title: Fiber-reinforced composite substructure: load-bearing capacity of an onlay restoration.
abstract: OBJECTIVE
  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.
  
  
  METHODS
  Specimens were prepared to simulate an onlay restoration, composed of a 2 to 3 mm FRC layer as the substructure (short random and continuous bidirectional fiber orientation) and a 1 mm surface layer of PFC. Control specimens were prepared from plain PFC. The specimens were incrementally polymerized with a hand-light curing unit for 40 s and then post-cured in a light-curing oven for 15 min. The specimens were cemented on dentin substrate of extracted human molars using a standard adhesive resin cementation technique. The specimens (n=8/group) were water stored either for 24 h at room temperature or for 4 weeks at 37 degrees C before they were statically loaded until fracture using a universal testing machine. Failure modes were visually examined.
  
  
  RESULTS
  ANOVA revealed that all specimens with FRC substructures had higher values of static load-bearing capacity than those obtained with plain PFC (p<0.001). The load-bearing capacity of all the specimens decreased after water storage (p<0.001).
  
  
  CONCLUSIONS
  Restorations made from a combination of FRC and PFC showed better load-bearing capacity than those obtained with PFC alone.
authors.affiliation: Department of Prosthetic Dentistry & Biomaterials Science, Institute of Dentistry, University of Turku, 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: Pekka K
authors.initials: PK
authors.lastname: Vallittu
mesh_terms: D000180:Acrylic Resins / Q000737:chemistry*; D000704:Analysis of Variance; D003188:Composite Resins / Q000737:chemistry*; D019232:Dental Restoration Failure; D006801:Humans; D007284:Inlays / Q000379:methods*; D008963:Molar; D011140:Polyurethanes / Q000737:chemistry*; D016474:Weight-Bearing
chemical_list: D000180:Acrylic Resins; C029012:Composite Dental Resin; D003188:Composite Resins; D011140:Polyurethanes