Angled Osteotomy Design Aimed to Influence the Lingual Fracture Line in Bilateral Sagittal Split Osteotomy: A Human Cadaveric Study.

Purpose: The traditional osteotomy design in the bilateral sagittal split osteotomy includes a horizontal lingual bone cut, a connecting sagittal bone cut, and a vertical buccal bone cut perpendicular to the inferior mandibular cortex. The buccal bone cut extends as an inferior border cut into the lingual cortex. This study investigated a modified osteotomy design including an angled oblique buccal bone cut that extended as a posteriorly aimed inferior border cut near the masseteric tuberosity.

Materials And Methods: The authors implemented a randomized controlled study. The study sample was comprised of 28 cadaveric dentulous mandibles. The primary outcome variable was the pattern of lingual fracture induced using the conventional (n = 14) and modified (n = 14) osteotomy designs. The secondary outcome variables included the incidence of bad splits and the status of the inferior alveolar nerve (IAN). Descriptive and bivariate statistics were computed.

Results: The angled osteotomy design resulted in a significantly larger number of the lingual fractures originating from the inferior border cut (odds ratio [OR] = 1.54; 95% confidence interval [CI], 1.27-1.86; P < .01), with a significantly more posterior relation of the fracture line to the mandibular canal (OR = 2.11; 95% CI, 1.22-3.63; P < .01) and foramen (OR = 1.99; 95% CI, 1.28-3.08; P < .01). No bad splits occurred with the angled design, whereas 3 bad splits occurred with the conventional design, although this difference was not statistically significant (OR = 1.11; 95% CI, 0.99-1.25; P = .07). IAN status was comparable between designs, although the nerve more frequently required manipulation from the proximal mandibular segment when the conventional design was used (OR = 1.21; 95% CI, 0.99-1.47; P = .06).

Conclusion: The results suggest that the angled osteotomy design promotes a more posterior lingual fracture originating from the inferior border cut and a trend was apparent that this also might decrease the incidence of bad splits and IAN entrapment. These results must be carefully extrapolated to the clinical setting, with future studies clarifying these findings.