# Three‐Dimensional Analysis of Maxillary Incisor Root Resorption Associated With Three Distinct Anterior Retraction Protocols: A Retrospective Study

## TL;DR

This study compares root resorption in maxillary incisors after three different orthodontic treatments using 3D analysis.

## Contribution

The study introduces a 3D analysis of root resorption differences across three anterior retraction protocols.

## Key findings

- Root volume and length changes were significant in all three treatment groups.
- Maxillary central incisors showed greater root volume changes than lateral incisors.
- Root resorption was positively correlated with patient age.

## Abstract

Our objective was to compare differences in the amount of apical external resorption of maxillary incisor roots before and after orthodontic treatment with an invisible aligner, fixed orthodontic without microimplant support, and fixed orthodontic with microimplant support.

This study collected the clinical data of patients with Class II malocclusion who underwent orthodontic treatment with the treatment plan of extracting four premolars between 2018 and 2022. There were 10 patients treated with an invisible aligner, 10 treated with a fixed orthodontic without microimplant support group, and 10 treated with a fixed orthodontic with microimplant support. Changes in root volume and the length of the maxillary incisors in the three groups before and after the treatments were measured using cone beam computed tomography (CBCT) and 3D‐Slicer software.

The t‐test results showed that after treatment, the root volume and length of maxillary incisors changed in all three groups of patients. The differences in volume and length before and after treatment within each group were statistically significant, but there were no statistically significant differences in the changes between the three groups. The amount of change of the root volume of the maxillary central incisors was significantly greater than that of the maxillary lateral incisors. Correlation analysis showed that the amount of change in the length of the roots was positively correlated with age.

Fixed orthodontic treatment with microimplant support had a greater effect on the root volume of the maxillary incisors than invisible orthodontic treatment and conventional fixed orthodontic treatment. The degree of external apical root resorption (EARR) was positively correlated with the patient’s age. Therefore, in clinical practice, for older patients or those requiring the use of mini‐implants for retraction, special attention should be paid to the root resorption.