OBJECTIVE: The objective of this in vitro study was to evaluate the effects of different surface finishing protocols and post-curing environments on the surface roughness (Ra) and Vickers hardness (VHN) of a 3-dimensionally (3D)-printed occlusal splint resin. MATERIALS AND METHODS: Ninety-six disc-shaped specimens (Ø16 × 3 mm) were fabricated from a photopolymerizable splint resin using a stereolithography 3D printer. The specimens were assigned to four surface finishing groups: as-printed (AP), polished (P), resin-coated (RC), and glaze-coated (GC). Each group was further subdivided according to the post-curing environment, air (A) or glycerin (G), resulting in eight experimental groups (n = 12): AP-A, AP-G, P-A, P-G, RC-A, RC-G, GC-A, and GC-G. Post-curing was performed at 60°C for 60 min. For the glycerin subgroups of the coated specimens (RC-G and GC-G), an initial curing period in air was applied before completing the post-curing in glycerin to stabilize the applied coating layer. Ra was measured using a surface profilometer, and VHN was determined using a microhardness tester. The data were analyzed using two-way ANOVA and post hoc Tukey HSD test (α = 0.05). RESULTS: Surface finishing significantly affected Ra and VHN (p 0.05). AP-A and AP-G specimens showed the highest Ra, while GC-A and GC-G specimens exhibited the highest VHN (p < 0.001). CONCLUSIONS: Surface finishing is essential for optimizing surface properties of 3D-printed occlusal splints. Although coating procedures, particularly glaze, were associated with higher surface hardness, polishing yielded smoother surfaces and provided consistent and clinically acceptable properties. CLINICAL SIGNIFICANCE: Surface finishing plays an important role in the clinical performance of 3D-printed occlusal splints. Although coating procedures yield high surface hardness, polishing provides smoother, more consistent surfaces, making it a practical and reliable option for routine clinical use.
Kader et al. (Tue,) studied this question.