In vitro comparison of biomechanical characteristics of sagittal split osteotomy fixation techniques

The aim of the present study was to compare the biomechanical stability of 10 different fixation methods used in sagittal split osteotomy. Twenty-five fresh sheep mandibles were stripped of all soft tissues and sectioned at the midline. A sagittal split osteotomy with 5mm advancement was performed on each hemimandible. The hemimandibles were randomly divided into 10 groups of 5, and then fixed with 5 different bicortical screws, 4 different miniplates with or without bicortical screws, and 1 resorbable screw configuration. All specimens were mounted on a specially designed 3-point biomechanical test model and compression loads were applied using the Lloyd LRX testing machine until 3mm displacement was reached. Load/displacement data were gathered and compared using the Mann-Whitney U-test with Bonferroni correction (P<0.01). The 3 bicortical screws in an inverted backward-L pattern provided the most biomechanical stability of the screw patterns tested. The miniplate fixed obliquely with 2 bicortical screws in the proximal segment provided the most biomechanical stability of the miniplate groups.