Using digital image correlation to measure displacement and strain during involving distal movement of anterior teeth...

To investigate methods to suppress the bowing effects of lingual inclination and anterior tooth extrusion, digital image correlation (DIC) was used to evaluate aligner displacement in three-dimensions through comparing the distal movement of six and four anterior teeth. Computed tomography scans were used to measure aligner thickness and shape. Based on displacement direction and magnitude, a desirable deformation mode with minimal lingual inclination and extrusion was observed during distal movement of four anterior teeth. The aligner had a rigid "constriction zone" between the lateral incisor and the canine, facilitating control localized to the anterior teeth and minimizing the reaction of the molars. The mechanical behavior of aligners was greatly affected by the method of anterior teeth movement and the shape of aligners. DIC-based displacement measurements are useful in investigating correction directionality.