Clinical Studies on Mandibular Prognathism Patients Treated with Orthognathic Surgery with Special Reference to the Changes of the Quantitative Masticatory Function After Surgery

Abstract

Purpose : The purpose of this study was to investigate the postoperative course of patients with skeletal mandibular prognathism. We examined the change of masticatory efficiency and the relationship between masticatory efficiency and relapse.
Patients and methods : A total of 21 patients underwent orthognathic surgery and were examined with masticatory efficiency tests pre and post operative. We evaluated the masticatory efficiency by means of measurement of absorbance using ATP particle and evaluated the ability of the biting off test using incisor teeth in 17 patients. And we analyzed the degree of relapse using cephalometry.
Results : All preoperative masticatory efficiency of the patients were lower than in healthy people, and there was no patient who had a higher masticatory efficiency than healthy people till one year after surgery. Improvements of masticatory efficiencies one year after surgery were recognized in 16 patients. Results of Biting off test using incisor teeth for all the patients got to the maximum level at the time of one year after surgery. As for the relationship between both masticatory efficiencies and relapse of SNB, overbite and overjet, correlations were recognized between poor masticatory efficiency and relapse of overbite. 5 in 6 patients who recognized malocclusion revealed poor masticatory efficiencies after surgery.
Conclusions : Disturbance of improvement of masticatory efficiency after surgery seemed to be caused by malocclusion in molars and decreasing of overbite by reason of relapse.