A Biomechanical Analysis of Titanium Miniplates Used for Treatment of Mandible Condylar Fracture with the Finite Element Method

摘要

Objective. This study aimed to evaluate the biomechanical behavior of titanium miniplates used for the treatment of condylar fractures of the human mandible using finite element (FE) analysis. The analyzed variables were the tangential displacements at fracture gap and the stress distribution on the implants. Study design. A 3D FE model of the natural mandible bone and four 3D FE models of surgically treated mandibles were developed. All treated mandible models employed 1.0 mm thickness titanium miniplates of four different geometries: single triangular miniplate (MDT Implantes, Rio Claro-Brazil), single Lambda miniplate, single trapezoidal miniplate and linear miniplate. Two load conditions were used on the computational simulations. Firstly, a maximal voluntary bite force condition was applied to both natural and treated mandibles. Secondly, a masticatory post-operatory load condition was applied only on the four treated mandibles. Results. The initial stability in terms of relative tangential displacements on the fracture surfaces provided by the Trapezoidal miniplate was 76% greater than that of the Lambda miniplate for the simulated post operatory mechanical environment. The stability of the other two plates reached intermediate values between the minima (Lambda) and maxima (Trapezoidal). Flexural and torsional efforts stressed the central region of the miniplates with higher values for the single-armed miniplates (Lambda, Triangular and Linear). When the masticatory load condition was applied, all miniplates present inter-fragmentary motions at fracture gap below 150 μm and were able to support the mechanical demand. Conclusion. The study confirmed the expected dependence of the inter-fragmentary motion at fracture gap on the design of miniplate fixing the fracture. A design with two arms (Trapezoidal) provided the stiffest condition.