No abstract

The purpose of the present study was to investigate the relationship between the inclination of the articular eminence and temporomandibular joint (TMJ) pathology in orthognathic surgery patients with signs and symptoms of TMJ disorders. Twenty-one female orthognathic surgery patients with signs and symptoms of TMJ disorders were examined using pre-treatment helical computed tomography scans. The slope of the eminence in the medial, central and lateral sections of the subjects with osteophyte formation was significantly less than in the subjects with no bone change, and the medial section of the subjects with osteophyte formation was also significantly less steep than in the subjects with erosion. The central and lateral sections in the subjects with anterior disc displacement with reduction were significantly steeper than in subjects with anterior disc displacement without reduction. These results suggest that eminence flattening might occur during changes from erosion to osteophyte formation and from anterior disc displacement with reduction to anterior disc displacement without reduction. This appears to represent adaptation of the condyle, articular disc and articular eminence to changes in loading.

The aim of this study was to investigate functional changes in occlusion during retention. Data on occlusal force (OcFr) and occlusal contact area (OcAr) was obtained using the pressure-sensitive sheet, from a treated group (20 female patients) who had had four premolar extractions and treatment with standard edgewise appliances, and a control sample who matched the treated group of retainer for sex, age and Angle classification at 1 year after removal. A repeated measures analysis of variance showed that the mean values of total OcFr and OcAr in the treatment group gradually increased during retention and were 669.3 N and 15.1 mm2, respectively, at 1 year after removal of retainer. The increases of OcFr and OcAr were larger in the molar region, especially at the second molar. At 1 year after removal of retainer, OcFr and OcAr in the second molar were significantly larger in the treatment group than in the control sample, and a similar distribution pattern of OcFr and OcAr to those in normal occlusion was seen. These results suggested that balanced OcFr and OcAr might be obtained during and after retention, due to the settling of molars that had been discluded by active orthodontic treatment.

The types of the maxillary arch forms in unilateral cleft lip and palate patients might play a stronger role in the stability of the maxillary dental arch widths after orthodontic treatment in patients with collapse of both segments and a severe degree of maxillary narrowness.