Objective: The purpose of this study was to elucidate positional relationships between temporomandibular joint (TMJ) components, including the articular discs, using magnetic resonance imaging (MRI) in patients with hemifacial microsomia (HFM).
Subjects and Methods: Twenty TMJs in 10 patients with HFM were examined at closed- and open-mouth positions using an MRI scanner. The condyle-fossa and disc-condyle relationships, disc configuration at the closed-mouth position, and the reduction of the disc at the open-mouth position were evaluated.
Results: On the unaffected side, the condyle-fossa and disc-condyle relationships appeared fairly normal at the closed mouth position. The disc-condyle relationship at the open-mouth position was also normal. The TMJ disc showed normal biconcave configurations at both closed- and open-mouth positions. On the affected side, there was considerable variation in the state of the TMJ. At the closed-mouth position, 5 of the 10 patients revealed fairly normal disc-condyle relationships, one patient showed anterior displacement of the disc, and four patients had no disc. Two patients appeared biconcave, three patients appeared biplanar, and one patient was hemiconvex. At the open-mouth position, the condyle and disc moved in harmony in five patients with normal disc-condyle relationships, but the disc was reduced in a patients with anterior disc displacement. The degree of the TMJ disc dysplasia did not necessarily correspond with the degree of mandibular dysplasia.
Conclusion: The present study contributes to an improved understanding of TMJ pathology in patients with HFM. The results suggest that, in HFM patients, the examination of the TMJ using MRI is helpful for determining treatment procedures in mandibular distraction osteogenesis.