Coronectomy in Lower Third Molar Surgery: A Systematic Review and Meta-Analysis.

Purpose: Coronectomy is an alternative approach to the complete removal of an impacted mandibular third molar. The present study conducted a systematic review and meta-analysis to compare coronectomy with extraction concerning complications associated with the inferior alveolar nerve injury (IANI).

Methods: This review followed the principles of systematic reviews and meta-analyses. We conducted a comprehensive literature search of 5 databases according to PRISMA guidelines. Research articles published in English before April 30, 2024 were reviewed. The keywords consisted of "coronectomy and lower third molar." In this study, Rayyan online software was used to identify and eliminate duplicate articles, and another reviewer was invited to screen the articles independently. The included articles' data were extracted, and conclusions were drawn after cross-comparison. The forest plot was drawn after analysis by the R program (JJ Allaire, Boston, Massachusetts, USA). The primary outcome variable of the present study was evaluating the incidence of IANI, and secondly, the lingual nerve injury (LNI), dry socket, postoperative infection, the necessity for surgical reintervention, root migration, root extraction, and coronectomy failure rate. These assessments were made concerning patients' chosen operative technique for managing third molars, either coronectomy or extraction, as predictor variables.

Results: After applying inclusion and exclusion criteria, 34 of the 564 articles were included in this study (24 cohort studies and 10 case‒control studies), with 7,115 wisdom teeth from 4,477 patients in different countries. Meta-analysis showed that coronectomy reduced the risk of IANI: relative risk (RR): 0.1; 95% confidence interval (CI): 0.0-0.2; I (inconsistency index) = 0%; P < .0001, the risk of LNI (RR: 0.2; 95% CI: 0.0-0.7; I = 0%; P = .01), dry socket (RR: 0.4; 95% CI: 0.3-0.7; I = 0%; P = .002), and postoperative infection (RR: 1.0; 95% CI: 0.5-2.1; I = 27%; P = .9). However, coronectomy exhibited a higher risk of surgical reintervention of 3.63% (111 of 3,055), root exposure of 2.66% (61 of 2,290), and a specific failure rate of 2.79% (119 of 4,261).

Conclusion: When the mandibular third molar with a higher risk of IANI needs to be removed, coronectomy can reduce the risk of IANI and LNI and the incidence of dry socket compared with traditional extraction. There was no significant difference in postoperative infection between the 2 groups. However, coronectomy exhibited a specific failure rate and higher odds of secondary surgical intervention. Guided bone regeneration can slow down the movement of residual roots and reduce the incidence of secondary surgery.