CBCT Study The Positional And Morphological Characteristics On Condyle-fossa Of TMJ Asymptomatic Patients With Class â…¡2Malocclusion

Objective:The purpose of this study was to quantify measure condylar parameters, access the condyle position within glenoid fossa of TMJ in TMJ asymptomatic adult patients with Class Ⅱ2malocclusions and normal occlusion on volumetric3D imaging, by taking this comparative study to investigate the difference of TMJ structure of volunteers between with Class Ⅱ2malocclusion and with Class I malocclusions.Materials and Methods:The study group included25TMJ asymptomatic patients with skeletal Class Ⅱ2malocclusion (male:11, female:14, mean age22years) and25healthy volunteers with normal occlusion as the controls (male:13, female:12, mean age24years), respectively. All subjects are symptom-free who had no pathological temporomandibular joint changes as verified by lateral tomographic imaging. Their joints had optimum function with the starting and end points of all functional jaw movements coincident with maximum intercuspation. The pictures were reconstructed in three-dimensional (3D) using Mimics16.01software rendering and measured in two dimension projection (2D) pictures, linear measurements examination was performed. The images obtained from the sagittal slices were used to quantify following condylar and glenoid fossa parameters:superior space, anterior space and posterior joint space; glenoid fossa width and height; tuberculum articulare angle; height and width of condyle, height of procesus condylaris. The images obtained from the axial slices were evaluated for possible asymmetries in size and position between the condylar processes associated with these malocclusions. Mean values were calculated separately for left and right side. The position of mandibular condyle was described as anterior, concentric or posterior according to Kamelchuk. Differences of the mean values were tested using paired t-test and χ2-test。Results:1.The mean AS, SS, and PS values in skeletal Class Ⅱ2group were1.71±0.75mm,2.37±0.69mm,2.47±0.54mm, on the right side, respectively; and the mean AS, SS, and PS values on the left side were1.76±0.54mm,2.42±0.25mm,2.59±0.63mm, respectively. There is no statistically difference of the three parameters between the two sides of the Class Ⅱ2group.2.The mean AS, SS, and PS values in Class I occlusial group were1.69±0.60mm,2.19±0.62mm,2.30±0.54mm on the right side, respectively;and the mean AS, SS, and PS values on left side werel.65±0.34mm,2.24±0.33mm,2.28±0.63mm, respectively. There were no statistically significant differences of the three parameters between the two sides of Class I malocclusion group.3. In the group of Class Ⅱ2, there was no statistically difference between the two sides of Class112group, with88%concentric positioning and12%posterior positioning; however,8%anterior positioning,8%posterior positioning and84%concentric positioning of the condyle was figured out in Class I occlusial group.4. In the Class112group, the height of condyle on the left and right sides were3.45±0.57mm、3.37±0.80mmm respectively, which is smaller than the result of control group (3.77±0.21mm、3.76±0.22mm, respectively); also, the results of condyle height were statistically different, but not condyle width. The angulations of the articular tubercle in the Class112group, were31.53±1.96°、31.47±1.96°, respectively for the left and right side, which were statistically significant from the results of Class Ⅰ group. Also, the measurements of condyle process between the two groups were not statistically different.Conclusions:1. There was no significantly statistically difference between the two TMJ sides in the Class Ⅰ malocclusial group.2. There was no significantly statistically difference between the two TMJ sides in the Class Ⅱ2malocclusial group.3. Compared with Angle I occlusial group, condyles without much position differnece were detected and the spaces were statistically normal.