Purpose The purpose of this study was to evaluate changes in calcium and phosphorus content in dental enamel when subjected to “in-office” whitening for an extended time by using a 35% hydrogen peroxide solution, with and without calcium. Materials and Methods 10 human teeth, from which the roots had been removed, were embedded in epoxy resin, and their surfaces were smoothed. The specimens were divided into two groups; in group 1, a whitening solution without calcium was used, while in group 2, the solution included calcium. Each specimen was evaluated at 6 different points before the bleaching treatment, and these points were reassessed after each session. A total of five sessions were carried out. Concentrations of calcium and phosphorus were measured by using the technique of X-ray fluorescence. Results After performing a statistical analysis, it was found that there was no statistically significant loss of calcium and phosphorus during the whitening treatment, and the groups showed no statistical differences. Conclusion Excessive use of hydrogen peroxide, with or without calcium, causes no loss of calcium and phosphorus.
The photostimulated luminescence (PSL) is the basis for the digital image formation of image plates (IPs). However, the PSL decreases exponentially with the increasing of the elapsed time between the exposure and the IP scanning (t), and consequently, there is a fading of the digital image. The purpose of this paper is to investigate the relationship between IPs physical structure and elemental composition with the fading behavior. Three different types of IPs, with distinct resolutions, were analyzed. The fading behavior with the time, t, has been measured and correlated with their physical structure. Furthermore, micro X‐ray fluorescence (μXRF) analysis was used to provide information on the elemental composition of this layer. The results showed that standard resolution plate have larger grains, thicker sensitive layer, and generate a bigger effect of image fading. The μXRF technique showed that, to compensate the low emission, the high‐resolution IP has a higher concentration of Br and Sr.
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