Effect of pulpal pressure on the microtensile bond strength of luting resin cements to human dentin.
OBJECTIVE
The objectives of this study were to examine the effect of pulpal pressure on the microtensile bond strength (mTBS) of luting resin cements to human dentin and the permeability of dentin surfaces pre-treated with an adhesive and a self-etching primer.


METHODS
Cylindrical composite blocks were luted with resin cements (RelyX ARC, 3M ESPE: ARC; Panavia F, Kuraray Medical Inc.: PF; RelyX Unicem, 3M ESPE: UN) in the absence or presence of simulated pulpal pressure. The application of Adper Single Bond 2 (3M ESPE) and ED primer 2.0 (Kuraray) was performed under 0 cm H(2)O. After each resin cement was applied, the pulpal pressure group was subjected to 20 cm H(2)O of hydrostatic pressure for 10 min during the initial setting period. Testing for mTBS was performed on 0.9 mm x 0.9 mm sectioned beams after 24h water-storage. Scanning electron microscopy was performed to investigate the fractured surfaces after mTBS testing and additional dentin surfaces that were treated by an etchant, ED primer 2.0 and UN. Fluid permeability was measured on dentin surfaces that were applied with Adper Single Bond 2 and ED primer 2.0.


RESULTS
Application of pulpal pressure reduced mTBS significantly in groups ARC and PF. Porous bonding interfaces due to water permeability through the cured adhesive were observed on fractured surfaces. Dentin surfaces that were applied with the adhesive and the primer were more permeable than smear layer-covered dentin. The mTBS of UN was significantly lower than ARC and PF regardless of the absence/presence of pulpal pressure.


CONCLUSIONS
Fluid permeation during the initial setting period deteriorated the bonding quality of resin cements.
Faculty of Dentistry, The University of Hong Kong, Prince Philip Dental Hospital, Pokfulam, Hong Kong SAR, China. hiraishinoriko@yahoo.com
N
N
Hiraishi
C K Y
CK
Yiu
N M
NM
King
F R
FR
Tay
D000134:Acid Etching, Dental / Q000379:methods; D017438:Bisphenol A-Glycidyl Methacrylate / Q000737:chemistry; D003188:Composite Resins / Q000737:chemistry; D001840:Dental Bonding; D003782:Dental Pulp / Q000502:physiology*; D003804:Dentin / Q000648:ultrastructure*; D003806:Dentin Permeability / Q000502:physiology; D017220:Dentin-Bonding Agents / Q000737:chemistry*; D019234:Dentinal Fluid / Q000502:physiology; D006801:Humans; D006874:Hydrostatic Pressure; D008422:Materials Testing; D008689:Methacrylates / Q000737:chemistry; D008855:Microscopy, Electron, Scanning; D011092:Polyethylene Glycols / Q000737:chemistry; D011109:Polymethacrylic Acids / Q000737:chemistry; D019279:Resin Cements / Q000737:chemistry*; D016369:Smear Layer; D013314:Stress, Mechanical; D013718:Tensile Strength; D013997:Time Factors; D014867:Water / Q000737:chemistry
D003188:Composite Resins; D017220:Dentin-Bonding Agents; C500742:ED Primer II; D008689:Methacrylates; C438843:Panavia-Fluoro; D011109:Polymethacrylic Acids; C483701:Rely X Unicem; C462240:RelyX ARC; D019279:Resin Cements; C115612:single bond; D014867:Water; D011092:Polyethylene Glycols; D017438:Bisphenol A-Glycidyl Methacrylate