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 (CR). Clinicians frequently rely on a splint-guided therapeutic position (ThP), without imaging confirmation of the condyle-disc relationship before for fabrication and adjustment of a repositioning splint. This case report presents magnetic resonance imaging across two mandibular positions-centric occlusion (CO) and ThP-and describes a mismatch between disc position and condylar seating. It suggests that partial disc recapture observed in a ThP may not coincide with a CR 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. CR was established using Dawson's manoeuvre after muscle deprogramming and recorded with addition silicone. Magnetic resonance imaging in CO, CR, ThP, 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 ThP, partial recapture of the left disc occurred, but the condyle still failed to reach a CR. 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 ThP may facilitate partial disc recapture and symptomatic relief in chronic temporomandibular disorder, yet the condyle may remain non‑physiologic position. Magnetic resonance imaging in CO, CR, and ThP may help identify discrepancies between disc position and condylar seating before selecting a mandibular position for prolonged splint therapy or irreversible prosthodontic or orthodontic treatment. The ThP can be considered a reversible, intermediate stage within a controlled splint protocol rather than a definitive target. As this is a single-case report, the observations are hypothesis-generating and require confirmation in case series or comparative observational studies.