Journal of Dental Research, Vol 70, 59-66, Copyright © 1991 by International & American Associations for Dental Research Online Journals
Effect of 2-(methacryloxy)ethyl phenyl hydrogen phosphate on adhesion to dentin
T. Wang and N. Nakabayashi
Division of Organic Materials, Tokyo Medical and Dental University, Japan.
A variety of methacrylate-based materials has been developed with the
capacity of adhering to dentin. This study investigated the effectiveness
of 2-(methacryloxy)ethyl phenyl hydrogenphosphate (phenyl-P) for bonding 5%
phenyl-P in methyl methacrylate (MMA) to dentinal surfaces. Polymerization
of the phenyl-P/MMA monomer was initiated by partially oxidized tri-n-butyl
borane catalyst (TBB). The mean tensile bond strength of 5% phenyl-P in MMA
to dentin that was pre-treated with an aqueous solution of 10% citric
acid/3% ferric chloride, abbreviated as 10-3, was found to be 10.5 MPa.
Scanning electron microscope examination demonstrated the formation of a
transitional or "hybrid" layer of resin-reinforced dentin, created by the
intermingling and entanglement of polymerized resin with collagen bundles
exposed by dentin pre-treatment with 10-3, an effective remover of the
dentinal smear layer. This "hybrid" layer or zone was essential for high
tensile bond strength to be attained. Phenyl-P was found to be effective in
promoting monomer diffusion and impregnating monomer into demineralized
dentinal surfaces. The formation of the "hybrid" layer of resin-reinforced
dentin followed in situ resin polymerization initiated by partially
oxidized tri-n-butyl borane (TBB). Ferric (Fe3+) ions deposited on dentinal
surfaces from the 10-3 solution also acted to improve monomer diffusion and
entanglement with demineralized dentin, and facilitated the formation of
the "hybrid" layer/zone.
