title: Fatigue resistance of endodontically treated teeth restored with three dowel-and-core systems.
abstract: BACKGROUND
  The successful restoration of endodontically treated teeth is enhanced by a crown design employing the ferrule effect. However, it is unclear which dowel-and-core system most effectively supports successful treatment.
  
  
  OBJECTIVE
  The purpose of this study was to compare the load fatigue resistance of 3 dowel-and-core systems.
  
  
  METHODS
  Fifteen endodontically treated maxillary central incisors were sectioned perpendicular to the long axis at a point 1.5 mm incisal to the cemento-enamel junction (CEJ). At the level of the CEJ, specimens were then prepared for crowns with 1-mm complete shoulder finish lines and 1.5 mm of axial wall height. The prepared teeth were divided into 3 groups (n=5) and restored with 1 of the following dowel-and-core combinations: Group CG, cast gold dowels and cores; Group TA, titanium alloy dowels (ParaPost XH) with composite cores; or Group FR, fiber-reinforced resin dowels (ParaPost FiberWhite) with composite cores. A dentin bonding agent (OptiBond Solo) was placed prior to the composite cores. Dowel-and-core castings and titanium alloy dowels were cemented with zinc phosphate cement. The fiber-reinforced dowels were cemented with a resin cement (ParaPost Cement). The crowns for all specimens were cast with an incisal notch for applying the fatigue load. The independent variable measured was the number of load fatigue cycles required to cause luting cement failure. The data were subjected to 1-way analysis of variance and the Student-Newman-Keuls test for 3 subsets (alpha=.05).
  
  
  RESULTS
  The mean value+/-standard deviation for the cycles to failure for each group was: Group CG: 11,897+/-4080 load cycles, Group TA: 24,384+/-8231 load cycles, and Group FR: 50,696+/-7063 load cycles. Significant differences were found between all groups ( P<.05).
  
  
  CONCLUSIONS
  Fiber-reinforced resin dowels and bonded composite cores under fatigue loading provided significantly stronger crown retention than cast gold dowels and cores and titanium alloy dowels with composite cores under fatigue loading.
authors.affiliation: University of Washington, Seattle, WA, USA. ygoto@usc.edu
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Goto
authors.forename: Jack I
authors.initials: JI
authors.lastname: Nicholls
authors.forename: Keith M
authors.initials: KM
authors.lastname: Phillips
authors.forename: Thomas
authors.initials: T
authors.lastname: Junge
mesh_terms: D000180:Acrylic Resins / Q000737:chemistry; D000704:Analysis of Variance; D017438:Bisphenol A-Glycidyl Methacrylate / Q000627:therapeutic use; D003188:Composite Resins / Q000737:chemistry; D003442:Crowns; D003738:Dental Cements / Q000627:therapeutic use; D017268:Dental Prosthesis Retention / Q000379:methods*; D019232:Dental Restoration Failure; D006046:Gold / Q000737:chemistry; D006801:Humans; D007180:Incisor; D008437:Maxilla; D008689:Methacrylates / Q000627:therapeutic use; D011140:Polyurethanes / Q000737:chemistry; D011176:Post and Core Technique; D014025:Titanium / Q000737:chemistry; D019553:Tooth, Nonvital / Q000628:therapy*; D016474:Weight-Bearing
chemical_list: D000180:Acrylic Resins; C029012:Composite Dental Resin; D003188:Composite Resins; D003738:Dental Cements; D008689:Methacrylates; C428805:OptiBond SOLO; C488490:ParaPost Cement; D011140:Polyurethanes; D017438:Bisphenol A-Glycidyl Methacrylate; D006046:Gold; D014025:Titanium