Evaluation of bond strenght of sealer to root dentin after the use of different chelating solutions in teeth previously submitted to radiotherapy

Abstract

The purpose of this in vitro study is to expose maxillary canines to radiotherapy by x-rays and subsequently perform root canal treatment to evaluate the bond strength of epoxy resin-based sealer to root dentin after final irrigation with different solutions (sodium hypochlorite, EDTA and chitosan) and the dentin/filling material interface, using the push-out test and scanning electron microscopy (SEM), respectively. Forty-eight maxillary canines will be assigned to 2 groups (n=24): Group I: Non-Irradiated and Group II: Irradiated, in which the teeth will be exposed to radiotherapy by 6MV X-rays; a cumulative radiation dose of 60 Gy fractionated in 30 fractions (2 Gy per fraction) will be delivered in 5 consecutive days per week, over 6 weeks. Biomechanical preparation of the root canals will be performed with Reciproc system (R50) and irrigation will be done with 1% sodium hypochlorite Each group will be divided into subgroups (n=8) according to the solution used for final irrigation: Subgroup A: 1% sodium hypochlorite (control); Subgroup B: 17% EDTA; and Subgroup C: 0.2% chitosan. The teeth will be filled with AH Plus sealer using the lateral condensation technique. The teeth will be sectioned into 1-mm-thick slices, obtaining 3 slices of each root third. The first slice of each third (in the crown-apex direction) will be used to evaluate the push-out bond strength and the failure pattern (with a stereomicroscope). The second and third will be used to evaluate qualitative and quantitative examination slice of the sealer penetration into the dentinal tubules as well as dentin/filling material interface by means of SEM analysis. The obtained data will be subjected to statistical analysis.