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Context: Alloplastic temporomandibular joint (TMJ) replacement is a treatment strategy for segmental mandibular defects with occlusal abnormalities. Aims: To describe our experience with extended total TMJ replacement (eTMJR) by reporting operative obstacles, complications, and patient-reported outcomes, as well as to suggest a subclassification system and paradigm shift. Setting and Design: University hospital and private clinic; case series with retrospective follow-up. Methods and Materials: Five patients (6 eTMJRs) were followed for more than 1 year after surgery. Patient-reported outcomes were assessed using FACE-Q™ “Satisfaction with Outcome” questionnaires (sum and corresponding transformed Rasch scores). Statistical Analysis: Descriptive analyses were performed. Results: Problems were related to contralateral mandibular osteotomy healing (if performed), keying the prosthetic condyle into the fossa component, intra- and postoperative prosthetic lag, and intraoperative proper establishment of the occlusion when unilateral replacement was performed. Patients reported high satisfaction with the outcome, with a mean Rasch score of 89.2/100. Conclusions: Unilateral eTMJR obstacles related to three-dimensional rotational repositioning of the remaining mandible. We suggest a paradigm shift, considering primary alloplastic replacement instead of microvascular osseous transplantation for reconstruction when radiotherapy is not required. This can avoid donor site morbidity and long reconstructive surgery. An autologous osseous transplant is still available in case of implant failure. A subclassification system is proposed for eTMJR, which accounts for contour corrections, occlusal adjustments, and simultaneous contralateral mandibular osteotomy.

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The wear of a novel temporomandibular joint (TMJ) prosthesis was evaluated in an animal model. The prosthesis consisted of an additively manufactured titanium alloy (Ti6Al4V) mandibular condyle and glenoid fossa created through selective laser melting, with a machined vitamin E‐enriched ultra‐high molecular weight polyethylene (UHMWPE) surface attached to the fossa. Thirteen TMJ prosthesis were implanted in sheep, six of which had condylar heads coated with HadSat® diamond‐like carbon (H‐DLC). Euthanasia took place after 288 days, equaling 22 years of human mastication. Linear and volumetric wear analysis of the fossa was performed by optical scanning. The condylar head surfaces were assessed by scanning electron and confocal laser microscopy. The average linear UHMWPE wear, when combined with the coated condyle, was 0.67 ± 0.28 mm (range: 0.34–1.15 mm), not significantly differing (p = .3765, t‐test) from the non‐coated combination average (0.88 ± 0.41 mm; range: 0.28–1.48 mm). The respective mean volumetric wear volumes were 25.29 ± 11.43 mm3 and 45.85 ± 22.01 mm3, not significantly differing (p = .1448, t‐test). Analysis of the coated condylar surface produced a mean Ra of 0.12 ± 0.04 μm and Sa of 0.69 ± 0.07 μm. The non‐coated condylar surface measured a mean Ra of 0.28 ± 0.17 μm and Sa of 2.40 ± 2.08 μm. Both Sa (p = .0083, Mann–Whitney U test) and Ra (p = .0182, Mann–Whitney U test), differed significantly. The prosthesis exhibits acceptable wear resistance and addition of the H‐DLC‐coating significantly improved long‐term condylar surface smoothness.

Context:Alloplastic temporomandibular joint replacement.Aims:To search for evidence for the use of periprosthetic autologous fat transplantation.Setting and Design:Systematic review.Materials and Methods:We searched in PubMed Central, Elsevier ScienceDirect Complete, Wiley Online Library Journals, Ovid Lippincott Williams and Wilkins, and Cochrane Library plus Results. Six studies reported improved results with the use of autologous fat graft (AFG) in patients treated with a total joint replacement, mainly about increased mobility. Three studies involved patients from the same surgeon with increased inclusions and increased follow-up period. A 1997 study by Wolford showed a significant difference in heterotopic bone formation between patients treated with AFG, compared to those who were not, indicating the potential and usefulness of AFG.Conclusion:A prospective multicenter randomized controlled trial of this promising concept is warranted before justifying common application because of the added morbidity and the questionable advantage.

Study Design Descriptive study (/review containing supporting case studies). Objective The temporomandibular joint has some distinctive features that were not taken into account during the initial development of temporomandibular joint prostheses, such as laterotrusive movements that are necessary for the proper grinding of food as well as synchronous and congruent movements made in conjunction with the healthy, contralateral joint. The aim of this article is to describe the development of a novel type of TMJ prosthesis that optimizes temporomandibular joint replacement. Methods The development was initiated by using contemporary technologies like computer-aided design customization, additive manufacturing, and surface treatments. Biocompatibility, proper fixation, and wear resistance, being prerequisites for the longevity of prostheses, were investigated next. Individual variables (condylar path, condylar axis angle, Bennet shift) were introduced as the main basis for physiological movements with the restoration of all functions. Early post-operative results ranging from 1 month to 4.5 years (11 patients, average follow-up period was 23.3 months) were assessed. Results The experience with 16 individualized total joint replacements in 11 patients is presented. The 3-year follow-up results of two-patient detailed studies are discussed, which show evidence of the promising restoration of all mandibular movements, when preoperatively present. Conclusions By incorporating various innovative and novel features (scaffold for re-attachment of lateral pterygoid, patient-specific functional parametrization, saddle-like design for retention, …) into a novel TMJ prosthesis concept, a major advance in function-reconstructive temporomandibular joint replacement was achieved. Early in vivo results (1 year after surgery) showed promising outcomes, involving both high increases in mandibular movements and decreases in pain scores.

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