Effects of post-curing atmosphere and thermal aging on the physico-mechanical properties of a 3D-printed splint...

This study investigated the effects of different post-curing atmospheres and thermal aging on the surface characteristics and mechanical properties of a 3D-printed splint material fabricated using liquid crystal display technology.

The 3D-printed specimens were divided into three groups based on the post-curing atmosphere (air, nitrogen, and vacuum) and subjected to either water storage at 37 °C for 50 h or 10,000 thermal cycles (5-55 °C). The degree of conversion, surface morphology and roughness, and water sorption/solubility of the specimens were evaluated. The surface hardness was measured using the Vickers hardness test, and the flexural strength was assessed using a three-point bending test. Data were analyzed using two-way ANOVA followed by Tukey's post-hoc test (P < 0.05) after confirming the normality and homogeneity of variances using Shapiro-Wilk and Levene's tests, respectively.

The nitrogen and vacuum groups exhibited comparable values for degree of conversion, surface roughness, and water sorption/solubility, which were all significantly higher than those of the air group. A significant difference in the surface hardness was observed among the three post-curing atmospheres (P < 0.001); however, the flexural strength was unaffected. After thermal aging, the surface hardnesses and flexural strengths of all the groups significantly decreased.

The post-curing atmosphere significantly influenced the degree of conversion, surface roughness, and water sorption/solubility of the additively manufactured specimens, whereas thermal aging degraded their mechanical properties.