Analysis Of Mandibular Morphology By CBCT In Class ? Skeletal Malocclusion Patients With Mandibular Deviation

Purpose:The clinical manifestations of skeletal class III malocclusion patients with mandibular deviation are common clinical malformations.The serious harm and distress of occlusal function and appearance are the focus of clinical treatment.Most patients need orthodontic and orthognathic treatment,and the orthodontic treatment before and after orthognatic surgery is the key to ensure the effect of treatment.Orthognatic surgery and orthodontic treatment can recover the correct position of the teeth in the alveolar,and the correct occlusal relationship,reduce the recurrence rate,at the same time conducive to the patients'facial beauty and the stability.Our study which analyses the morphology of the adult class ? skeletal malosslusion patients with mandibular deviation by CBCT can provide guiding significance for orthognatic surgery and orthodontic treatment,and conductive to the evaluation of the efficiency of the patients' treatment.Materials and Methods:Randomly select 50 adults aged from 20 to 40 years old,who suffer from class? skeletal malocclusion with mandibular deviation,25 males and 25 females in Shandong university stomatology school.The CBCT(cone-beam computed tomography)is used to get the three-dimensional morphologic data of the mandible.Mimics 15.0 is used for three-dimensional reconstruction of the mandible.The specific points in mandible which respect bone structure can be selected to build three-dimensional coordinate system.The patients are divided into two groups according to the symmetry of the mandible,and the asymmetric group is divided into two groups by gender.SPSS22.0 is used to for statistical analysis for mandibular variables.Result:1.In the condylar measurement,comparision of condylar length(m-1),condylar length(a-p)and condylar unit length showed that the opposite side were significantly greater than skew side(p<0.05).The skew side was significantly greater than the opposite side in coracoid unit length.There was no difference in condylar inclination-coronal plane angle(p>0.05).In the skew group,the differences of condylar length(m-1),condylar length(a-p),condylar unit length of the male were greater than that of female(p<0.01).There were no significant differences in the coracoid length and condylar-coronal plane angle(p>0.05).2.In the mandibular measurement,comparison of the mandibular total length,mandibular length and mandibular ramus length showed that the opposite side was larger than that of skew side(p<0.01).The mandibular angle of opposite side was larger than that of skew side(p<0.01).In the skew group,the differences of mandibular total length,mandibular length and mandibular ramus length of the male were more significant than that of the female(p<0.01).3.In the measurement of condylar symmetry relative to the skull base,comparison of the conmed-coronal,conlat-coronal,conmed-sagittal and conlat-sagittal planes showed that the skew side was greater than that of opposite side(p<0.01).The conmed-horizontal and conlat-horizontal planes of skew side were smaller than that of opposite side(p<0.05).In the skew group,the differences of conmed-coronal,conlat-coronal,conmed-sagittal,conlat-sagittal,conmed-horizontal,conlat-horizontal plane of the male were significantly greater than that of female(p<0.01).4.In the measurement of the symmetry of the mandible relative to the skull base,comparison of the go-coronal and go-sagittal planes showed that the skew side were larger than that of the opposite side(p<0.01).The Go-horizontal plane of the skew side was smaller than that of the opposite side(p<0.01).In the skew group,the differences of Go-coronal and Go-sagittal planes were larger in the male group than that of female group(p<0.01).Conclusion:1.As orthognathic digitization has been gradually applied to clinic,analysis of mandibular morphology by CBCT in class III skeletal malocclusion patients with mandibular deviation can accurately assess the condylar and mandibular morphological features,provide reference for preoperative diagnosis,prognosis evaluation and preparation of the plywood.2.In class ? skeletal malocclusion patients with mandibular deviation,compared with the oblique contralateral side,the skewed condyles were in a backward,outward and upward position.It suggests that in the treatment of Class ? malocclusions with mandibular deviation,early condylar resection and orthodontic treatment to correct the condylar growth direction can avoid severe mandibular deviation and reduce the difficulty of operation.For the unnormal mandibular condyles size caused by adult mandibular deviation,condylar resection and mandibular sagittal split can correct the mandibular deviation.3.In class ? skeletal malocclusion patients with mandibular deviation,the length of the mandibular body lost control with abnormal trajectory,and no restricted growth of opposite side was found compared with the skew side.Mandibular grew mainly backwards while the movement was forward and downward,and the change of rise side was upwards.It suggests that as the focus of orthognathic operation in clinic,such growth is difficult to control.4.In class ? skeletal malocclusion patients with mandibular deviation,the mandibular body was over grew in the male compared with the female.It suggests that the chief complaint of the male patients should be roundly considerd in the diagnosis and treatment.