Objectives: To establish the effects of a silica-based whitening toothpaste containing blue covarine (Signal White Now) on the contrast between the colour of extracted human teeth (incisors and pre-molars) and restorations. Methods: Cavities were prepared on labial/buccal surfaces, filled with one of four restoration materials, and placed in pooled, whole saliva overnight. Each set of restored teeth was sub-divided into three groups (n=4), which were submerged in an exaggerated treatment for 96hours. The three treatments comprised MilliQ water, red wine and a 1:2 slurry of test toothpaste/water. After soaking, teeth were rinsed in water. Images were recorded at baseline and after soaking, using a calibrated digital imaging system. Results: Images were analysed in Adobe Photoshop to obtain values of red, green and blue (RGB). Separate RGB values were obtained for the unfilled tooth and the restoration. RGB values were converted into CIELAB values, where:
ΔE=√(ΔL*2+Δa*2+Δb*2)
To establish any changes in contrast between tooth and restoration after each treatment, differences between DE values before and after treatment were calculated for tooth and restoration, and absolute differences between these compared. In some cases, treatments affected enamel more than the restoration, and vice versa.
Material | Change in ΔE with red wine(s.d.) | Change in ΔE with toothpaste(s.d.) | Change in ΔE with water(s.d.) |
Fuji II LC | 4.69(2.37) | 0.13(2.79) | 0.14(0.93) |
Ketac Fil | 2.07(3.54) | 0.68(0.99) | 0.86(1.82) |
Filtek Supreme | 7.94(1.53) | 0.83(0.56) | 0.83(1.00) |
TPH Spectrum | 1.19(4.99) | 0.13(1.25) | 0.14(0.44) |
Whereas soaking in red wine produced a significant increase in contrast between tooth and restoration (p{redwinewater}=0.0139), the table shows that the toothpaste does not affect the contrast (p{toothpastewater}=0.5569). Conclusion: Exaggerated treatment with Signal White Now toothpaste does not significantly affect the colour contrast between restorations and teeth.