Evaluation Of The Temporomandibular Joint Of Teenagers And Adults In Class Ⅱ Subdivision Malocclusions With Cone-beam Computed Tomography

ObjectiveThe purpose of this study was to evaluate the characteristics of the temporomandibular joint of teenagers and adults in Class II subdivision malocclusions.MethodsCone-beam computed tomographic images of 40 patients with Class II subdivision malocclusion(20 teenagers and 20 adults)were three-dimensionally reconstructed using the Invivodental software,measured bilateral TMJ related indicators.Paired-samples t-tests were used to compare the average differences between the Class I and Class II sides.Two independent sample t-tests were used to analysis differences between teenagers and the adults in the Class I side,to analysis the differences between teenagers and the adults in the Class II side.Results1.No statistically differences were observed between the two sides in teenagers patients(P>0.05).2.The temporomandibular joint structures were significantly Differences between the two sides in adults.The medialateral diameter(P<0.05),anteroposterior diameter(P<0.05),medialateral diameter-sagittal plane angle(P<0.05),Maximum area(P<0.05),height of the top of condylar(P<0.05),Inner,Superior and Posterior joint space(P<0.05)were significantly different between the two sides in adults,the Class Ⅱ sides were smaller than Class I side;The depth of fossa glenoid(P<0.05)and the anterior joint space(P<0.05)were significantly different the two sides in adults,the Class Ⅱ sides were bigger than Class I side;The condylar-mid sagittal plane distance,the medial joint space,the outer joint space,the length of fossa glenoid and the angle of posterior wall of the articular tubercle were no statistically different between the two sides in adults(P>0.05).3.The medialateral diameter(P<0.05),anteroposterior diameter(P<0.05),maximum area(P<0.05),height of the top of condylar(P<0.05),depth of fossa glenoid(P<0.05)and length of fossa glenoid(P<0.05)were significantly different between teenagers and adults in the Class I side;The condylar-mid sagittal plane distance,medialateral diameter-sagittal plane angle,joint space(inner,medial,outer,anterior,superior,posterior)and the angle of posterior wall of the articular tubercle were no statistically different between teenagers and adults in the Class I side(P>0.05).4.The medialateral diameter(P<0.05),anteroposterior diameter(P<0.05),height of the top of condylar(P<0.05),the anterior joint space(P<0.05),depth of fossa glenoid(P<0.05)and length of fossa glenoid(P<0.05)and the angle of posterior wall of the articular tubercle(P<0.05)were significantly different between the Class Ⅱ sides in teenagers and adults,the Class Ⅱ sides were bigger than Class I side.The medialateral diameter-sagittal plane angle(P<0.05),maximum area(P<0.05),Inner,Superior and Posterior joint space(P<0.05)were significantly different between teenagers and adults in the Class II side,the Class Ⅱ sides were smaller than Class I side.The condylar-mid sagittal plane distance,the medial joint space,the outer joint space were no statistically different between the Class I sides in teenagers and adults(P>0.05).Conclusions1.The results of this study indicate that the temporomandibular joint in adolescent has no statistically differences.2.The condylar of the adult Class II side was smaller,and went backwards,up and into.3.The results of this study indicate that the temporomandibular joint in adolescent has significant growth potential.4.There are influences that occur in the Class II side about Class II subdivision malocclusions may exist.