A Study Of Hard Tissues Change In Patients With Skeletal Class â…¢Malocclusion After Mandibular And Bimaxillary Orthognathic Sugery

Skeletal class â…¢ deformity is one of the most common dento-maxillofacial deformities in the clinical, correction of it has been the focus attention of stomatology doctors. Combined orthodontic and orthognathic treatment is widely used to correct skeletal class â…¢ adult patients. Maxillary Le Fort â…  osteotomy and mandibular bilateral ramus sagittal split ramus osteotomy (BSSRO) are two operation methods used to correct skeletal Class â…¢ malocclusion. We usually choose one or two kinds of the operation methods in the basis of the position and degree of the deformity. According to the operation site is usually divided into single-jaw or double-jaw procedures,but the criteria is not clear. Analyze the changes of hard tissues at each treatment stage in patients with Skeletal Class â…¢ malocclusion after mandibular or bimaxillary orthognathic sugery, and to discuss the different effects after treatment, so as to give some guidelines for clinical work.Although orthognathic surgery has achieved great progress, but the postoperative stability is still plague Stomatology doctors. Postoperative stability is the key measure of orthognathic surgery success. Reports on postoperative stability almost are the study of single-jaw or double-jaw procedures at home and abroad, seldom in single-jaw versus double-jaw procedures. Comparison skeletal changes after single and double jaw procedures can provide reliable theoretical basis for the selection of operation.Objective:The purpose of this study was to analyze the changes of hard tissues at each treatment stage in patients with Skeletal Class III malocclusion after mandibular or bimaxillary orthognathic sugery, and to discuss the different effects and skeletal stability after treatment, so as to give some guidelines for clinical work.Methods:60patients who had been diagnosed with Class III skeletal deformities were divided into2groups and had undergone mandibular or bimaxillary orthognathic sugery. The standardized lateral cephalograms were taken at the following stages:before treatment(To);before surgery(Ti);6weeks after surgery(T2); after treatment (T3). A total of17hard tissues landmarks were selected. We measured and evaluated the alteration of these points in angular and distance measurements, horizontal and vertical directions between the different stages. SPSS20.0soft ware was used to analyze the changes of the hard tissues.Results(1) Except the landmarks of the upper incisors in the single jaw group shown no significant changes(P>0.05), all the landmarks of both upper and lower incisors have significant changes(P<0.05)at the stage of T1compared with the stage of To.(2) Compared with the stage of Ti, in the bimaxillary surgery group the maxilla move forwards and downwards,while the mandible move backwards and upwards at the stage of T2(P<0.05)In the single jaw surgery group only the mandible moved backwards and upwards(P<0.05).The change of the SNA angle in the bimaxillary surgery group and the SNB angle, ANB angle, Wits appraisal in both group have passed the statistical significance level in both group(P<0.05). In contrast with the single jaw surgery group, an increase in occlusal plane inclination in bimaxillary surgery group was found(P<0.05). In the bimaxillary surgery group, upper and lower facial height change significantly(P<0.05), the vertical facial proportions more harmonious. All the patients have established good occlusion relationship after surgery. (3) Although there was some relapse in the maxilla of the bimaxillary surgery group and in the mandible of both group,it has no meaning in statistics (P>0.05). The horizontal mandibular skeletal of double-jaw procedure was more stable when compared with the single-jaw procedure(P<0.05). No other differences in vertical mandibular skeletal stability was identified (P>0.05).Conclusion(1)These results indicate that, bimaxillary surgery is preferable to correct maxilla deformity,improve vertical facial proportions,change occlusal plane inclination than single-jaw procedure.(2)The double-jaw procedure may lead to more stability, leading to less skeletal relapse, than single-jaw procedure in horizontal. No differences were noted between the two groups when examining the mandibular vertical stability.