“…8,9 Some of the complications of applying bleaching agents in tooth hard tissues are changes in tooth chemical structure, demineralization and decreases in the mineral content including calcium and phosphate, 14,25,26 decreases in the fluoride content of enamel, 11 and changes in the micromorphology of enamel. 9,27,28 However, other studies have reported different results with no statistically significant differences in tooth hard tissue characteristics, including enamel and dentin surface roughness, after bleaching with 10% and 15% carbamide peroxide. 17,18,[29][30][31] The discrepancies in the results of various studies might be attributed to differences in the formulation and concentration of bleaching agents; the duration of daily applications or treatment protocols; differences in study designs, including the environments in which the specimens are stored (eg, artificial or human saliva); the use of remineralizing agents; continuous use of fluoridated toothpastes; and the technique of toothbrushing during the procedure and after bleaching.…”