title: Resistance to degradation of bonded restorations to simulated caries-affected primary dentin.
abstract: OBJECTIVE
  To investigate the resistance to degradation of resin modified glass-ionomer cement (RMGIC) and adhesive/composite restorations in sound and simulated caries-affected dentin of primary teeth subjected to carious challenge using a pH-cycling model and load-cycling, by means of a microtensile test.
  
  
  METHODS
  Occlusal cavities were prepared in 60 sound exfoliated primary second molars. Half the specimens were submitted to pH-cycling to induce simulated caries lesion. The teeth were randomly restored with one of the two materials: (1) a RMGIC (Vitremer) and (2) a total-etch adhesive system (Adper Single Bond 2) followed by resin composite (Filtek Z100). After storage in distilled water at 37 degrees C for 24 hours, control group specimens were subjected to test procedures while the specimens in the experimental groups were subjected to two different aging methods: load-cycling (50,000 cycles, 90N, 3Hz) or carious challenge (pH-cycling: alternately 8 hours in demineralizing and 16 hours in remineralizing solutions, for 10 days). Teeth were sectioned into 1 mm2 beams and tested to failure under tension. ANOVA and multiple-comparisons tests were used (P<0.05).
  
  
  RESULTS
  Vitremer bond strength was not altered by the condition of dentin. Conversely, Adper Single Bond 2 showed significantly lower bond strength values when bonded to simulated caries-affected dentin. Load-cycling did not influence bond strength for any of the tested materials, while carious challenge resulted in a significant decrease in microtensile bond strengths of Adper Single Bond 2, but not of Vitremer restorations.
authors.affiliation: Department of Orthodontics and Pediatric Dentistry, University of São Paulo, USP, Brazil.
authors.forename: Marcela
authors.initials: M
authors.lastname: Marquezan
authors.forename: Raquel
authors.initials: R
authors.lastname: Osorio
authors.forename: Ana Lidia
authors.initials: AL
authors.lastname: Ciamponi
authors.forename: Manuel
authors.initials: M
authors.lastname: Toledano
mesh_terms: D003188:Composite Resins; D001840:Dental Bonding; D003731:Dental Caries / Q000473:pathology*; D019232:Dental Restoration Failure; D003793:Dental Restoration, Permanent / Q000379:methods; D003799:Dental Stress Analysis; D003804:Dentin / Q000473:pathology* / Q000648:ultrastructure; D017220:Dentin-Bonding Agents; D005899:Glass Ionomer Cements; D006801:Humans; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D019279:Resin Cements; D013718:Tensile Strength; D014094:Tooth, Deciduous
chemical_list: D003188:Composite Resins; D017220:Dentin-Bonding Agents; D005899:Glass Ionomer Cements; D019279:Resin Cements