Surface Roughness and Microhardness of Heat-Cured, Milled, and 3D-Printed Occlusal Splints: A Comparative Study of Unpolished and Polished Surfaces

This study aimed to evaluate the variations in surface roughness and microhardness among different occlusal splint materials and compare these properties between their unpolished and polished surfaces. Seventy-two specimens (10×10×5 mm3) were made using three methods: heat-cured (HC) (Meliodent-Heat Cure, Kulzer), milled (ML) (Smile-Cam, Pressing Dental SRL), and 3D-printed (3D) (MED610, Stratasys). One side of each specimen was polished using 600-, 800-, and 1000-grit sandpaper, followed by pumice and tallow. The surface roughness (Ra) was determined on 36 specimens (12 per group), and the Vickers microhardness (HV) was determined on the remaining specimens. Statistical analysis was done using SPSS 29.0. The Ra values for the unpolished surfaces demonstrated significant differences (P < 0.001), with 3D < ML < HC. Similarly, the polished surfaces also displayed significant differences (P < 0.001), with ML < HC < 3D. The polishing reduced Ra for HC and ML, but increased Ra for 3D (P < 0.05). Regarding the HV values, the unpolished surfaces had significantly different values (P < 0.001), with ML > HC > 3D, and the same trend was observed for the polished