Effects of chemical and mechanical cleaning methods on the surface, physicochemical, and microbiological properties of extrinsically characterized 3D‐printed denture base resins after exposure to different pigmenting solutions

PURPOSE: To investigate the effects of chemical and mechanical cleaning methods on the surface, physicochemical, optical, and microbiological properties of heat-polymerized and extrinsically characterized 3D-printed denture base resins after staining with different pigmenting solutions. MATERIALS AND METHODS: Square specimens (8.0 mm × 8.0 mm × 3.0 mm) were fabricated from two types of resins (n = 160): an intrinsically characterized heat-polymerized resin (HT-STG) and an extrinsically characterized 3D-printed resin (3D-P). The specimens (n = 40) were immersed in four staining solutions (coffee, tea, wine, and tobacco) for 7 days and then subjected to cleaning protocols for 14 days using chemical methods (n = 10) (Corega Tabs, Efferdent, and BM4 NOVA Power 22%) or a mechanical method (Polident). Analyses were performed at three time points (baseline, staining, and cleaning) to evaluate surface roughness, Vickers hardness, water sorption and solubility, chemical composition, color, microbiological analysis, and scanning electron microscopy. Data were analyzed using four-way ANOVA, three-way ANOVA, and Tukey's post hoc test (α = 0.05). RESULTS: Surface roughness, hardness, and color change were significantly influenced by interactions among resin type, cleaning protocol, staining solution, and evaluation time (p < 0.05). HT-STG showed greater color change, whereas 3D-P exhibited greater surface changes. Whitening was most effective for color recovery, whereas Efferdent better preserved surface smoothness. Water sorption, solubility, and chemical composition remained stable, although biofilm formation varied among conditions. CONCLUSIONS: Different combinations of tested resin type, cleaning protocol, stain type, and time play a role in maintaining surface roughness, hardness, color stability, and biofilm behavior.