Influence of CO2 (10.6 μm) and Nd:YAG laser irradiation on the prevention of enamel caries around orthodontic brackets

One possible undesirable consequence of orthodontic therapy is the development of incipient caries lesions of enamel around brackets. The aim of this study was to compare the effects of CO2 (lambda = 10.6 mu m) and Nd:YAG (lambda = 1,064 nm) lasers associated or not with topical fluoride application on the prevention of caries lesions around brackets. Brackets were bonded to the enamel of 65 premolars. The experimental groups (n = 13) were: G1-application of 1.23 % acidulated fluoride phosphate gel (AFP, control); G2-Nd:YAG laser irradiation (0.6 W, 84.9 J/cm(2), 10 Hz, 110 mu s, contact mode); G3-Nd:YAG laser irradiation associated with AFP; G4-CO2 laser irradiation (0.5 W, 28.6 J/cm(2), 50 Hz, 5 mu s, and 10 mm focal distance); and G5-CO2 laser irradiation associated with AFP. Quantitative light-induced fluorescence was used to assess enamel demineralization. The data were statistically compared (alpha = 5 %). The highest demineralization occurred in the Nd:YAG laser group (G2, 26.15 % +/- 1.94). The demineralization of all other groups was similar to that of the control group. In conclusion, CO2 laser alone was able to control enamel demineralization around brackets at the same level as that obtained with topical fluoride application.