Mandibular ramus split patterns following sagittal split ramus osteotomy - evaluation with multifactorial risk analysis.

OBJECTIVES: The present study aimed to identify novel risk factors that influence buccal and lingual split patterns by focusing on individual mandibular ramus patterns in sagittal split ramus osteotomy (SSRO) cases. MATERIALS AND METHODS: This retrospective cohort study analyzed 658 splits from patients who underwent an SSRO with the Hunsuck technique. Predictor variables included demographic and mandibular anatomy factors, while split patterns were used as outcome variables. RESULTS: Posterior ramus length and buccal horizontal osteotomy (BHO)-buccal type showed significant correlations with buccal bad split patterns. A 1-mm decrease in posterior ramus length increased the risk by up to 25%. As compared with the BHO-caudal type, BHO-buccal type had up to a 22-fold greater likelihood of pattern induction. For lingual split patterns, age, gender, transverse ramus width, posterior ramus length, and BHO were significant factors, with younger age, male gender, wider transverse ramus width, and BHO-buccal type associated with a higher incidence of long lingual splits, while shorter posterior ramus length and BHO-lingual type were linked to increased incidence of short lingual splits. CONCLUSIONS: Buccal and lingual split patterns are associated with patient demographics, and considered to be mandibular anatomical risk factors. While posterior ramus length, age, gender, and transverse ramus width are congenital and uncontrollable, BHO type can be adjusted to prevent complications. CLINICAL RELEVANCE: The anatomical risk factors identified in this study can help surgeons evaluate individual patients received SSRO for risk as well as treatment planning to prevent complications associated with split patterns.