Abstract:

Objective To get reference for the diagnosis design and the clinical diagnosis, the difference is compared among lip profile on malocclusion of ClassⅠ, Ⅱ and Ⅲ from patients in Harbin, and the relationship is established between the linear cephalometric measurements and the regional cephalometric measurements. Methods 120 female patients，18-25 years old, were selected. According to the value of ∠ANB which was measured on the pre-treatment cephalographs, they were divided into three groups—Class Ⅰ, Ⅱ and Ⅲ. Each group had 40 patients. Each patient had the same type of skeletal pattern and occlusion pattern, and then 21 lip soft tissues were measured. Finally, the results of measurements were statistically analyzed with ANOVA and were compared between members in each group via SPSS 13.0 software. Results The differences among patients with lip profile on malocclusion had statistic significances（P<0.05）. In order of Class Ⅱ, Ⅰ and Ⅲ, the UL-E, ULP, ULP-LLP, Sn-Ns-B′ and S4 were progressively decreased and the B′-LL-FH, S-Ns-B′ and S1 were increased. In order of Class Ⅱ, Ⅲ and Ⅰ, the LL-B′-Pos and Z-angle were raised and LL-E was reduced. The length of the upper lip and the lower lip had no statistic significance（P>0.05）. Conclusion There is difference among the ClassⅠ, Ⅱ and Ⅲ. The lip covering area is inclined to decrease the changes of the upper lip and increase the changes of the lower lip progressively with the variation of skeletal patterns in order of Class Ⅱ, Ⅰ, and Ⅲ. Moreover, the condition of lip tissues can be accurately presented by the regional cephalometric measurements.

Key words: malocclusion, lip, profile, cephalometric analysis, area measurement