Printing Parameters and Surface Treatments on Color and Translucency Stability

Additive manufacturing (AM) has expanded in dentistry, yet the color and translucency stability of 3-dimensional-printed resin-based materials remain insufficiently understood. This study investigated the main and interaction effects of printing orientation, specimen thickness, and surface treatments on the color and translucency stability of a 3-dimensional printed resin-ceramic hybrid material. Ninety AM specimens were fabricated using a factorial design combining 3 printing orientations, 3 specimen thicknesses, and 2 surface treatments (3 × 3 × 2, n = 5 per condition) and compared with 30 subtractively manufactured control specimens (Vita Enamic). Aging was simulated by thermocycling (5000 cycles, 5-55 °C). Color coordinates were measured via the Commission Internationale de l'Éclairage L*a*b* color system, and color change and translucency change were calculated. Degree of conversion, water sorption, and surface roughness were also evaluated. Printing orientation and specimen thickness significantly affected color change and translucency change (P < 0.05), with the 90° orientation showing lower changes than 0° and 45°. Surface treatment had a limited influence on color and translucency stability, although glazing resulted in higher water sorption as compared with polishing (P < 0.05). No significant effects of printing orientation were observed for degree of conversion or surface roughness, whereas surface treatment significantly influenced surface roughness (P < 0.05). Despite these variations, all groups remained within clinically acceptable thresholds for color and translucency changes. Overall, the findings suggest that AM resin-ceramic restorations have potential for use in definitive restorations. Optimizing printing orientation and material thickness may enhance the color and translucency stability of AM resin-ceramic restorations, supporting their clinical applicability.