Abstract
Aims: To 1. Assess the horizontal lip position and lip thickness in both Class I and Class II Division 1 subjects; 2. To investigate the effect of gender on the horizontal lip position and lip thickness; 3. To identify the effect of skeletal differences on lip position and thickness. Materials and Methods: The sample consisted of 60 cephalometric radiographs of 30 dental and skeletal Class I subjects (15 males, 15 females) and 30 dental and skeletal Class II Division 1 subjects (15 males, 15 females). The hori-zontal lip position and thickness was analyzed using 11 linear and 4 angular measurements. Using SPSS software package (version 11.5), descriptive statistics and independent sample t–test were meas-ured to compare between the two Classes and two genders. The differences were considered significant at p < 0.05. Results: In Class I no significant differences were noticed in most of the variables except in upper lip (Ls) to Steiner line and lower lip (Li) to Holdaway line where females showed more retruded position and larger nasolabial angle (NLA) when compared to males. In Class II Division 1 subjects, the upper and lower lips were significantly protrusive in males when compared with females in relation to Sushner line (S2). Class II Division 1 males showed more protruded upper and lower lips in relation to S2 line, significantly smaller Z angle and higher H angle when compared with Class I males. Comparison between Class I and Class II Division 1 females showed a significantly higher val-ue of upper lip in relation to Steiner line (S1), and significantly smaller upper and lower lips in relation to E line, smaller Z angle and larger H angle. Conclusions: Some of the variables were not affected neither by gender nor by skeletal base while other showed statistically significant differences following gender or skeletal Class or both. However, the effect of skeletal base difference was more obvious as higher number of significant differences were seen between the two Classes
