The Analysis Of Mandibular Morphological Features Before And After Orthognathic Surgery And Postoperative Fracture In Patients With Mandibular Prognathism And Deviation

Objective:Image data before and after orthognathic surgery in patients with mandibular prognathism and deviation was analyzed by The three-dimensional reconstruction of the jaw bone to study the bony structural features of the mandible before and after orthognathic surgery and the effect of BSSRO on the treatment of mandibular prognathism with deviation.And also to analyze the relationship between postoperative BSSRO infection,lingual bone splitting method,mandibular deviation direction and postoperative jaw fracture in patients with bony mandibular.Research objects and methods:Experiment one:The patients with mandibular prognathism and deviation who underwent BSSRO surgery in our hospital from January 2015 to October 2019 were selected.According to the inclusion and exclusion criteria,a total of 16 study subjects were selected which included 5 females and 11 males.CBCT data of all subjects before and after BSSRO operation was collected,and divided them into 2 groups(The T0 group included the CBCT image data of all patients before operation,and the T1 group included the CBCT image data of 6-8 months after operation)according to CBCT image data of different periods before and after operation.The side of the chin that deviated from the midline of the facial was defined as the deviation side,and the other side was the opposite side.Obtained craniofacial DICOM data based on CBCT images,and inputted the data into Mimics19.0 software for 3D reconstruction of the jaw,and then importted the 3D reconstruction data into 3-Matic software to measure the relevant data of the jaw.Learned the mandible relevant data by statistical analysis to compare the differences between the mandibular structure before and after BSSRO in such patients and to explore the therapeutic effect of BSSRO on mandibular prognathism with deviation jaw deformity.Experiment two: 23 patients with mandibular prognathism and deviation whounderwent BSSRO surgery in our hospital from January 2015 to October 2019 were selected as the analysis objects,included 7 females and 16 males.The right deviation of the mandible were 13 objects and the left deviation of the mandible were 10 objects.Then collected the CBCT image data of all the subjects before and after 2-3months of operation and carried out three-dimensional reconstruction of the jaw bone.The bone splitting methods were divided into different types according to the way of line-breaking by retrospectively analyzed the healing situation of the patients after BSSRO to analyze the relationship between the bony splitting method,infection,mandibular deviation direction and the jaw fracture after BSSRO.Results:Experiment one:In the patients with mandibular deviation before orthognathic surgery,the length of the contralateral mandibular body and the total length of the mandible of the opposite sides were significantly greater than that of the deviated side(p<0.01).The mandibular inclinations in coronal and the angle between condyle inclination and coronal plane of the deflected side were smaller than the opposite side(p<0.05);while the preoperative mandibular inclination of the sagittal plane,Go-sagittal plane,Go-coronal plane and Conlat-coronal plane were smaller than the deviation side(p<0.05),indicated that there was a certain degree of asymmetry in the mandibular bone structure on both sides of the mandibular deviation patients.However,there was no statistical difference between the two sides of the mandibular structure after BSSRO,indicated that BSSRO surgery reduced the difference between the deviation side and the opposite side,suggested that orthognathic surgery had a good effect on improving the deformity of the mandible.Experiment two: A total of 7 wounds were infected after BSSRO in the study,included 3 sides jaw fracture occurred.TypeⅠbone splitting accounted for 69.6% of all splitting types,and no fracture occurred.Type Ⅱ bone splitting accounted for30.4% of the total splitting types,included 3 sides of fractures in type Ⅱ bone splitting.No accidental fracture occurred or the splitting line extended to the buccal side.Statistical analysis showed that there was a statistical difference between the way of bony fracture of the mandibular ascending lingual side and postoperativewound infection and the occurrence of jaw fracture after BSSRO operation.Compared with the non-infected side,the wound on the infected side was more likely to fracture.Type Ⅱ bone splitting was more likely to fracture than typeⅠbone splitting.Gender and direction of mandibular deflection had no significant effect on postoperative fractures.Conclusion:Experiment one: There was a certain degree of asymmetry in the structure between the mandibles of the patients with mandibular prognathism and deviation,suggested that the mandibular deviation is mainly due to the asymmetry of the mandible structure on both sides.Sagittal split ramus osteotomy was the main method of clinical correction of maxillofacial deformities,and it had a significant therapeutic effect on improving asymmetric deformities of the mandible.The increase in the distance between the mandibular after BSSRO suggests that patients with high aesthetic requirements should undergo mandibular contour modification at the same time to reduce the impact of postoperative mandibular angle widening.Experiment two:There was a certain relationship between wound infection and medial ascending bone splitting after orthognathic surgery and the occurrence of jaw fracture after surgery in patients with mandibular prognathism and deviation.Comprehensive analyses and predictions of bone splitting methods before surgery,proficiency in clinical operations and postoperative infection prevention were important for promoting bone healing and preventing fractures.