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Development of a patient-specific TMJ prosthesis2419IntroductionThe temporomandibular joint (TMJ) has multiple supportive functions (breathing, chewing, supporting the upper airway, sucking, swallowing, making facial expressions, vocalizing, and sustaining correct pressure in the middle ear) which are all derived from protrusion, retrusion, and lateralization of the mandible and opening of the mouth. Indications for prosthetic replacement include TMJ ankylosis and end-stage joint disease resulting from trauma, infection, degenerative arthrosis, cancer, developmental/inherited craniofacial anomalies affecting the mandible and TMJ, failed/failing TMJR devices or failed prior invasive surgery.(1–4) The decision to replace the affected joint is based on the severity of the reduced quality of life, mainly related to mandibular function, food intake and pain.While stock prostheses may reduce pain and aid mouth opening, they do not naturally function in alignment with the healthy, contralateral joint because they have not been adapted based on the patient’s anatomy nor do they allow for proper grinding movements. This is because the lateral pterygoid muscle was sacrificed during condylectomy and not reattached. Optimal biological integration and acceptable wear of alloplastic components are prerequisites for any TMJ prosthesis. Moreover, for optimal success, the TMJ prosthesis should be made of biocompatible materials, should be able to withstand the loads delivered over the full range of function of the joint, must be stable in situ and the surgery to implant the prosthesis must be performed for the proper indications, and it must be performed aseptically.(5)Regardless of whether the TMJ is reconstructed with alloplastic, allogeneic, or autogenous material, it should improve mandibular function and form, reduce suffering and disability, contain excessive treatment and cost and prevent morbidity.(6)According to a review performed by De Meurechy et al.(7) no extensive research has been conducted (over the last 20 years) to improve TMJ prostheses regarding both materials and functionality. To optimize and Nikolas de Meurechy NW.indd 241 05-06-2024 10:14