Morphological Study On Temporomandibular Joint In High-angle Patients With Different Sagittal Skeletal Pattern By CBCT

ObjectiveThe aim of this study is to analyze the bony structural characteristics of temporomandibular joint of various sagittal malocclusion adults with high mandibular plane angle,as a reference to the orthodontic diagnosis and treatment of high-angle patients.Methods60 cases of malocclusion adults with high-angle were selected and were divided into three skeletal groups according to ANB angle(Class I group,Class II group,Class III group,each group consist 20 cases).20 normal occlusion cases were selected.The images of the temporomandibular joint were scanned by cone-beam computed tomography(CBCT).Reconstructed images of TMJ were analyzed statistically with Invivo5 software and obtained the reference values respectively.Spss19.0 was used for statistical analysis and condyle position of four groups were calculated.Results1.The shape and structure of TMJ showed no significant difference between the right and left sides in patients of different sagittal malocclusion groups(P>0.05).2.In the index indicating the position of condyle:(1)The superior space of Class I,II,III group was smaller than the normal occlusion group(P<0.05),while there was no statistic difference among Class I,II,III high angle group.(2)The anterior space of Class II and Class III group was smaller than the posterior group(P<0.05).There was no significant difference between the anterior and posterior space in Class I group.(3)60% of the condyle in Class I group were in centric position,while 42.5% of Class II and 37.5% Class III patients were presented with anterior condyle position.3.In the index related to condylar morphology:(1)The condylar angulation of Class I was greater than that of the normal occlusion group(P<0.05).The condylar mediolateral diameter,axial proportion Class II group were less than that of the normal occlusion group(P<0.05).The condylar width,condylar height,condylar anteroposterior diameter,condylar mediolateral diameter,axial proportion,the ratio of condylar height to the height of condylar process of Class III group were less than that of the normal occlusion group(P<0.05),while the height of condylar process was higher than that of the normal occlusion group(P<0.05).(2)The condylar anteroposterior diameter,condylar mediolateral diameter,axial proportion and the condylar angulation of Class II group were less than that of the Class I group(P<0.05).The condylar width,condylar height,condylar anteroposterior diameter,axial proportion,the ratio of condylar height to the height of condylar process of Class III group were less than the Class I group(P<0.05),while the height of condylar process was higher than that of the Class I group(P<0.05).The condylar width,condylar height,the ratio of condylar height to the height of condylar process of Class III group were less than the Class II group,while the height of condylar process was higher than that of the Class II group.4.In the index related to mandibular morphology: the angle of the mandibular ramus tangent and FH plane is smaller in Class II,III group than in the Class I group(P<0.05).The length of mandibular ramus and mandibular branch were greater in Class III group than in Class II group(P<0.05).The ratio of condylar process height to the height of mandibular ramus shows no difference among Class I,II,III groups.5.In the index related to glenoid morphology:(1)The width of glenoid fossa of Class I,II,III group were greater than that of the control group(P<0.05).The inclination of articular eminence and the ratio of glenoid height to glenoid width of Class III group were less than that of the control group.There was no significant difference between the inclination of articular eminence and the ratio of glenoid height to glenoid width among Class I,II group and control group(P>0.05).The depth of the glenoid fossa was not significant in the four groups(P>0.05).(2)The inclination of articular eminence of Class III group was less than that of the Class I group(P<0.05).The inclination of articular eminence and the ratio of glenoid height to glenoid width of Class III group were less than that of the Class II group(P<0.05).Conclusions1.The structures of bilateral TMJ were symmetric in Class I,Class II,Class III adults with high-angle.2.The superior space of glenoid fossa was smaller in high-angle adults than normal occlusion adults,while no diference were showed among Class I,II,III adults.Most of the condyle were centric in Class I adults.Class II and Class III patients were characterized by more anterior positioned condyle.3.Differences exist between individuals with normal occlusion and patients with high angle facial pattern,which are listed successively as follows: Class III>Class II >Class I.4.The condylar anteroposterior diameter,mediolateral diameter and axial proportion of Class II and Class III adults were less than that of the Class I adults.The mediolateral diameter was smaller in Class II adults than in Class I adults.5.Class III high angle adults have longer condylar process than Class I and Class II high angle adults.The ratio of condylar process height to the height of mandibular ramus showed no difference among Class I,II,III adults.6.High angle patients have wider glenoid fossa than normal occlusion people.Compared with Class II adults,Class III adults have milder articular eminence and wider,shallower glenoid fossa.