| Objectives To reconstruction and measure the skeletal structure of temporomandibular joint(TMJ) and the opposite position of condyle and glenoid fossa in Class II1malocclusion in the permanent dentition using cone-beam computed tomography(CBCT) and invivo5software. Comparing the differences between maxillary protrusion and mandibular retrusion to comprehensive clear the malocclusion’s effects on morphology and structure of TMJ.Methods Select the permanent dentition on60cases of Class II1malocclusion patients for the study, in patients with anterior maxillary and mandibular retrusion in15patients each group. The original images scanned by CBCT were reconstructed with invivo5software and then obtain the three-dimensional reconstruction images to located. Axial plane which was tangential to the lower edge of articular tubercle was used to be the reference plane, then 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 width and height of condyle, depth and width of glenoid fossa, the value of long axis of condyle, the distance from the front to the back, the distance from the left to the right, the anterior, superior and posterior joint space, then make the statistical analysis to the data. Independent samples t test was used for the measurement results by using SPSS17.0, and analyse the results.Results:1.In the maxillary protrusion sample, there was no statistically significant difference of the shape of TMJ between two sides (P>0.05)2.In the maxillary protrusion sample, there was obviously correlation in the skeletal structure of TMJ between two sides (P<0.05)3.In the maxillary protrusion sample, most of the condyles are in concentric and anterior in the glenoid fossa; There was statistically significant(P<0.05); the condylar positions were50%concentric,46.7%anterior and3.3%posterior.4.In the mandibular retrusion sample, there was no statistically significant of the shape of TMJ difference between two sides (P>0.05)5.In the mandibular retrusion sample, there was obviously correlation in the skeletal structure of TMJ between two sides (P<0.05)6.Although anterior space of TMJ is larger than posterior space in the two sides of mandibular retrusion sample, there was no statistically significant (P>0.05); the condylar positions were50%concentric,33.3%anterior and6.7%posterior.7. Some of the skeletal structure of TMJ were different between maxillary protrusion sample and mandibular retrusion sample. Statistically significant difference(P<0.05) was observed.Conclusion:1.In the Class II Division1sample, The skeletal structures of TMJ were relatively symmetry between two sides in the maxillary protrusion sample.2.In the Class II Division1sample, The skeletal structures of TMJ were relatively symmetry between two sides in the mandibular retrusion sample.3.There were significant differences in morphology of TMJ between the maxillary protrusion group and the mandibular retrusion group in the Class II Division1sample.4.Compared with the mandibular retrusion sample, the characteristics of TMJ in maxillary protrusion sample is that the condyle is wider and longer and the glenoid fossa is deeper and wider.But the condyle is thiner and shorter and the glenoid fossa is shallower and narrower in the other sample.5.In the maxillary protrusion group, most of the condyles are in concentric and anterior in the glenoid fossa, but they are in concentric position in the mandibular retrusion group. Compared with the mandibular retrusion sample, the position of condyle in the glenoid fossa was more anterior and closer to the center of face in the horizontal,and was higher in articular tubercle,which allows the condylar position in the glenoid fossa in the relatively more stable for maxillary protrusion.6.The Class II1malocclusion affects the structure and morphology of TMJ. |
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