What question did this study set out to answer?

The study aims to compare the collum angle and labial surface angle of maxillary central incisors in various skeletal malocclusion classes and between genders.

April 11, 2026Open Access

Cephalometric evaluation of maxillary central incisor crown-root morphology in different skeletal malocclusion

Key Points

The study aims to compare the collum angle and labial surface angle of maxillary central incisors in various skeletal malocclusion classes and between genders.
Conducted a cross-sectional study using lateral cephalograms of 504 patients seeking orthodontic consultation.
Classified skeletal malocclusions based on ANB angle, Wits appraisal, and Beta angle.
Digitized landmarks with tpsDig and obtained measurements using a custom Python script.
Employed ANOVA for intergroup comparisons and t-tests for gender comparisons.
Mean collum angles varied significantly among skeletal classes with Class II retroclined incisors showing the highest angle.
Labial surface angles showed no significant differences across skeletal classes.
Females exhibited significantly greater labial surface angles than males.
Overall significant differences in collum angles were found with ANOVA (f = 7.9, p < 0.001).

Abstract

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.

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