Biomechanical comparison of three-dimensional titanium and CFR-PEEK plates for mandibular subcondylar fracture fixation: a three-dimensional finite element analysis

BACKGROUND: Fixation of mandibular subcondylar fractures presents challenges due to limited surgical access and the small size of the proximal fragment; therefore, single-piece and easily applicable three-dimensional (3D) plates may be considered as an alternative. Although titanium is frequently used as a plate material, it has been reported to have certain clinical and imaging-related limitations. In comparison, Carbon Fiber-Reinforced Polyetheretherketone (CFR-PEEK) has emerged as a favorable alternative for mandibular fracture fixation due to its bone-like elastic properties, radiolucency, and biocompatibility. This study aimed to compare CFR-PEEK and titanium in terms of stress distribution and fixation stability under loading conditions using 3D finite element analysis (FEA). METHODS: Three single-piece, 3D plate designs (lambda, rhombic, and trapezoid) were modeled with two materials (titanium alloy and 30% CFR-PEEK), yielding six fixation models of mandibular subcondylar fracture. Two static loading conditions were applied: contralateral molar loading and incisal loading. Von Mises stresses in plates and screws, principal stresses in cortical and cancellous bone, and interfragmentary displacement were calculated. RESULTS: For both simulated loading conditions, CFR-PEEK exhibited lower von Mises stresses in plates and screws and lower principal stresses in cortical and cancellous bone than titanium, but showed greater interfragmentary displacement. Contralateral molar loading produced higher stresses and displacement than incisal loading. The lowest von Mises stresses in both plates and screws were observed with the CFR-PEEK lambda plate, whereas bone stresses were lowest and most uniformly distributed with the CFR-PEEK rhombic plate. Interfragmentary displacement was minimal in the titanium lambda model and maximal in the CFR-PEEK trapezoid model. CONCLUSIONS: Compared with titanium, CFR-PEEK 3D plate constructs reduced stress concentrations in the fixation hardware and surrounding bone but resulted in greater interfragmentary displacement under both loading conditions. Plate geometry and material choice should balance the clinical priority of rigidity versus stress mitigation.