Adaptability of stock TMJ prosthesis to joints that were previously treated with custom joint prosthesis.

The purpose of this study was to determine if a temporomandibular joint (TMJ) replaced by a custom joint prosthesis could have been replaced by a stock joint prosthesis. Stereolithic models of patients treated with TMJ Concepts® patient fitted joint prosthesis (e.g., custom) were obtained. Biomet Microfixation® TMJ prostheses (e.g. stock) were adapted to these models. Intra-operative insertion of prosthesis, fit and size of stock joints were simulated and evaluated. Adaptability and stability of condyle and fossa as well as their articulation were recorded. 20 models consisting of 34 joints were examined by two oral and maxillofacial surgeons who were blinded to the patient's diagnosis. Overall, 77% of the stock TMJ system fit the stereolithic models. 3mm or less of bone modification was necessary to achieve an acceptable fit. In the majority of the cases examined, a stock TMJ prosthesis had good anatomical adaptation to stereolithic models of patients previously treated with custom TMJ prosthesis, so a stock TMJ prosthesis could have been an acceptable option for these patients. Further prospective clinical studies to compare both systems are necessary.