Human enamel erosion in constant composition citric acid solutions as a function of degree of saturation with respect to hydroxyapatite

Abstract

The objective of this study was to investigate human enamel erosion under constant composition conditions, as a function of solution degree of saturation (DS) with respect to hydroxyapatite. The experimental conditions were relevant to the initial stages of enamel erosion by soft drinks. Nanoindentation was used to compare enamel surface softening caused by a control mineral water and two citric acid solutions with DS = 0.000 and DS = 0.032, both having pH 3.30. Enamel hardness and reduced elastic modulus were measured after 0, 30, 60, 120, 300 and 600 s exposure. A statistically significant change in enamel hardness was detected after 30 s exposure to both citric acid solutions, indicating that nanoindentation is extremely sensitive to the initial stages of erosion. There was a statistically significant difference between the mechanical properties of enamel exposed to the two citric acid solutions after 30, 60 and 120 s. At these times, the solution with DS = 0.000 caused twice as much enamel softening as that with DS = 0.032. This demonstrates that it may be possible to design a soft drink with a low erosive potential and a good taste by a small change in DS, at a typical drink pH.

In vitro evaluation of the microhardness of bovine enamel exposed to acid solutions after bleaching

“…10 The acid substances responsible for this process are not produced by the oral microbiota; on the contrary, they may be produced by gastroesophageal disorders, an acid diet, and also by other substances, such as bleaching products. 11,12 The factors responsible for dental structural loss may be classified as Declaration of Interests: The authors certify that they have no commercial or associative interest that represents a conflict of interest in connection with the manuscript. extrinsic and intrinsic.…”

Scanning Electrochemical Microscopy as a Tool for the Characterization of Dental Erosion

“…The dissolution rate of enamel during acid erosion is dependent on some chemical parameters such as pH and calcium and phosphate-containing salts concentration [23]. From the results shown in this work, one can suggest that the enamel dissolution is a relatively fast process that causes the proton diffusion layer to extend to a large distance into the bulk solution.…”

“…On the other hand, a different situation was noticed when the solution was stirred for homogenization prior to the acquisition of a new image (d). In the beginning of this experiment the current is similar to the one obtained in the bulk solution, but its decay is very fast probably because of the removal of the chemical resistant enamel outer layer [6,23]. A final experiment (image not shown) was carried out using an acetate buffer solution of the same pH = 3.4.…”

Thickness and nanomechanical properties of protective layer formed by TiF4 varnish on enamel after erosion

“…Similarly, it was demonstrated by the nanoindentation test that there was significant enamel softening after a 30 s exposure to the soft drink. 28 Fluoride varnishes have the capacity to adhere to the tooth surface, allowing for an increased contact time with the tooth and providing a positive effect on erosion prevention. 8,12,14 The antierosive effect of experimental TiF 4 varnish is mainly compared to that of the conventional NaF varnish, and studies have prompted speculations about the thickness and properties of protective layers formed by NaF and TiF 4 varnishes.…”