The effect of thickness, cement type, and substrate color on the optical properties of three-dimensional-printed composite resin

AIM: With the rapid advancements in three-dimensional (3D) printing technology, understanding the effects of material thickness, cement type, and substructure shade on the optical properties of composite resin materials is crucial for achieving optimal esthetic outcomes. This study aims to evaluate the effects of material thickness, cement type, and substructure shade on the optical properties of 3D-printed composite resin materials. SETTINGS AND DESIGN: This is an in vitro study. MATERIALS AND METHODS: A total of 120 composite resin specimens were fabricated using additive manufacturing (90° and 50 μm). The specimens were divided into eight groups based on two thicknesses (0.8 mm and 1.5 mm), two substructure shades (B1 and C3), and two cement types (translucent and opaque). The color measurements were performed using a spectrophotometer based on the Commission Internationale de l'Éclairage (CIE) Lab* system, both before and after cementation. The color difference (ΔE₀₀) and translucency parameter (TP₀₀) were calculated using the CIEDE2000 formula. STATISTICAL ANALYSIS USED: The data were analyzed using the Shapiro-Wilk test, independent and paired t-tests, the Mann-Whitney U-test, and a one-way ANOVA with appropriate post hoc tests. RESULTS: Significant differences were observed in both the TP₀₀ and ΔE₀₀ values among the eight material combinations. At 0.8 mm thickness, the specimens with translucent cement showed higher TP₀₀ and ΔE₀₀ values, particularly over the C3 substructure. The thicker specimens (1.5 mm) generally exhibited lower color differences and translucency. The influence of the cement type and substructure shade was more pronounced in the thinner specimens and over darker backgrounds. CONCLUSION: The material thickness, substructure shade, and cement type significantly influenced the optical performance of the 3D-printed composite resin materials. These parameters should be carefully considered to achieve optimal esthetic outcomes.