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

• Grant number: 15/14880-8
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: October 01, 2015
• End date: September 30, 2016
• Field of knowledge: Health Sciences - Dentistry - Endodontics
• Principal Investigator: Manoel Damiao de Sousa Neto
• Grantee: Fabiana de Goes Paiola
• Host Institution: Faculdade de Odontologia de Ribeirão Preto (FORP). Universidade de São Paulo (USP). Ribeirão Preto , SP, Brazil

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.