Conversion of one-step to two-step self-etch adhesives for improved efficacy and extended application.
OBJECTIVE
One-step self-etch adhesives have restricted use due to their acid-base incompatibility with autocured composites and their behavior as permeable membranes after polymerization. This study examined the feasibility of their conversion to two-step self-etch adhesives via the adjunctive use of a non-solvented, relatively hydrophobic resin coating.


METHODS
iBond, Xeno III and Adper Prompt were used either in multiple coats, or in a single coat followed by the use of a layer of Scotchbond Multi-Purpose Plus bond resin for coupling to light- and auto-cured composites. Four types of experiments were performed. Bonded specimens were examined with TEM after immersion in an ammoniacal silver nitrate tracer. Fluid flow measurements of iBond were conducted using the two application protocols to compare the permeability of the bonded dentin with the original smear layer. Permeability of vital dentin bonded with both application protocols were compared for the transudation of dentin fluid across the bonded dentin. Microtensile bond strengths of dentin bonded with the two protocols were examined for their compatibility with an auto-cured composite.


RESULTS
The results of the four experiments were complementary. iBond and Xeno III exhibited "apparent incompatibility" to auto-cured composites that resulted from their inherent permeability. This was confirmed by the presence of dentin fluid transudate on the adhesive surfaces when they were bonded to vital dentin. Conversely, Adper Prompt exhibited "true incompatibility" to auto-cured composites that was caused by adverse acid-base interaction, masking the inherent permeability of this adhesive. "True" and "apparent" incompatibility issues were eliminated upon their conversion to two-step self-etch adhesives.
Pediatric Dentistry & Orthodontics, University of Hong Kong, China.
Nigel M
NM
King
Franklin R
FR
Tay
David H
DH
Pashley
Masanori
M
Hashimoto
Shuichi
S
Ito
William W
WW
Brackett
Franklin
F
García-Godoy
Michelle
M
Sunico
D017438:Bisphenol A-Glycidyl Methacrylate / Q000737:chemistry; D003188:Composite Resins / Q000737:chemistry; D001840:Dental Bonding / Q000379:methods*; D003804:Dentin / Q000648:ultrastructure; D003806:Dentin Permeability; D017220:Dentin-Bonding Agents / Q000737:chemistry*; D019234:Dentinal Fluid / Q000378:metabolism; D005240:Feasibility Studies; D006801:Humans; D057927:Hydrophobic and Hydrophilic Interactions; D008422:Materials Testing; D010755:Organophosphates / Q000737:chemistry; D019279:Resin Cements / Q000737:chemistry; D016622:Silver Staining; D016369:Smear Layer; D013499:Surface Properties; D013718:Tensile Strength
C489661:Adper Prompt Self-Etch; D003188:Composite Resins; D017220:Dentin-Bonding Agents; D010755:Organophosphates; D019279:Resin Cements; C425844:Scotchbond Multi-Purpose Plus; C487957:Xeno III; C477386:iBond; D017438:Bisphenol A-Glycidyl Methacrylate