title: Comparison of the fracture resistance of endodontically treated teeth restored with prefabricated posts and composite resin cores with different post lengths.
abstract: OBJECTIVE
  This study evaluated the fracture strengths of endodontically treated teeth restored with prefabricated posts with different post lengths.
  
  
  METHODS
  Thirty freshly extracted canines were endodontically treated. They were randomly divided into groups of 10 teeth and prepared according to 3 experimental protocols, as follows; Group 1/3 PP: teeth restored with prefabricated post and composite resin core (Z250) with post length of 5.0mm; Group 1/2 PP and Group 2/3 PP: teeth restored with prefabricated post and composite resin core (Z250) with different combinations of post length of 7.5mm and 10mm, respectively. All teeth were restored with full metal crowns. The fracture resistance (N) was measured in a universal testing machine (crosshead speed 0.5mm/min) at 45 degrees to the tooth long axis until failure. Data were analyzed by one-way analysis of variance (alpha=.05).
  
  
  RESULTS
  The one-way analysis of variance demonstrated no significant difference among the different post lengths (P>.05) (Groups 1/3 PP = 405.4 N, 1/2 PP = 395.6 N, 2/3 PP = 393.8 N). Failures occurred mainly due to core fracture.
  
  
  CONCLUSIONS
  The results of this study showed that an increased post length in teeth restored with prefabricated posts did not significantly increase the fracture resistance of endodontically treated teeth.
authors.affiliation: Department of Prosthodontics, Bauru School of Dentistry, University of São Paulo.
authors.forename: Accácio Lins
authors.initials: AL
authors.lastname: do Valle
authors.forename: Jefferson Ricardo
authors.initials: JR
authors.lastname: Pereira
authors.forename: Fábio Kenji
authors.initials: FK
authors.lastname: Shiratori
authors.forename: Luiz Fernando
authors.initials: LF
authors.lastname: Pegoraro
authors.forename: Gerson
authors.initials: G
authors.lastname: Bonfante