# Root morphometry of the lateral incisor as a contributing factor to the impaction of maxillary canines: A comparative study

## TL;DR

This study found that shorter root lengths in lateral incisors are linked to impacted maxillary canines, especially in bicortical cases.

## Contribution

The study introduces root morphometry of lateral incisors as a novel etiological factor for maxillary canine impaction.

## Key findings

- Root dimensions on the impacted side were significantly smaller in the sagittal section compared to the non-impacted side.
- Bicortical impacted canines showed the shortest lateral incisor root lengths, about 2 mm shorter than other types.
- The prevalence of canine impaction was higher in females and mostly unilateral with a palatal position.

## Abstract

This study aimed to evaluate root morphometry of the lateral incisor using cone beam computed tomography (CBCT) as an etiological factor in the occurrence of impacted maxillary canines (IMC).

A total of 99 CBCT scans from individuals of both sexes were analyzed, revealing 139 impacted maxillary canines, categorized as buccal, palatal, and bicortical, across sagittal and coronal sections of the adjacent incisors (AI). Thus, 59 contralateral incisors from the non-impacted side in unilateral cases were examined. The study evaluated several parameters: sagittal root length of the lateral incisor (SRLI), coronal root length of the lateral incisor (CRLI), sagittal root dilaceration angle (SRD), coronal root dilaceration angle (CRD), sagittal root convergence angle (SRC), and coronal root convergence angle (CRC). In total, 198 lateral incisor roots were assessed. The statistical analyses included Chi-square tests, Student's t-tests, and Tukey's tests, with a significance level set at P<0.05.

The study found that cases of canine impaction were more prevalent in females, with the majority being unilateral (47.5%) and located in a palatal position. Bilateral cases were predominantly buccal (52.5%) (p=0.001). Root dimensions on the impacted side were significantly smaller in the sagittal section (14.75 mm) compared to the non-impacted side (15.67 mm) (p=0.001). In the coronal section, measurements were also smaller on the impacted side (mean difference of 0.57 mm), but this difference was not statistically significant (p=0.082). The root lengths in both coronal and sagittal sections were shortest in the bicortical group (12.67 mm and 12.95 mm, respectively) compared to the palatal (15.34 mm coronal / 15.62 mm sagittal) and buccal (14.89 mm coronal / 15.54 mm sagittal) groups (p<0.05).

Individuals with impacted maxillary canines (IMC) exhibit shorter root lengths of the adjacent lateral incisor compared to the non-impacted side, with bicortical IMC cases showing the shortest lengths, approximately 2 mm shorter than other types of impactions. Orthodontists should consider this condition when planning treatments involving IMC.