Comparison of Crown Root Morphology in Maxillary and Mandibular Anterior Teeth of Different Sagittal Skeletal Patterns in Bengali Population: A Retrospective CBCT Study

Introduction: Individual diversity is the cornerstone of human biology and this is also reflected in the crown and root morphology of teeth. The maxillary and mandibular anterior teeth can be differentiated based on their crown-root morphology, collum angle, Labial Surface Angle (LSA) and torque angle. In clinical orthodontic practice, the collum angle is often assumed to be zero, as seen in standardised cephalometric incisor tracing templates. This assumption overlooks the variations in collum angles observed in different malocclusions, leading to difficulties in achieving proper root angulation after treatment. Aim: To evaluate and correlate the collum angle, LSA and torque angle in maxillary and mandibular anterior teeth across different skeletal patterns in the Bengali population. Materials and Methods: This retrospective study was conducted at the Department of Orthodontics and Dentofacial Orthopaedics , Guru Nanak Institute of Dental Sciences and Research, Kolkata, West Bengal, India, from March 2022 to January 2024. It involved 90 Cone-Beam Computed Tomography (CBCT) scans of young adult patients aged 18–24 years, with no history of orthodontic treatment, cleft lip and palate, or oral habits. Participants were divided into three groups based on the angle between Point A, Point B and Nasion (ANB angle): skeletal Class-I (2°<ANB<4°), Class-II (ANB>4°) and Class-III (ANB<2°), with 30 subjects in each group. The collum angle, LSA and torque angle were measured for different malocclusions and compared using Pearson's correlation analysis and one-way Analysis of Variance (ANOVA) (p<0.05). Results: A positive correlation (p<0.05) was found between the collum angle and LSA in all types of malocclusions. The smallest collum angle was observed in the lower left central incisor. The maxillary lateral incisor showed a larger crown-root angulation than the central incisor. The maxillary canine and mandibular central incisor exhibited the smallest collum angles in the maxillary and mandibular arches, respectively. An increase from 3.5 mm to 5 mm in the calculation of LSA resulted in a difference of 3.7° for maxillary incisors and 3.5° for mandibular incisors. In skeletal Class-I malocclusion, the maxillary lateral incisor showed the largest torque angle, while the mandibular lateral incisor had the smallest. In Class-II malocclusion, the maxillary central incisor had the largest torque angle, whereas the maxillary canine had the smallest. In Class-III malocclusion, the maxillary lateral incisor exhibited the highest torque angle, while the mandibular canine showed the smallest. Conclusion: A statistically significant difference was observed in the crown-root morphology of maxillary and mandibular anterior teeth. Understanding the variations and correlations among the collum angle, torque angle and LSA across different sagittal skeletal malocclusions can help refine orthodontic treatment planning and improve post-treatment outcomes.