Three-Dimensional Assessment of Composite Attachment Wear in Clear Aligner Therapy: A Prospective Cohort Study.

INTRODUCTION

Clear aligner therapy relies on composite attachments for precise tooth movement; however, wear may compromise force delivery and treatment efficacy. This study quantitatively assessed morphometric changes in the attachment dimensions and volume over six months and explored patterns according to sex, jaw, and tooth position.

MATERIALS AND

METHODS

This prospective cohort study included 12 adults (aged >18 years) with mild-to-moderate malocclusion, contributing 50 attachments bonded with G-ænial Universal Flo (GC Corporation, Tokyo, Japan) composite material. Intraoral scans were obtained post-attachment bonding (T1) and at six months (T6). Attachments were isolated and analyzed using SOLIDWORKS software (Dassault Systèmes SolidWorks Corp., Waltham, Massachusetts) for changes in width, length, height, and volume. Non-parametric tests and linear mixed models were used to evaluate the wear patterns (significance: p < 0.05).

RESULTS

A significant reduction of attachments occurred over six months in all dimensions. The mean width, length, height, and volume decreased from 2.95 (1.90-3.18) to 2.30 (1.40-2.50) mm, 2.25 (2.10-2.50) to 1.60 (1.50-1.90) mm, 1.20 (1.10-1.03) to 1.00 (0.90-1.10) mm, and 9.50 (7.15-10.85) to 7.35 (5.70-8.50) mm³, respectively. The consistent and large Cohen's d effect size indicated a substantial magnitude of change. Posterior attachments showed greater width and volume loss than anterior attachments. Mandibular attachments had higher volume loss than maxillary attachments. No significant sex differences were observed (p > 0.05).

CONCLUSIONS

Significant reductions in attachment dimensions and volume were observed over six months, confirming progressive wear during clear aligner therapy. Posterior and mandibular attachments demonstrated greater attrition, highlighting the influence of biomechanical loading and anatomical location. Regular monitoring of attachment integrity and the use of more wear-resistant materials may improve force delivery, treatment efficiency, and clinical predictability.