Influency of mode emission pulse of CO2 laser and acidulated phosphate fluoride in the control of enamel demineralization: in vitro and in situ analysis

Abstract

Despite the importance and prevalence of dental caries and the absence of published literature on the influence of the emission of CO2 laser pulse associated with 1.23% acidulated phosphate fluoride (APF) in the control of enamel demineralization, the purpose of this study is to evaluate in vitro and in situ the different modes of the laser pulse emission of CO2, associated or not with 1.23% acidulated phosphate fluoride in the control of demineralization of enamel. The best in vitro results will be analyzed in situ. In vitro study the factors studied will be the way of CO2 laser pulse at 4 levels (A. continuous, B. repeated pulse, C. Ultra pulse, D. absence of irradiation - control) and surface treatments at two levels (A. acidulated phosphate fluoride gel 1.23%, B. gel placebo - control). For this, one hundred and twenty enamel fragments will be subjected to cariogenic challenge (pH cycling) and randomly assigned to groups according to the treatment tha will be performed. Irradiation will be performed with CO2 laser with » = 10.6 ¼m with power of 1 W, in non-contact, out of focus at a distance of 4 mm, using a device that fixes the laser pen. The microhardness will be measured at 30 µm of surface area. Scanning electron microscopy will be used to obtain representative images. The in situ study will be 2x2 crossover, double blind, with two phases of 14 days each, with a wash-out period of 7 days. For this, 14 volunteers (n = 14) will use an intraoral appliance containing bovine enamel blocks that will be previously submitted to pH cycling and also one of the treatments: 1.23% acidulated phosphate fluoride (APF) + CO2 laser, FFA, placebo gel (PG) +CO2 and GP. Biofilm will be accumulate on the blocks and eight times a day, volunteers will drip sucrose solution, simulating a cariogenic challenge. The response variable will be subsurface microhardness, that will be held in half of the specimens. On the fourteenth day biofilm formed on the enamel blocks will be collected for microbiological analysis. Scanning electron microscopy will be used for qualitative analysis of enamel surfaces. (AU)