Effect of Er,Cr:YSGG Laser Irradiation on Enamel Caries Prevention

Objectives: To evaluate the effect of different parameters of Er,Cr:YSGG (l=2,78 µm) laser on enamel caries prevention. Methods: Forty enamel samples obtained from 10 human molars were randomly divided in 4 groups (n=10). A 2x2mm-area on enamel of each sample was delimited and irradiated (scanning mode, 20Hz,Φ=600mm ) for 20 seconds, using the following parameters:G1- 4.48J/cm², 30% air and no water; G2- 4.48J/cm², 30% air and 10% water; G3- 8.94J/cm², 30% air and no water; G4- 8.94J/cm², 30% air and 10% water. Then, the samples were subjected to a 2-week cariogenic challenge (pH Cycling), consisted of daily immersion in de-remineralizing solutions for 6 and 18h, respectively. After that, samples were sectioned, polished and the Knoop microhardness test was performed (25g, 10sec) at different depths from the enamel surface (20mm -100mm). As control, measures in a non-irradiated enamel area were performed in each sample and used to obtain the inhibition percental. Data analysis was performance by two-way ANOVA and Fisher's test (a=5%). Results: The percentage of lesion inhibition observed on group 1 (13.30%) was significantly higher than groups 2 (3.20%) and 4 (6.58%) (p<0.05). Group 3 (9.48%) showed similar results to groups 1 and 4, but was higher than group 2. Conclusions: The findings of the present study suggest that the energy densities of 4.48 and 8.94J/cm² were equally effective in increasing the acid resistance of human enamel. Moreover, the presence of water during irradiation did not allow the Er,Cr:YSGG laser to promote a caries preventive effect on enamel. (Grant: FAPESP 2007/08140-5)