The purpose of this study was to evaluate
bite force, occlusal contact area and masticatory efficiency before and after
sagittal split ramus osteotomy in 27 patients with mandibular
prognathism, in comparison with 27 control subjects with normal occlusion.
Bite force and occlusal contact area were simultaneously measured with a computerized occlusal analysis system, the Dental Prescale system. Masticatory efficiency was estimated by a low-adhesive colour-developing
chewing-gum system. The data were collected at initial medical consultation, immediately before surgery, and at 6 weeks, 3 months, 6 months, 1 year and more than 2 years after surgery. Both
bite force and occlusal contact area of the patients before surgery were significantly less than those of the controls. Although all three parameters had improved after
orthognathic surgery, the
bite force and occlusal contact area did not reach the values of the controls within 2 years postoperatively; masticatory efficiency at 2 years after surgery drew near to control levels.
Bite force correlated with occlusal contact area in the patients postoperatively, whereas masticatory efficiency did not correlate with either of the other two parameters. These results suggest that further adjustment of occlusion and mechanical advantage should be considered before the end of treatment.