Three-dimensional Assessment Of The Temporo-mandibular Joints In Skeletal Class Ⅱ Malocclusion Females With Different Vertical Patterns

The incidence of skeletal class Ⅱ malocclusion was highly among people, especially in Asian, which was usually accompanied with intricate mechanism of facial and skeletal disharmony, may seriously harm the facial aesthetic and oral function. As it was studied, the vertical problem of Class II malocclusion accounted for nearly half of the class Ⅱ patients who received orthodontic treatment.Recently, many researchers studied the relationships between the temporal-mandibular joints and dental malocclusion. However, there were few studies focued on the relationships between maxilla-mandible development and temporal-mandibular joints. As a key of mandibular growth and development, condyle was closely related with the skeletal problems. The purpose of this study was using the CBCT technique and three-dimensional measurements, measured and analyzed the condylar bony structures of skeletal class Ⅱ female patients, expected to provide some scientific reference to clinical.Experiment One:Analysis of the cranio-maxillo facial type composition of skeletal class Ⅱ female patients in Shaanxi ProvinceObjective: To analysis the craniofacial morphology in sagittal, vertical and both cross constitute among 103 skeletal class Ⅱ famale patients in Shaanxi Province. Methods: A cephalometric study was carried out on a sample consisted of 103 female patients with skeletal class Ⅱ. Divided these patients into 6 groups by their sagittal patterns and 3 groups by their vertical skeletal patterns. SPSS17.0 statistical software was used for analysis and evaluation the craniofacial morphology in sagittal, vertical and both cross constitute of these patients. Results: Sagittal constitutes results displayed the proportion of S2 group was the highest, accounting for 40.8%; Vertical composition displayed the V2 group accounts for about half, V3 group accounts for slightly more than V1; Cross analysis shows that S2V2 combination had the highest percentage. Conclusion: Skeletal class Ⅱ female patients in Shaanxi region mainly to the lack of jaw development and normal maxilla, bout 50% of patients combines with vertical problem. The high-angle Class Ⅱ patient often accompanied with mandible’s clockwise rotation and mandibular retrusion. On the contrary, the low-angle Class Ⅱ patient reveals truly mandible growth deficiency. Understanding the craniofacial types of skeletal class Ⅱ malocclusion patients can be speculated the pathogenesis, help to better treatment options.Experiment Two:Three-dimensional assessment of the temporo-mandibular joints in skeletal class Ⅱ females with high mandible angleObjective: The purpose of this study was to evaluate the morphology and position of temporo-mandibular joint with high angle patterns in class Ⅱ female subjects. Methods: Forty-one CBCT films(20 for control group; 21 for high angle group) were collected, using Mimics 17.0 software to construct the three-dimensional direction position and morphology of condyle,, which included forms of fossa and joint spaces. Results: Compared to the control group, the condyles located more posterior in high angle patients, as well as the angles of posterior joint node bevels were smaller. The condyles were shorter, thinner and tipped more anterior in comparison to control group and. t The position of the conyles was more anterior.Conclusions: Class Ⅱ skeletal type adult females with high askeletal patternsngle had different forms of fossae, and different positions and forms of condyle compared to the control group.Experiment Three:Three-dimensional assessment of the temporo-mandibular joints in skeletal class Ⅱ2 malocclusion females with low vertical patternsObjective: The purpose of this study was to evaluate the morphology and position of temporo-mandibular joint with low angle in adult females with class Ⅱ. Methods: Fifty-six CBCT films(20 for control group; 21 for high angle group; 15 for low angle group) were collected. Using Mimics 17.0 software to evaluate the position and morphology of condyle, which included forms of fossa and joint spaces. Results: Compared to the control group, the condyles in low angle patients located more posterior and lower and the condyles were thicker and tipped more posterior. The position of the conyles was more posterior. Compared to the high angle group, the condyles in low angle patients were thicker, longer and tipped more posterior. The angles of posterior joint node bevels were bigger. Conclusions: Class Ⅱ skeletal type adult females with low angle patterns had different forms of fossae, and different positions and forms of condyle compared to the control group and high angle group.