# Cone-beam CT evaluation of impacted mandibular third molars and their possible association with mandibular incisor crowding

## TL;DR

This study uses cone-beam CT to investigate if impacted lower wisdom teeth are linked to crowding in lower front teeth.

## Contribution

It provides new empirical evidence on the weak association between bilateral impacted third molars and incisor crowding.

## Key findings

- Bilateral impaction showed higher crowding scores than unilateral cases.
- No significant differences in arch dimensions or associations with age or gender were found.
- Crowding remains multifactorial, and CBCT offers additional assessment insights.

## Abstract

The relationship between impacted mandibular third molars and mandibular incisor crowding remains controversial. This study aimed to evaluate whether the impaction pattern of mandibular third molars is associated with lower incisor crowding using cone-beam computed tomography (CBCT).

A retrospective sample of 140 patients was analyzed, including 70 with unilateral and 70 with bilateral mandibular third molar impactions. Little's Irregularity Index (LII) was measured on CBCT images to quantify incisor crowding. Arch length, depth, intercanine width, and intermolar width were also recorded. Non-parametric tests were used to compare groups, and intra-observer repeatability was assessed.

The mean LII was 9.04.8, with 85% of patients showing some degree of crowding. Bilateral impaction cases presented significantly higher LII scores than unilateral cases (p=0.047). However, no significant differences were found in arch dimensions between groups, and LII was not associated with gender or age. Categorical analysis of crowding prevalence did not differ significantly between unilateral and bilateral groups.

Bilateral mandibular third molar impaction showed a weak association with greater mandibular incisor irregularity. Crowding is a multifactorial condition, and CBCT may provide additional insight into its assessment in patients with impacted third molars.