Self-assembled nano-layering at the adhesive interface

According to the 'adhesion-decalcification' concept,specific functional monomers within dental adhesives can ionically interact with hydroxyapatite (hap). such ionic bonding has been demonstrated for 10-methacryloyloxydecyl dihydrogen phosphate (mdp) to manifest in the form of self-assembled 'nano-layering'. however,it remained to be explored if such nano-layering also occurs on tooth tissue when commercial mdp-containing adhesives (clearfil se bond,kuraray; scotchbond universal,3m espe) were applied following common clinical application protocols. we therefore characterized adhesive-dentin interfaces chemically,using x-ray diffraction (xrd) and energy-dispersive x-ray spectroscopy (eds),and ultrastructurally,using (scanning) transmission electron microscopy (tem/stem). both adhesives revealed nano-layering at the adhesive interface,not only within the hybrid layer but also,particularly for clearfil se bond (kuraray),extending into the adhesive layer. since such self-assembled nano-layering of two 10-mdp molecules,joined by stable mdp-ca salt formation,must make the adhesive interface more resistant to biodegradation,it may well explain the documented favorable clinical longevity of bonds produced by 10-mdp-based adhesives. © 2012 international & american associations for dental research.