Which factors affect the lingual fracture pattern in sagittal split ramus osteotomy?

The purpose of this study was to elucidate the effects of mandibular anatomy and osteotomy technique on lingual fracture patterns in SSRO. The predictor variables were: length of horizontal medial osteotomy; type of border osteotomy; buccolingual width; and vertical length of the basal cortex. The outcome variable was the type of lingual split pattern. This was categorized into four types according to a lingual split scale (LSS): LSS 1, true Hunsuck; LSS 2, fracture line to posterior border of the ramus; LSS 3, through to mandibular canal; LSS 4, unfavorable fracture pattern. Data were analyzed using analysis of variance and the Pearson chi(2) test. Values of p < 0.05 were considered statistically significant. The study sample comprised 312 lingual split patterns in 156 patients. The most common type of lingual split pattern was LSS 1 (n = 204). There was a significant relationship between inferior border osteotomy type and LSS type (p = 0.001). Whilst LSS 1 was the most common among all border osteotomy types. LSS 4 was most frequently observed in cases where the lower border osteotomy remained in the buccal surface. According to the results of this study, the likelihood of an unfavorable split pattern increases when the lower border osteotomy remains in the buccal surface.