Effect of bleaching on sound enamel and with early artificial caries lesions using confocal laser microscopy

Abstract

The aim of this study was to evaluate effect of bleaching agents on sound enamel (SE) and enamel with early artificial caries lesions (CL) using confocal laser scanning microscopy (CLSM). Eighty blocks (4 x 5 x 5 mm) of bovine enamel were used and half of them were submitted to a pH cycling model to induce CL. Eight experimental groups were obtained from the treatments and mineralization level of the enamel (SE or CL) (n=10). SE groups: G1 -unbleached (control); G2 -4% hydrogen peroxide (4 HP); G3 -4 HP containing 0.05% Ca (Ca); G4 -7.5% hydrogen peroxide (7.5 HP) containing amorphous calcium phosphate (ACP). CL groups: G5 -unbleached; G6 -4 HP; G7 -4 HP containing Ca; G8 -7.5 HP ACP. G2, G3, G6, G7 were treated with the bleaching agents for 8 h/day during 14 days, while G4 and G8 were exposed to the bleaching agents for 30 min twice a day during 14 days. The enamel blocks were stained with 0.1 mM rhodamine B solution and the demineralization was quantified using fluorescence intensity detected by CLSM. Data were analyzed using ANOVA and Fisher's tests (α=0.05). For the SE groups, the bleaching treatments increased significantly the demineralization area when compared with the unbleached group. In the CL groups, no statistically significant difference was observed (p>0.05). The addition of ACP or Ca in the composition of the whitening products did not overcome the effects caused by bleaching treatments on SE and neither was able to promote remineralization of CL.

Effect of resin infiltration on the color and microhardness of bleached white‐spot lesions in bovine enamel (an in vitro study)

“…Treatments that whiten discolored teeth have become popular in recent years, as they are an easy, inexpensive, and conservative method for improving the color of such teeth. Bleaching is also considered to be a simple and effective procedure for removing internal and external discolorations from teeth . Tooth whitening has also been recommended as a way to camouflage the appearance of WSLs, as it can reduce the contrast between these lesions and the enamel adjacent to it .…”

“…Bleaching is also considered to be a simple and effective procedure for removing internal and external discolorations from teeth. 18 Tooth whitening has also been recommended as a way to camouflage the appearance of WSLs, as it can reduce the contrast between these lesions and the enamel adjacent to it. 19 However, it is currently unclear whether bleaching agents have a negative impact on WSLs.…”

Changes in surface roughness and color stability of two composites caused by different bleaching agents

“…Much has been investigated on the changes in surface morphology of teeth (5,6) and restorative materials, as well as changes with regard to their chemical, physical and mechanical properties caused by peroxide bleaching. Some studies have shown a significant increase in surface roughness and the amount of porosity in composites, asserting that resurfacing or replacement of the restorations is necessary after bleaching.…”

Remineralization potential of a carbamide bleaching agent

“…The teeth were covered with acid resistant varnish except for the selected areas. 3. DIAGNOdent pen was used to register the values of the enamel surfaces left uncovered with the varnish before the bleaching.…”