title: Effect of two types of composite fibers on fracture resistance of endodontically treated maxillary premolars: an in vitro study.
abstract: OBJECTIVE
  The aim of the present study was to evaluate the effect of the use of composite fibers (glass fiber and polyethylene fiber) at the gingival third of mesio-occlusodistal (MOD) cavities on the fracture resistance of endodontically treated premolars.
  
  
  METHODS
  A total of 45 extracted premolars underwent endodontic treatment. MOD cavities, 2.5 ± 0.2 mm thick at the buccal and lingual heights of contour, were prepared, with the gingival cavosurface margin 1.5 mm coronal to the cementoenamel junction. Then the teeth were randomly divided into three groups. In group 1, the cavities were restored with Z250 composite resin without the use of any fibers. In groups 2 and 3, the teeth were restored in the same manner as that in group 1 after placement of glass fiber and polyethylene fiber at the gingival third of the cavities, respectively. Subsequent to thermocycling, fracture resistance of the specimens was measured in Newton (N).
  
  
  METHODS
  Data were analyzed with one-way ANOVA and a post hoc Tukey test at a significance level of p < 0.05.
  
  
  RESULTS
  There were significant differences in the means of fracture resistance values between the three groups (p = 0.001). Statistically significant differences were observed in the fracture resistance between group 2 and groups 1 and 3 (p < 0.05). However, the differences between groups 1 and 3 were not significant (p = 0.25).
  
  
  CONCLUSIONS
  The type of fiber influenced the fracture resistance of endodontically treated human premolars.
  
  
  CONCLUSIONS
  Using glass and/or polyethylene fibers in the gingival third of composite restorations leads to different results in fracture resistance of endodontically treated maxillary premolars.
authors.affiliation: Department of Operative Dentistry, School of Dentistry, Iran.
authors.forename: Parnian Alizadeh
authors.initials: PA
authors.lastname: Oskoee
authors.forename: Mohammad Esmaeel Ebrahimi
authors.initials: ME
authors.lastname: Chaharom
authors.forename: Soodabeh
authors.initials: S
authors.lastname: Kimyai
authors.forename: Jafar Sadjadi
authors.initials: JS
authors.lastname: Oskoee
authors.forename: Sahar
authors.initials: S
authors.lastname: Varasteh
mesh_terms: D000134:Acid Etching, Dental / Q000379:methods; D001641:Bicuspid / Q000473:pathology*; D017438:Bisphenol A-Glycidyl Methacrylate / Q000737:chemistry; D003188:Composite Resins / Q000737:chemistry*; D003737:Dental Cavity Preparation / Q000145:classification / Q000379:methods; D003764:Dental Materials / Q000737:chemistry*; D003793:Dental Restoration, Permanent / Q000145:classification / Q000379:methods*; D003799:Dental Stress Analysis / Q000295:instrumentation; D017220:Dentin-Bonding Agents / Q000737:chemistry; D005898:Glass / Q000737:chemistry*; D006801:Humans; D008422:Materials Testing; D063065:Organophosphonates / Q000737:chemistry; D020959:Polyethylene / Q000737:chemistry*; D012389:Root Canal Obturation / Q000379:methods; D018915:Root Canal Preparation / Q000379:methods; D013314:Stress, Mechanical; D014082:Tooth Fractures / Q000503:physiopathology; D019553:Tooth, Nonvital / Q000628:therapy*
chemical_list: D003188:Composite Resins; D003764:Dental Materials; D017220:Dentin-Bonding Agents; C467913:Filtek Flow; C444701:Filtek Z250; D063065:Organophosphonates; C454540:Scotchbond etchant; C009753:fiberglass; C115612:single bond; D017438:Bisphenol A-Glycidyl Methacrylate; D020959:Polyethylene