Résumé
[Abstract] Objective To investigate the cant of the occlusal planes in Chinese adult class Ⅱ malocclusions with hypodivergent, normodivergent, and hyperdivergent facial vertical patterns using cone-beam CT. Methods The descriptive, cross-sectional study evaluated 123 cephalogram from CBCT(CCB) of patients in Department of Orthodontics, the Affiliated Hospital of Qingdao University. According to cephalometric analysis, 89 Chinese adult class Ⅱ patients were divided into three groups according to the angle between FH-MP and the angle between SN-MP. In comparison, 34 Class I normodivergent malocclusions individuals were selected as the control group. Comparing the cephalometric result between 4 groups. Results As expected,the hyperdivergent group had steeper anterior occlusal planes(14. 73±3. 76) . and posterior occlusal planes(21. 42±5. 77)., there was a significant statistical difference between the hyperdivergent group and other 2 groups in class Ⅱ patients (P<0. 05). The height of maxillary second molar increased from high angle group to low angle group (P<0. 01). Conclusion There are different characters of the occlusal planes in varied vertical facial pattern. The inclinations of anterior and posterior occlusal planes in Chinese class Ⅱ hyperdivergent group were steeper than other 3 groups. The difference of posterior occlusal plane inclination is mainly caused by the height of maxillary second molar.
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Objective:To investigate the effect of mandibular angle osteotomy on the morphological changes of mandible by using cone beam computed tomography (CBCT) scanning data and three-dimensional cephalometry.Methods:According to included and excluded criteria, the complete CBCT data of 20 female patients (aged 20-35 years with an average age of 25.5 years) from January 2016 to June 2018 who underwent curved mandibular angle osteotomy combined with splitting cortiectomy were selected. Seven items reflecting mandibular morphology before and after surgery were measured respectively. All the data were analyzed by the means of SPSS 12.0; linear correlation analysis and paired t test were used to evaluate the change of andibular morphology.Results:The measurement results of the mandible pre- and post-operative 10 days showed as follows: Go-Go decreased, both sides of Cd-Go, Go-Ri and MR-MA decreased, both sides of Go-Me became longer, both sides of Ar-Go-Me and MP-FH increased. The paired t-test results showed that there was significant difference before and after operation ( P<0.05), but there was no significant difference between the left and right measurement items ( P>0.05). Compared with that in 10 days after operation, the measurement items also changed 6 months after operation. There was no statistical difference between the above measurement items 6 months after surgery and 10 days after surgery ( P>0.05), and no statistical difference between the left and right sides ( P>0.05). Conclusions:The mandibular three-dimensional model which is reconstructed based on CBCT data, not only displays the three-dimensional anatomical structure that cannot be presented on X-ray film visually and comprehensively by means zoom, rotation and other operations, but also precisely and accurately shows the change of the shape of the mandible from the sagittal, coronal and horizontal plane with arbitrary cutting and rotation. The measurement of mandible is more accurate and reliable, and the surgical plan of mandibular angle osteotomy can be accurately planned preoperatively, and the operative effect can be quantitatively evaluated postoperatively.
Résumé
Objective:To explore the influence of gender and age on the measurement of cone beam CT (CBCT) in normal and occluded craniofacial hard tissues for Han nationality in Changsha area.Methods:A total of 80 CBCT data of normal and occluded craniofacial hard tissues for Han nationality in Changsha area were collected,including 40 adults [16 males and 24 females,aged (17.57±1.83) years] and 40 children[16 males and 24 females,age (11.50±1.26) years].Threedimensional cephalometric measurements were carried out by Dolphion Imaging software,and the influence of gender and age was compared.Results:The symmetry of craniofacial hard tissues in male and female in the adults was good (the maximum asymmetric rate R was 6.39％ and the minimum asymmetric rate R was 0.08％).There was no significant differencein the anterior palatal width,palatal width,the upper incisor protrusion distance,the lower incisor protrusion distance,hyoid-mandibular plane,basal epiglottis width,and palatal plane airway width between the males and females (all P＞0.05);while the remaining indicators were significantly higher in males than those in females (all P＜0.05).There was no significant gender difference in angle indicators (all P＞0.05).There were significant differences in the posterior height,the maxillary length,the lower incisor protrusion,and the mandibular plane angle between the adults and the children(all P＜0.05);but the rest of indicators were not significant difference (all P＞0.05).Conclusion:The symmetry of craniofacial hard tissues for Han nationality in Changsha area is good.The gender and age affect the line space measurements but not affect the most of the angle measurements.