The Study On Morphology And Structure Of Temporomandibular Joint By CBCT For Angle I, Angle II And Angle III Patients

Objective: The aim of this experiment was to study malocclusion effect on morphology and structure of temporomandibular joint (TMJ) using cone-beam computed tomography (CBCT) to obtain three-dimensional reconstruction images and DOLPHIN IMAGING software to measure these images.Method: Fifteen patients selected respectively for various malocclusions were scanned by CBCT and original images were reconstructed with DOLPHIN IMAGING software. Axial plane which was tangential to the lower edge of articular tubercle was used to be the reference plane, then coronal plane, sagittal plane, oblique position paralleled to the long axis of condyle and oblique position perpendicular to the long axis of condyle were reconstructed. Some parameters was measured including the distance between the condyle center and mid-sagittal line, horizontal angle, gradient of articular tubercle , length of condyle, height and width of glenoid fossa, the value of long and short axis of condyle, the anterior, superior and posterior joint space, then determine the position of condyle in the glenoid fossa by Pullinger analysis methods. All three-dimensional images of patients were measured three times by same researcher so as to be calculated mean value, then data was analyzed by SPSS 17.0 .Results:1.The differences between the left and right structures of various malocclusions patients were statistically significant only in the superior joint space of Class II1 and length of condyle of Class III patients(P<0.05).2.There were significant differences in the gradient of articular tubercle , length of condyle and width of glenoid fossa among three types of malocculusion(P<0.05); The differences not only between Class II1 and Class I but also Class II1and Class III were statistically significant in long and short axis of condyle(P<0.05), the axes of Class II1 were smaller than both Class I and III by comparing means; there were also statistically differences in the height of glenoid fossa not only between Class III and Class I but also Class III and Class II1 (P<0.05), the height of Class III was smaller than another two malocculusion by comparing means.3.The difference between Class II1 and ClassII2 patients was statistically significant only in the articular tubercle gradient and the height of glenoid fossa(P<0.05).4.All joint spaces of Class II1 were bigger than Class III by comparing means, the differences had statistic meaning(P<0.05); there were significant differences in all joint spaces not only between Class I and Class III but also Class II1 and II2(P<0.05); the antieror and superior spaces of Class I were smaller than Class II1 by comparing means, the differences had statistic meaning(P<0.05).Conclusion:1.Existing and subtle asymmetric structure of TMJ can be found by CBCT, although there may be no evident clinical symptoms.2.Most condyles of angle II1 and angle III were anteriorly positioned in the glenoid fossa; most condyles of angle I were concentrically positioned and most ones of angle II2 were posteriorly positioned.3.The temporomandibular joint area of angle II1 patients was looser than angle I and angle III patients.