Effects of primers containing sulfur and phosphate monomers on bonding type IV gold alloy

Objective: The purpose of the present study was to evaluate the effect of five primers (two sulfur, one phosphate, and two sulfur-phosphate dual-function primers) on the bond strength between a self-curing luting agent and gold-copper-silver (Au-Cu-Ag) alloy. Methods: The primers used were two sulfur primers (V-Primer and Metaltite), one phosphate primer (Epricord), and two primers which contained a sulfur monomer and a phosphate monomer (Alloy Primer and Metaltite/Epricord). The surface of Au-Cu-Ag specimens were blasted with alumina, and then bonded with acrylic rods using a tri-n-butylborane-initiated self-curing luting agent. Shear bond strengths were determined after 5000 thermocycles. An additional alumina-blasted Au-Cu-Ag alloy specimen was subjected to X-ray photoelectron spectroscopy (XPS) analysis. Results: The maximum shear bond strengths were obtained with Metaltite/Epricord (29.6 +/- 2.3 MPa) and Alloy Primer (23.0 +/- 1.6 MPa), followed by Metaltite (10.3 +/- 4.2 MPa), V-Primer (8.9 +/- 0.6 MPa), Epricord (6.4 +/- 1.5 MPa), and No primer control (2.0 +/- 0.5 MPa). The XPS analysis detected six chemical elements (Au, Cu, Ag, Al, O, and C) on the Au-Cu-Ag alloy. In addition to pure Au element, the metal oxide-states of Ag2O, AgO, Cu2O, and CuO were suggested. Conclusion: The combined use of a sulfur monomer and a phosphate monomer significantly improved the bond strength of resin to Au-Cu-Ag alloy which should be especially significant to clinicians. (C) 2008 Elsevier Ltd. All rights reserved.