Improvements in occlusion after orthognathic surgery.

Orthognathic surgery has widely been employed for the treatment of dentofacial deformities in both functional and morphological aspects, and has been studied extensively with respect to the therapeutic plan and the evaluation of its therapeutic efficacy from various points of view.We devised an instrument on an experimental basis for the measurements of occlusal force, occlusal contact area and occlusal pressure using a pressure sensitive sheet, and then compared the occlusal states between subjects with normal occlusion and patients with dentofacial deformity with this instrument.N'Ve also quantitatively measured changes in occlusion by orthognathic surgery.As a result, our conclusion was made as follows:1.In the normal occlusion group, the occlusal force and occlusal contact area were largest on the second molar in both male and female subjects, and then the first molar, second premolar and first premolar in this order.2.The occlusion pressure in the normal occlusion group did not differ among teeth or between male and female subjects.3.The mean occlusal force in the entire molar area for both male and female subjects was found to be 105.9 kg in the normal occlusion group and 46.3 kg in the non-treated deformity group with the mean occlusal contact area of 21.7 mm2 and 8.6 mm2, respectively, showing markedly significant statistical differences between the 2 groups.The mean occlusal pressure was measured to be 5.05 kg/mm2 in the normal occlusion group and 5.68 kg/mm2 in the nontreated deformity group, indicating a significant difference between them.4. When changes with time elapsed from a preoperative period up to 1 year after the orthognathic surgery were determined, the occlusal force and occlusal contact area were found to be minimum at the time of removal of intermaxillary fixation, gradually increased to nearly preoperative levels thereafter.And reached the values more than double of the preoperative levels 1 year after operation.The occlusal pressure was measured to be highest at the time of removal of intermaxillary fixation, gradually decreased thereafter, and than showed the lowest value being almost equal to the preoperative value at 1 year after operation.5.Since our method can provide an accurate and simple measurement with high reproducibility even under a poor postoperative condition seen in the field of oral maxillofacial surgery, it will widely be available for the determination of occlusal condition.