title: Effect of glass-fiber reinforcement and water storage on fracture toughness (KIC) of polymer-based provisional crown and FPD materials.
abstract: OBJECTIVE
  The effect of glass-fiber reinforcement and water storage on the fracture toughness (KIC) of polymer-based provisional crown and fixed partial denture (FPD) materials was investigated.
  
  
  METHODS
  Five unreinforced single-edged, notched control specimens and five test specimens reinforced with unidirectional E-glass fibers (Stick) were fabricated from three dimethacrylate-based provisional materials and one monomethacrylate-based provisional material. The specimens were stored in water at 37 degrees C for 1, 7, 30, or 60 days. Specimens were loaded in three-point bending at a cross-head speed of 0.1 mm/s. Mode I plane-strain KIC was calculated using the maximum load, and results of the two groups were compared. The water storage effect on KIC with time was also evaluated.
  
  
  RESULTS
  The KIC of provisional materials reinforced with glass fibers (range 7.5 to 13.8 MNm(-1.5)) was significantly higher than that of unreinforced materials (range 1.3 to 3.1 MNm(-1.5)), by a factor of 4.4 to 5.5. A small, gradual decrease of KIC in reinforced specimens occurred with aqueous storage, but it was not statistically significant.
  
  
  CONCLUSIONS
  The KIC of polymer-based provisional crown and FPD materials was significantly increased when they were reinforced with unidirectional E-glass fibers. Water storage for up to 2 months still left the reinforced materials with KIC values in excess of 7 MNm(-1.5). Hence, their performance was satisfactory.
authors.affiliation: Department of Prosthetic Dentistry, Ewha Womans University, Seoul, Republic of Korea. ksh1250@ewha.ac.kr
authors.forename: Sung-Hun
authors.initials: SH
authors.lastname: Kim
authors.forename: David Christopher
authors.initials: DC
authors.lastname: Watts
mesh_terms: D000180:Acrylic Resins; D000704:Analysis of Variance; D003188:Composite Resins; D003442:Crowns; D003794:Dental Restoration, Temporary; D003799:Dental Stress Analysis; D003830:Denture, Partial, Fixed; D003833:Denture, Partial, Temporary; D004356:Drug Storage; D004548:Elasticity; D005898:Glass; D008422:Materials Testing; D008689:Methacrylates; D018583:Pliability; D011109:Polymethacrylic Acids; D014867:Water
chemical_list: D000180:Acrylic Resins; D003188:Composite Resins; D008689:Methacrylates; D011109:Polymethacrylic Acids; C488491:Quicktemp; C483029:Temphase; C009753:fiberglass; D014867:Water; C091347:vinyl ethyl methacrylate; C069714:Protemp