title: The static strength and modulus of fiber reinforced denture base polymer.
abstract: OBJECTIVE
  Partial fiber reinforcements have been employed to strengthen dentures both during repair and in the manufacturing process. The reinforcing fibers can be evenly distributed in the denture base polymer or alternatively fiber-rich phase in the denture base polymer can form a separate structure. The aim of this study was to determinate static three-point flexural strength and modulus of denture base polymer that had been reinforced with different fiber reinforcements.
  
  
  METHODS
  The test specimens (3 x 5 x 50 mm) were made of auto-polymerized denture base polymer and reinforced with different fiber reinforcements. The test groups were: (A) no fibers; (B) non-impregnated polyethylene fibers; (C) light-polymerized monomer impregnated glass fibers; (D) porous polymer preimpregnated glass fibers and (E) light-polymerized monomer-polymer impregnated glass fibers. The fibers were oriented parallel to the long axis of the specimen and embedded into the denture base resin on the compression side (n=7) or tension side (n=7). Dry specimens were tested with three-point static flexural strength test set-up at crosshead speed of 5 mm/min.
  
  
  RESULTS
  The statistical analysis by two-way analysis of variance showed that the brand and the location of the fiber reinforcements significantly influenced the flexural strength (p<0.0001). However, the location of the fiber reinforcements did not influence the flexural modulus (p<0.722).
  
  
  CONCLUSIONS
  The results suggest that impregnated and preimpregnated fibers reinforce denture base polymer more than non-impregnated fibers. Fiber reinforcements placed on the tensile side resulted in considerably higher flexural strength and flexural modulus values compared with same quantity of fibers placed on the compression side.
authors.affiliation: Department of Prosthetic Dentistry and Biomaterials Research, Institute of Dentistry, University of Turku, Lemminkäisenkatu 2, FIN-20520 Turku, Finland. katja.narva@utu.fi
authors.forename: Katja K
authors.initials: KK
authors.lastname: Narva
authors.forename: Lippo V
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; D019245:Compressive Strength; D003799:Dental Stress Analysis; D003819:Denture Bases; D004548:Elasticity; D005898:Glass; D008422:Materials Testing; D044367:Phase Transition; D018583:Pliability; D020959:Polyethylene; D011095:Polyethylenes / Q000737:chemistry; D019904:Polymethyl Methacrylate / Q000737:chemistry; D013718:Tensile Strength
chemical_list: D000180:Acrylic Resins; D003188:Composite Resins; C113550:FiberKor, sculpture; D011095:Polyethylenes; C084063:RIBBOND; C485628:Stick resin; C496140:everStick; C009753:fiberglass; D020959:Polyethylene; D019904:Polymethyl Methacrylate