Experimental comparison of biomechanical properties of fixation techniques used in sagittal split ramus osteotomies on sheep mandibula

The aim of this study is to compare the biomechanical stability of locked mini plate and standard mini plate in sheep mandibula which undergone Obwegeser- Dal pont and Epker modification of sagittal split ramus osteotomy. The soft tissue of 20 fresh sheep mandibles was cleaned and divided into midline and 40 hemimandibula were obtained. The jaws were randomly divided into two main groups; After sagittal split ramus osteotomies were performed with Obwegeser-Dal Pont or Epker modifications, a space was created that mimics the advancement of 5 mm between the bone segments. These main groups were divided into two sub-groups within each group and the number of subjects in each group was 10 (n = 10). For fixation of the segments, 4 holes standard miniplate with 4 monocortical screws and 4 holes locking miniplate with 4 monocortical screws are used. After the hemimandibles were fixed to the platform designed specifically for the 2-point biomechanical experiment model, the force was applied to the servohydraulic tester (Universal Autograph AGS®, Shimadzu Scientific Instruments, Kyoto, Japan) by force test on flattened molar teeth. The mean and standard deviation values of the displacement amounts from 10 N to 100 N are recorded. The averages between the groups were compared using a one-way ANOVA and post hoc Tukey test at 95% confidence interval. According to the results of the statistical analysis, no significant difference was found between the groups. It has been observed that the groups using the locked mini plate system, especially the Epker modification, performed better than other groups against the occlusal forces. Keywords: Sagittal split ramus osteotomy, Dal-Pont, Epker, Locking miniplate, Biomechanical, Sheep mandible