Measuring color change of tooth enamel by in vitro remineralization of white spot lesion.

Introduction : Objective colour determination is based on calculating the colorimetric distance (ΔE) within a colour space. So far, the most used colour space in dentistry is CIE L*a*b (Comission Internationale de l´Eclairage). CIE L*C*h* has been recently developed, showing a better correlation with the perception of the human eye. Objective : To determine the ability of an in vitro remineralisation substance to mimic the colour of white spot lesions (WSL) with sound enamel, determining ΔE by using the CIE L*C*h* colour space. Methods: In vitro WSL was generated by immersing 10 samples obtained from human third molars in a demineralization solution for 72 h. Amorphous calcium phosphate stabilized by casein phosphopeptide (CPP-ACP) was then applied for 60 days while maintaining the samples in artificial saliva at 37o C. To evaluate the colour of enamel, images were taken from the samples placed in specifically designed silicone moulds after generating the WSL (pre stage) and after remineralisation by scanning, applying the colorimetric distance equation (ΔE*CMC) according to the Color Measurement Committee. Results: Treatment with CPP-ACP caused a significant ΔE decrease with respect to the pre stage (p <0.001), while the analysis of parameters that make up the colour showed a reduction in the difference of hue (∆H) (p< 0,001) and brightness (∆L) (p< 0,01) after applying CPP-ACP. Discussion: CPP-ACP penetrated to the depth of the white spot lesion, making its appearance similar to that of the sound enamel, probably because of the formation of different mineral phases than that of the original structure, although pores were not completely filled.