The color change in artificial white spot lesions measured using a spectroradiometer

Objectives: The purpose of this study was to determine the color of white spot lesions. Materials and methods: Human premolars were subjected to a pH cycling to produce artificial caries lesions and classified into groups (n = 10/group): group 1, immersion in deionized water; group 2, pH cycling without fluoride (F) application; group 3, pH cycling with immersion in 1,000 ppm NaF solution; and group 4, pH cycling with immersion in 5,000 ppm NaF solution. CIE L*a*b* color parameters of the tooth were determined using a spectroradiometer at baseline, after demineralization and after pH cycling. The extent of demineralization was evaluated by scanning electron microscopy (SEM) and electron microprobe analysis (EPMA). Results: Significant degrees of color change (ΔE*) were observed after demineralization (p<0.05). The changes were mainly due to an increase in lightness (L*) and a decrease in yellowness (b*). F application induced a significantly large ΔE* in group 4 (p<0.05). The color reversal after remineralization was mostly due to the recovery of L*. SEM and EPMA verified that net mineral gains occurred in the subsurface lesions. Conclusions: The initially white appearance of enamel caries was a result of changes of L* and b*. F treatment partially restored the color of white spot lesions. Clinical relevance: F-driven remineralization induced both mineral gains and esthetic enhancement of artificially produced enamel white spot lesions. The increase of L* and the decrease of b* contributed to the color changes.