title: Influence of therapeutic cancer radiation on the bond strength of an epoxy- or an MTA-based sealer to root dentine.
abstract: OBJECTIVE
  To evaluate the influence of radiation on root canal sealer push-out bond strength to dentine and sealer/dentine interface in teeth filled with AH Plus (Dentsply Ind. Com. Ltda, Petrópolis, RJ, Brazil) and MTA Fillapex (Angelus Ind. Prod. Odontológicos S/A, Londrina, PR, Brazil).
  
  
  METHODS
  Thirty-two maxillary canines were selected and randomly assigned to 2 groups (n = 16): one group was not irradiated, and the other was subjected to a cumulative radiation dose of 60 Gy. Root canals were prepared with the Reciproc system (VDW GmbH, Munich, Germany), and each group was divided into 2 subgroups (n = 8) according to the sealer - AH Plus or MTA Fillapex - using the single-cone filling technique. Then, 1-mm-thick dentine slices were obtained from each root third for the push-out test to evaluate sealer bond strength to dentine and for scanning electron microscopy (SEM) to examine the sealer/dentine interface. Failure mode after debonding was determined with a stereomicroscope at ×25 magnification. Bond strength data were analysed by two-way anova with a split-plot design and post hoc Tukey's test (α = 0.05).
  
  
  RESULTS
  Significantly lower bond strength (P < 0.0001) was obtained after irradiation (0.71 ± 0.20 versus 0.97 ± 0.29 MPa) and in specimens filled with MTA Fillapex (0.70 ± 0.18 MPa) compared with AH Plus (1.00 ± 0.27 MPa). Percentage of adhesive failures increased after radiation in all root thirds in the teeth filled with AH Plus. SEM revealed more gap-containing regions and fewer tags at the sealer/dentine interface in irradiated specimens, with more tag formation and fewer gaps with AH Plus sealer.
  
  
  CONCLUSIONS
  Radiation was associated with a decrease in the push-out bond strength of sealers to intraradicular dentine and formation of more gaps and fewer tags at the sealer/dentine interface regardless of the sealer.
authors.affiliation: Department of Restorative Dentistry, School of Dentistry of Ribeirão Preto, University of São Paulo, Ribeirão Preto, Brazil.
authors.forename: C V
authors.initials: CV
authors.lastname: Martins
authors.affiliation: Department of Restorative Dentistry, School of Dentistry of Ribeirão Preto, University of São Paulo, Ribeirão Preto, Brazil.
authors.forename: G B
authors.initials: GB
authors.lastname: Leoni
authors.affiliation: Department of Internal Medicine, Faculty of Medicine of Ribeirão Preto, University of São Paulo, Ribeirão Preto, Brazil.
authors.forename: H F
authors.initials: HF
authors.lastname: Oliveira
authors.affiliation: Department of Pediatric Dentistry, School of Dentistry of Ribeirão Preto, University of São Paulo, Ribeirão Preto, Brazil.
authors.forename: J
authors.initials: J
authors.lastname: Arid
authors.affiliation: Department of Pediatric Dentistry, School of Dentistry of Ribeirão Preto, University of São Paulo, Ribeirão Preto, Brazil.
authors.forename: A M
authors.initials: AM
authors.lastname: Queiroz
authors.affiliation: Department of Pediatric Dentistry, School of Dentistry of Ribeirão Preto, University of São Paulo, Ribeirão Preto, Brazil.
authors.forename: L A B
authors.initials: LA
authors.lastname: Silva
authors.affiliation: Department of Restorative Dentistry, School of Dentistry of Ribeirão Preto, University of São Paulo, Ribeirão Preto, Brazil. sousanet@forp.usp.br.
authors.forename: M D
authors.initials: MD
authors.lastname: Sousa-Neto
mesh_terms: D017607:Aluminum Compounds / Q000528:radiation effects*; D017610:Calcium Compounds / Q000528:radiation effects*; D003481:Cuspid; D001840:Dental Bonding; D019232:Dental Restoration Failure; D003799:Dental Stress Analysis; D003804:Dentin / Q000528:radiation effects*; D019583:Dose Fractionation, Radiation; D004338:Drug Combinations; D004853:Epoxy Resins / Q000528:radiation effects*; D006258:Head and Neck Neoplasms / Q000532:radiotherapy; D006801:Humans; D008422:Materials Testing; D008437:Maxilla; D010087:Oxides / Q000528:radiation effects*; D012387:Root Canal Filling Materials / Q000528:radiation effects*; D017640:Silicates / Q000528:radiation effects*
chemical_list: D017607:Aluminum Compounds; D017610:Calcium Compounds; D004338:Drug Combinations; D004853:Epoxy Resins; D010087:Oxides; D012387:Root Canal Filling Materials; D017640:Silicates; C086631:mineral trioxide aggregate
keywords: bond strength; radiotherapy; root canal filling and sealer penetration