title: Is there one optimal repair technique for all composites?
abstract: OBJECTIVE
  The aim of this study was to investigate the effectiveness of a variety of techniques to bond new composite to artificially aged composite of different compositions.
  
  
  METHODS
  Composite resin blocks were made of five different commercially available composites (n=30) (Clearfil AP-X, Clearfil PhotoPosterior, Photo Clearfil Bright, Filtek Supreme XT and HelioMolar). After aging the composite blocks (thermo-cycling 5000×), blocks were subjected to one of 9 repair procedures: no treatment (control), diamond bur, sandblasting alumina particles, CoJet™, phosphoric acid, 3% hydrofluoric acid 20s or 120s, 9.6% hydrofluoric acid 20s or 120s. In addition, the cohesive strength of the tested composites was measured. Two-phase sandwiches ('repaired composite') were prepared using each of the 9 repair protocols, successively followed by silane and adhesive (OptiBond FL) treatment, prior to the application of the same composite. Specimens were subjected to micro-tensile bond strength testing. Data were analyzed using ANOVA and Tukey's HSD (p<0.05).
  
  
  RESULTS
  For all composites the lowest bond strength was obtained when no specific repair protocol (control) was applied; the highest for the cohesive strength. Compared to the control for the microhybrid composite (Clearfil AP-X) five repair techniques resulted in a significantly higher repair strength (p<0.05), whereas for the nano-hybrid composite (Filtek Supreme XT) and hybrid composite containing quartz (Clearfil PhotoPosterior) only one repair technique significantly increased the bond strength (p<0.01).
  
  
  CONCLUSIONS
  None of the surface treatments can be recommended as a universally applicable repair technique for the different sorts of composites. To optimally repair composites, knowledge of the composition is helpful.
authors.affiliation: College of Dental Sciences, Department of Cariology, Endodontology & Pedodontology, Radboud University Nijmegen Medical Centre, The Netherlands. b.loomans@dent.umcn.nl
authors.forename: B A C
authors.initials: BA
authors.lastname: Loomans
authors.forename: M Vivan
authors.initials: MV
authors.lastname: Cardoso
authors.forename: F J M
authors.initials: FJ
authors.lastname: Roeters
authors.forename: N J M
authors.initials: NJ
authors.lastname: Opdam
authors.forename: J
authors.initials: J
authors.lastname: De Munck
authors.forename: M C D N J M
authors.initials: MC
authors.lastname: Huysmans
authors.forename: B
authors.initials: B
authors.lastname: Van Meerbeek
mesh_terms: D000134:Acid Etching, Dental; D020906:Air Abrasion, Dental; D003188:Composite Resins / Q000737:chemistry; D001840:Dental Bonding / Q000379:methods; D019232:Dental Restoration Failure; D058250:Dental Restoration Repair / Q000379:methods*; D003799:Dental Stress Analysis; D013499:Surface Properties; D013718:Tensile Strength
chemical_list: D003188:Composite Resins