title: Effect of fiber position and orientation on fracture load of fiber-reinforced composite.
abstract: OBJECTIVE
  The aim of this study was to determine the effect of fiber position and orientation on the initial and final fracture loads of fiber-reinforced composite (FRC).
  
  
  METHODS
  Test specimens made of two indirect particulate composites (BelleGlass HP, Kerr, Orange, CA) or (Targis, Ivoclar Vivadent, Amherst, NY) were reinforced with ultra high molecular weight polyethylene (UHMWPE) fiber ribbon (Connect, Kerr, Orange, CA), woven E-glass fibers (Vectris Frame, Ivoclar Vivadent, Amherst, NY) or unidirectional R-glass fibers (Vectris Pontic, Ivoclar Vivadent, Amherst, NY). Fibers were placed with different positions, orientations or geometry into the rhombic test specimens (2 x 2 x 25 mm3). Control specimens did not contain fiber reinforcement. The test specimens (n=6) were stored in distilled water for 1 week at 37 degrees C before testing in a three-point loading test to determine the initial and final fracture load values.
  
  
  RESULTS
  Initial failure loads varied from 22.6 to 172.1 N. The lowest value resulted from one UHMWPE reinforcement fiber located in diagonal orientation and the highest from two unidirectional glass fiber reinforcements, one located on the tension side and the second on the compression side.
  
  
  CONCLUSIONS
  Position and fiber orientation influenced the load to initial and final failure, and specimen deflection. Tension side reinforcement was most effective in increasing the load to initial and final fracture.
authors.affiliation: Department of Restorative Dentistry, Division of Biomaterials and Biomechanics, Division of Prosthodontics, School of Dentistry, Oregon Health and Science University, 611 SW Campus Drive, Portland, OR 97239, USA. dyers@ohsu.edu
authors.forename: Scott R
authors.initials: SR
authors.lastname: Dyer
authors.forename: Lippo V J
authors.initials: LV
authors.lastname: Lassila
authors.forename: Mikko
authors.initials: M
authors.lastname: Jokinen
authors.forename: Pekka K
authors.initials: PK
authors.lastname: Vallittu
mesh_terms: D000704:Analysis of Variance; D003188:Composite Resins / Q000737:chemistry*; D019232:Dental Restoration Failure; D003799:Dental Stress Analysis / Q000379:methods; D019544:Equipment Failure Analysis; D005898:Glass; D005899:Glass Ionomer Cements; D008422:Materials Testing; D008689:Methacrylates / Q000737:chemistry*; D011095:Polyethylenes; D012823:Silicate Cement; D018709:Statistics, Nonparametric; D013718:Tensile Strength
chemical_list: D003188:Composite Resins; C495566:Connect resin; D005899:Glass Ionomer Cements; D008689:Methacrylates; D011095:Polyethylenes; C485630:Vectris Pontic; C110370:belleGlass; C111282:dental polyglass; C009753:fiberglass; D012823:Silicate Cement