Surface characteristics of a modified acidulated phosphate fluoride gel with nano‐hydroxyapatite coating applied on bovine enamel subjected to an erosive environment

Abstract

This study evaluated the antierosive effect applying a modified acidulated phosphate fluoride (APF) gel containing nano-hydroxyapatite (nHAp) on the enamel surface before erosion. After polishing, the exposed flat enamel surfaces (n = 7/group) from bovine incisors were treated with artificial saliva (S -negative control), orange juice (ERO), APF gel (positive control) and APF_nHAp gel. All samples were subjected to six cycles of demineralization (orange juice, pH~3.5, 10 min) followed by remineralization (saliva, 37 C, 1 hr). The enamel surface morphology, topography, and inorganic composition were analyzed using scanning electron microscopy, roughness testing, and micro energy-dispersive X-ray fluorescence spectrometry, respectively. The mean (standard deviation) roughness values (Ra, μm) were S, 0.13 (0.05); ERO, 0.25 (0.07); APF, 0.22 (0.08); and APF_nHAp, 0.17 (0.04). Ra values were significantly higher after ERO (p < .01) and APF (p < .05) treatments than after S. The enamel surface morphology was altered by the treatments, except for the S specimens.The mineral content of the enamel showed a clear trend with Ca and P reduction in the order of APF < S < APF_nHAp < ERO and APF < S < ERO < APF_nHAp, respectively. We can conclude that APF gel increased mineral concentration on the enamel. Moreover, the APF_nHAp material modified the composition and morphology of the enamel surface. K E Y W O R D S enamel, energy dispersive X-ray fluorescence spectrometry, fluoride, hydroxyapatite, scanning electron microscopy

Influence of Remineralizing Agents on the Surface Roughness of Eroded Dental Enamel: in Vitro Study

“…18 In the present study the pH of the erosive drink used was 2.8 at a temperature of 10ºC, below to 5.5 and 6.5 that are the critic pH of enamel and dentin, respectively, 19 thus showing that the utilized juice has an acidic pH enough to cause tooth demineralization by increasing the surface roughness at the enamel. It probably occurs because at low pH like that observed for the lemon juice, the amount of H + increases, wakening the binding of Ca +2 ions, leading then into solution, 16 changing the enamel surface by the increasing at the surface roughness, what was observed in this study ( Table 1). Other authors found by SEM images analyses that citric fruit juice caused morphological changes to the enamel surface, including the presence of craters and surface irregularities.…”

“…14 In addition, bovine incisors are frequently used in dental research due to the difficult to obtain intact human teeth, 15 and its larger surface allow the use of demineralization and remineralization researches. 5,6,8,16,17 In this study it was observed that there was no significant difference in statistical values between the groups of the control region, that indicates that the waterproofing of the specimens with the nail enamel and sticky wax was effective (Table 1). However, in the experimental region of the specimens the values of surface roughness presented statistical similar values between the groups and statistically higher when compared with that obtained at the control region ( Table 1).…”

“…Other authors found by SEM images analyses that citric fruit juice caused morphological changes to the enamel surface, including the presence of craters and surface irregularities. 16 The tested treatments for the erosion in this study were the application of 1.23% APF, 4% fluoride varnish and Regenerate, which has been used as a clinical treatment of demineralized enamel. 20 However, the tested materials were not capable to repair the surface roughness of the specimens after the acid challenge.…”

“…This can be explained because the fluoride treatments can form fluoridated apatites in the enamel structure and accelerate the deposition of CaF -2 -like material and calcium phosphate from the supersaturated gel. 16,19 Besides, the fluoride can result in lower pH, making calcium available for interaction with fluoride in the form of a layer of CaF 2 . 16 Conversely, although the calcium silicate and sodium phosphate-based material can to release calcium ions to the surrounding oral fluids under acid conditions, to inhibit the enamel hydroxyapatite solution and to buffer the protons absorption at the eroded enamel surface, 14 in the present study, the Regenerate application did not promote the decrease of the surface roughness at the enamel.…”

Chemical and morphological evaluation of enamel and dentin near cavities restored with conventional and zirconia modified glass ionomer subjected to erosion‐abrasion

“…In this study, SEM was selected to analyze the effect of the abrasion, erosion, and saliva on enamel and dentin morphology to measure substance loss accurately and provide visual information on surface precipitates and change of the surface morphology. Conversely, μ‐EDXRF provides a specific method to determine the concentration of chemical elements on substratum surfaces, being previously used in some studies in dentistry (De Carvalho Filho et al, ; Gomes et al, , ; Soares et al, ; Soares & De Carvalho Filho, ; Soares, De Oliveira, et al, ; Soares et al, ; Soares et al, ).…”