Comparison of different fixation methods used in advancedadvancement and counterclockwise rotation of mandible

The purpose of this study is, comparing the fixation methods after BSSO, in cases which required advanced advancement and counterclockwise rotation of the mandible. 25 sythetic resin models of hemimandibles were produced as standard with the incision made with 3D planning technique in accordance with the hardness/stiffness/rigidity value of the mandible. Subsequently, models were divided into 5 groups and fixated with 5 different methods in accordance to the advancement and counterclockwise movement of the mandible. Each group had 5 subjects(n=5). For group 1, 1 4-hole miniplate and 4 miniscrews; for group 2, 2 4- hole miniplate and 8 miniscrews; for group 3, 3 bicortical screws placed in a straight linet o the top edge of the mandible; for group 4, 3 bicortical screws placed in a reversed-L configuration; for group 5, 1 bicortical screw, 1 4-hole miniplate and 4 miniscrews were used for fixation. The prepared models were placed into a servohydraulic tester which is designed for 2-point test models, so that a constant force could be applied to the same point. A constant force of 1 mm/min was apllied to each sample in 5 groups, from a notch placed in the molar area. All of the data related to force and displacement up to the breaking point, were saved electronically. The averages of each group were evaluated with non-parametric Kruskal-Wallis test. There were meaningful differences among applied force values in the range of displacement of 1-to-5 mm. It was shown that, in the range of tolerable 1-3 mm displacement values, group 5 models, in which hybrid fixation was used, were shown to be the most successful; followed by group 4 and group 3 samples; whereas the groups in which miniplate fixation is used were shown to be least stable.