Changes Of The Hard And Soft Tissues In Patients With Skeletal Class Ⅲ Malocclusion After Combined Orthodontic And Surgical Treatments

The shape and function of the maxillofacial systerm is correlated. The stable of the maxillofacial systerm is based on the nomal activity of the facial muscles. The combined orthodontic and surgical treatment has changed the facial sleletal structure. The soft tissue profile and the muscular function of the maxillofacial system are correspondly changed, no report is found to systemly and quantifacationly research this process by now, how the maxillofacial muscular function adjust the the changes of the facial skeletal structure.The electromyographic activity of masticatory muscles and the oral facial muscular pressure can inpersonaly and quantifiacationlyindicate the function of the oral facial muscular system. This provide a effective method to the study of the oral facial system and the evaluation of the clinic curetive effect . This study has systemly analyzed the changes of the hard and soft tissues in patients with skeletal class III malocclusion after combined orthodontic and surgical treatments for the first time. The results illustrate that the facial skeletal system and muscular system are coordinated. After combined treatment, it still need a relitive long period to fully nomalize the masticatory function for the satisfactory curetive effect.Objective: The aim of the this study was to investigate the changes of the hard and soft tissues in patients with skeletal class III malocclusion by orthodontic and surgical treatments and evaluate the effects of the combined treatments for the skeletal class III malocclusion.Methods All of 20 patients in this research were diagnosed to be skeletal class III malocclusion. The lateral X-ray cephalometric films were taken at the beginning and the end of the treatment were analyzed the changes of the hard and soft tissues . Mean Cumulative Voltage (MCV) of the masseter muscle, temporal anterior and diagastric anterior were measured to evaluate the function of the masticatory muscles. And the perioral muscular pressures acting oncentral incisors, cuspids and first molars were measured buccally and lingually before and after treatment by orthodontic and surgery. Results:Hard tissue: The hard tissue changes were focus on the mandible after the combined treatment. SNB reduced 6.52 (P<0.01); SL and SE were decreased 6.72mm (P<0.01 ) and 1.82mm (P<0.01) respectively. The related abnormal position between the skull and the mandible, which include the chin and the condylus, were back to the normal.Soft tissue: After the treatment, more significant changes were found in the soft tissues than the hard tissue, compare to the beginning of the treatment, most index of the soft tissue in this study were the statistic changed, such as S-N'-Si (from 89.48 to 85.78 ) Ls-E (from 4.10mm to 2.08mm) and Li-E (from -1.55mm to Omm). The facial type of the patients had changed from type III to nomal type I.Masticatory muscles: Most Mean Cumulative Voltage (MCV) of the masseter muscle, temporal anterior and diagastric anterior were decreased significantly after orthodontic and surgical treatments. The masseter muscle was the most sensitive muscle to the treatment. But, the masticatory muscles was less active during chewing and maximum clenching after orthodontic and surgical treatments. Thismeans that it needs a long period of function training to fully recover the function of the masticatory muscles. The perioral muscular pressures: Before and after the treatment, characters of the perioral forces are simlar in someway. Such as: the perioral forces on the right side were no significant difference with the left relative side. The perioral forces on the mandibular area were larger than the maxillar correspondence area (P<0.01) . The perioral forces on the labial side were larger than the lingual correspondence side(P<0.01). After the treatment, the perioral force on the labial side of mandibular incisors, which is the largest (P<0.01) before the treatment, decreased more than others. And the perioral force on the mandibular lingual area became the largest one.