<ORIGINAL>Combined Effects of Erbium : YAG laser and Fluoride Application on Acid Resistance of Tooth dentin in vitro

This study examined the inhibition of dentin demineralization in initial caries with Er : YAG laser irradiation only and laser irradiation combined with fluoride application. Dentin blocks were prepared from the roots of bovine incisors and pretreated with one of the following five procedures : A) untreated, B) Er : YAG laser irradiation for 5min at 50mJ/pulse, C) APF gel application for 5min, D) Er : YAG laser followed by APF application for 5min,and E) APF treatment for 5min followed by Er : YAG laser irradiation. Subsequently the samples were demineralized in a 0.1M lactic acid gel (pH5.0) containing 6wt% CMC at 37℃ for 2 weeks. The mineral distributions in the dentin surfaces were assessed quantitatively by transversal microradiography (TMR) and videodensitometry. The mineral parameter values were not significantly different for samples with and without laser treatment at p=0.05, as tested by paired t-tests. The present results suggest that the progress of demineralization in dentin lesions is not effectively inhibited by the single treatment with laser irradiation. Combined Er : YAG laser and APF treated samples had the highest acid resistance with significantly lower lesion depth (ld) and mineral loss (ΔZ) values lower even than the APF treated samples