Abstract
The aim of this study was to evaluate the effect of bleaching agents containing different concentrations of hydrogen peroxide (HP) on color-change and on enamel-surface in bovine teeth. Furthermore the influence on cell viability and proliferation was investigated. Two hundred and forty teeth were randomly assigned into four groups (home bleaching ≤6%, in-office bleaching ≤6%, in-office bleaching > 6% HP, and control group). Bleaching was performed after artificial staining and the bleached index (BI) as well as the whiteness index (WID) was measured at several time points. Chemical analysis for HP concentrations and the pH of the bleaching products was done. Furthermore, enamel surfaces of randomly selected specimens were analyzed using scanning electron microscopy (SEM) and cytotoxicity of the tested bleaching products was evaluated in vitro using dental pulp cells (DPCs) and L929 cells. A statistically significant whitening effect was observed in almost all products. As expected all investigated products resulted in decreased cell viability, however, with different values of LC50 (median lethal concentration). SEM analysis showed an analog of enamel alterations with decreasing pH, increasing exposure time, and increasing HP concentration. Bleaching agents containing a low HP concentration are considered to be effective and to have less damaging effects on enamel and tested cells.
Highlights
Tooth bleaching has grown considerably in importance in the daily routine of general dentistry due to the increased esthetic awareness of patients
In the first group the three tested products (Opalescence R PF 10%, OP 10CP; Philips ZOOM R ! NiteWhite R 16%, PNW 16CP; and Philips ZOOM R ! DayWhite R 6%, PDW 6HP) showed a statistically significant whitening effect indicated by a decrease of the bleached index (BI) 21 days after bleaching (p < 0.001 each)
In the second group Philips ZOOM R ! 6% (PZ 6HP) showed a statistically significant decrease of BI 21 days after bleaching (p < 0.001), while the other two products of this group showed no statistical significant difference
Summary
Tooth bleaching has grown considerably in importance in the daily routine of general dentistry due to the increased esthetic awareness of patients. Since various factors can cause tooth discoloration different treatment alternatives may be required. Extrinsic tooth stains caused by consumption of coloring consumables such as black tea, red wine, and cigarettes can be removed by professional oral hygiene. Intrinsic tooth discoloration resulting e.g., from the disintegration. Bleaching With Different H2O2 Concentrations of hemoglobin after a dental trauma or medications like Tetracyclines (Botelho et al, 2017) require chemical auxiliaries to break large color pigments (Nathoo, 1997). The most commonly used chemical agents for tooth bleaching are hydrogen peroxide (HP) and carbamide peroxide. The resulting bleaching effect depends on the peroxide concentration, the application mode, and the exposure time (Matis et al, 2006; Meireles et al, 2012)
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