(22) Does Removal of Third Molars at the Time of Sagittal Split Osteotomy Impact Intraoperative Complications? A Retrospective Review from a Single institution and Single Surgeon from 2015-2021

Abstract: Introduction
The sagittal split osteotomy (SSO) is a predictable and reliable procedure to correct dentofacial deformities of the mandible. First performed by Obwegeser, there have been many modifications to the procedure. The decision to simultaneously remove mandibular third molars at the time of SSO has been debated in the literature1 and within clinical practice, with evidence supporting both sides. In addition, de Souza et. al. meta-analysis of 19 articles showed no statistical difference in unfavorable fractures or neurosensory disturbances in those that had third molars removed simultaneously with SSO2.

Purpose
The aim of this study is to determine the rate of intraoperative complications, specifically unfavorable fractures and inferior alveolar nerve (IAN) injury, in patients who have absence of mandibular third molars vs those who have their mandibular third molars simultaneously removed at the time of their SSO. The hypothesis is that the intraoperative complication rate in patients with simultaneous removal of third molars is not higher than in the group without mandibular third molars prior to SSO.

Methods
This is a retrospective study at a single institution and single surgeon with chief-level residents over six years (2015-2021). There were four categories of surgery included in this study – BSSO alone (20), LeFort with BSSO (78), LeFort with BSSO and genioplasty (86), and BSSO and genioplasty (47). Exclusion criteria included patients requiring unilateral SSO with a different treatment to the contralateral mandible (eg, inverted L osteotomy), inadequate imaging or lack of follow up, and patients undergoing simultaneous condylectomy in conjunction with SSO. There were a total of 462 SSO included in this study. There were 133 women (58%) and 98 men (42%) in this study, with an average age of 23.7 years old with an age range of 12 – 67 years old.

Results
There were a total of 64 complications of the 462 SSOs performed (14%). This included 29 unfavorable fractures (6.3%) and 35 IAN injuries (7.6%). Unfavorable fracture occurred at a rate of 7.1% in patients without third molars at the time of surgery (5.4% male and 9% female) and a rate of 5.3% in patients who underwent simultaneous removal of third molars during their SSO (6.1% male and 5% female). Regarding nerve injuries, the patients without third molars had a prevalence of 7.5% (7.7% in males and 7.2% in females). Patients with simultaneous third molar removal had a prevalence of 7.7% (6.2% males and 9.1% females). Regarding the category of surgery, the highest rate of unfavorable split and IAN injuries both occurred in the Lefort with BSSO group at 16.6% and 21%, respectively. The highest complication rate by age was in the 50-59 age group with 1 complication per 0.5 of expected complications. Overall, there was no statistical difference in intraoperative complications between the group with mandibular third molars present at the time of SSO vs those that did not have mandibular third molars present.

Conclusion
There remains mixed evidence for removing third molars prior to orthognathic surgery. This review, however, found no statistical difference in intraoperative complications with simultaneous removal of mandibular third molars during orthognathic surgery. The benefits of a single surgery, saving healthcare resources, and a single recovery has an appeal.

Works Cited:
Precious DS, Lung KE, Pynn BR, Goodday RH. Presence of impacted teeth as a determining factor of unfavorable splits in 1256 sagittal-split osteotomies. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 1998;85:262-65
de Souza BB, da Silveira MLM, Dantas WRM, A C Almeida R, Germano AR. Does the presence of third molars during sagittal split mandibular ramus osteotomy favour complications? Systematic review and meta-analysis. Int J Oral Maxillofac Surg. 2023 Jan;52(1):51-59.