Effectiveness of home bleaching agents in discolored teeth and influence on enamel microhardness

Abstract

Objectives:This study evaluated the effectiveness of different home bleaching agents on color alteration and their influence on surface and subsurface microhardness of discolored bovine enamel.Material and Methods:Forty-five fragments of bovine incisors were randomly allocated into 3 groups (n=15) according to the bleaching agent: 10% carbamide peroxide gel (CP10), 16% carbamide peroxide gel (CP16) and 6.5%-hydrogen-peroxide-based strip (HP6.5). Before bleaching treatment, initial values of Knoop surface microhardness and color (CIEL*a*b*) were obtained and the fragments were artificially stained in hemolyzed rat blood. Then, bleaching treatments were performed over a 21-day period. Color changes (ΔE) were assessed at 7, 14 and 21 days, and final surface microhardness reading was done after 21 days. Thereafter, the fragments were bisected to obtain subsurface microhardness. Data were subjected to ANOVA and Tukey's tests (α=5%).Results:Color changes produced by CP16 were similar to those of CP10, and the color changes produced by these materials were significantly superior to those produced by HP6.5. Color changes at 21 days were superior to 7 days and similar to 14 days. The time did not influence color changes for CP16, which showed similarity between the 14- and 21-day results. No statistically significant differences were found among the home bleaching agents for surface and subsurface microhardness.Conclusions:Microhardness of bovine enamel was not affected by the bleaching agents. The 16% carbamide peroxide gel was the most effective for bleaching the stained substrate.

Effect of sodium ascorbate on the bond strength of silorane and methacrylate composites after vital bleaching

“…19 Due to the chemical properties of the bleaching agents, the mineral content of the dental hard tissue could change. 20 Enamel bleaching immediately before bonding with adhesive systems might decrease the BS between materials.…”

Effect of repeated bleaching by low hydrogen peroxide regimens – with and without MI Paste Plus – on enamel hardness and composition

“…Low HP dentist prescribed regimen of 10% carbamide peroxide; CP (~3.35% HP) gel at only 1 h/day for 14 days was recommended due to its safety [1,4e6] and is typically used for mild-tomoderate discolorations. In addition, the whitening strips (9.5% HP at 0.5 h/day) that may be easier to use and at the same time efficient [2], might also provide sufficient safety for enamel [6,7]. Adjunct enamel remineralization may be additionally performed by fluoride [8e10] or Casien Phosphopeptide Amorphous Calcium Phosphate (CPP-ACP) [11e14].…”

“…Bleaching did not cause any clinically visible enamel damage [1], however it has been proved that it could reduce its inorganic [20] and alter its organic contents [1]. In literatures, enamel hardness was found to be either reduced [3,8e11,21] or not affected [6,7,22] that may be due to the different tested bleaching regimens and testing protocols. Fourier Transform Infrared spectroscopy (FTIR) was also found to be an accurate method for qualitative and semi-quantitative analysis of both enamel [23,24] and dentin [25].…”

Atmospheric Pressure Plasma Jet as an Accelerator of Tooth Bleaching

“…Tooth bleaching can be generally divided into two types: "in home bleaching" in which the patient uses a tray containing a low concentration of carbamide peroxide (CP) gel for two or three weeks and "in office bleaching" in which dental practitioners use a higher concentration of hydrogen peroxide (HP) gels 15-45% and higher concentrations 30-37% of CP gels, which is directly applied to the teeth for a total period of 30-60 minutes (10)(11)(12). The mechanism of bleaching is based on the HP or CP gel's ability to penetrate tooth structure and produce free radicals that oxidize organic stains within the tooth (13).…”