Evaluation of Outcome Following Coronectomy for the Management of Mandibular Third Molars in Close Proximity to Inferior Alveolar Nerve

Abstract

Introduction: Iatrogenic damage to Inferior Alveolar Nerve (IAN) is a significant risk factor following prophylactic or therapeutic removal of impacted mandibular third molar. The risk to IAN injury increases many fold, when the third molar root overlaps the nerve canal as identified by the radiographic imaging. Various methods like orthodontic assisted extraction, staged removal of tooth or coronectomy have been advocated to reduce the incidence of IAN injury in high risk cases with variable outcome.

Aim: The aim of present study was to evaluate the fate of the root (resorbed, exfoliated, covered by bone) after coronectomy or intentional root retention of impacted mandibular 3(rd) molars in patients with high risk for inferior alveolar nerve damage as evaluated by the intra oral periapical radiograph.

Materials and methods: Twenty impacted mandibular third molar teeth, in 18 patients with high risk of injury to IAN based on Rood's Criteria in an intra oral periapical radiographic examination, between the age group of 18 to 40 years, were included in the study. Preoperatively the impacted third molars were evaluated clinically as well as radiographically. Pederson Difficulty Index and Winter's Classification of impacted tooth was recorded. Coronectomy was done at the cemento enamel junction leaving the roots 2-3mm below the alveolar crest and primary closure was done. Patients were evaluated periodically for two years at six months interval. Post operative pain, swelling, IAN injury or any other complications were observed and recorded.

Results: None of the patients had IAN injury and none required second surgical removal. There was no incidence of post-operative infection and none required second surgical intervention. However, two of our patients had failed coronectomy (10%) due to mobilization of roots intra operatively and the roots were removed. One patient developed profuse bleeding intra-operatively in the failed coronectomy case. One patient had temporary lingual nerve paresthesia.

Conclusion: Coronectomy procedure is effective in controlling inferior alveolar nerve injury following third molar surgery, in radiographically evaluated high risk cases and it has very low incidence of complications.

Keywords: Impacted mandibular third molar; Rood’s Criteria; Wisdom tooth.

[Table/Fig-1a-g]:

Rood’s criteria. a. Darkening of the root. b. Deflection of the root. c. Narrowing of the root. d. Dark and bifid apex of the root. e. Interruption of white line of canal. f. Diversion of the canal. g. Narrowing of the canal.

[Table/Fig-3a-c]:

Coronectomy photographs. a. Vertical impaction b. Mesio angular impaction c. Horizontal impaction

[Table/Fig-5]:

Enamel lipping.

[Table/Fig-6a-e]:

Formation after coronectomy. a. Pre-operative, b. Immediate post-operative, c. Six months post-operative d. One year post-operative, e. Two year post-operative.

[Table/Fig-7a-c]:

Root migration after coronectomy. a. Pre-operative b. Immediately after coronectomy c. Six months after coronectomy.