To compare the collum angle (CA) and labial surface angle (LSA) of the maxillary central incisors across different skeletal malocclusion classes and between genders. This cross-sectional study screened lateral cephalogram of 504 patients above 18 years seeking for orthodontic consultation. Skeletal classification was based on ANB angle, Wits appraisal and Beta angle; Class II cases were further divided by maxillary incisor inclination to the SN plane. Landmarks were digitised using tpsDig, and measurements were obtained via a custom Python script. CA and LSA were compared across skeletal classes using ANOVA and between genders using t-tests. The data of 432 patients (213 males, 219 females) were analysed after eligibility assessment. The mean CA were found to be 1.45°, -1.44°, 4.80°, and 1.20° for Class I, Class II with proclined incisors, Class II with retroclined incisors and Class III respectively, with a statistically significant difference in ANOVA (f = 7.9, p < 0.001). Similarly, mean LSA were 20.55°, 21.35°, 22.11°, and 20.83° for Class I, Class II with proclined incisors, Class II with retroclined incisors and Class III respectively, with no significant intergroup difference in ANOVA (f = 1.135, p = 0.335). No significant gender difference was found with t-test for the CA (t = 0.577, p = 0.564). However, the LSA was significantly greater in females compared to males (t = − 2.158, p = 0.031). Skeletal Class II patients with retroclined incisors exhibited a greater CA compared to other skeletal classes. The LSA was slightly greater in females than in males.
Gyawali et al. (Thu,) studied this question.