Effect of build orientation on the wear resistance and hardness of denture teeth fabricated using digital light processing: An in vitro study

Purpose: This in vitro study investigated the effect of build orientation on the wear resistance and hardness of denture teeth fabricated using digital light processing (DLP) compared to other denture tooth materials. Methods: Disc-shaped specimens were prepared using denture tooth monomers and DLP devices in three build orientations: 0 degrees, 45 degrees, and 90 degrees. Specimens of the same shape were fabricated using denture tooth materials for subtractive manufacturing, commercially available polymethylmethacrylate (PMMA) resin, and composite resin. The wear resistance was evaluated as the wear volume loss after 50,000 wear cycles using a ball-on-disc wear device in water for two-body wear and poppy seed slurry for three-body wear. The Vickers hardness values of the materials were measured. Two-way and one-way analyses of variance were performed for wear resistance and hardness, respectively, followed by Tukey's honest significance test. Results: The interaction between the denture tooth resins and maximum wear volume was significant (P < 0.01). The 0 degrees build orientation exhibited the lowest wear volume in the three-body wear test and the highest hardness among the three build orientations. The 0 degrees DLP-fabricated specimens demonstrated significantly less wear volume than that of the PMMA specimens and a wear volume comparable to that of the milled specimens. However, the 0 degrees DLP-fabricated specimens showed significantly lower hardness than that of the milled and PMMA specimens. The composite resin specimens exhibited the highest wear resistance and hardness. Conclusions: A 0 degrees build orientation is recommended for DLP-fabricated denture teeth compared to 45 degrees and 90 degrees orientations to achieve greater wear resistance and hardness.