Comparison of the frictional resistance of 3D-printed brackets and conventional brackets

This study attempted to compare frictional resistance among three-dimensional (3D) printed resin brackets, and also with conventional metal and ceramic brackets under in vitro conditions.

3D bracket designs were created digitally and converted to stereolithography (STL) file format. Subsequently, brackets were produced using a FormLabs 3B+ printer using Permanent Crown and Biomed Clear resins. Half of these 3D-printed brackets were aged by thermal cycling, and then the frictional resistances of aged resin, non-aged resin, ceramic and metal brackets were measured using a universal testing machine.

Shrinkage was 5.41% for Permanent Crown brackets and 7.84% for Biomed Clear brackets. Resin-based brackets produced by 3D printing demonstrated the highest frictional resistance. After the aging process, the frictional resistance of the 3D-printed brackets was reduced. Frictional resistance was lowest for the stainless steel wire and stainless steel bracket combination, and highest for the beta-titanium wire and resin bracket combinations (P < 0.05).

As the Permanent Crown resin bracket demonstrated frictional resistance comparable to ceramic brackets after aging, advances in more durable 3D printing materials with improved surface properties are expected to further enhance the clinical applicability of 3D-printed brackets.