A Comparative Study Of Craniofacial Structures Of Different Vertical Types Of Class â…¢ Patients In Permanent Dentition

Objective : The purpose of this study was to compare the craniofacial structures of different vertical types of Class III patients in permanent dentition. Methods: 73 Class III malocclusion patients were selected from the department of orthodons of the affiliated stomatology Hospital of Jiangxi medical University which met the selection criteria..The subjects were divided into two groups according to the mandibular plane angle. Group I comprised of 35 subjects with high mandibular plane angle(11 male,24 female,aged 13.51+1.88 years). Group II comprised of 38 subjects with low mandibular plane angle(17 male,21 female,aged 14.13+1.30). Lateral cephalometric radiographs were took for all patients before treatment.The cephalograms were traced on acetate paper by one investigator,and 45 measurements were obtained. All the measurements were compared statistically. Results: 1,The angle of N-S-Ba in high-angle group was significantly larger than that in low-angle group. There were no statistically significant differences in the angle of N-S-Ar and the distances of S-N, S-Ba and N-Ba between the two groups. 2 ,The angle of SNA in high-angle group was significantly smaller than that in low-angle group. The distances of A-Ptm and S-Ptm in high-angle group were significantly smaller than those in the low-angle group. The angle of PP-SN in the high-angle group were significantly larger than that in low-angle group. There was no statistically significant difference in the angle of FH-PP between the two groups. 3,The angle of SNB in the high-angle group was significantly smaller than that in low-angle group. The distances of Ar-Go, Go-Po, Ar-Gn and Po-NB in high-angle group were significantly smaller than those in low-angle group. The angle of Ar-Go'-Me, SN-MP, FH-MP and PP-MP in high-angle group were significantly larger than those in low-angle group. There were no statistically significant differences in the angle of FH-RP, SN-RP and CV between the two groups. 4,The distances of N-Me and ANS-Me in high-angle group were significantly greater than those inlow-angle group. The distance of S-Go in the high-angle group was significantly smaller than that in low-angle group. The index of FHI in high-angle group was significantly smaller than that in low-angle group, and ANS-Me/N-Me in the high-angle group were significantly larger than those in the low-angle group. There was no statistically significant difference in the distance of N-ANS between the two groups. 5,The angle of U1-SN, L1-MP and U1-L1 in high-angle group were significantly smaller than those in low-angle group. The angle of SN-OP, FH-OP, PP-OP and MP-OP in high-angle group were significantly larger than those in low-angle group. The distances of Xchchd and Klhhd in high-angle group were significantly smaller than those in low-angle group. The distance of U1-PP and Ui-PP in high-angle group were significantly larger than those in low-angle group. There were no statistically significant differences in the distance of U6-MP, Li-MP and L1-MP between the two groups. Conclusion: 1,The craniofacial morphology of high-angle and low-angle facial skeletal types showed significant differences, The distance of N-Me in high-angle group was significantly greater than that in low-angle group,while the distanceof S-Go was smaller than that in low-angle group.The angle of Ar-Go'-Me,SN-MP,FH-MP and PP-MP in high-angle group were significantly larger than those in low-angle group,while the distance of Ar-Go,Go-Po and Ar-Gn were smaller than those in low-angle group. 2,The adaptability of the dentoalveolar processes and compensatory tooth movements can compensate for the hyperdivergency of the jaw-base relationship.The thickness of the mandibular symphysis and the alveolar process in high-angle group were significantly thinner than those in low-angle group. The angle of U1-SN, L1-MP and U1-L1 in high-angle group were significantly smaller than those in low-angle group. The distance of U1-PP and Ui-PP in high-angle group were significantly larger than those in low-angle group.