Masahiko Terajima

To assess the three-dimensional (3D) position of the temporomandibular joint (TMJ) in the cranial base structure, the 3D morphology of the TMJ, and the fossa-condyle interspaces in subjects with normal occlusion and patients with mandibular asymmetries using 3D computed tomography (CT) images. We hypothesized that the fossa-condyle interspaces and the shape or size of the TMJ would correlate with mandibular asymmetry. Twenty women with mandibular asymmetry and nine control subjects were recruited. The TMJ position, linear distances, angles, surface areas, and the fossa-condyle relationship were assessed with 3D CT images of the TMJ. The fossa surface area was larger on the contralateral side, although no significant difference was observed in the linear or angular measurements of the fossa. The condylar neck height and condylar angle on the contralateral side were larger than those on the deviated side, and the frontal neck angle on the deviated side was larger than that on the contralateral side and of the control. No significant difference was observed in the condylar area. The fossa-condyle interspaces in the posterolateral section of the TMJ were smaller on the deviated side. The condyle in the patients with mandibular asymmetry was rotated posterolaterally within the fossa on the deviated side. Patients with mandibular asymmetry showed larger fossas and longer condylar processes on the contralateral side and narrower fossa-condyle interspaces on the deviated side, especially in the posterolateral section of the TMJ.