Synergistic effect of fluoride and laser irradiation for the inhibition of the demineralization of dental enamel

Abstract

Both laser irradiation and fluoride treatment alone are known to provide increased resistance to acid dissolution. CO2 lasers tuned to a wavelength of 9.3 μm can be used to efficiently convert the carbonated hydroxyapatite of enamel to a much more acid resistant purer phase hydroxyapatite (HAP). Further studies have shown that fluoride application to HAP yields fluoroapatite (FAP) which is even more resistant against acid dissolution. Previous studies show that CO2 lasers and fluoride treatments interact synergistically to provide significantly higher protection than either method alone, but the mechanism of interaction has not been elucidated. We recently observed the formation of microcracks or a “crazed” zone in the irradiated region that is resistant to demineralization using high-resolution microscopy. The microcracks are formed due to the slight contraction of enamel due to transformation of carbonated hydroxyapatite to the more acid resistant pure phase hydroxyapatite (HAP) that has a smaller lattice. In this study, we test the hypothesis that these small cracks will provide greater adhesion for topical fluoride for greater protection against acid demineralization.

Variation on Molecular Structure, Crystallinity, and Optical Properties of Dentin Due to Nd:YAG Laser and Fluoride Aimed at Tooth Erosion Prevention

“…Also, the obtained results suggest that high-intensity laser irradiation presents a long-lasting effect when compared to the effects promoted by APF-gel application, and the association of treatments had no benefits when compared to the effects of treatments alone. The literature is contradictory on reporting the effects of the association of laser with fluoride [ 40 , 41 , 42 , 43 ], and it depends mainly if APF-gel is applied before or after laser irradiation. While some studies state that laser can attenuate or even increase fluoride diffusion into dental hard tissue [ 42 ], others say that laser irradiation can favor the CaF 2 -like material formation and retention on the irradiated surface [ 6 , 44 ].…”

Combined effects of a topical fluoride treatment and 445 nm laser irradiation of enamel against a demineralization challenge: A light and electron microscopic ex vivo study

“…The demineralization solution was composed of 2.0 mmol l–1 Ca, 2.0 mmol l–1 P, and 0.075 mol l–1 acetate buffer at pH 4.3 (Fa. Merck, Darmstadt, Germany) [ 30 , 31 ]. Each sample was placed individually in 20 ml of the demineralization solution at 37 °C.…”

Effects of 9,300 nm Carbon Dioxide Laser on Dental Hard Tissue: A Concise Review

“…They used acidulated phosphate fluoride, sodium fluoride, and silver diamine fluoride. 9,18,19,[33][34][35][36] Some studies showed that enamel treated with a 9,300 nm carbon dioxide laser before fluoride treatment had less mineral loss after acid challenge than those treated with laser or fluoride. 9,18,33,35 Also, 9,300 nm carbon dioxide laser irradiation before fluoride can also enhance the cariespreventive effect of fluoride on enamel and dentine.…”

“…9,18,33,35 Also, 9,300 nm carbon dioxide laser irradiation before fluoride can also enhance the cariespreventive effect of fluoride on enamel and dentine. 19,34,36 There is only one paper studying the combined treatment of a 9,300 nm carbon dioxide laser and fluoride on dentine. The study demonstrated that, compared with a laser group, the combined treatment group showed an increase in resistance of dentine to demineralization.…”