Roughness and Translucency of 3D-Printed Splints Following Different Surface Treatments

Objectives: To compare surface treatments (as-is, polished, glazed) of two 3D-printed occlusal splint resin materials (KeySplint Soft and Nightguard Flex) to reference milled and heat-cured materials for surface roughness and translucency.
Methods: Disc-shaped specimens (2mm thick) from two 3D-printed splint resins, KeySplint Soft (KSS, Keystone Industries) and Nightguard Flex (NGF, SprintRay) were printed using a DLP 3D Printer (Pro 95, SprintRay), and post-processed (ProWash S and ProCure 2, SprintRay). Milled specimens (MILL, ProArt CAD, Ivoclar) were fabricated using a 5-axis milling unit (inLab MC X5, Dentsply Sirona), and heat-cured specimens (HC, Excel Fromula Heat Cure Denture Base Material, St. George Technology) were produced using a wax pattern and heat-curing technique. For 3D-printed materials, specimens received either no further treatment (as-is), a thin coat of the corresponding resin followed by additional curing (glazed), or polishing with 600grit SiC paper (polished). Milled and heat cured materials were only tested polished. Surface roughness (Sa) was analyzed using a non-contact profilometer (VHX, Keyence). Translucency parameter (ΔE2000) was measured using a spectrophotometer over black and white backgrounds. Data were analyzed with 1-way ANOVA and Tukey post-hoc tests (alpha=.05).
Results: Data for roughness and translucency are presented in the Table. 1-way ANOVA determined that there were significant differences between groups for roughness and translucency (p<0.001). Tukey post-hoc analyses found significant differences between groups as indicated by different letters in the same column in the Table.
Conclusions: Both polishing and glazing 3D-printed materials reduced their roughness, however, polished milled splint materials showed the lowest roughness. Glazing tended to improve the translucency of 3D-printed materials whereas polishing reduced translucency. Glazed or as-is 3D-printed materials were generally as or more translucent that polished milled and heat-cured materials.