The aim of this study was to verify whether the irradiation of carbon dioxide (CO2) laser with a wavelength of 10.6 µm and density of 10.0 J/cm2 combined with the use of fluoridated toothpaste (1100ppm F) could reduce enamel demineralization around orthodontic brackets, subjected to a situation of high cariogenic challenge in the oral environment. For this, 0 human third molars retained were cut into 160 specimens of 5 mm x 5 mm x 2 mm, which were divided into the groups. During two phases of 14 days each, 20 volunteers (mean age 24 years) used a device intraoral palatal containing four specimens of human enamel, which were randomly divided into 4 groups: 1- Non Fluoride Toothpaste (NFT) (control), 2- Non Fluoride Toothpaste + CO2 Laser (NFT+L), 3- Fluoride Toothpaste (FT) and 4- Fluoride toothpaste + CO2 Laser (FT+L). To simulate a high cariogenic challenge, volunteers dripped on the slabs a 20% sucrose solution eight times a day at predetermined times. After each phase, the biofilm around the brackets was collected and the fluoride concentration in the dry biofilm was analyzed, using an ion specific electrode. The mineral loss around orthodontic brackets was determined by cross-sectional microhardness measurement. The results of the fluoride concentration in the dried biofilm were analyzed by ANOVA and Kruskal-Wallis test followed by the Student Newman-Keuls test (± = 0.05%) and the results of the mineral loss were analyzed by Shapiro-Wilk followed by the Kruskal-Wallis test. Regarding the fluoride concentration in the dry biofilm, the data showed a significant difference between groups 1 (NFT) and 2 (NFT + L) when compared to groups 3 (FT) and 4 (FT + L), and the groups 3 and 4 showed a higher fluoride concentration in the biofilm, as expected. The results showed no difference between the groups regarding mineral loss, since the adhesive may have been a protective agent during the demineralization stages of the experiment. Furthermore, 14 days of the experiment at each stage may have been insufficient time for the formation of white spot lesions around orthodontic brackets. It was concluded that the association between irradiation with a CO2 laser and the use of fluoride toothpaste was not able to reduce demineralization around orthodontic brackets.
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