The Research About Three Dimensional Evaluation,Classification And Surgical Simulation In Maxillomandibular Asymmetry

Objectives:1.To analyze the characteristics of asymmetric deformities by using facial and mandibular mid-sagittal planes as reference plane,propose a classification system of maxillomandibular asymmetry from jaw position and mandibular shape,providing the basis for clinical diagnosis and treatment.2.To plan personalized surgical program for guiding operation and observe its application effect in clinical treatment by surgical simulation technique and three-dimensional measurement based on mid-sagittal plane of face and mandible as reference planes in facial asymmetry.Materials and Methods:1.86 patients with facial asymmetry were selected.Reconstruct three dimensional bone model in Proplan CMF software using CBCT date.To analyze the symmetry of jaw position and mandibular contour by a three-dimensional measurement system and mirror using facial and mandibular mid-sagittal planes as reference plane,propose a classification system for maxillomandibular asymmetry from two aspects of jaw position and mandibular shape based on the results of three-dimensional measures.2.The CBCT date of preoperative of 28 patients with facial asymmetry were imported into Proplan CMF for three-dimensional reconstruction.Analyze the characteristics of jaw position and mandibular contour asymmetry by using middle sagittal plane of face and mandible as reference planes.To define its classification according to three-dimensional measurement results,and then formulate appropriate personalized surgical program by three dimensional surgical simulation technology to guide surgery.after 6-12 months review postoperative CBCT,evaluate the clinical effect of this method in facial asymmetry by mirror overlay images and the contrast of preoperative and postoperative.Results:1.According to the characteristics of asymmetry of jaw position and mandibular shape,maxillomandibular asymmetry is divided into three categories: jaw positiondeviation,mandibular shape deviation,jaw position and mandibular shape deviation.jaw position deviation:Type T(transverse asymmetry): Type T1(mandibular horizontal rotation deviation),Type T2(mandibular translational deviation),Type T3(Maxillary deviation,mandibular horizontal rotation deviation),Type T4(Maxillary deviation,mandibular translational deviation),Type V(vertical asymmetry),mandibular shape deviation :Type C(mandibular contour asymmetry),Type D(chin asymmetry).Each of the above subclasses is combined to form a new category,There was significant difference in DA,UI-CMSP and UOP-FCMSP except for LI-CMSP by Kruskal-Wallis Test among jaw position asymmetry groups(P<0.05).2.The results of composition ratio of facial asymmetry:86 patients have mandibular asymmetry deformity,only jaw position asymmetry contains 7patients(8.1 %),only mandibular shape asymmetry includes 15 cases(17.4 %),maxillomandibular position and mandibular shape asymmetry accounted for 74.5 %(64)of cases.There are 40 cases of T1,2 cases of T2,13 cases of T3,2 cases of T4,14 cases of V,2 cases of C,3 cases of D,13 cases of C and D.3.Symmetry analysis of mandibular structure in jaw position asymmetry : In T1 and T3 groups,there were Statistically significant in body length,ramus length,lateral ramal inclination and frontal ramal inclination(P<0.05).In T2 and T4 groups,these measurement items were not brought into statistical analysis due to the few number of cases.In Type V,frontal ramal inclination and ramus length were statistically significant difference(P<0.05),but the others were no statistically significant.In Mandibular contour asymmetric group,the difference of contour measurement items were significant significance(P<0.05).4.Preoperative assessment of the second experiment:16 cases of type T1,2cases of type T3,2 cases of type T4,3 cases of type V,2 cases of type D,3 cases of type C and D were detected by three-dimensional measurement and mirror imaging.There were 21 patients with maxillomandibular position and mandibular shape asymmetry.5.Postoperative assessment:The difference of bone tissue measurement items between preoperative and postoperative were significant statistical significance(P<0.05)except for Go-lat-MMSP and maxillary occlusion canting.facial symmetrywas significantly improved,in addition to 2 cases had residual asymmetry who required secondary surgery,Other patients were symmetry,all patients were satisfied with facial shape.Postoperative mirror overlay images show good facial symmetry which is consistency with the preoperative assessment.Conclusion1.The classification system of maxillomandibular asymmetry can provide the clinical basis for the diagnosis of disease and the formulation of surgical program.2.The application of mandibular and facial mid-sagittal and 3D surgical simulation technology in developing personalized surgical program,can reduce the postoperative facial residual asymmetry and the risk of secondary surgery,improve the accuracy of the expected surgical results with high clinical value and feasible.3.Proplan CMF simulation software in the application of facial asymmetry deformity is important for accurately diagnose,design treatment program,simulate the surgical process,assess the risk of surgery and postoperative effect,has a high clinical value.