Biomechanical analysis of the effect of Class II traction configurations and aligner overtreatment on molar distalization: a finite-element study.

This study investigates the biomechanical effects of aligner overtreatment on upper second molar distalization using clear aligners through finite-element analysis. It compares different attachment designs (no attachment, horizontal, vertical) on the second molar, evaluates Class II elastic traction methods (precision cut vs. button) applied on canines, and examines varying degrees of aligner overtreatment involving additional distal root tipping. Results indicate that vertical attachments enhance molar distalization more effectively than horizontal or no attachments, while Class II elastic traction—particularly via the precision-cut configuration—improves molar movement and reduces unwanted displacement of anchorage teeth. Furthermore, appropriate aligner overtreatment promotes bodily distalization of the second molar and mitigates adverse biomechanical effects on anterior teeth. The study acknowledges limitations inherent to finite-element modeling and the absence of patient-specific biological variability.