Polymerization contraction stress in dentin adhesives bonded to dentin and enamel.
OBJECTIVE
In a previous study on of polymerization contraction stress determinations of adhesives bonded to dentin a continuous decline of stress was observed after the adhesives had been light-cured. The decline was ascribed to stress relief caused by diffusion into the adhesive layer of water and/or solvents, left in the impregnated dentin surface after drying and/or evaporation in the application procedure. The purpose of the present study was to test the hypothesis that the contraction stress of adhesives bonded to enamel will not decline after light-curing, based on the assumption that water and/or solvents are more efficiently removed from impregnated enamel surfaces in the drying and/or evaporation step.


METHODS
Contraction stress was determined in a tensilometer for three total-etching adhesives Scotchbond multi-purpose, Single bond and One-step plus and four self-etching adhesives Clearfil SE Bond, Clearfil Protect Bond, AdheSE, and Xeno III. The adhesives were placed in a thin layer between a glass plate and a flat dentin or enamel surface pre-treated with phosphoric acid or self-etching primer and light-cured under constrained conditions.


RESULTS
All adhesives bonded to enamel showed a stress decline, but significantly less than for dentin with the exception of two self-etching adhesives. The greatest decline was found for the total-etching adhesive systems bonded to dentin. The presence of hydrophobic monomers in the adhesives had a significant influence on the decline.


CONCLUSIONS
The experiments indicate that fluids are withdrawn from the resin impregnated tooth structures, which may result in small defects in the tooth-resin interfaces.
Hashimoto
Masanori
M
Division of Biomaterials and Bioengineering, School of Dentistry, Health Sciences University of Hokkaido, 1757 Kanazawa, Ishikari-Tobetsu, Hokkaido 061-0293, Japan. masanori-h@mue.biglobe.ne.jp
de Gee
Anton J
AJ
Feilzer
Albert J
AJ
D000134:Acid Etching, Dental; D000180:Acrylic Resins / Q000737:chemistry; D000818:Animals; D017438:Bisphenol A-Glycidyl Methacrylate / Q000737:chemistry; D002417:Cattle; D001840:Dental Bonding; D003743:Dental Enamel / Q000648:ultrastructure*; D003804:Dentin / Q000648:ultrastructure*; D017220:Dentin-Bonding Agents / Q000737:chemistry*; D003890:Desiccation; D057927:Hydrophobic and Hydrophilic Interactions; D008027:Light; D008422:Materials Testing; D011108:Polymers / Q000737:chemistry; D019279:Resin Cements / Q000737:chemistry; D012997:Solvents / Q000737:chemistry; D013314:Stress, Mechanical; D014867:Water / Q000737:chemistry
D000180:Acrylic Resins; C489662:AdheSE cement; C503075:Clearfil Protect Bond; C438313:Clearfil SE Bond; D017220:Dentin-Bonding Agents; D011108:Polymers; D019279:Resin Cements; C084018:Scotchbond Multi-Purpose; D012997:Solvents; C487957:Xeno III; C115612:single bond; D014867:Water; D017438:Bisphenol A-Glycidyl Methacrylate