Remineralizing effect of commercial fluoride varnishes on artificial enamel lesions

Abstract

The aim of this study was to evaluate soluble and insoluble fluoride concentrations in commercial varnishes, and their remineralization effect on artificial caries enamel lesions using surface and cross-sectional microhardness evaluations. Forty bovine enamel blocks were separated into four groups (n=10): control (no treatment), Enamelast (Ultradent Products), Duraphat (Colgate-Palmolive) and Clinpro White Varnish (3M ESPE). Surface enamel microhardness evaluations were obtained, artificial enamel caries lesions were developed by dynamic pH-cycling, and the varnishes were then applied every 6 days, after which the enamel blocks were submitted to dynamic remineralization by pH cycles. After removal of the varnishes, the enamel surfaces were reassessed for microhardness. The blocks were sectioned longitudinally, and cross-sectional microhardness measurements were performed at different surface depths (up to 300 μm depth). Polarized light microscopy images (PLMI) were made to analyze subsurface caries lesions. The fluoride concentration in whole (soluble and insoluble fluoride) and centrifuged (soluble fluoride) varnishes was determined using an extraction method with acetone. The data were analyzed to evaluate the surface microhardness, making adjustments for generalized linear models. There was a significant decrease in enamel surface microhardness after performing all the treatments (p<0.0001). Enamelast and Duraphat showed significantly higher enamel microhardness values than the control and the Clinpro groups (p = 0.0002). Microhardness loss percentage was significantly lower for Enamelast (p = 0.071; One-way ANOVA). PLMI showed that subsurface caries lesions were not remineralized with the varnish treatments. No significant differences in the in-depth microhardness levels (p = 0.7536; ANOVA) were observed among the treatments. Enamelast presented higher soluble and insoluble fluoride concentrations than the other varnishes (p < 0.0001; Kruskal-Wallis and Dunn tests). Enamelast and Duraphat varnishes promoted enamel surface remineralization, but no varnish remineralized the subsurface lesion body. Although insoluble and soluble fluoride concentration values did not correspond to those declared by the manufacturer, Enamelast presented higher fluoride concentration than the others.

Efficacy of fluoride varnishes with different compositions on white spot lesions remineralization

“…Clinpro White varnish presents a lower concentration of insoluble and soluble fluoride than Duraphat [27]. Despite of this, it showed similar efficacy on enamel remineralization, which is in accordance with the literature [5,8].…”

Biomimetic Effect of Nano-Hydroxyapatite in Demineralized Enamel before Orthodontic Bonding of Brackets and Attachments: Visual, Adhesion Strength, and Hardness in In Vitro Tests

“…In the literature, many techniques and materials have been investigated in order to test remineralizing agents both on dentine [24] and enamel [25]. Most studies explored fluoride-based varnishes [26] or casein phosphopeptideamorphous calcium phosphate pastes [27].…”

Effect of Remineralizing Agents and Resin Infiltration on Resistance to Demineralization of Artificial Enamel Lesions

“…All specimens were sectioned longitudinally into two halves. The sectioned specimens were later mounted on the self-cured acrylic resin (Acrostone, Egypt) and polished, leaving the cross-sectioned surface exposed for microhardness measurement 7 . Each specimen was measured by five indentations starting at 100μm from the surface and then 50μm step-up to 300μm in a line perpendicular to the surface, across the sectioned enamel lesion 7,25 .…”

“…The sectioned specimens were later mounted on the self-cured acrylic resin (Acrostone, Egypt) and polished, leaving the cross-sectioned surface exposed for microhardness measurement 7 . Each specimen was measured by five indentations starting at 100μm from the surface and then 50μm step-up to 300μm in a line perpendicular to the surface, across the sectioned enamel lesion 7,25 . The test was conducted at load 100gram for 10 seconds using microhardness tester (INNOVATEST Micro Vickers Hardness Tester Nova 240 with IMP-2, Netherlands) 17 .…”

“…These varnishes aid in remineralization via rebuilding a new surface on the remaining subsurface crystals and formation of CaF 2 reservoirs on the enamel substrate. Fluoride also helps in changing the hydroxyapatite into more acid-resistant fluorapatite 7 .…”