RELATIONSHIP BETWEEN PALATALLY IMPACTED CANINES AND MAXILLARY LATERAL INCISOR’S CROWN-ROOT ANGULATION AND ROOT-CROWN RATIO; A THREE-DIMENSIONAL CONE BEAM COMPUTED TOMOGRAPHY EVALUATION

Abstract

Background: The adjacent relationship of the canine with the lateral incisor root suggests that it provides a guide for canine’s eruption and an absent lateral incisor or malformed lateral incisor root will alter the eruption of the canine. This study aimed at determining the mean crown-root angulations and root-crown ratio of lateral incisors with maxillary canines on the impacted and non-impacted side by using Cone Beam Computed Tomography.
Study design: Comparative cross sectional study
Place & duration of the study: This study was conducted at Margalla Institute of Health Sciences, Rawalpindi from October 2024 to December 2024.

Methodology: After taking ethical approval from the Ethical Review Committee (ERC), Margalla Institute of Health Sciences, Rawalpindi. Cone Beam Computed Tomography (CBCT) scans of patients aged 12 to 45 years, of either gender, were collected using non-probability consecutive sampling from the available imaging pool at MIHS. The sample size was calculated using the OpenEpi calculator, resulting in 65 participants per group. Accounting for a 20% potential dropout rate, 78 CBCT scans were evaluated in each group. Group A consisted patient’s CBCT showing palatally impacted canines whereas Group B included normally erupted canines on CBCT. Planmeca software was used to measure the angles between the long axis of the crown and the long axis of the root of each maxillary lateral incisor on the CBCT in sagittal view. Furthermore, the mesial, upright, and distal root angulations were noted. The lengths of the root and crown were measured independently, and the root length was divided by the crown length to determine the root-to-crown ratio. A standardized performa was used to record all findings. Each assessment's findings were recorded in performa. SPSS version 22 was utilized to analyze the data. The Mann Whitney U test was utilized to identify statistically significant differences between groups because the data was non-parametric. The significance level was set at p≤0.05.

Result: The study comprised 78 participants, the majority of whom were female (67.9%), with a mean age of 18.42 ± 3.55 years. Group A (palatally impacted canines PIC) had a lateral incisor angulation of 19.53°± 11.03, while  Group B (non-palatally impacted NPIC) had an angulation of 8.1°±6.69.  There was statistically a significant difference between angulation of lateral incisor among PIC and NPIC (p=0.00). Group A crown-to-root ratios (1.46 ± 0.30 mm) were marginally lower than Group B(1.60 ± 0.47 mm). 71.8% of the people in Group A had mesial angulation (16.9° ±10.53), and none of them were upright. However, in Group B, 93.5% of the lateral incisors were upright (7.12°±5.79), making mesial (5.1%) and distal (1.28%) angulation very rare.

Conclusion: This study concluded that lateral incisors in group A had considerably higher mesial angulation and lower crown-to-root ratios than the group B.