title: Fracture resistance of endodontically treated teeth restored with glass fiber posts of different lengths.
abstract: BACKGROUND
  Endodontically treated teeth are known to have reduced structural strength. Glass fiber posts may influence fracture resistance and should be evaluated.
  
  
  OBJECTIVE
  The purpose of this study was to evaluate the influence of glass fiber post length on the fracture resistance of endodontically treated teeth.
  
  
  METHODS
  Forty intact human maxillary canines were selected and divided into 4 groups, the control group consisting of teeth restored with a custom gold cast post and core, with a length of two-thirds of the root. Other groups received prefabricated glass fiber posts in different lengths: group 1/3, removal of one-third of the sealing material (5 mm); group 1/2, removal of one-half of the sealing material (7.5 mm); and group 2/3, removal of two-thirds of the sealing material (10 mm). All the posts were cemented with resin cement, and the specimens with glass fiber posts received a composite resin core. All the specimens were restored with a metal crown and submitted to a compressive load until failure occurred. The results were evaluated by 1-way ANOVA, and the all pairwise multiple comparison procedures (Tukey honestly significantly difference test) (α=.05).
  
  
  RESULTS
  The ANOVA showed significant differences among the groups (P<.002). The Tukey test showed that the control group presented significantly higher resistance to static load than the other groups (control group, 634.94 N; group 1/3, 200.01 N; group 1/2, 212.17 N; and group 2/3, 236.08 N). Although teeth restored with a cast post and core supported a higher compressive load, all of them fractured in a catastrophic manner. For teeth restored with glass fiber posts, the failure occurred at the junction between the composite resin core and the root.
  
  
  CONCLUSIONS
  The length of glass fiber posts did not influence fracture load, but cast post and cores that extended two-thirds of the root length had significantly greater fracture resistance than glass fiber posts.
authors.affiliation: Private practice, Bauru, SP, Brazil. Department of Prosthodontics, Bauru Dental School, University of São Paulo (USP), São Paulo, Brazil.
authors.forename: Erico Braga
authors.initials: EB
authors.lastname: Franco
authors.affiliation: Professor, Department of Prosthodontics, Bauru Dental School, University of São Paulo (USP), São Paulo, Brazil.
authors.forename: Accacio
authors.initials: A
authors.lastname: Lins do Valle
authors.affiliation: Professor, Department of Prosthodontics, Bauru Dental School, University of São Paulo (USP), São Paulo, Brazil.
authors.forename: Ana Lúcia
authors.initials: AL
authors.lastname: Pompéia Fraga de Almeida
authors.affiliation: Professor, Department of Prosthodontics, Bauru Dental School, University of São Paulo (USP), São Paulo, Brazil.
authors.forename: José Henrique
authors.initials: JH
authors.lastname: Rubo
authors.affiliation: Professor and Research Coordinator, Department of Prosthodontics, Dental School, University of Southern Santa Catarina (UNISUL), Santa Catarina, Brazil. Electronic address: jeffripe@rocketmail.com.
authors.forename: Jefferson Ricardo
authors.initials: JR
authors.lastname: Pereira
mesh_terms: D002484:Cementation / Q000379:methods; D003188:Composite Resins / Q000737:chemistry; D003442:Crowns; D003481:Cuspid / Q000503:physiopathology; D003722:Dental Alloys / Q000737:chemistry; D003764:Dental Materials / Q000737:chemistry*; D017267:Dental Prosthesis Design; D019232:Dental Restoration Failure; D003799:Dental Stress Analysis / Q000295:instrumentation; D005898:Glass / Q000737:chemistry*; D006047:Gold Alloys / Q000737:chemistry; D006801:Humans; D008422:Materials Testing; D011176:Post and Core Technique / Q000295:instrumentation*; D019279:Resin Cements / Q000737:chemistry; D013314:Stress, Mechanical; D013499:Surface Properties; D014082:Tooth Fractures / Q000503:physiopathology*; D014092:Tooth Root / Q000293:injuries; D019553:Tooth, Nonvital / Q000503:physiopathology* / Q000628:therapy
chemical_list: D003188:Composite Resins; D003722:Dental Alloys; D003764:Dental Materials; D006047:Gold Alloys; D019279:Resin Cements; C009753:fiberglass