surgery [J]. Br J Oral Maxillofac Surg, 1990, 28(1): 20-25.
[11] Juodzbalys G, Daugela P. Mandibular third molar impaction: review of literature and a proposal of a classification [J]. J Oral Maxillofac Res, 2013, 4(2): e1.
[12] Xu GZ, Yang C, Fan XD, et al. Anatomic relationship between impacted third mandibular molar and the mandibular canal as the risk factor of inferior alveolar nerve injury [J]. Br J Oral Maxillofac Surg, 2013, 51(8): e215-219.
[13] Ge J, Yang C, Zheng JW, et al. Four osteotomy methods with piezosurgery to remove complicated mandibular third molars: a retrospective study [J]. J Oral Maxillofac Surg, 2014, 72(11): 2126-2133.
[14] 张志愿, 俞光岩. 口腔颌面外科学 [M]. 第7版. 北京:人民卫生出版社, 2012: 112-134.
[15] Bauer SE, Romanos GE. Morphological characteristics of osteotomies using different piezosurgical devices. A scanning electron microscopic evaluation [J]. Implant Dent, 2014, 23(3): 334-342.
[16] Park W, Choi JW, Kim JY, et al. Cortical integrity of the inferior alveolar canal as a predictor of paresthesia after third-molar extraction [J]. J Am Dent Assoc, 2010, 141(3): 271-278.
[17] Komerik N, Muglali M, Tas B, et al. Difficulty of impacted mandibular third molar tooth removal: predictive ability of senior surgeons and residents [J]. J Oral Maxillofac Surg, 2014, 72(6): 1062.e1-e6.
[18] Selvi F, Dodson TB, Nattestad A, et al. Factors that are associated with injury to the inferior alveolar nerve in high-risk patients after removal of third molars [J]. Br J Oral Maxillofac Surg, 2013, 51(8): 868-873.
[19] Suomalainen A, Ventä I, Mattila M, et al. Reliability of CBCT and other radiographic methods in preoperative evaluation of lower third molars [J]. Oral Surg Oral Med Oral Pathol Oral Radiol Endod, 2010, 109(2): 276-284.
[20] Hasegawa T, Ri S, Shigeta T, et al. Risk factors associated with inferior alveolar nerve injury after extraction of the mandibular third molar-a comparative study of preoperative images by panoramic radiography and computed tomography [J]. Int J Oral Maxillofac Surg, 2013, 42(7): 843-851.
[21] Neves FS, de Almeida SM, Bóscolo FN, et al. Risk assessment of inferior alveolar neurovascular bundle by multidetector computed tomography in extractions of third molars [J]. Surg Radiol Anat, 2012, 34(7): 619-624.
[22] Cheung LK, Leung YY, Chow LK, et al. Incidence of neurosensory deficits and recovery after lower third molar surgery: a prospective clinical study of 4338 cases [J]. Int J Oral Maxillofac Surg, 2010, 39(4): 320-326.