Comparison of the Sliding Resistance of Metallic, Composite and In-House 3D-Printed Brackets: An In Vitro Study

Objective: To evaluate the differences in frictional resistance between in-house 3D-printed resin brackets (IH3DBs) and two types of commercially available brackets in combination with three different archwires. Methods: Friction tests were performed using a dynamometer and a millimetre sled to simulate first premolar post-extraction space closure. Three different brackets, namely PRIMO metallic brackets, Crystal composite brackets and in-house 3D-printed brackets, were tested in combination with three different archwires (0.016-inch NiTi, 0.019 × 0.025-inch NiTi and 0.019 × 0.025-inch SS). Statistical analysis was performed to verify the differences in friction among the bracket and archwire combinations. For all the tests, the significance level was set at p < 0.05. Results: There were significant differences among the three brackets tested with both the 0.016-inch NiTi and 0.019 × 0.025-inch SS archwires (p = 0.026 and p = 0.017, respectively). Only tests with the 0.019 × 0.025-inch NiTi archwire yielded no statistically significant differences between the groups. The composite bracket generated clinically and statistically more friction than both the IH3DB and metallic bracket, with no differences between the latter two. Conclusions: The IH3DBs demonstrated comparable frictional resistance properties to the metal brackets and better than the composite brackets with all the archwires tested.