Abstract
BackgroundCommercial bleaching gels with remineralizing agents were developed to reduce the adverse effects of dental bleaching. The present study evaluated the effects on teeth of in-office bleaching gels containing 35-40% hydrogen peroxide (HP) with Calcium (Ca) or Fluoride (F). Material and MethodsBovine enamel/dentin blocks (4x4x2.5 mm) were randomly divided into the following groups (n=12): no treatment (control); 35% HP (Whiteness HP, FGM); 35% HP with Ca (Whiteness HP Blue, FGM); 40% HP with F (Opalescence Boost, Ultradent). The specimens were analyzed for color (ΔL*, Δa*, Δb*, and ΔE), roughness (Ra), and Knoop microhardness (KHN). The color and KHN data were submitted to ANOVA and Tukey’s test, while Ra values were analyzed using mixed models for repeated measures and Tukey-Kramer’s test (α=0.05). ResultsThe bleached groups did not exhibit statistical differences among them for color. For roughness, 35% HP provided a slight increase of Ra, which was statistically different from the control. For microhardness, 35% HP and 40% HP with F presented KHN values that were statistically lower from the control, while the 35% HP with Ca did not statistically differ from the control. ConclusionsThe presence of Ca or F in bleaching gels did not interfere with bleaching efficacy. However, only the enamel exposed to the bleaching gel containing Ca obtained microhardness values similar to unbleached enamel. Key words:Hydrogen peroxide, tooth bleaching, tooth bleaching agents, laboratory research.
Highlights
High beauty standards and cosmetic care are highly valued in Dentistry
The aim of this in vitro study was to evaluate commercially available in-office bleaching gels based on 35-40% hydrogen peroxide (HP), without or with calcium or fluoride, on the bleaching efficacy, roughness, and microhardness of enamel
Based on the enamel microhardness results (Fig. 2), 35% HP and 40% HP with F presented the smallest Knoop microhardness (KHN) values, which were statistically different from the control group (p < 0.01) and statistically similar to each other (p = 0.21)
Summary
High beauty standards and cosmetic care are highly valued in Dentistry. The desire to have a harmonious smile with well-aligned white teeth has become a basic standard of aesthetics, which increases the demand for dental treatments [1]. Regardless of the technique and bleaching agent employed, adverse effects have been reported, to include: tooth sensitivity [8]; changes in surface morphology; and changes to the physical-chemical properties of the dental hard tissues such as an increase in enamel roughness, a decrease in surface microhardness, and an alteration in mineral content [9,10,11,12,13] Some remineralizing compounds, such as fluoride, calcium, bioactive glass, arginine/calcium carbonate, and nanohydroxyapatite; have been investigated to minimize these adverse effects [10,12,14,15,16]. The significance level was set at 0.05
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