| Objective : The aim of this study is to used the cone-beam computed tomography(CBCT)to study the surgical procedure of bilateral sagittal split osteotomy and receding of bilateral mandible in the treatment of adult mandibular protruding deformity.The effect of two different fixation methods on the condyle shape and its position in the temporomandibular joint fossa was different.The objective evaluation of the effect of different fixation methods during bssro on the tmj of this kind of patients was the clinical analysis and diagnosis of this kind of disease,to provide a reference for the clinical analysis diagnosis,treatment design and curative effect prediction of this kind of disease.Method:From July 2012 to October 2017,a total of 26 adult patients with skeletal iii type malfunction,10 men and 15 women,were selected from hospitalization in oral and maxillofacial surgery,affiliated stomatology hospital of Nanchang University.The operation was performed by the same doctor using the bilateral split ramus osteotomy procedure.The patients were divided into two groups according to the intraoperative fixation.In group A,16 patients were treated with single screw fixation at the proximal end of the osteotomy line,distal end bone mass was fixed with double screws.Group B,9 patients were treated with double screw fixation for proximal and distal end of osteotomy.Each patient was taken CBCT sacn as well as their TMJ symptom was checked and recorded at the following stage: before the BSSRO(T0);within 1 week after BSSRO(T1);1 month after surgery(T2);3month after surgery(T3);6 month after surgery(T4).And use the same station of CBCT to acquisition of image data.Then the condyle morphology and its position data in temporomandibular joint fossa were measured by Mimics software,and the influence of different fixation methods on condyle morphology and its position in temporomandibular joint fossa was analyzed.The Spss17.0 software is used to carry out independent sample test of the measurement results,and the test level is set as α=0.05.Results:(1)There were no significant differences in condylar morphology at different stages after bilateral sagittal split osteotomy with two different fixation methods(P 〉 0.05).(2)No significant difference was found between the two temporomandibular joint measurements before bssro in each group(P>0.05),and there was also no significant difference between male and female groups in terms of measurement items.(P>0.05).(3)There were significant differences in the changes of anterior and posterior interarticular spaces between the two groups within one week after operation(P<0.05).(4)Three months after operation,there were significant differences in condylar angle α and anterior articular space L1 F between the two groups(P<0.05).conclusion:(1)The position of condyle process was closer to the position of condyle in temporomandibular joint fossa immediately after single screw fixation,but the position of condylar process in double screw fixation group was closer to that of preoperative position.(2)After 1 weeks to 6 months after operation,the condylar position of the single screw fixation group and the double screw fixation group showed a trend of adaptive regression to preoperative level.(3)Compared with the single screw fixation group,the condylar process rotated inward immediately after operation,which continued until the third month after operation and disappeared at the 6th month after operation.(4)No apparent condylar absorption or condylar morphological changes occurred within 6 months after operation. |
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