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Updated: Jun 19, 2026
A Finite Element Approach for Locating the Center of Resistance of Maxillary Teeth
Published on: April 8, 2020
Effectiveness of Clear Aligner Thickness and Attachment Design in the Intrusion of Posterior Teeth: Finite Element
Begüm Tosun1, Merve Nur Eglenen1
1Department of Orthodontics, Faculty of Dentistry, Yeditepe University, Istanbul, Turkiye.
Objectives:
This study aimed to investigate the biomechanical effects of different clear aligner thicknesses and attachment design on the intrusion of maxillary premolars and molars, utilising finite element analysis (FEA) without the incorporation of auxiliary mechanics.
Materials And Methods:
Three-dimensional models of the maxilla, dentition, periodontal ligaments and clear aligners were reconstructed from cone-beam computed tomography (CBCT) data. A total of nine experimental groups were defined based on aligner thicknesses (0.75, 0.95 and 1.15 mm) and attachment types (No attachment (NA); horizontal attachment (HA); occlusally bevelled horizontal attachment (OHA)). A simulated intrusion of 0.2 mm was applied to the premolars and molars and the resulting tooth displacements and stress distributions within the aligner and periodontal ligament were analysed via FEA.
Results:
Analysis confirmed effective posterior intrusion with maximum values of 0.115 mm in second molars (Model 9). OHA achieved greater intrusion than HA. Von Mises stress values demonstrated a systematic hierarchy (NA < HA < OHA) across all thickness groups, ranging from 0.594 MPa (Model 1) to 0.949 MPa (Model 9), with aligner deformation showing inverse correlation (0.647-0.487 mm).
Conclusion:
Aligner thickness and attachment design significantly influenced posterior intrusion biomechanics. The combination of 1.15 mm aligner thickness with OHA represents the optimal configuration for posterior intrusion. Attachment geometry plays a critical role in force distribution, with bevelled designs providing enhanced effectiveness. These findings establish evidence-based guidelines for future clinical clear aligner applications in posterior intrusion cases.
