Experimental comparison of fixation methods with different plates in sagittal split ramus osteotomy

This is an in vitro experimental study designed to evaluate fixation methods used after sagittal split ramus osteotomy (SSRO), particularly in cases where significant mandibular advancement is necessary. In clinical settings, postoperative relapse is one of the major challenges following SSRO, especially when the mandible is advanced more than a few millimeters. To minimize relapse, optimal stabilization of the mandibular segments is essential. Therefore, the objective of this study is to compare the biomechanical stability of three different fixation systems: single miniplate, double miniplates, and single reconstruction plate, under progressive loading conditions. A total of 45 fresh sheep hemimandibles underwent SSRO, and each was advanced 7 mm to simulate a clinically significant advancement. The specimens were randomly divided into three equal groups (n = 15). Group 1 was fixed with one miniplate and four screws; Group 2 with two miniplates and eight screws; and Group 3 with one reconstruction plate and four screws. Vertical forces ranging from 10 to 200 Newton (N) were applied in increments of 10 N. Segment displacement was measured for each force level. Data were analyzed using the Shapiro-Wilk test for normality, Kruskal-Wallis test for group comparisons, and Bonferroni correction for pairwise significance (p < 0.05). The double miniplate and reconstruction plate groups showed significantly lower displacement compared to the single miniplate group. There was no significant difference between double miniplates and reconstruction plates. For cases requiring major mandibular advancement, reconstruction plates or double miniplates are recommended for enhanced mechanical stability and relapse prevention.