Comparative evaluation of the accuracy of customized lingual orthodontic brackets fabricated by metal 3-dimensional printing and casting: An in vitro study.

Introduction: Customized lingual orthodontic brackets require high accuracy for optimal clinical performance. Metal 3-dimensional (3D) printing and casting techniques using 3D-printed wax patterns have emerged as fabrication methods. However, comparative evaluations of their dimensional accuracy and frictional behavior remain limited. This study aimed to evaluate and compare the accuracy and frictional characteristics of customized lingual brackets fabricated using selective laser melting and conventional casting.

Methods: Thirty-six customized lingual brackets (n = 18 per group) were fabricated. The trueness and actual gaps of the bracket base were assessed using triple-scan superimposition. Positional accuracy was evaluated by linear and angular deviations, and dimensional accuracy was assessed through slot height error and convergence angle. Frictional force was measured by pulling an archwire through the bracket slot. After polishing and thermocycling, dimensional and frictional evaluations were repeated. Data were analyzed using independent samples t tests (P <0.05).

Results: Three-dimensional-printed brackets showed significantly higher trueness errors (34.5 μm) and slot height errors (29.69 μm) than cast brackets (25.2 and 21.28 μm). Frictional force was also significantly higher in the as-fabricated 3D-printed group (3.61 and 2.46 N; P <0.001). Postpolishing significantly reduced friction but did not eliminate the differences, whereas dimensional differences were no longer statistically significant between groups. Positional accuracy and convergence angle showed no significant differences between groups.

Conclusions: Three-dimensional printing and casting techniques both achieved clinically acceptable positional accuracy. However, dimensional discrepancies and higher friction in 3D-printed brackets highlight the need for optimized postprocessing to enhance clinical performance.