Three-dimensional Evaluation Of Long-term Stability After Chin Advancement Genioplasty

Objective:To construct a reliable three-dimensional method for analyzing the postoperative stability of genioplasty,verify whether it has good stability after genioplasty,understand the difference between bimaxillary simultaneous genioplasty and simple genioplasty,and preliminarily explore the trend and causes of relapse after genioplasty,so as to guide the operation plan and predict the postoperative effect.Methods:Part 1: Collecting CT data of patients who received genioplasty,apply Proplan CMF 3.0 software for CT reconstruction,osteotomy,matching,and analysis of marker points.Part 2: 1.Select 30 patients with chin deformity who received genioplasty,and process the CT before operation,immediately after operation and 12 months after operation.Using three-dimensional analysis method to analyze the amount of surgical movement,relapse and angle changes of patients.2.Select 30 patients with skeletal class II Malocclusion and 20 patients with skeletal class III Malocclusion who received bimaxillary simultaneous genioplasty,and process the CT before operation,immediately after operation and 12 months after operation.Using three-dimensional analysis method to analyze the amount of surgical movement,relapse and angle changes of patients.And compared with simple genioplasty.3.Select 30 patients with skeletal class II Malocclusion who received bimaxillary simultaneous genioplasty,and process the CT before operation,immediately after operation and 12 months after operation.Using the three-dimensional analysis method,the whole head is selected as the registration plane,to analyze the amount of surgical movement,relapse and angle changes of patients.4.The patients were grouped according to the type of jaw deformity before operation and sagittal moving distance.The moving amount and recurrence amount of patients were calculated by three-dimensional method to verify the influence of them on the relapse amount.Results:1.12 months after genioplasty,the sagittal recurrence of the pog point was0.46mm(±0.37),and the sagittal recurrence of the centre of mass was 0.54mm(±0.35).In terms of angle,at 12 months after operation,the chin was further rotated 1.98°(±2.70)along the left and right axis.It shows that the anterior part of the chin descends and the posterior part moves upward.P<0.05,The results are statistically significant.2.Patients with skeletal class II Malocclusion underwent bimaxillary simultaneous genioplasty.12 months after operation,the recurrence of the pog point in sagittal direction was 0.52mm(±0.32),further decreased 0.50mm(±0.31)in vertical direction,and the recurrence of the centre of mass in sagittal direction was 0.60mm(±0.31),further decreased0.37mm(±0.25)in vertical direction.In terms of angle,at 12 months after operation,the chin was further rotated 1.01°(±1.61)along the left and right axis.P < 0.05,The results are statistically significant.Patients with skeletal class III Malocclusion underwent bimaxillary simultaneous genioplasty.12 months after operation,the recurrence of the pog point in sagittal direction was 0.48mm(± 0.32),further decreased 0.25mm(±0.54)in vertical direction,and the recurrence of the centre of mass in sagittal direction was 0.48mm(±0.31).P<0.05,The results are statistically significant.There was no statistical difference in the sagittal recurrence between bimaxillary simultaneous genioplasty and simple genioplasty,P>0.05.3.Patients with skeletal class II Malocclusion underwent bimaxillary simultaneous genioplasty.12 months after operation,the sagittal absolute recurrence of the pog point was 0.85mm(±1.75),and the sagittal recurrence of the centre of mass was 0.96mm(±1.80).In terms of angle,at 12 months after operation,the chin and the mandibular body as a whole was further rotated 1.87°(±2.41)along the left and right axis.P<0.05,The results are statistically significant.4.There was no statistical significance between different type of jaw deformity before operation and movement,as well as their interaction and sagittal recurrence.Conclusions:1.The three-dimensional method constructed in this subject has good repeatability and can be used for three-dimensional evaluation of stability after genioplasty.2.The genioplasty is stable as a whole,but there is a certain recurrence in the three-dimensional direction and angle after operation.,mainly in the sagittal direction.The rotation trend of chin after genioplasty is worthy of attention3.There was no increased risk for bimaxillary simultaneous genioplasty.4.The amount of sagittal relapse after genioplasty is not correlated with the degree of sagittal bone advancement and the type of jaw deformity before operation.