The Effect of Different Surface Treatments on the Roughness, Translucency, and Staining of 3D-Printed Occlusal Device Materials.

Objectives: To compare surface treatments (as-printed, optical polish, resin-coated, polished) of two 3D-printed occlusal device materials (KeySplint Soft and NightGuard Flex 2) cured with or without glycerin for surface roughness, translucency, and coffee staining.

Materials and methods: Discs (2 mm thick) from two 3D-printed occlusal resins (KeySplint Soft and NightGuard Flex 2) were printed using a DLP 3D printer (SprintRay Pro 95), cleaned (ProWash S), and cured (ProCure 2) with or without glycerin. Some specimens were printed in an optical polish tank. Specimens were either as-printed, resin-coated, or polished. Reference milled (ProArt CAD Splint) and heat-cured (Excel Formula Heat Cure Denture Base Material) specimens were also prepared. Surface roughness was analyzed using a contact profilometer. Translucency was measured using a spectrophotometer. Staining was evaluated after 24 days in coffee at 37°C. Data were analyzed with ANOVA and Tukey post hoc tests.

Results: Surface treatments and glycerin curing showed significant differences (p < 0.01). Polishing and resin-coating produced the smoothest surfaces. Optical polish tanks improved smoothness. Polishing increased translucency. Glycerin curing reduced staining except in polished specimens. Milled materials stained less than 3D-printed materials.

Conclusions: Polishing and resin-coating optimized roughness and translucency. Polishing or curing glycerin optimized stain resistance.

Clinical significance: 3D-printed occlusal devices should have their external surfaces polished or resin-coated and receive a final cure in glycerin to prevent staining of their internal as-printed surface. Printing in a tank with an optical polish can help to improve the roughness and translucency of the internal surface of an occlusal device.