Understanding the biomechanical behavior following a mandibular fracture has significant implications for the postoperative recovery. The aim of this prospective study was to evaluate the biomechanics of the fracture gaps, plates and screws after surgical intervention with three fixation modalities for mandibular fractures.

Three models of mandible after fixation were analyzed utilizing finite-element analysis at postoperative time points of 0, 4, 8, and 12 weeks with maximum occlusal forces. The performance of the gaps, fixation devices was assessed based on deformations and Von-Mises stresses.

The deformations of 4&4 are the smallest of the three models and the plates of 4&4 have high levels of Von-Mises stresses. At weeks 4 and 8, the stresses in the 4&2 and 2&4 were higher than that in the 4&4. The plates near the lower edge of the mandible had higher average Von-Mises stresses than the plates above them in all three models.

Double 4-hole plates have good torsional resistance and provide good stabilization for the fracture. The 4&2 and 2&4 allow for early contact stress in the fracture gap, but the 4&2 should be chosen with caution in clinical use for its weakness in the lower edge of the mandible.