Temporomandibular Joint Symptoms and Mandibular Stability after Orthognathic Surgery in Patients with Mandibular Retrognathism

Abstract

In this study, changes in temporomandibular joint symptoms and mandibular stability after orthognathic surgery in patients with mandibular retrognathism were investigated. Eight patients were examined clinically for pain, sound, movement and limitation of TMJ and by computed tomography (CT) and lateral cephalograms. TMJ signs and symptoms disappeared in two of the symptomatic patients after surgery, whereas two of the asymptomatic patients developed TMJ signs and symptoms postoperatively. The incidences of TMJ signs and symptoms before treatment and a year after surgery were both 3/8 (27.5%). The position of the disk and the condylar morphology were evaluated with CT. Six patients had disk displacements before treatment and seven patients a year after surgery. Erosions and/or deformities of the condyles were observed in six patients before treatment and all (eight) patients a year after surgery. The diagnosis in five patients was progressive condylar resorption because the ramus vertical hights decreased more than 4mm and/or counterclockwise rotation of the proximal segment was observed on the cephalograms, and remarkable resorption was also identified on postoperative CT. There was no association between signs and symptoms of TMJ and CT findings. The mean anterior movement of the mandible at surgery was 10.1mm at pogonion, and the mean horizontal relapse was 4.1mm. Large horizontal relapses were recognized in cases with progressive condylar resorption.
In conclusion, patients with large mandibular advancement and counterclockwise rotation at surgery and condylar erosive bone change at preoperative examination appear to be at risk for progressive condylar resorption, but the mechanism is obscure.