title: Fracture resistance of endodontically restored, weakened incisors.
abstract: OBJECTIVE
  To test the fracture strength of weakened bovine incisors endodontically treated with mineral trioxide aggregate (MTA), calcium phosphate bone cement (CPBC) or fibre reinforced composite (FRC) posts, and to evaluate the fracture mode.
  
  
  METHODS
  Weakened bovine incisors (n = 75), standardized according to the dentinal wall thickness at the cervical area, were randomly assigned to one control group and three experimental groups. Unfilled teeth were assigned to group 1 (n = 20) and served as control group. Group 2 (n = 17) consisted of teeth filled with MTA. In group 3 (n = 18), the incisors were filled with CPBC and in group 4 (n = 20) with FRC posts. All specimens were subjected to load at a cross-head speed of 60 mm min(-1) until fracture occurred. The initial (IL) and final fracture (FL) loads (N) were recorded, and the failure mode among the different groups was evaluated.
  
  
  RESULTS
  anova showed a statistically significant difference in fracture load among the groups. Tukey's test revealed a significant difference for the IL between the control group and the experimental groups with exception of the MTA group. The FL was not significantly different among the experimental groups. A high percentage of favourable fractures was seen in the FRC and CPBC groups.
  
  
  CONCLUSIONS
  FRC posts and CPBC could be promising materials to strengthen non-vital structurally compromised teeth.
authors.affiliation: Department of Paediatric Dentistry and Special Care - Paecomedis Research Group Research, Ghent University, Ghent, Belgium.
authors.forename: Rita G E C
authors.initials: RGEC
authors.lastname: Cauwels
authors.affiliation: Department of Biomaterials Science and Turku Clinical Biomaterials Centre - TCBC, Institute of Dentistry, University of Turku, Turku, Finland.
authors.forename: Lippo V J
authors.initials: LVJ
authors.lastname: Lassila
authors.affiliation: Department of Paediatric Dentistry and Special Care - Paecomedis Research Group Research, Ghent University, Ghent, Belgium.
authors.forename: Luc C
authors.initials: LC
authors.lastname: Martens
authors.affiliation: Department of Biomaterials Science and Turku Clinical Biomaterials Centre - TCBC, Institute of Dentistry, University of Turku, Turku, Finland.
authors.forename: Pekka K
authors.initials: PK
authors.lastname: Vallittu
authors.affiliation: Department of Basic Medical Science-Biomaterials Group, Ghent University, Ghent, Belgium.
authors.forename: Ronald M H
authors.initials: RMH
authors.lastname: Verbeeck
mesh_terms: D000293:Adolescent; D001938:Brazil; D002648:Child; D005260:Female; D006801:Humans; D008297:Male; D012390:Root Canal Therapy; D014082:Tooth Fractures
keywords: MTA; calcium phosphate bone cement; fibre reinforced composite post; fracture resistance; immature teeth