The aim of this study is to investigate the effect of different parameters of Er: YAG laser (Super Short Pulse-SSP) in caries-affected dentine produced artificially. The flattened occlusal dentin of 115 human molars will be protected with acid resistant varnish in half of the occlusal surface (sound dentin - control) and on the other half will be produced caries affected dentine with a microbiological method for 7 days. Thereafter different conditioning surface parameters will be applied (G1 - no conditioning; G2 - 80mJ, 2Hz, 50µs; G3 - 70mJ, 2Hz, 50µs; G4 - 60mJ, 2Hz, 50µs; G5 - 50mJ, 2Hz, 50µs) and the morphological analysis will be accomplished through: Surface Microscopy (SEM) (n = 2), morphological evaluation of the bonding interface by SEM (n = 2), transmission electron microscopy (n = 2) and test ultramicrohardness (n = 5 .) To evaluate the bond strength the microshear test will be performed (n = 12). A self-etching system will be used together with a nanohybrid composite, analysis will be performed after storage for 24 hours and 6 months. We intend to determine a conditioning parameter with laser Er: YAG (SSP) in caries affetcted dentine in order to improve adhesion and durability of adhesive restorations. The quantitative data obtained will be statistically analyzed and the qualitative comparison will be described in relation to control tissue.
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