Tomographic assessment of alterations of the temporomandibular joint after orthognathic surgery.

The aims of the study were: (1) to identify absolute condylar displacements and glenoid fossa changes; (2) to assess alterations in the condyle-fossa relationships following orthognathic surgery, by means of linear temporomandibular joint tomography. The sample consisted of 44 adults who received pre- and post-operative orthodontic therapy and management of their dentofacial deformities with various osteotomies (maxillary: 10; mandibular: 24; combined: 10). The material consisted of the tomograms of the right temporomandibular joints taken within 1 week pre-operatively, immediately post-surgery, and 6 months postoperatively. The X-rays were taken with the mouth closed. Tracing, superimposition, and interpretation of the tomograms were made according to a new method. The findings of the study regarding the groups which received mandibular or combined osteotomies indicated that immediately post-operatively there was a tendency for the condyle to be distracted downward and anteriorly from its original position in the fossa. However, in the 6 months follow-up the condyle showed a tendency to re-establish its initial position. Large variation in posterior space was observed among the patients of the mandibular osteotomy group who were also examined individually. In the maxillary osteotomy group no significant post-operative changes were observed on the average. Remodelling was noticed in both condylar and fossa surfaces of all groups.