In-House 3D-Printed vs. Conventional Bracket: An In Vitro Comparative Analysis of Real and Nominal Bracket Slot Heights

Abstract

Aims: The purpose of this study was to evaluate the accuracy of the slot height of in-house 3D-printed resin brackets, comparing them with other types of brackets on the market today, both ceramic and metallic. Methods: Seven different types of bracket systems were selected. For each system, ten brackets for tooth 2.1 with 0.022 × 0.028-inch slots were selected (total n° 70). Considering the whole sample, five types were commercially available and two were in-house 3D-printed. The entire sample was divided into four different groups according to the bracket material and the method of holding the archwire. Precision pin gauges with 0.002-mm increments were inserted inside the slot of each bracket, and the slot heights were measured, microscopically ensuring that the gauge completely filled the slot, with full contact between both the bottom and the top of the slot. Results: With respect to the other five types of brackets on the market, the two types of in-house 3D-printed resin brackets showed great accuracy of slot height (0.558 ± 0.001 mm). There was a statistically significant difference between the real height measured and the nominal height declared by the manufacturers (p < 0.05) of all the samples investigated, with the exception of in-house 3D-printed resin brackets. Furthermore, the difference in slot height accuracy between commercially manufactured and in-house 3D-printed resin brackets was statistically significant. Conclusions: In-house 3D-printed resin brackets have a remarkably precise slot height, unlike commercially available brackets, whose slot heights tend to be significantly oversized with respect to the nominal values declared by the manufacturers.