# Retrospective clinical audit of extraction cases treated with clear aligner therapy

## TL;DR

This study evaluates how accurate clear aligners are in moving teeth after premolar extractions by comparing predicted and actual tooth movements.

## Contribution

The study provides new insights into clinically significant discrepancies in tooth movement with clear aligners after extractions.

## Key findings

- Clinically significant linear discrepancies were found in the maxillary and mandibular arches for specific tooth groups.
- Angular discrepancies in both dental arches were statistically and clinically significant.
- Loss of torque and unplanned tipping near extraction sites were clinically significant and should be addressed during treatment planning.

## Abstract

To evaluate the accuracy of clear aligners in premolar extraction cases by measuring the differences between predicted and achieved tooth movements.

The sample consisted of 32 patients undergoing extraction treatment with clear aligners, with a mean age of 21.2 (+-7.6) years. Discrepancies between achieved and predicted tooth movements were determined using paired t-tests and independent t-tests. The discrepancies per tooth group were assessed per dental arch and were evaluated for clinical significance (> 2 degrees; >0.5 mm).

Linear discrepancies that demonstrated clinical significance (> 0.5 mm) in the maxillary arch were the buccal-lingual and occlusal-gingival discrepancies for the central incisors (0.61 mm and 0.87 mm) and the buccal-lingual discrepancy of the first premolars (0.59 mm). The first and second molars in the mandibular arch showed buccal-lingual discrepancies of 0.51 mm and 0.65 mm, respectively. In comparison, the central (0.66 mm) and lateral incisors (0.57 mm) and first and second premolars (both 0.55 mm) showed clinically significant discrepancies in the occlusal-gingival direction. All angular discrepancies in the maxillary and mandibular dentition were statistically and clinically significant (> 2 degrees).

Loss of torque and occlusal-gingival discrepancies of the upper and lower incisors were clinically significant. Unplanned tipping of teeth adjacent to the extraction site was also clinically significant. These factors should be considered and mitigated at the ClinCheck stage to aid efficiency.