Effects of post-polymerization conditions on color properties, surface roughness, and flexural strength of 3D-printed permanent resin material after thermal aging

Purpose: To evaluate the color, surface properties, and flexural strength of 3D-printed permanent crown resin subjected to different post-polymerization conditions after artificial aging.

Materials and methods: Ninety (10 × 2 mm) disc-shaped specimens were printed by using permanent crown resin with SLA technology. Specimens were divided into nine different groups, subject to post-polymerization conditions at three different times (15, 20, and 30 min) and three different temperatures (40, 60, and 80°C) (n = 10). Color and surface roughness measurements were repeated pre-post thermal aging (5.000 cycles, 5-55°C) and a flexural strength test was carried out. Data were analyzed with Shapiro-Wilk, Kruskal-Wallis, ANOVA, Tukey HSD, and Dunn tests (α < 0.05).

Results: ΔE₀₀ values showed results below the acceptable color threshold, except for the 30 min 40°C group (ΔE₀₀ <1.8). No difference was found between the relative translucency parameter and surface roughness values of the 20 min 60°C group recommended by the manufacturer and the other groups. A significant difference was found between the flexural strength values of the groups (p < 0.001).

Conclusions: The color properties, surface topography, and mechanical properties of the printed permanent crown material were affected by different post-polymerization conditions: polymerized at different times and temperatures. Although the flexural strength and color change values showed promising results, more studies are required to evaluate its suitability for clinical use.