Objective: The objectives of this study were (1) to evaluate and compare sagittal lip position between skeletal Class II division 1 and 2 patients according to different cephalometric reference lines and (2) to evaluate the interrelation of the sagittal lip position and the inclination of the incisors.
Materials and Methods: A total of 100 patients with skeletal Class II (ANB>4°) and finished adolescent growth peak, evaluated with an improved version of the cervical vertebral maturation (CVM) method, were distributed into division 1 and 2, based on the inclination of the upper incisors. The inclination of upper and lower incisors was assessed by various methods. Sagittal lip position was evaluated using Burstone B, Ricketts E, Steiner S, and Holdaway H reference lines. For statistical analysis SPSS Statistics 17.0 software was used. Mann-Whitney U test and Student’s t-test were applied to evaluate the significance of the average difference between samples while LS least squares method assessed the dependence between the samples. Level of significance was set at p < 0.05.
Results: Division 1 patients showed statistically significant higher sagittal upper and lower lip position values than division 2 patients. According to the B line, the upper lip value was 4.79±1.81 mm in division 1 and 2.29±1.37 mm – in division 2, while the lower lip values were 3.23±3.01 mm and 0.76±1.78 mm, respectively. Due to the E line, the respective values were -1.07±2.38 mm and –4.40±1.78 mm in the upper lip and S line values were 1.46±2.01 mm and -1.56±1.49 mm, respectively. A statistically significant dependence was found between sagittal lip position and incisor inclination.
Conclusions: Skeletal Class II division 1 patients had more protrusive upper and lower lips, compared to division 2 patients. Sagittal lip position highly depended on the inclination of the incisors.
Keywords: cephalometry; orthodontics, Class II malocclusion