Biomechanical Comparison of Monoplanar and Biplanar Miniplate Fixation for Unfavorable Mandibular Angle Fractures: A Finite Element Analysis

Introduction: Unfavorable mandibular angle fractures are biomechanically challenging because functional masticatory forces may result in displacement of fracture segments and compromise fixation stability. Various plating configurations have been proposed; however, there is limited evidence regarding the biomechanical performance of monoplanar and biplanar plating techniques. This study aimed to compare the biomechanical behaviors of monoplanar and biplanar plating techniques using titanium miniplates with monocortical fixation for the management of unfavorable mandibular angle fractures using finite element analysis. Materials and methods: A three-dimensional finite element model of an unfavorable mandibular angle fracture was developed using archived computed tomography data. Two fixation configurations were evaluated: monoplanar (Model 1) and biplanar (Model 2) plating. The models were subjected to right unilateral molar clenching (RMOL), left unilateral molar clenching (LMOL), and incisal clenching (INC) tests. von Mises stresses in the plates, screws, and surrounding bone, as well as interfragmentary displacement across the fracture site, were calculated and compared. Results: The highest plate stress was observed during LMOL in the monoplanar model (546.10 MPa), whereas the biplanar model demonstrated plate stresses of 476.92, 462.90, and 185.76 MPa during RMOL, LMOL, and INC, respectively. Screw stresses were consistently lower in the biplanar model, with values of 57.00, 43.34, and 24.70 MPa compared with 149.28, 235.89, and 53.32 MPa in the monoplanar model during RMOL, LMOL, and INC, respectively. Bone stress values were also reduced in the biplanar model (59.40, 110.30, and 38.30 MPa) compared with those in the monoplanar model (227.20, 137.0, and 62.7 MPa). Interfragmentary displacement was lower in the biplanar model under all loading conditions, ranging from 18.86 to 30.41 μm compared with 22.98 to 38.20 μm in the monoplanar model. Conclusion: Biplanar plating demonstrated lower screw stress, reduced bone stress, and decreased interfragmentary displacement compared with monoplanar plating, indicating superior biomechanical stability for the fixation of unfavorable mandibular angle fractures.