Effect of attachment wear on maxillary canine rotation in clear aligner therapy: a three-dimensional finite element...

This study aimed to explore the effect of attachment wear on maxillary canine rotation in clear aligner therapy through three-dimensional finite element analysis.

Finite element models, comprising the maxillary bone, periodontal ligament, upper dentition, attachments (initial and worn), and clear aligners, were created to simulate maxillary canine rotation. Two attachment types (vertical rectangular and rotation-optimized) with five wear levels (M0, M2, M4, M6, and M8) were considered for canine rotation analysis. Tooth displacement and equivalent stress in the roots and periodontal ligaments were analyzed.

With increased attachment wear, both groups showed reduced canine rotation angles and lower stress levels in roots and periodontal ligaments. The most significant reduction in the canine rotation angles and stress values for the rectangular group occurred between M2 and M4, with the efficiency of canine rotation falling below 50% from M4 onward. In contrast, the optimized group experienced the most substantial decline between M6 and M8, with the efficiency of canine rotation falling below 50% at M8.

Attachment wear decreased maxillary canine rotation efficiency. It is preferable to use optimized rotation attachments when correcting maxillary canine rotation. After six months of optimized attachment use, if maxillary canines still require rotation, orthodontists should closely monitor attachment wear to ensure treatment effectiveness. Immediate restoration or re-bonding of the attachments is required if it is determined to be essential.