title: Effect of water storage on the flexural properties of three glass fiber-reinforced composites.
abstract: OBJECTIVE
  The effect of water sorption on the flexural strength and flexural modulus of three fiber-reinforced composites was studied.
  
  
  METHODS
  Bar-shaped specimens of each material were prepared according to the manufacturers' instructions. The flexural strength and modulus of each specimen were tested after the specimens were immersed in distilled water for 1, 7, 60, and 180 days. SEMs were taken to examine the mode of failure. The volume percentage of fiber content of each fiber-reinforced composite was experimentally estimated.
  
  
  RESULTS
  The ascending order of flexural strength and modulus among the materials was generally: FibreKor < Stick < Vectris. The flexural strengths of Stick and FibreKor specimens at 1 and 180 days were not significantly different. Although the 180-day Vectris specimens possessed significantly lower flexural strength than the 1-day specimens, the flexural strengths of Vectris specimens at 1, 7, 60, and 180 days remained significantly higher than those of Stick and FibreKor. The difference in flexural modulus for each fiber-reinforced composite related to the duration of water immersion was not significant.
  
  
  CONCLUSIONS
  Water immersion affected the flexural strengths of the three composites to a different degree but did not affect their flexural moduli significantly. For each duration of water immersion, the flexural property of the fiber-reinforced composite, in ascending order of significant difference, was: FibreKor < Stick < Vectris.
authors.affiliation: Northwestern University, Evanston, Illinois, USA. jchai@northwestern.edu
authors.forename: John
authors.initials: J
authors.lastname: Chai
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Takahashi
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Hisama
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Shimizu
mesh_terms: D000704:Analysis of Variance; D003188:Composite Resins / Q000737:chemistry; D003799:Dental Stress Analysis; D004548:Elasticity; D005898:Glass; D007101:Immersion; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D018583:Pliability; D019904:Polymethyl Methacrylate; D018709:Statistics, Nonparametric; D014867:Water
chemical_list: D003188:Composite Resins; C113550:FiberKor, sculpture; C485628:Stick resin; C485630:Vectris Pontic; C009753:fiberglass; D014867:Water; D019904:Polymethyl Methacrylate