This in vitro study aimed to compare the mechanical properties of fully customized lingual brackets (FCLBs) designed and manufactured in-house using open-source software with two commercially prefabricated lingual brackets.

The FCLBs were designed with Liberteeth 3D, a plug-in within the open-source software Blender 3D. The .stl files of the brackets were printed using a direct laser metal sintering machine. The comparison groups included prefabricated In-Ovation® L (IOL) and New STb™ brackets (STb). The sample included 24 lingual brackets, eight per group. The groups were compared in vitro regarding static and kinetic friction using a universal testing machine, and slot size and surface roughness were evaluated through scanning electron microscopy and non-contact laser profilometry. Intergroup comparisons were performed using Kruskal-Wallis and One-way Analysis of Variance tests.

No differences in static and kinetic friction were found. All tested brackets showed slight deviations in slot sizes compared to the manufacturer's prescription. IOL brackets demonstrated a significantly smaller slot size in both height (MD: −32.17; CI: −56.66, −19.71; P=0.001) and width (MD: −137.31; CI: −188.46, −105.17; P<0.001) compared with STb brackets. The FCLBs presented significantly greater surface slot roughness compared with the In-Ovation® (MD: −0.41; CI: −0.49, −0.34; P<0.001) and New STb™ (MD: −0.39; CI: −0.47, −0.32; P<0.001) brackets.

The design and manufacture of FCLBs using open-source software is feasible. However, the sintering and surface polishing processes require improvement to achieve optimal clinical outcomes in a future clinical perspective.