Biomechanical comparison of plate materials and designs for subcondylar fracture fixation: An in silico assessment

Mandibular subcondylar fractures present challenges in fixation due to high complication rates and the uncertainty in selecting optimal plate design and material. Previous computational studies have primarily relied on simplified models, point loading, and plate-only analyses. This study examines the combined influence of fixation plate design and material properties on fracture stability, with interfragmentary displacement as a key indicator of post-surgical stability. A finite element approach implemented in ANSYS Mechanical APDL v2022 R2, incorporating soft tissues such as the periodontal ligament, was employed to assess fixation stability using five materials - Nitinol, Magnesium alloys, Titanium alloys (Ti-6Al-4V and Ti-29Nb-13Ta-4.6Zr), and Stainless Steel 316L - across four plate designs under ipsilateral and contralateral molar clenching simulated using physiologically-mimetic muscle forces. Results showed a reduction in mandibular strain (up to 4% from around 1635 {micro}{varepsilon} to 1569 {micro}{varepsilon}) with increase in the plate stiffness during ipsilateral clenching, while for contralateral clenching, this trend (up to 5.4% from around 1482 {micro}{varepsilon} to 1402 {micro}{varepsilon}) was observed only for double mini and lambda plates due to enhanced resistance to bending moments from additional screw placement. Among designs, the double mini plate demonstrated the greatest reduction in the interfragmentary gap (by 77% during ipsilateral clenching; by 58% during contralateral clenching) and emerged as the most stable option across materials. Regarding materials, Titanium alloys (TNTZ and Ti-6Al-4V) were mechanically preferable, demonstrating higher safety margins based on factory of safety (FoS) ratios (TNTZ: FoS 5.57 ipsilateral, 3.21 contralateral; Ti-6Al-4V: FoS 5.05 ipsilateral, 2.98 contralateral), indicating reduced risk of yielding under functional loading. These findings underscore the critical interplay between screw configuration, material selection, and loading conditions, offering valuable guidance for implant design optimization.