title: Fiber-reinforced composite substructure: load-bearing capacity of an onlay restoration and flexural properties of the material.
abstract: OBJECTIVE
  The aim of this study was to determine the static load-bearing capacity of composite resin onlay restorations made of particulate filler composite (PFC) with two different types of fiber-reinforced composite (FRC) substructures. In addition, flexural properties of the material combination and the effect of polymerization devices were tested.
  
  
  METHODS
  Specimens were prepared to simulate an onlay restoration, which consisted of 2 to 3 mm of FRC layer as a substructure (short random and continuous bidirectional fiber orientation) and a 1 mm surface layer of PFC. Control specimens were prepared from plain PFC. In Group A the specimens were incrementally polymerized only with a hand-light curing unit for 40 s, while in Group B the specimens were post-cured in a light-curing oven for 15 min before they were statically loaded with a steel ball. Bar-shaped test specimens were prepared to measure the flexural properties of material combination using a three-point bending test (ISO 10477).
  
  
  RESULTS
  Analysis of variance (ANOVA) revealed all specimens with a FRC substructure have higher values of static load-bearing capacity and flexural properties than those obtained with plain PFC (p<0.001).
  
  
  CONCLUSIONS
  The load-bearing capacity of all the specimens decreased after post-curing and water storage. Restorations made from a material combination of FRC and PFC showed better mechanical properties than those obtained with plain PFC.
authors.affiliation: Institute of Dentistry, University of Turku, Finland. sufgar@utu.fi
authors.forename: Sufyan K
authors.initials: SK
authors.lastname: Garoushi
authors.forename: Lippo V J
authors.initials: LV
authors.lastname: Lassila
authors.forename: Arzu
authors.initials: A
authors.lastname: Tezvergil
authors.forename: Pekka K
authors.initials: PK
authors.lastname: Vallittu
mesh_terms: D000704:Analysis of Variance; D003188:Composite Resins / Q000737:chemistry* / Q000528:radiation effects; D003799:Dental Stress Analysis; D004548:Elasticity; D005898:Glass; D006244:Hardness; D007284:Inlays; D008422:Materials Testing; D010316:Particle Size; D044367:Phase Transition; D018583:Pliability; D019904:Polymethyl Methacrylate / Q000737:chemistry / Q000528:radiation effects
chemical_list: D003188:Composite Resins; C444701:Filtek Z250; C485628:Stick resin; C009753:fiberglass; D019904:Polymethyl Methacrylate