Analysis of the Color and Fluorescence Alterations of Enamel and Dentin Treated With Hydrogen Peroxide

Abstract

The aim of this study was to evaluate the effect of hydrogen peroxide whitening on fluorescence and color of bovine enamel and dentin. Twenty five dentin discs and 25 enamel discs, with 6 mm diameter and 1 mm thick, were obtained. Direct fluorescence (spectrofluorophotometry) and color (spectrophotometry) were assessed. After fluorescence and color baseline measurements, specimens were immersed in a 35% hydrogen peroxide (HP) solution for 1 h. This procedure was repeated after 7 days. Final fluorescence and color measurements were performed after the second immersion. Chemical characterization of 5 additional specimens was also performed. Data were submitted to repeated analysis of variance and Tukey's test for fluorescence and unpaired t-test for color and chemical components (p<0.05). Fluorescence decreased significantly in dentin specimens after whitening. Enamel presented lower fluorescence than dentin at baseline, but this parameter did not decrease after whitening. Color changes were observed for both substrates, with significantly greater whitening effect in dentin (ΔE=10.37) (p<0.001). Whitening by hydrogen peroxide induced significant decrease in fluorescence of tooth dentin and promoted significant color changes in dentin and enamel with more accentuated outcomes in dentin.

Whitening effect of 35% hydrogen peroxide in simulation of tooth with orthodontic bracket

“…Penetrability allows peroxide-generated oxygen-free radicals to act polydirectionally and degrade pigments responsible for dental darkening. 1,2,6,7,9,10,18 Thus, this study was developed to evaluate the whitening effect in bovine teeth simulating the existence of orthodontic bracket, varying the fragment thickness and number of whitening sessions.…”

“…This diffusion phenomenon was first described by Haywood 6 in 1990 and consists in the ability of peroxide to diffuse through the tooth structure, 2,7-9 generate free radicals and degrade organic molecules responsible for intrinsic or extrinsic staining of dental structure. 1,2,7,[9][10][11] Color change in teeth with orthodontic bracket has been proven by some studies and this undesirable result might be caused by the permanent iatrogenic enamel effects associated with bonding, debonding, and cleaning procedures, [12][13] enamel demineralization, 14 exogenous and endogenous discoloration of the tooth and remaining adhesive material 12,15 and the color instability of the resin used to retain the bracket. 16 Among the doubts of the orthodontic patient is wondering when is the best time to perform the whitening procedure, as in addition to well-aligned teeth, they idealize white teeth and want the procedure as soon as possible.…”

Fluorescence of natural teeth and restorative materials, methods for analysis and quantification: A literature review

“…Another aspect discussed in the literature is the change in fluorescence intensity after tooth whitening. Articles indicate a mineral loss in the enamel after the use of a bleaching agent, with almost no change in the intensity of enamel fluorescence . However, a significant decrease in the organic content of dentin after the use of hydrogen peroxide appears to be responsible for a reduction in dental fluorescence .…”

“…35,36 However, a significant decrease in the organic content of dentin after the use of hydrogen peroxide appears to be responsible for a reduction in dental fluorescence. 36 Fluorescence changes after bleaching were observed for both 35% and 10% carbamide peroxide concentrations. 37 A recent article evaluated the fluorescent properties of human teeth extracted and bleached with peroxide hydrogen at 40%, and the authors observed a significant reduction in fluorescence after bleaching.…”

“…Articles indicate a mineral loss in the enamel after the use of a bleaching agent, with almost no change in the intensity of enamel fluorescence . However, a significant decrease in the organic content of dentin after the use of hydrogen peroxide appears to be responsible for a reduction in dental fluorescence . Fluorescence changes after bleaching were observed for both 35% and 10% carbamide peroxide concentrations .…”