Background and Objectives: One form of treatment for degenerative temporomandibular joint diseases such as osteoarthritis, rheumatic arthritis, TMJ ankylosis, and condylar resorption is total joint replacement. The aim of this study was to examine the function of the temporomandibular joint after prosthetic joint replacement. Materials and methods: Fifteen patients with unilateral or bilateral TMJ total joint replacements and 15 healthy controls were evaluated via a SICAT JMT+ device. This non-invasive system measures 3D position and linear movements in all degrees of freedom and allows undisturbed functional mandibular movements to provide a quantitative evaluation. In addition, a TMJ questionnaire consisting of the subjective symptoms was also obtained. To date, no similar studies have been cited in the literature. Results: Mandibular movements after prosthetic joint replacement were recorded during opening, closing, protrusion, and lateral excursive movements and were all significantly decreased compared to those of controls. In the treatment group, the maximum incisal opening was 33.46 ± 5.47 mm, left lateral movement was 1.91 ± 2.7 mm, right lateral movement was 1.74 ± 1.74 mm, and protrusive movement was 2.83 ± 2.05 mm. The p-value comparison study and control group indicated significant difference (p < 0.0001) between the two groups. The study group stated a high level of satisfaction with the total joint replacement. Conclusion: Within the limitations of the study, the following conclusions can be drawn: (1) TMJ replacement patients showed significantly limited jaw movements compared to the control group; (2) a small percentage of TMJ replacement patients still present low levels of pain but improved chewing ability and quality of life.
Keywords: jaw movements; jaw tracking; joint replacements; orthodontics; orthognathic surgery.