The Difference in sagittal lip position and soft tissue convexity between class ii division 1 and division 2 patients: cephalometric analysis

Abstract

AIMS: To evaluate the influence of upper and lower incisor inclination to sagittal lip position and to compare the soft tissue profile between divisions using Worms soft tissue analysis. SUBJECTS AND METHOD: The records of 120 randomly selected patients. All included patients were skeletal Class II (ANB >4°) and had finished the adolescent growth peak, which was evaluated according to an improved version of the cervical vertebral maturation (CVM) method. The inclination of the upper and lower incisors was assessed using the Steiner method and sagittal lip position was evaluated using Worms method by measuring the distance from the upper and lower lip to the reference line (Sn’-Pog’). Worms method was also used to estimate soft tissue convexity. Cephalometric analysis was performed with the Dolphin Imaging 11 program. In order to conduct statistical analysis, SPSS Statistics 17.0 software was used. Significance of the average difference between independent samples was evaluated using the Mann-Whitney U test. Correlation between samples was determined by Pearson correlation coefficient. To evaluate the dependence between the samples, the least squares method was applied. The level of significance for the analysis was set at P < 0.05. RESULTS: Both the upper and lower lips showed a vsignificant difference between the Class II divisions: the value of upper lip was 3.6 ± 2.03 mm in division 1 and 2.28 ± 1.22 mm in division 2, while the lower lip was 2.14 ± 2.87 mm and 0.81 ± 1.78 mm, respectively. A strong correlation and significant dependence were found between the upper and lower incisors and sagittal lip position. A significant difference of soft tissue convexity occurred between the divisions, the value being 21.77 ± 38 degrees in division 1 and 18.09 ± 4.02 degrees in division 2. CONCLUSION: Class II division 1 patients have more protrusive upper and lower lips in comparison to Class II division 2 subjec...