Discrepancy between centric relation and therapeutic position in TMJ disc displacement: a case report

Background: Temporomandibular disorders often involve internal derangements such as anterior disc displacement, which can alter the centric relation position. Clinicians frequently rely on a splint-guided therapeutic position as a functional reference without imaging confirmation of the condyle–disc relationship. This case is notable for integrating magnetic resonance imaging across three mandibular positions—centric occlusion, centric relation, and splint-guided therapeutic position—revealing a clinically relevant mismatch between disc position and condylar seating. It shows that partial disc recapture in a therapeutic position does not necessarily correspond to a physiologic centric relation in long-standing, structurally advanced joint pathology. Case presentation: A 30-year-old female reported over seven years of nocturnal clenching and persistent right-side clicking. Her history included fixed orthodontic treatment (2014–2016) followed by retention splints. A nightguard fabricated in 2018 did not alleviate symptoms. Examination revealed a reproducible reciprocal click on the right. Centric relation was established using Dawson’s manoeuvre after muscle deprogramming and recorded with addition silicone. Magnetic resonance imaging in centric occlusion, centric relation, therapeutic position, and maximal opening demonstrated advanced degenerative changes and anterior disc displacement without reduction on the right, with no recapture in any position; the left joint showed anterior displacement with reduction. In the therapeutic position, partial recapture of the left disc occurred, but the condyle still failed to reach a physiologic centric relation. A maxillary repositioning splint with retrusive control and anterior guidance was fabricated from the constructive bite. With nocturnal wear and 10–14-day follow-ups over three months, joint clicking diminished and function improved, with all effects remaining reversible. Conclusions: A splint-guided therapeutic position may facilitate partial disc recapture and symptomatic relief in chronic temporomandibular disorder, yet the condyle may remain non-physiologic. Magnetic resonance imaging in centric occlusion, centric relation, and therapeutic position is essential to detect discrepancies between disc position and condylar seating before using any mandibular position for long-term splint therapy or definitive prosthodontic or orthodontic treatment. The therapeutic position should be considered a reversible, intermediate stage within a controlled splint protocol, not a definitive target.