Effects of storage media on mechanical properties of adhesive systems.
OBJECTIVE
To evaluate the effects of water vs. oil storage on the mechanical properties of dental adhesives over 3 and 6 months.


METHODS
Adhesive resin sheets were prepared by pouring either Single Bond (SB), One-Step (OS) or Clearfil Liner Bond 2V (CL) into a mold measuring 15 x 15 x 0.8 mm. After solvent evaporation, the adhesives were light-cured, removed from the mold and trimmed to either hourglass or I-beam shapes that were used to determine the true stress (TS) and modulus of elasticity (E), respectively. Control adhesive specimens were subjected to tensile testing at 0.6 mm/minute after 24 hours of immersion in distilled water. Experimental specimens were stored at 37 degrees C in either distilled water or mineral oil and tested after 3 and 6 months. The data were analyzed by two-way ANOVA and Tukey's test.


RESULTS
Storage in water significantly decreased the TS and E of SB and OS specimens after 3 and 6 months (P < 0.05), but did not cause significant changes in either TS or E of CL specimens in the same periods (P > 0.05). Storage in oil significantly increased the TS of the three adhesives after 3 and 6 months (P > 0.05), and the same trend was observed for E value of CL sample (P > 0.05).


CONCLUSIONS
Exposure of cured adhesive systems to long-term immersion in water caused marked reduction in their mechanical properties. Reduced mechanical properties of the adhesive system may compromise resin/dentin bonds and have a clinical implication on the longevity of adhesive restorations.
Carrilho
Marcela R O
MR
Department of Restorative Dentistry, Piracicaba School of Dentistry, University of Campinas, SP, Brazil.
Carvalho
Ricardo M
RM
Tay
Franklin R
FR
Pashley
David H
DH
D000268:Adhesiveness; D000704:Analysis of Variance; D017438:Bisphenol A-Glycidyl Methacrylate; D003793:Dental Restoration, Permanent / Q000379:methods*; D003799:Dental Stress Analysis; D017220:Dentin-Bonding Agents; D004356:Drug Storage; D004548:Elasticity; D057927:Hydrophobic and Hydrophilic Interactions; D008422:Materials Testing; D008689:Methacrylates; D009821:Oils; D019279:Resin Cements; D013718:Tensile Strength; D014867:Water
C103506:Bis-GMA, BPDM, HEMA dental-bonding resin; C084544:Clearfil Linerbond System; D017220:Dentin-Bonding Agents; D008689:Methacrylates; D009821:Oils; D019279:Resin Cements; C115612:single bond; D014867:Water; D017438:Bisphenol A-Glycidyl Methacrylate