Biomechanical comparison in vitro between 2.0-mm conventional and locking fixation systems of mandibles with freedom in the three-axes of the space

Abstract

ObjectiveTo evaluate the vertical and horizontal stiffness and rupture strength with freedom of movement in the three axes of the space in vitro of mandibles fixed with 2.0-mm conventional and locking systems in unilateral angle fractures. MethodsTwenty mandibles of sheep underwent an osteotomy reproducing a fracture and were divided into three groups according to the fixation used: F1CP - conventional plate on oblique line; F2CP - two conventional plates in a single plane; and FLP - locking system plate on oblique line. A universal test machine was used, with a metal support coupled with wheels for the mandibles. The systems were analyzed in three different moments: pre and post osteotomy/fixation stiffness and rupture strength. Findings were submitted to analysis of variance (p < 0.050). ResultsVertical stiffness, horizontal stiffness and rupture strength between pre and post osteotomy/fixation showed a significant decrease (p < 0.001). In the comparison between the groups, there was a significant difference for vertical stiffness (p = 0.009) and the F2CP group showed greater stiffness. There was no significant difference for the remaining tests. ConclusionsThe fixation system with two conventional plates showed higher resistance to vertical stiffness than the other systems, and there was no statistically significant difference between the groups for horizontal stiffness and rupture strength.