Effect of whitening toothpastes on cigarette smoke staining of Resin-Based and 3D-Printed restorative materials

This in vitro study aimed to evaluate and compare preclinical effectiveness of two whitening toothpastes hydrogen peroxide based and activated charcoal based on cigarette smoke-induced discoloration in three restorative materials: a micro-hybrid composite, a nano ceramic composite, and a 3D printed ceramic based resin material.

Seventy-two disc-shaped samples (n = 8 per subgroup) were fabricated from micro-hybrid composite, nano ceramic composite and a 3D-printed ceramic resin-based material. After baseline color measurements, all specimens were stained using a standardized cigarette smoke exposure protocol (four cycles, 10 min each). Subsequently, the specimens were brushed with either a hydrogen peroxide containing toothpaste, an activated charcoal containing toothpaste, or distilled water (control), using an electric brushing simulator at 2 N force. Color measurements (ΔE₀₀) were obtained spectrophotometrically at three timepoints: baseline (T₀), post-smoking (T₁), and post-brushing (T₂). Color differences (ΔE₀₀) were analyzed using three-way repeated measures ANOVA for intra-group comparisons over time and one-way ANOVA with Tukey's post hoc test for inter-group comparisons at each time point (p < 0.05).

All materials exhibited clinically unacceptable discoloration after cigarette exposure (ΔE₀₀ >1.8), with the 3D printed resin-based material group showing the highest color change (ΔE₀₀ ≈ 15.3). Post brushing, both hydrogen peroxide and activated charcoal toothpastes significantly reduced discoloration in micro-hybrid composite resin and nano ceramic composite resin groups (p < 0.001), with hydrogen peroxide showing greater efficacy. No statistically significant improvement was observed in the 3D printed ceramic resin-based material group regardless of the toothpaste used (p > 0.05). Overall, ΔE₀₀ values remained above clinical acceptability after brushing in all groups.

3D-printed ceramic-based resin exhibited the highest discoloration after cigarette smoke exposure, while the nano-ceramic composite showed the lowest. Both whitening toothpastes significantly improved color recovery following cigarette smoke-induced discoloration. However, they remained ineffective in fully reversing discoloration, particularly in 3D-printed ceramic resin-based materials.