title: Fracture strength of endodontically treated teeth with flared root canals and restored with different post systems.
abstract: BACKGROUND
  Many post systems are available to clinicians, yet no consensus exists about which one is better in restoring endodontically treated teeth.
  
  
  OBJECTIVE
  This study evaluated the fracture strength of teeth with flared canals and restored with two fiber-reinforced resin systems (glass fiber: FRC Postec [Ivoclar Vivadent, Schaan, Liechtenstein]; quartz fiber: D.T. Light-Post [Bisco Dental Products, Schaumburg, IL, USA]), and one custom cast base metal (Ni-Cr) post and core system.
  
  
  METHODS
  Thirty anterior teeth had their crowns removed below the cemento-enamel junction and were endodontically treated. The canals were prepared for post fixation, and the canal walls were flared using a taper diamond bur. The prepared roots were randomly divided into three groups according to the post system. All posts were cemented with an adhesive resin cement. For the fiber-reinforced resin posts, cores were built up using microhybrid composite. Metallic crowns were luted using zinc phosphate cement. Specimens were loaded at 45 degrees in a universal testing machine at a crosshead speed of 0.5 mm/min until failure. The mode of failure was classified as repairable or nonrepairable.
  
  
  RESULTS
  Teeth restored with cast posts had fracture strength twice that of teeth restored with resin posts. Fiber-reinforced resin posts failed at a compressive force comparable to clinical conditions, but all failures were repairable.
  
  
  CONCLUSIONS
  Fracture strength and mode of failure in anterior teeth with flared canals varied according to the type of post used to support a crown.
  
  
  CONCLUSIONS
  Under the conditions of this study, cast posts are preferable to restore endodontically treated teeth with flared canals and no ferrule.
authors.affiliation: Department of Prosthodontics, Pontifical Catholic University of Rio Grande do Sul, Porto Alegre, RS, Brazil.
authors.forename: Paulo César
authors.initials: PC
authors.lastname: Maccari
authors.forename: Dúcia Caldas
authors.initials: DC
authors.lastname: Cosme
authors.forename: Hugo Mitsuo
authors.initials: HM
authors.lastname: Oshima
authors.forename: Luiz Henrique
authors.initials: LH
authors.lastname: Burnett
authors.forename: Rosemary Sadami
authors.initials: RS
authors.lastname: Shinkai
mesh_terms: D000180:Acrylic Resins / Q000737:chemistry*; D003188:Composite Resins / Q000737:chemistry*; D003786:Dental Pulp Cavity / Q000033:anatomy & histology*; D006801:Humans; D011140:Polyurethanes / Q000737:chemistry*; D011176:Post and Core Technique; D014082:Tooth Fractures / Q000517:prevention & control*; D019553:Tooth, Nonvital / Q000150:complications*
chemical_list: D000180:Acrylic Resins; C029012:Composite Dental Resin; D003188:Composite Resins; D011140:Polyurethanes