Introduction Total alloplastic replacement of the temporomandibular joint (TMJ) is a viable treatment option for severe TMJ disorders (TMDs) unresponsive to conservative approaches, as well as for reconstruction of congenital or acquired TMJ defects. However, clinical data on indications, outcomes, complications and long-term effects remain limited, and no global registry currently exists. This study aims to address this gap by establishing an international registry to collect data from patients undergoing total alloplastic TMJ replacement systematically. The registry will document clinical indications and disease progression, explore relationships between treatments, outcomes and quality of life, identify predictors of favourable outcomes and inform future research. Methods and analysis This international, prospective, multicentre, observational registry will enrol approximately 200 patients with TMD requiring total alloplastic TMJ replacement, with follow-up lasting up to 5 years postoperatively. The data collected will include underlying disease, treatment details, functional outcomes, patient-reported outcomes and procedure-related adverse events. The registry will also monitor patients who decline surgery and record their reasons. All treatments will adhere to the standard of care at each participating centre. Ethics and dissemination Ethics approval was obtained from the responsible ethics committee (EC) at each participating site prior to TMJ surgery. All patients will be enrolled following an informed consent process approved by the relevant EC. Study results will be disseminated through peer-reviewed publications. Approving ECs include: Krishnadevaraya College of Dental Sciences and Hospital EC, KCDS/Ethical Comm/54/2022–23; Ethikkommission Nordwest- und Zentralschweiz, 2019–02387; University of Belgrade School of Dental Medicine EC, 36/19; National Videnskabsetisk Komité, 2401881; University of KwaZulu-Natal Biomedical Research EC, BREC/00001592/2020; Etikprövningsmyndigheten, 2019–04477; Ethikkommission Medizinische Hochschule Hannover, 8660BOK₂019; Ethik-Kommission an der Medizinischen Fakultät der Universität Leipzig, 080/21-lk; Comité de Ética de la Investigación con Medicamentos Hospital Universitario 12 de Octubre, 19/392; Landesärztekammer Rheinland-Pfalz EC, 2025–18012-andere Forschung/nachberatend; Local Ethical Committee at National Medical and Surgical Centre named after NI Pirogoov, LEC meeting 5; Ethikkommission bei der LMU München, 19–589; Komisja Bioetyczna przy Warmińsko-Mazurskiej Izbie Lekarskiej w Olsztynie, 12/2021; De Medisch Ethische Toetsings Commissie Erasmus MC, MEC-2019–0696 and Comissão Nacional de Ética em Pesquisa, 3. 825. 711. Trial registration number NCT03991728.
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