The effect of bleaching and remineralizing agent on color and chemical / mechanical properties of artificial initial carious lesions

Abstract

Objectives The purpose of this study was to evaluate the effect of bleaching and remineralization with casein phosphopeptide–amorphous calcium phosphate (CPP-ACP) on color and chemical / mechanical properties of teeth with white spot lesions.

Materials & Methods Carious lesions with standardized whiteness were produced on the buccal and lingual surfaces of human premolars by pH cycling. Specimens were subjected to four experimental conditions (n = 20/group) as follows: Group 1, control

Group 2, caries formation followed by remineralization using fluoride-containing CPP-ACP (Tooth Mousse Plus, GC)

Group 3, caries formation followed by bleaching using 10% carbamide peroxide

Group 4, caries formation followed by both bleaching and remineralization. The CIEL*a*b* values were measured with a spectroradiometer, the mineral content was measured with electron probe microanalysis (EPMA) on the cross-sectional surface of each specimen, and the Knoop microhardness test was carried out along the EPMA scan line. Two-way analysis of variance was performed with Tukey post hoc comparison.

Results The CIEL*a*b* values of the specimens at baseline (BA) and after caries formation (CA) were not significantly different among all groups. The change in the CIEL*a*b* values was not significantly different between the caries-formed (∆E*=7.03) and the bleached enamel (∆E*=7.60). Bleaching of the carious enamel extended the whiteness (∆E*=3.38)(p < 0.05) without additional mineral loss. The remineralization treatment significantly increased the calcium (Ca), phosphate (P), and fluoride content of the subsurface lesion area (p < 0.05). Each microhardness value of the surface, subsurface, and total lesion area did not show a significant difference across groups. The cross-sectional microhardness values correlated well with the Ca and P content (r > 0.80).

Conclusions Bleaching reduced the color disparities between sound and carious enamel without deteriorating the chemical and mechanical properties. The application of CPP-ACP paste enhanced mineral deposition in the subsurface lesion area of carious enamel.