Analyzing Color, Surface Roughness, and Microhardness on the Unpolished and Polished Surfaces of Occlusal Splint...

To evaluate the color, surface roughness, and microhardness of occlusal splints fabricated using conventional and CAD-CAM techniques and to compare the properties of the unpolished and polished surfaces.

A total of 114 specimens (10 × 10 × 5 mm³) were prepared, including one group each of self-cured (SC) and heat-cured (HC) occlusal splints, along with two groups each of milled (ML-A and ML-B) and 3D-printed (3D-A and 3D-B) splints. One side of each specimen was polished using a sequence of 600-, 800-, and 1000-grit sandpaper, followed by pumice and tallow. The specimens were then tested for color parameters (L ^∗, a ^∗, b ^∗), color change (∆E), surface roughness (Ra), and Vickers hardness number (VHN). Statistical analysis was performed using SPSS Version 29.0.

Significant variations were observed in color, surface roughness, and microhardness across the six materials (p < 0.001). For the unpolished surface, the highest and lowest color values were observed in ML-B (75.10) and SC (60.55) for L ^∗, SC (0.14) and 3D-B (-2.19) for a ^∗, and HC (2.47) and SC (-8.92) for b ^∗. There was a significant difference in ∆E (p = 0.011), with ML-A showing the lowest ∆E. The two with the lowest Ra values were ML-A (0.085 µm) and ML-B (0.117 µm). The highest microhardness values were found in ML-B (19.74 VHN) and HC (18.85 VHN). Polishing significantly affected the properties (p < 0.05), with significant differences in L ^∗ > a ^∗ > b ^∗, reduced Ra across all groups, and decreased the VHN in HC and 3D-B groups.

Occlusal splint materials fabricated using different techniques had significant differences in color, surface roughness, and microhardness. The ML-B occlusal splint showed the best overall performance, with high L ^∗, near-zero b ^∗, moderate a ^∗, low surface roughness, and the highest microhardness. Polishing generally followed the color trend L ^∗ > a ^∗ > b ^∗, reduced surface roughness in all groups, and decreased microhardness in HC and 3D-B splints. Hence, some CAD-CAM materials can perform similarly to conventional splints, highlighting the importance of considering both material and fabrication methods to optimize clinical outcomes.