Artificial Aging and Its Impact on Surface Properties of Conventional and CAD-CAM Occlusal Splint Materials: An In Vitro Comparative Study.

PURPOSE: This study aimed to evaluate and compare the surface roughness, microhardness, and color stability of various materials after dry storage (control) and artificial aging (intervention). MATERIALS AND METHODS: One-hundred-eight 10 × 10 × 5 mm3 specimens were fabricated from three clear acrylic resin types: heat-cured (HC), milled (ML), and 3D-printed (3D). Each specimen underwent a stepwise polishing process on one side. For the pre-test measurement, 36 specimens (12 per group) were evaluated for surface roughness (Ra), 36 for Vickers microhardness (Vickers hardness number [VHN]), and 36 for color stability (∆E). Half of the specimens in each test were stored in dry conditions for 30 days, while the other half was aged in 37°C distilled water for 30 days. Post-test evaluations were conducted using the same procedures. The statistical analyses of Ra, VHN, and ∆E were performed using SPSS 29.0. RESULTS: Significant differences in Ra were observed among all materials (p < 0.05), with ML and 3D exhibiting low Ra. The artificial aging condition did not significantly influence Ra, however, polishing significantly affected Ra. The VHN values also differed significantly among materials (p < 0.05), with ML demonstrating the highest VHN. Polishing did not affect VHN, but all materials had reductions in VHN (p = 0.002) after artificial aging. The ∆E values varied significantly across material types, with ML demonstrating the least color change. CONCLUSION: This study demonstrated significant variations in surface roughness, microhardness, and color stability among occlusal splint materials after the aging conditions. ML exhibited superior performance with low Ra, low ∆E, and high VHN.