title: Fracture resistance of upper central incisors restored with different posts and cores.
abstract: OBJECTIVE
  To determine and compare the fracture resistance of endodontically treated maxillary central incisors restored with different posts and cores.
  
  
  METHODS
  Forty-eight upper central incisors were randomly divided into four groups: cast post and core (group 1), fiber-reinforced composite (FRC) post and composite core (group 2), composite post and core (group 3), and controls (group 4). Mesio-distal and bucco-lingual dimensions at 7 and 14 mm from the apex were compared to ensure standardization among the groups. Twelve teeth were prepared for crown restoration (group 4). Teeth in other groups were endodontically treated, decoronated at 14 mm from the apex, and prepared for posts and cores. Resin-based materials were used for cementation in groups 1 and 2. In group 3, composite was used directly to fill the post space and for core build-up. All samples were restored by standard metal crowns using glass ionomer cement, mounted at 135° vertical angle, subjected to thermomechanical aging, and then fractured using a universal testing machine. Kruskal-Wallis and Mann-Whitney U tests were used to analyze the data.
  
  
  RESULTS
  Fracture resistance of the groups was as follows: Control (group 4) > cast post and core (group 1) > fiber post and composite core (group 2) > composite post and core (group 3). All samples in groups 2 and 3 fractured in restorable patterns, whereas most (58%) in group 1 were non-restorable.
  
  
  CONCLUSIONS
  Within the limitations of this study, FRC posts showed acceptable fracture resistance with favorable fracture patterns for reconstruction of upper central incisors.
authors: Dental Material Research Center, Faculty of Dentistry, Babol University of Medical Sciences, Babol, Iran. ; Department of Prosthodontics, Faculty of Dentistry, Babol University of Medical Sciences, Babol, Iran.
authors: Maryam
authors: M
authors: Rezaei Dastjerdi
authors: Dental Material Research Center, Faculty of Dentistry, Babol University of Medical Sciences, Babol, Iran. ; Department of Prosthodontics, Faculty of Dentistry, Babol University of Medical Sciences, Babol, Iran.
authors: Kamran
authors: K
authors: Amirian Chaijan
authors: Department of Prosthodontics, Faculty of Dentistry, Babol University of Medical Sciences, Babol, Iran.
authors: Saeid
authors: S
authors: Tavanafar
keywords: Cast post and core; Fiber-reinforced composite; Fracture resistance; Thermo-mechanical aging