title: In vitro fracture resistance of four-unit fiber-reinforced composite fixed partial dentures.
abstract: OBJECTIVE
  The aim of this in vitro study was to investigate the influence of glass fiber-reinforcement on the fracture resistance of four-unit composite fixed partial dentures (FPDs) in the posterior region.
  
  
  METHODS
  A total of 70 FPDs were fabricated of the composites Sinfony, Vita Zeta and Targis. With each material, 10 FPDs were made without glass fiber-reinforcement and 10 were reinforced with the new glass fiber system EverStick. In addition, 10 FPDs were fabricated of the material combination Targis/Vectris. After thermocycling, all FPDs were loaded until failure in a universal testing machine. The FPDs were then cut and cross-sectional areas were examined by scanning electron microscopy (SEM).
  
  
  RESULTS
  The load to fracture of the fiber-reinforced FPDs lay between 615 and 1191 N, which was significantly greater than the values found with unreinforced FPDs (between 178 and 307 N). The highest values were found with the combinations Targis/Vectris (1191 N) and Sinfony/EverStick (1137 N). SEM showed that the FPDs with EverStick reinforcement not only exhibited fracture lines in the fiber-composite interface, but also more often in the area of the fiber-reinforcement than was the case with the FPDs with Vectris reinforcement. The load to fracture was not significantly dependent on fiber quantity or course of fracture.
  
  
  CONCLUSIONS
  It may be concluded that the fracture resistance of four-unit composite FPDs can be significantly raised by glass fiber frameworks (p<0.05). The reinforcement effect of EverStick depended significantly on the composite used (p<0.05).
authors.affiliation: Department of Prosthetic Dentistry, Hannover Medical School, Carl-Neuberg-Str. 1, 30625 Hannover, Germany. stiesch.meike@mh-hannover.de
authors.forename: Meike
authors.initials: M
authors.lastname: Stiesch-Scholz
authors.forename: Kerstin
authors.initials: K
authors.lastname: Schulz
authors.forename: Lothar
authors.initials: L
authors.lastname: Borchers
mesh_terms: D003188:Composite Resins / Q000737:chemistry*; D003764:Dental Materials / Q000737:chemistry*; D003799:Dental Stress Analysis / Q000295:instrumentation; D003801:Dental Veneers; D003779:Denture Design; D003830:Denture, Partial, Fixed; D005898:Glass / Q000737:chemistry*; D005899:Glass Ionomer Cements / Q000737:chemistry; D006801:Humans; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D012823:Silicate Cement / Q000737:chemistry; D013314:Stress, Mechanical; D013499:Surface Properties
chemical_list: D003188:Composite Resins; D003764:Dental Materials; D005899:Glass Ionomer Cements; C477352:Sinfony composite resin; C509999:Vita Zeta LC; C111282:dental polyglass; C496140:everStick; C009753:fiberglass; D012823:Silicate Cement