Assessing the impact of surface treatment, aging, and post-curing conditions on the water sorption and solubility of 3D-printed denture base resins compared to conventional and milled alternatives

Abstract Background High water sorption and solubility in total denture base materials are primary factors contributing to prosthetic failure, as they compromise both mechanical and aesthetic properties. This study investigated how three distinct surface treatments, varying aging protocols, and different curing parameters collectively influence the water sorption (Wsp) and solubility (Wsl) of 3D-printed denture base materials. Materials and methods This study evaluated the water sorption and solubility of 420 disc-shaped specimens (Ø15 × 2 ± 0,2 mm) fabricated from one conventional heat-cured acrylic resin (Probase; HC), one CAD-CAM Prepolymerized PMMA block (Bilkim; M), and one 3D-printed denture base material (Formlabs; 3DP ). All groups underwent three distinct surface treatments (mechanical polishing, Optiglaze, or Vita Akzent Glaze). The 3D-printed specimens were additionally subjected to four curing durations (10, 15, 30, 60 min) and two curing atmospheres (air and glycerin). Water sorption (Wsp) and solubility (Wsl) were assessed after three distinct aging protocols: 7 days of immersion in distilled water (Wsp-DW and Wsl-DW), 6 days of immersion in a denture cleaner (Wsp-DC and Wsl-DC), and 2000 thermocycles (Wsp-TC and Wsl-TC). Statistical analysis was conducted using non-parametric tests, as the Kolmogorov-Smirnov test revealed that the data were not normally distributed (p < 0.05). The Mann-Whitney U test was applied for comparisons between two categorical variables, while the Kruskal-Wallis test was used for three or more categories. For related groups, the Friedman test was employed. Pairwise comparisons were performed to identify specific differences among groups. All statistical analyses were conducted with significance levels set at α = 0.05 and 0.01. Results This study demonstrates that both manufacturing technology and surface treatment significantly influence the water sorption and solubility of dental acrylics. Conventional heat-polymerized acrylics exhibited the highest water sorption, whereas 3D-printed materials consistently showed the lowest (p < 0.01). Regarding solubility, heat-cured materials generally displayed the lowest values. Conversely, 3D-printed materials had the highest Wsl-DW and Wsl-TC, but the lowest Wsl-DC (p < 0.01). Glaze application effectively reduced both water sorption and solubility across all groups compared to mechanical polishing. Lastly, while glycerin curing of 3D-printed resins led to higher sorption but lower solubility, curing duration generally had no significant impact, with some 10-minute cured groups occasionally showing higher solubility (p < 0.01). Conclusion All 3D-printed groups, irrespective of surface treatment or curing parameters, demonstrated water sorption (Wsp) and solubility (Wsl) values within the limits defined by ISO 4049 − 2019 (Wsp < 40 µg/mm³; Wsl < 7.5 µg/mm³). While glaze application effectively reduces these properties, adequate curing time and the use of a glycerin curing medium can similarly diminish solubility. However, curing duration was not found to have a statistically significant impact on water sorption.