Effects of Fluoride on Two Chemical Models of Enamel Demineralization

Abstract

This study evaluated the effects of fluoride on subsurface enamel demineralization induced by two commonly used chemical models. Forty-eight enamel blocks were demineralized at pH = 5.0 by an acetate buffer (Group 1), a lactate buffer (Group 2), an acetate buffer with 0.02 ppm fluoride (Group 3) and a lactate buffer with 0.02 ppm fluoride (Group 4) at 25 °C for 3 weeks. The surface destruction percentage (SDP), mineral loss and lesion depth of the blocks were studied using micro-computed tomography. An elemental analysis of the enamel surface was evaluated using an energy-dispersive X-ray spectroscopy. Surface micro-hardness was determined by the Knoop Hardness Test. The mean lesion depth of Groups 1 through 4 were 134.1 ± 27.2 μm, 96.1 ± 16.5 μm, 97.5 ± 22.4 μm and 91.1 ± 16.2 μm, respectively (p < 0.001; group 1 > 2, 3 > 4). The SDPs of groups 1 through 4 were 7.8 ± 8.93%, 0.71 ± 1.6%, 0.36 ± 1.70% and 1.36 ± 2.94% (p < 0.001; group 1 > 2, 3, 4). The fluoride in mean weight percentages of groups 1 through 4 were 1.12 ± 0.24%, 1.10 ± 0.20%, 1.45 ± 0.40% and 1.51 ± 0.51%, respectively (p < 0.001; group 3, 4 > 1, 2). The mean Knoop hardness values of groups 1 through 4 were 27.5 ± 13.3, 39.7 ± 19.3, 73.6 ± 44.2 and 91.0 ± 57.2, respectively (p < 0.001; group 4 > 3 > 2 > 1). The chemical model using an acetate buffer solution created significantly deeper zones of subsurface demineralization on enamel than the lactate buffer solution. An acetate buffer may damage the enamel surface, but the surface damage can be prevented by adding fluoride.

Toothpaste Composition Effect on Enamel Chromatic and Morphological Characteristics: In Vitro Analysis

“…There are a few studies addressing the clinical efficacy of whitening dentifrices and, for this particular reason, our results emphasize the equilibrium between cosmetic effects and enamel protection when recommending a toothpaste [36,37]. The results of this in vitro study establish the balance between patient apprehensions, associated mainly with dental colour and practitioners’ concerns, related to enamel morphological irreversible alteration [38,39]. Our results decline the null hypothesis that the evaluated toothpastes did not exert effects on enamel optical and structural characteristics.…”

Acid-induced demineralisation of human enamel as a function of time and pH observed using X-ray and polarised light imaging

“…The surface zone feature of dental caries has been traditionally described [21]. It is thought to form due to a significant amount of fluorine (from toothpaste and mouthwashes) substituting hydroxyl groups in HAp crystallites producing fluorhydroxyapatite (FHAp) or fluorapatite (FAp) which occurs preferentially at the enamel free surface [30]. FAp has a lower average acid solubility than HAp, i.e.…”

Effect of Polymer-Induced Liquid Precursor Process Containing Polyaspartic Acid on Intrafibrillar Dentin Remineralization (Micro-Computed Tomography Analysis)

“…Acetate buffer produces artificial carious lesions that are deeper than those produced by lactate buffer at the same pH. In this study, dicalcium phosphate dihydrate was added to the acetate buffer demineralization solution to resemble normal salivary content containing calcium and phosphate ions so that it would later produce artificial carious lesions with images resembling natural carious lesions [8,14,15].…”