title: The effect of surface roughness on repair bond strength of light-curing composite resin to polymer composite substrate.
abstract: OBJECTIVE
  The purpose of this study was to analyze the shear bond strength of a new composite resin to polymer-based composite substrates using various surface roughnesses and two kinds of polymer matrices.
  
  
  METHODS
  Particulate filler composite resin with cross-linked polymer matrix and fiber-reinforced composite with semi-interpenetrating polymer matrix were used as bonding substrates after being ground to different roughnesses. Substrates were aged in water for one week before bonding to new resin composites. Twelve specimens in the substrate groups were ground with grinding papers of four grits; 320, 800, 1200 and 2400.
  
  
  RESULTS
  Corresponding values of surface roughness (Ra) varied from 0.09 to 0.40 for the particulate filler composite resin and 0.07 to 0.96 for the fiber-reinforced composite resin. Characteristic shear bond strength between the new resin and particulate filler composite resin was highest (27.8 MPa) with the roughest surface (Weibull modulus: 2.085). Fiber-reinforced composite showed the highest bond strength (20.8 MPa) with the smoothest surface (Weibull modulus: 4.713).
  
  
  CONCLUSIONS
  We concluded that surface roughness did not increase the bonding of new resin to the substrate of IPN based fiber-reinforced composite, whereas the roughness contributed to bonding the new resin to the particulate filler composite resin with a cross-linked polymer matrix.
authors.affiliation: Department of Biomaterials Science and Turku Clinical Biomaterials Centre - TCBC, Institute of Dentistry, University of Turku, Turku, Finland.
authors.forename: Timo T
authors.initials: TT
authors.lastname: Kallio
authors.forename: Arzu
authors.initials: A
authors.lastname: Tezvergil-Mutluay
authors.forename: Lippo V J
authors.initials: LV
authors.lastname: Lassila
authors.forename: Pekka K
authors.initials: PK
authors.lastname: Vallittu
keywords: Bond strength; adhesion; bonding.; composite; repair