Long-term TEM analysis of the nanoleakage patterns in resin-dentin interfaces produced by different bonding strategies.
OBJECTIVE
The aim of this study was to evaluate the ability of etch-and-rinse and self-etching adhesive systems to prevent time- and water-induced nanoleakage in resin-dentin interfaces over a 6-month storage period.


METHODS
Five commercial adhesives were tested, which comprise three different strategies of bonding resins to tooth hard tissues: one single-step self-etching adhesive (One-up Bond F (OB), Tokuyama); two two-step self-etching primers (Clearfil SE Bond (SE) and an antibacterial fluoride-containing system, Clearfil Protect Bond (CP), Kuraray Inc.); two two-step etch-and-rinse adhesives (Single Bond (SB), 3M ESPE and Prime&Bond NT (PB), Dentsply). Restored teeth were sectioned into 0.9 mm thick slabs and stored in water or mineral oil for 24 h, 3 or 6 months. A silver tracer solution was used to reveal nanometer-sized water-filled spaces and changes that occurred over time within resin-dentin interfaces. Characterization of interfaces was performed with the TEM.


RESULTS
The two two-step self-etching primers showed little silver uptake during the 6-month experiment. Etch-and-rinse adhesives exhibited silver deposits predominantly within the hybrid layer (HL), which significantly increased for SB after water-storage. The one-step self-etching adhesive OB presented massive silver accumulation within the HL and water-trees protruding into the adhesive layer, which increased in size and quantity after water-storage. After storage in oil, reduced silver deposition was observed at the interfaces for all groups.


CONCLUSIONS
Different levels of water-induced nanoleakage were observed for the different bonding strategies. The two-step self-etching primers, especially the antibacterial fluoride-containing system CP, showed the least nanoleakage after 6 months of storage in water.
Reis
Andre F
AF
Department of Restorative Dentistry, Division of Operative Dentistry, Piracicaba School of Dentistry, University of Campinas, Av. Limeira 901, Piracicaba, CEP 13414-903, SP, Brazil.
Giannini
Marcelo
M
Pereira
Patricia N R
PN
D000134:Acid Etching, Dental / Q000379:methods; D017438:Bisphenol A-Glycidyl Methacrylate / Q000737:chemistry; D001840:Dental Bonding / Q000379:methods*; D003763:Dental Leakage / Q000145:classification*; D003804:Dentin / Q000648:ultrastructure*; D017220:Dentin-Bonding Agents / Q000737:chemistry*; D006801:Humans; D008422:Materials Testing; D008689:Methacrylates / Q000737:chemistry; D046529:Microscopy, Electron, Transmission; D008899:Mineral Oil / Q000737:chemistry; D036103:Nanotechnology; D011109:Polymethacrylic Acids / Q000737:chemistry; D019279:Resin Cements / Q000737:chemistry; D016622:Silver Staining; D013499:Surface Properties; D013997:Time Factors; D014867:Water / Q000737:chemistry
C503075:Clearfil Protect Bond; C438313:Clearfil SE Bond; D017220:Dentin-Bonding Agents; D008689:Methacrylates; C446260:One-Up-Bond F; D011109:Polymethacrylic Acids; C425843:Prime and Bond NT; D019279:Resin Cements; C115612:single bond; D014867:Water; D017438:Bisphenol A-Glycidyl Methacrylate; D008899:Mineral Oil