Effects of variable attachment shapes and aligner material on aligner retention.

Objective: To evaluate the retention of four types of aligners on a dental arch with various attachments.

Materials And Methods: For this study, three casts were manufactured, two of which contained attachments (ellipsoid and beveled), and one without any attachments to serve as a control. Four types of aligners were thermoformed: Clear-Aligner (CA)-soft, CA-medium, and CA-hard, with various thicknesses, and Essix ACE.