Influence of Er:YAG laser irradiation settings on dentin‐adhesive interfacial ultramorphology and dentin bond strength

Abstract

This study evaluated the effects of Erbium-doped yttrium aluminium garnet (Er: YAG) laser settings and dentin bonding agents on ultramorphological characteristics of resin-laser-irradiated dentin interfaces and dentin bond strength (BS) of these adhesive systems. Additionally, dentin depth affected by Er:YAG laser irradiations was measured. The experiments were performed on occlusal dentin surfaces of third molars that were flattened with 600-grit SiC sandpaper. Treateddentin with laser settings (250 mJ/4 Hz and 160 mJ/10 Hz) were the experimental groups, while SiC abraded dentin was the control. These three dentin treatments and three adhesives (two self-etchings and one etch-&-rinse adhesive) formed nine groups for the ultramorphology of laser-ablated dentin-adhesives interfacial analysis, using a transmission electron microscope (TEM). For BS (n = 8), the same nine groups were tested with addition of the two evaluation times (24 h after sample preparation or 1 year). The depths of Er:YAG laser effects into the dentin were measured using a TEM (n = 10). Ablated-dentin depth and BS data were analyzed by one-and three-way ANOVA, respectively, and Tukey's test (α = 0.05). Hybrid layer formation was only observed for controls, while for laser-treated dentin, adhesives were bonded to dentin with resin tags formation.