title: The effect of glass fiber-reinforced epoxy resin dowel diameter on the fracture resistance of endodontically treated teeth.
abstract: OBJECTIVE
  To determine the effect of glass fiber-reinforced epoxy resin (FRC) dowels of different diameters on the failure load of endodontically treated teeth with different remaining dentine and reinforcing resin composite (RRC) thicknesses and the mode of failure in each group.
  
  
  METHODS
  Fifty extracted intact human maxillary central incisors were decoronated 2 mm incisal to the buccal cementoenamel junction and endodontically treated. The teeth were randomly assigned to one of five groups (n = 10): group B, dowel space prepared with size 0 dowel drill/size 0 FRC dowel/no RRC; group W, size 1 dowel space/size 1 FRC dowel/no RRC; group R, size 3 dowel space/size 3 FRC dowel/no RRC; group WR, size 3 dowel space/size 1 FRC dowel/RRC; group BR, size 3 dowel space/size 0 FRC dowel/RRC. Ferrules of 2 and 0.5 mm were prepared at the facio-lingual and proximal margin respectively. All specimens were restored with a Ni-Cr crown, thermocycled and loaded at 135° from the long axis in a universal testing machine at a 0.5 mm/min crosshead speed until fracture. Data were analyzed using ANOVA followed by post hoc comparisons (Bonferroni) with α = 0.05.
  
  
  RESULTS
  Mean failure loads (N) for groups B, W, R, WR, and BR were as follows: 1406 (SD = 376), 1259 (379), 1085 (528), 959 (200), and 816 (298). Significant differences were found between groups B and BR. Group B had the highest favorable failure mode.
  
  
  CONCLUSIONS
  Within the limitations of this study, the use of a smaller FRC dowel and RRC is recommended rather than enlargement of dowel spaces to accurately fit larger FRC dowels, as the enlargement of dowel space may increase the risk of unfavorable failure.
authors.affiliation: Department of Conservative Dentistry, University of Malaya, Kuala Lumpur, Malaysia.
authors.forename: Kuan Chuan
authors.initials: KC
authors.lastname: Tey
authors.forename: Joo Loon
authors.initials: JL
authors.lastname: Lui
mesh_terms: D002858:Chromium Alloys / Q000737:chemistry; D003188:Composite Resins / Q000737:chemistry; D003442:Crowns; D003764:Dental Materials / Q000737:chemistry*; D017267:Dental Prosthesis Design; D003786:Dental Pulp Cavity / Q000648:ultrastructure; D003799:Dental Stress Analysis / Q000295:instrumentation; D003804:Dentin / Q000648:ultrastructure; D004853:Epoxy Resins / Q000737:chemistry*; D005898:Glass / Q000737:chemistry*; D006801:Humans; D008422:Materials Testing; D011176:Post and Core Technique / Q000295:instrumentation*; D011897:Random Allocation; D019279:Resin Cements / Q000737:chemistry; D018915:Root Canal Preparation / Q000295:instrumentation; D013314:Stress, Mechanical; D013499:Surface Properties; D013696:Temperature; D014082:Tooth Fractures / Q000503:physiopathology*; D019231:Tooth Preparation, Prosthodontic / Q000379:methods; D019553:Tooth, Nonvital / Q000503:physiopathology* / Q000628:therapy
chemical_list: D002858:Chromium Alloys; D003188:Composite Resins; D003764:Dental Materials; D004853:Epoxy Resins; D019279:Resin Cements; C009753:fiberglass
keywords: Glass fiber dowel; diameter; dowel and core; endodontically treated teeth; fracture resistance; reinforcing resin composite