Early findings of morphological changes in the temporomandibular joint after orthognathic surgery in mandibular prognathism with facial asymmetry.

This study was performed to investigate early morphological changes in the temporomandibular joint (TMJ), after patients with mandibular prognathism with facial asymmetry (MPA) received orthognathic surgery. The morphological changes in the TMJ were analyzed on computed tomography multi-sectional reconstructed images first taken before preoperative orthodontic treatment and then again 6 months after orthognathic surgery, in 39 patients with MPA. A combination of Le Fort I osteotomy and bilateral sagittal split osteotomy (BSSO) was performed in 22 patients and BSSO alone was performed in 17 patients. Compared to the non-deviated side, both before preoperative orthodontic treatment and 6 months after surgery, the posterior slope of the articular eminence was significantly steeper (P < 0.001, P < 0.001, respectively), and the mandibular fossa significantly deeper on the deviated side (P < 0.001, P = 0.002, respectively). However, 6 months after surgery, on the non-deviated side the posterior slope of the articular eminence had become significantly steeper (P = 0.005), and the mandibular fossa significantly deeper (P = 0.009), compared to their preoperative morphologies, suggesting a gradual improvement in the morphological asymmetry of the TMJ. These early morphological changes in the TMJ on the non-deviated side at 6 months postoperatively may be due to improvements to the asymmetric loading in the temporomandibular joints, associated with the surgical improvement of facial asymmetry.