Effect of pH and Temperature on the Surface Roughness of 3D-Printed and Milled Dental Hybrid Resin–Ceramic

Chemical and thermal shifts in the oral cavity can damage the surface of 3D-printed hybrid resin-ceramic materials, and research on these effects is still limited. This study investigated the effects of pH and temperature variations on the surface roughness (Ra) of two milled materials, a resin nanoceramic (Cerasmart^®; CS) and a polymer-infiltrated ceramic network (Vita Enamic^®; EN), and a 3D-printed (VarseoSmile Crown plus^®; VS) material. A total of 135 rectangular specimens (12 × 14 × 2 mm), 45 per material, were aged for 30 days under acidic (pH 5), alkaline (pH 9), cold (5 °C), and hot (60 °C) conditions, with neutral (pH 7, 37 °C) as a control. Ra was measured before and after aging using an optical micro-coordinate system. Two-way ANOVA and Tukey's test assessed the effects of material type and aging condition. Paired <i>t</i>-tests evaluated changes over time. Variations in pH did not significantly increase Ra for any materials. Cold and hot temperatures increased Ra for the milled materials (<i>p</i> < 0.001). VS showed greater stability than the milled materials (CS and EN) despite its higher Ra both before and after aging under all conditions. All Ra values remained below the clinical threshold for biofilm accumulation (0.2 µm) under all conditions.