Effects of high temperature with pressure post-treatment on the Vickers hardness, color stability, and translucency of 3D-printed denture teeth resin under thermocycling conditions

This study aimed to evaluate the effects of post-treatment at elevated temperature and pressure on the hardness, color stability, and translucency of 3D-printed denture teeth resin, both before and after thermocycling. One hundred specimens were randomly assigned to five groups: four post-treated groups (121 °C at 2 bar for 4, 30, 60, and 90 min) and one untreated control group. Fifty specimens were used for hardness test, and fifty for optical tests. Specimens underwent thermocycling. Hardness was measured under a 50 g load for 15 s. Color differences were assessed using a spectrophotometer, and translucency was calculated from CIE L*a*b* values. Statistical analysis included Welch’s ANOVA with Dunnett’s T3 test for hardness, and one-way ANOVA with Tukey’s post hoc test for optical tests. Paired t-tests compared pre- and post-thermocycling values (α = 0.05). Post-treated groups exhibited significantly higher hardness than the control group. After thermocycling, specimens treated for 30 min or longer maintained significantly higher hardness compared to the 4-minute and control groups. Color difference was higher in the 60- and 90-minute groups, and thermocycling further increased color difference in all groups except the 90-minute group. Post-treatment significantly affected translucency, which increased after thermocycling in the 30- and 60-minute groups. Under the limitations of this study, post-treatment improved hardness, especially with durations exceeding 30 min, although longer treatments caused greater color difference after thermocycling. Translucency was not significantly altered by post-treatment alone, whereas it increased in the longer-treated groups after thermocycling.