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Abstract:Objective:the malocclusion happens increasingly high to the teenagers recent years. Among the malocclusion patients, Class Ⅱ&class Ⅲ malocclusion owns a big percentage about47.2%. Class Ⅱ&class Ⅲ malocclusion has their typical profile respectively. In the various clinical features, both convex and concave have big impact on the beauty of lateral soft tissue profile. There are some researches compared class Ⅱ&class Ⅲ malocclusion with the normal occlusion lateral soft tissue profile. But very few researches are for the comparative analysis of class Ⅱ division1, class Ⅱ division2&class Ⅲ malocclusion, especially for which of nasal morphology, nasolabial sulcus and mentolabialis sulcus. This experiment will use cephalometric films to analyze and compare the lateral soft tissue profile of class Ⅱ division1, class Ⅱ division2and class Ⅲ malocclusion of the early permanent dentitions for the teenagers. This experiment will also explore the effect of morphology of hard tissue to the soft tissue profile shape, which providing more comprehensive and scientific reference for orthodontic treatment. Methods:selecting the lateral cephalometric film of20patients respectively for treatment of class Ⅱ division1, class Ⅱ division2&class Ⅲ malocclusion cephalometric radiographs form Orthodontic Department of Stomatology Hospital Affiliated to Luzhou Medical College from2010to2012. The patients were between12to17years old, all from Sichuan province and Han nationality, with ratio4:5of male and female. They were healthy and growing well. They were in early permanent dentitions period and had not taken any orthodontic treatment before. They didn’t have any temporomandibular joint diseases, facial deformity, nose deformity, and facial cosmetic operations. Through the analysis of measurement of class Ⅱ and class Ⅲ malocclusion soft tissue related sign, this experiment observed the differences of lateral profile of early permanent dentitions of the teenagers, and analyzed the relative hard tissue elements which caused the differences, therefore to give the evidence to support clinical diagnosis and treatment. All data were analyzed statistically by software SPSS17.0. Results:1. The nasal morphology has no obvious difference between class Ⅱ division1, class Ⅱ division2and class Ⅲ malocclusions.2.Among the analysis of class Ⅱdivision1malocclusion group and class Ⅲ malocclusion groups of single factor variance, there were significant differences between the8soft tissue measurement indexes (P<0.05), which were FH-N’Pg’, H angle, Sn-H line, Si-H line, Pg-Pg’, Pg’ HSi, SiPg’ Li, LiSiPg’. There were also significant differences between other8hard tissue indexes (P<0.05), which were SNB, ANB angle, A-NPg angle, Li-MP, Li-NB, U1-L1, FH-MP, Y axis, No significant differences were in other measuring indexes (P>0.05). Soft and hard tissue correlation analysis showed the jaw position, inclination of upper and lower incisors, facial height, mandibular growth direction are related to the mentolabialis sulcus.3. Single factor analysis of variance of the grouped data of class Ⅱ division2malocclusion and class Ⅲ malocclusion group shows statistically significant difference of8indexes of soft tissues (P<0.05), which were upper lip concave deep, H angle, Li-H line, Si-H line, SnLsCm angle, CmSnLs angle, LiSi angle Pg’, L/FH, and statistically significant difference of6hard tissues (P<0.05), which were SNB, ANB angle, A-NPg angle, Ul-SN, Ul-NA, Ul-L1.nasolabial angle and mentolabial regin showed significant differences (P<0.05), Soft and hard tissue correlation analysis showed the jaw position, inclination of upper and lower incisors, facial height, mandibular growth direction are not related to the nasolabial regin,L/FH is related to inclination of upper incisors, mentolabial regin is related to the jaw position.4. Single factor analysis of variance of the grouped data of class Ⅱ division Ⅰ malocclusion and class Ⅱ division2malocclusion showed significant difference (P<0.05) of4soft tissue measurement indexes, which were FH-N’Pg’, H angle, Sn-H line, Li-H line. Except for3hard tissue measurement indexes, the others are valid for statistical significance (P<0.05). No statistical significance differences of nasolabial region and the mentolabial region morphology.Conclusion:1. The nasal morphology has no obvious difference between class Ⅱdivision1, class Ⅱ division2and class Ⅲ malocclusions;2. The main difference of lateral soft tissue profile of class Ⅱ division1and class Ⅲ malocclusion appears in mentolabialis area. The mentolabialis sulcus angle is125.5°±13.0°of class Ⅱ division1, which is obviously smaller than the mentolabialis sulcus angle142.8°±10.5°of class Ⅲ;3. The main difference of lateral soft tissue profile of class Ⅱ division2and class Ⅲ malocclusion appears in nasolabial and mentolabialis areas. The malocclusion nasolabial angle is110.9°±12.8°of class Ⅱ division2, bigger than which of class Ⅲ,98.2°±12.2°. The malocclusion mentolabialis sulcus is5.4±1.8, bigger than which of class Ⅲ,2.5±1.4;4. The lateral soft tissue profile of class Ⅱ division1and class Ⅱ division2malocclusions have no obvious differences in nasolabial and mentolabialis areas;5. H angle is a reliable index of angle analysis. The angle dimension increases gradually from class Ⅲ, class Ⅱ division2to class Ⅱ division1, which are14.9°±3.3°,18.1°±3.3°,24.1°±3.3°respectively.
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