In vivo wear behavior and chemical alterations in a cohort of total temporomandibular joint replacements from a single design.

Total temporomandibular joint (TMJ) replacement (TMJR) is a salvage management option for end-stage TMJ pathologies. This study assessed implant damage generated in vivo of 25 surgically-retrieved TMJR prostheses. Surface damage features on mandibular ramus condylar heads and fossae were recorded using a stereomicroscope. Laser scanning confocal microscopy was used to measure roughness parameters on the mandibular ramus condylar heads and linear wear penetration on the fossae. Polyethylene oxidation index (OI) through the fossa component thickness were assessed using infrared spectroscopy. Mild wear was observed in both the TMJR mandibular ramus condylar heads and fossae. Wear features on the fossae included polishing, protuberances characteristic of striated patterns, and fine scratches. The mean ± standard deviation maximum linear wear was 87.35 ± 110.17 µm. Wear and time in situ were linearly correlated, with an estimated wear rate of 0.71 µm/month. Samples with wear scars had higher OIs within the wear scar subsurface, with OI increasing with longer time in situ. This study is novel in reporting a wear rate in TMJR polyethylene bearings. As TMJR is increasing as a management option for end-stage TMJ pathologies, knowledge of wear mechanisms associated with implant design/material is essential to ensure implant safety and effectiveness.