title: Composite-composite repair bond strength: effect of different adhesion primers.
abstract: OBJECTIVE
  Recently, new products have been introduced to repair composite restorations that may be used as 'one-step' primers or monomers and silane compounds which are used separately as 'multi-step' primers. The aim of this study was to compare the shear bond strength of the new composite resin to aged composite, by using different adhesion primers.
  
  
  METHODS
  The substrates were particulate filler composite (Z250, 3M-ESPE), which was aged by boiling for 8 h and storing at 37 degrees C in water for 3 weeks. The aged substrate surfaces were wet-ground flat with 320-grit silicon carbide paper and subjected randomly (n=8) to either one-step adhesion primer: Compoconnect (CC) (Heraus Kulzer), or multi-step: Clearfil Repair (CF) (Kuraray) or an intermediate resin: Scothchbond Multi-purpose adhesive resin (3M-ESPE) according to the manufacturers' recommendations. Specimens with no surface treatment were used as control (C). New composite resin (Z250) was added to the substrate using 2 mm layer increments and light cured. The specimens were either water stored for 48 h or water stored for 24 h and then thermocycled for 6000 cycles. The shear bond strengths were measured with a crosshead speed of 1.0 mm/min using a universal testing machine. Data were analysed by two-way ANOVA and Tukey's post-hoc tests (p=0.05).
  
  
  RESULTS
  All surface treatment methods showed significant difference compared to control (p<0.05). CF showed higher bond strength than CC and MP (p<0.05). Storage condition did not show a significant difference (p>0.05) in bond strength values.
  
  
  CONCLUSIONS
  It was concluded that multi-step adhesion primer yielded higher bond strength compared to one-step primer or intermediate resin.
authors.affiliation: Department of Prosthetic Dentistry and Biomaterials Research, Institute of Dentistry, University of Turku, Lemminkäisenkatu 2, FIN-20520 Turku, Finland. arztez@utu.fi
authors.forename: A
authors.initials: A
authors.lastname: Tezvergil
authors.forename: L V J
authors.initials: LV
authors.lastname: Lassila
authors.forename: P K
authors.initials: PK
authors.lastname: Vallittu
mesh_terms: D000704:Analysis of Variance; D003188:Composite Resins / Q000737:chemistry*; D001840:Dental Bonding; D017269:Dental Prosthesis Repair; D003793:Dental Restoration, Permanent; D006801:Humans; D019279:Resin Cements / Q000737:chemistry*; D013314:Stress, Mechanical; D013499:Surface Properties; D013696:Temperature; D013997:Time Factors; D014867:Water / Q000737:chemistry
chemical_list: C480092:Clearfil repair; D003188:Composite Resins; C444701:Filtek Z250; D019279:Resin Cements; C084018:Scotchbond Multi-Purpose; C480091:compoconnect; D014867:Water