title: Bond strength of dental nanocomposites repaired with a bulkfill composite.
abstract: BACKGROUND
  The aim of this study was to analyze the bond strength of aged resin based nanocomposites repaired with the same and bulk fill composites.
  
  
  METHODS
  Seventy-two disc shaped resin composites consisted of three different nanocomposite resins (Filtek Ultimate/FU, Herculite XRV Ultra/HXRV, and Reflectys/R) were produced. After storing the samples for 8 weeks in distilled water, each material was combined with the same material or the bulk-fill composite resin system (Filtek Ultimate+Filtek Ultimate/Group-1; Filtek Ultimate+Tetric BF/Group-2; Herculite XRV+Herculite XRV/Group-3; Herculite XRV+Tetric BF/ Group-4; Reflectys+Reflectys/Group 5; Reflectys+Tetric BF/Group-6), for repair. Then specimens were subjected to shear bond strength testing(SBS), and the debonded surfaces were examined.
  
  
  RESULTS
  There was a significant difference among three materials(repaired with itself+bulk fill) for SBS testing values (p=0.001). FU and R were found to be similar, while HXRV was significantly different from them. A significant difference between group-1 and 2 (p=0.006) was detected, while there were no differences between group 3 and 4 (p= 0.142), and 5 and 6 (p=0.346). Among the six groups, repair SBS testing values with TBF were higher than repair with itself except for FU.
  
  
  CONCLUSIONS
  The bulk-fill repaired materials showed higher bond strength except for FU, which showed the highest SBS value when repaired with itself. An increased incidence of adhesive fracture was observed at low strengths.Key words:Resin-based composites, nanofillers, surface treatment, macro-shear, repair.
authors.affiliation: Postdoc Researcher, Hacettepe University, Department of Restorative Dentistry.
authors.forename: Uzay
authors.initials: U
authors.lastname: Koç-Vural
authors.affiliation: Research Assistant, Hacettepe University, Department of Restorative Dentistry.
authors.forename: Leyla
authors.initials: L
authors.lastname: Kerimova
authors.affiliation: Postdoc Researcher, Ankara University, Department of Restorative Dentistry.
authors.forename: İsmail H
authors.initials: İH
authors.lastname: Baltacioglu
authors.affiliation: Professor, Hacettepe University, Department of Restorative Dentistry.
authors.forename: Arlin
authors.initials: A
authors.lastname: Kiremitçi