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

Abstract

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.