Temporomandibular Joint Ankylosis: Long-Term Outcomes with One-Stage Resection and Reconstruction Using Total Joint Alloplastic Replacement—A 20-Year Experience

<b>Background/Objectives:</b> Temporomandibular joint (TMJ) ankylosis, characterized by osseous-fibrous fusion, severely impairs mandibular function. While alloplastic total joint replacement (TJR) is the gold standard, long-term outcomes remain understudied. The aim of this study is to evaluate the long-term esthetic and functional outcomes of prosthetic replacement and to retrospectively analyze our 20-year experience. <b>Methods:</b> A retrospective observational study (2003-2024) was conducted at a tertiary referral center in Turin and enrolled patients who underwent alloplastic total joint replacement for TMJ ankylosis. Data collected included demographic variables, etiology, characteristics of the ankylosis, prosthesis type (stock/custom), surgical details, and outcomes (maximal interincisal opening [MIO], pain, quality of life, diet consistency, Helkimo index, complications). <b>Results:</b> Among 28 patients (61% female, mean age 51.8 years), etiologies included post-traumatic (39%), osteoarthritis (32%), congenital (25%) and neoplastic (4%) causes. Custom prostheses were used in 57% of cases. Median follow-up was 11.5 years. Significant improvements were observed in MIO (<i>p</i> = 0.001), pain level (<i>p</i> = 0.001), quality of life (<i>p</i> = 0.001), diet score (<i>p</i> = 0.002), and Helkimo index (<i>p</i> = 0.001). Complications included facial nerve dysfunction (32.1%), salivary leakage (14.3%), and one recurrence (2.2%). <b>Conclusions:</b> Alloplstic TJR provides durable functional and esthetic restoration for TMJ ankylosis, with custom prostheses excelling in complex anatomies. Long-term stability (>10 years) supports its role as a definitive solution.