The treatment of intraradicular dentin with antioxidant agents and laser irradiation aim to make the dental surface more receptive to adhesive procedures. The purpose of this study is to evaluate the effect of Er:YAG laser irradiation or sodium ascorbate solution on intraradicular dentin on glass fiber post cementation. Forty eight bovine incisor roots will be standardized at 15 mm of length and will be submitted to biomechanical preparation up to #70 endodontic file. Root canals will be filled with Sealer 26 using the lateral condensation technique. After the setting time, the removal procedure will be done with a #5 largo drill. The roots will be divided into 4 groups according to intraradicular dentin treatment (n=12): G1- irrigation with distilled water (control); G2 - 10% sodium ascorbate solution (10 min); G3 - Er:YAG laser (60 mJ/4Hz and 20 s) and G4 - Er:YAG laser with 10% sodium ascorbate solution. Glass fiber posts will be cemented into root canals with Relyx U200. The roots will be sectioned into slices and the following variables will be analyzed: 1° slice of each third - bond strength of the material to dentin (push out test) and failure pattern in confocal laser scanning microscope (CLSM); 2° slice of each third - Knoop microhardness (KHN) of the dentin adjacent to the canal, and the cement penetration on dentin under CLSM. Data will be subjected to the appropriate statistical analysis for each test (p<0.05).
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