A biomechanical evaluation of mandibular angle fracture plating techniques.

PURPOSE: The purpose of this investigation was evaluate the biomechanical behavior of a vast array of fixation philosophies and techniques that address mandibular angle fractures. MATERIALS AND METHODS: A total of 150 polyurethane synthetic mandible replicas (Synbone, Laudquart, Switzerland,) were used in this investigation. Five controls and 5 each of 14 different fixation philosophies and techniques were subjected to vertical loading at the incisal edge and then repeated for contralateral loading in the molar region by an Instron 1331 (Instron, Canton, MA) servohydraulic mechanical testing unit. The fixation philosophies and techniques evaluated were the lag screw technique, monocortical superior border plating techniques with varying sizes of plates and screws, monocortical 2-plate techniques with varying forms of fixation, monocortical tension band systems with associated bicortical stabilization plates of various types, and various forms of reconstruction plates. Load/displacement data within a 0 to 200 N range were recorded. Yield load, yield displacement, and stiffness were determined. Mean and standard deviations were calculated, and statistically significant differences within and among categories were determined using an analysis of variance (P <.05). Second-order polynomial best-fit curves were also created for each group to further evaluate and compare the mechanical behavior. RESULTS: For incisal edge loading, statistically significant differences (P <.05) were found for stiffness between some of the monocortical superior border fixation techniques, as well as for yield displacement between several forms of monocortical 2-plate fixation techniques. No other differences were found within categories or among the groups that best represented their categories. For contralateral molar loading, statistically significant differences existed within and among categories. CONCLUSIONS: Under the conditions of this experiment, all systems met or exceeded currently identified postoperative functional requirements for incisal edge loading, but failed to meet them for contralateral molar loading.