Effect of 30 % hydrogen peroxide on mineral chemical composition and surface morphology of bovine enamel

Abstract

A combination of atomic absorption spectroscopy (AAS), Fourier transform infrared spectroscopy (FTIR), scanning electronic microscopy (SEM), and gas adsorption techniques was used to characterize the effect of 30 % hydrogen peroxide (HP) on enamel surface. To perform the analyses of AAS, 1 ml of 30 % HP was added to 30 mg of a bovine enamel powder sample (150-200 µm fractions) for times of 5, 20, 60, 90, and 120 min; then 5 ml of the solution was withdrawn after each time period to measure [Ca(2+)] ions. The remaining powder was recovered and analyzed by FTIR. For SEM and gas adsorption tests, 4 × 4 mm(2) enamel sectioned samples were polished and 30 % HP was applied on the surface for the same time periods. AAS data show that 30 % HP treatment mobilized calcium from the enamel at all times studied. FTIR spectra showed that the total amount of phosphate and carbonate mineral contents such as amide I decreased significantly. SEM revealed that randomly distributed areas throughout the smooth enamel surface treatment became rougher and more irregular. These alterations indicate that surface damage increases with increasing durations of HP treatment. Gas adsorption analysis proved that bleached enamel is a typically non-porous material with a small specific surface area which decreases slightly with the 30 % HP treatment. In sum, 30 % HP induced a significant alteration of the organic and mineral part of the enamel, leading to the release of calcium and a rougher, more irregular enamel surface on randomly distributed areas.

The effect of different biomimetic materials as a remineralization protocol on microhardness and ultramorphology of bleached enamel

“…In the present study, the results of microhardness test and SEM analysis, as expected, revealed that HP alone could result in significant microhardness loss and morphological change of enamel. These findings are consistent with studies (3,(8)(9)(10) that suggested that morphological change of enamel is due to the demineralization caused by acidic HP, while microhardness loss is due to the combined effects of demineralization and destruction of organic matter by HP. hydrogen peroxide induced enamel mineral loss after bleaching and this process can lead to demineralization of the enamel surface and compromise its mechanical properties.…”

“…(4,5) It is known that the oxidationreduction reaction of the bleaching agent might cause dissolution of the organic and inorganic dental matrix until only carbon dioxide and water remain. Additionally, it has been shown that bleaching with 35-38% hydrogen peroxides may change enamel morphology and alter mineral content (3,4,(8)(9)(10) . Thus, efforts have been made to achieve a protocol capable of remineralizing bleached enamel, recovering microhardness loss and surface alterations (11)(12)(13)(14)(15) .…”

“…All of these factors contribute to the difficulty of repairing dental enamel tissue. (8,10) In order to minimize such demineralization after contact with bleaching agents, some ingredients such as fluoride (11)(12)(13) , calcium (14) or amorphous calcium phosphate (11) are added into the bleaching gel by manufacturers. Some biomimetic materials such as nano hydroxyapatite and nano structured bioactive glass have been advocated as new techniques for enamel reconstruction that have been a challenging topic of research in material sciences and dentistry .…”

Analysis of the Chemical Modification of Dental Enamel Submitted to 35% Hydrogen Peroxide “In-Office” Whitening, with or without Calcium

“…Several side effects caused by whitening vital teeth have been reported in the literature, and the one that is most often cited is dental sensitivity [ 6 , 11 , 18 – 20 ], but there are others, such as a change in mechanical properties of enamel, dentin, and direct restorative materials [ 6 , 8 , 9 , 21 – 23 ], an increase in roughness of these tissues [ 1 , 8 , 13 , 24 – 30 ], and change in mineral content [ 1 , 12 , 20 , 25 , 29 – 32 ].…”

“…A literature review in 2007 [ 6 ] showed that, as of the date of publication, the studies were almost unanimous in stating that there was no change in mineral content in the enamel surface. However, many studies performed after that date have shown the opposite [ 1 , 13 , 21 , 26 , 30 – 33 ]. This is due to the wide variety of methodologies, without there being a well-defined protocol for this type of study, and the use of nonideal tests to measure loss of calcium and phosphorous in tooth enamel.…”