title: Fracture resistance of endodontically treated teeth with different direct corono-radicular restoration methods.
abstract: BACKGROUND
  Endodontically treated teeth are widely considered to be more susceptible to fracture than vital teeth. Obturation procedures and post placement have been a main cause of vertical root fracture.
  
  
  METHODS
  Forty-eight human premolars with standardized weakened roots were endodontically treated and allocated to four experimental groups (n=12). After root canal treatment, in group 1, fiber posts #1 were cemented in root canals using Estelite Core Quick, and the crowns were restored with resin composite. For group 2 and 3, the roots and crowns were restored using a light-cured and self-cured adhesive and resin composites respectively. In group 4, it was used the Panavia F 2.0 resin cement and resin composite for corono-radicular reconstruction. In group 5, the teeth remained untouched. After 24 hours storage and 1000 thermocycles, samples were loaded at a cross head speed of 1 mm per minute.
  
  
  RESULTS
  A significant difference was observed in fracture resistance among groups 4 and 5 compared to other groups.
  
  
  CONCLUSIONS
  Root reconstruction with fiber post and Panavia resin cement, and crown building using light-cured resin composite resulted in increased fracture resistance equal to that of intact teeth.Key words:Fracture resistance, fiber post, resin cement, resin composite.
authors.affiliation: Associate Professor of Dental Materials Research Center and Department of Operative Dentistry, Faculty of Dentistry, Mashhad University of Medical Sciences, Mashhad, Iran.
authors.forename: Horieh
authors.initials: H
authors.lastname: Moosavi
authors.affiliation: Assistant Professor of Dental Materials Research Center and Department of Operative Dentistry, Faculty of Dentistry, Mashhad University of Medical Sciences, Mashhad, Iran.
authors.forename: Safora
authors.initials: S
authors.lastname: Afshari
authors.affiliation: DDS, Dentist, Mashhad University of Medical Sciences, Mashhad, Iran.
authors.forename: Fatemeh
authors.initials: F
authors.lastname: Manari