# The Accuracy of Maxillary Canines’ Rotation with Different Attachment Designs: A Retrospective Study

## TL;DR

This study compares different attachment designs to improve the accuracy of rotating maxillary canines using clear aligners.

## Contribution

The study evaluates three crescent-shaped attachment orientations for maxillary canine rotations with clear aligners.

## Key findings

- Oblique attachments showed a trend toward better rotational accuracy compared to vertical ones.
- No significant differences were found among all three attachment designs overall.
- Digital models were used to assess rotational accuracy in a retrospective analysis.

## Abstract

Background/Objectives: The rotation of maxillary canines represents one of the least predictable movements with clear aligners, particularly in cases requiring rotations greater than 10°, due to the rounded crown morphology and limited aligner grip. The aim of this retrospective study was to compare three different crescent-shaped attachment designs (vertical, horizontal, and oblique) for maxillary canine rotations greater than 10° with clear aligners. Methods: Seventy-eight maxillary canines were retrospectively selected and allocated into three equal groups (n = 26) according to the orientation of the applied attachment: vertical, horizontal, or oblique crescent-shaped attachments. Digital STL models (initial, predicted, and final) were imported into Dolphin 3D software 12.0.63 to assess the accuracy of maxillary canine’s rotation through the comparison between planned and achieved values. Results: Mean rotational accuracy was 55.10% ± 15.60 for the vertical group, 62.40% ± 16.10 for the horizontal group, and 64.60% ± 19.40 for the oblique group. One-way ANOVA showed no statistically significant differences among groups (p = 0.09). Pairwise analysis revealed a statistically significant difference between the oblique and vertical designs (p = 0.05). Conclusions: Attachment orientation may influence the accuracy of maxillary canine rotation with clear aligners, with oblique crescent-shaped attachments showing a trend toward improved rotational control.