Effects of different aligner materials and attachments on orthodontic behavior

Background/purpose: The orthodontic aligner becomes popular worldwide in orthodontic therapy as an esthetic alternative to fixed labial braces. This study evaluated orthodontic tooth movement behavior using different aligner materials and attachment shapes for the movement of a single tooth. Materials and methods: First bicuspid extracted resin typodont models were printed with a 3D printer. Three type of attachments, an ellipsoid shape (thick and thin) and a bar, were designed to fit the canine crown surface. Three types of aligner materials, Polyethylene Terephthalate enhanced with glycol (BIOSTAR) Polyethylene Terephthalate (BenQ), and Thermoplastic polyurethanes (TPU) were used to fabricate different aligners. The typodonts with aligners were sunk in a water bath to simulate canine distal movement in vivo. The canine crown, root movement, and long axis angle changes in each step were calculated and recorded. The data were analysed using a oneway ANOVA statistical method. Results: Comparing the three aligners, the changes the long axis of the canine showed that the BENQ group had a smaller change in the long axis angle. The BENQ group canine involved bodily movement, but the canine movement of the BIOSTAR and TPU group involved tipping. Comparing the three attachments, the bar type attachment had more canine crown tipping in the BIOSTAR and TPU groups. The thick and thin ellipsoid-shaped attachments showed no statistical differences in tooth movement. Conclusion: Attachment shape or size had little influence on the bodily movement of the tooth. A high modulus material may thus be suitable for clinical applications.