Effect of Er:Yag laser on dentin demineralization around restorations

The aim of this study was to evaluate the effect of cavity preparation with Er:YAG laser on dentin adjacent to restorations submitted to cariogenic challenge in situ, by subsuperficial microhardness analysis. Bovine incisors were sectioned, flattened, and polished, resulting in 40 dentin slabs. The slabs were randomly assigned to four groups (n = 10), according to the cavity preparation method: I-high-speed handpiece (control); II-Er:YAG laser (160 mJ; 3 Hz); III-Er:YAG laser (260 mJ; 3 Hz); IV-Er:YAG laser (300 mJ; 3Hz). Cavities were restored with composite resin, and the specimens were fixed in intra-oral appliances, which were worn by 10 volunteers for 14 days for simulating cariogenic challenge in situ. During the experimental period, 20% sucrose solution was dripped over each specimen 6 times a day. Samples were removed, sectioned, and examined for subsuperficial Knoop microhardness at 100, 200, and 300 μm from the restoration and at 30 μm from dentin surface. Split-plot analysis of variance showed no significant difference among the cavity preparation techniques (p = 0.1129), among distances (p = 0.9030), as well as no difference in the interaction between the main factors (p = 0.7338). It was concluded that the cavity preparation with Er:YAG laser did not influence on dentin microhardness submitted to cariogenic challenge in situ.