Effect of brushing and staining cycling on roughness, gloss, and color of resin-based composites

OBJECTIVES: To evaluate the effect of brushing and staining media cycling on surface properties (roughness and gloss) and color parameters of a nano-hybrid resin-based composite (RBC).

MATERIALS AND METHODS: Forty-eight cylindrical-shaped specimens (10×2 mm) were prepared with a nano-hybrid RBC (Clearfil Majesty ES-2 Classic, A3) and randomly divided in 4 groups according to the experimental staining procedure:
– G1, static immersion in a staining (coffee) solution (44 °C±1 °C);
– G2, cycling (32 cycles – 45 min) between coffee (44 °C±1 °C) and distilled water (37 °C±1 °C) with an experimental staining machine;
– G3, staining cycles as in G2 + brushing with a low abrasive toothpaste (RDA = 30) (Elmex Sensitive Professional) after every coffee cycle;
– G4, same experimental design as in G3 but a very strong abrasive toothpaste (RDA = 90) (Lacult Active) was used.

Roughness (Ra), gloss (GU) and color parameters (L*, a*, b*) and color difference (ΔE) were evaluated at baseline (T0), after staining procedures (T1) and repolishing (T2) using a profilometer, a glossmeter and a spectrophotometer.

RESULTS: For Ra at T1 and T2 G4 was significantly higher than other all groups (p <0.001); G1 and G2 as well as G2 and G3 were significantly different (p <0.001) at T2. For GU, at T1 G1 was significantly higher than other groups (p <0.001); G4 was significantly lower than other groups at T1 and T2 (p <0.001). L*, a*, and b* parameters showed significant differences (p <0.001) at T1 and T2.
G1 and G3 showed respectively highest and lowest ΔE. Repolishing procedure partially recovered surface and color properties.

CONCLUSIONS: The investigated procedure induced significant differences in roughness, gloss and color parameters. The use of a very strong abrasive toothpaste (RDA = 90) induced higher roughness and color change and lower gloss than a low abrasive one (RDA = 30).

CLINICAL SIGNIFICANCE: Clinicians should be aware that staining liquids and toothpastes may influence surface and color stability of resin-based composites.

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