Primer for bonding resin to metal.

OBJECTIVES

The purpose was to examine the effect on the bond strength and durability of a resin bond to metal of modification of a primer consisting of thiophosphoric methacrylate with phosphoric methacrylates and/or benzoyl peroxide.

METHODS

Acrylic rods were bonded with a luting resin consisting of poly(methyl methacrylate) powder and a mixture of methyl methacrylate and tributylborane initiator to silver-palladium alloy (Ag-Pd), gold-silver alloy (Au-Ag), cobalt-chromium alloy (Co-Cr), and titanium (Ti) surfaces treated with various primers. The bonded samples were thermocycled for 2,000 cycles and the mean bond strengths were compared using one-way ANOVA and Duncan's new multiple range test at p < 0.05.

RESULTS

Using primers of thiophosphoric methacrylate or phosphoric methacrylates alone, the bond strengths of Ag-Pd decreased significantly (p < 0.05) after thermocycling. The durability was significantly improved (p < 0.05) when thiophosphoric methocrylate was used in combination with the phosphate monomers. The additional use of benzoyl peroxide and heat treatment resulted in a significant increase (p < 0.05) in the durability of two groups; the mean bond strengths over 20 MPa and the lowest values remained unchanged even after 2,000 thermocycles.

SIGNIFICANCE: The highest level of bond strength and durability to dental noble metals was achieved using a mixture of thiophosphoric and phosphoric methacrylates and benzoyl peroxide. These bond strength results are comparable to values obtained for base metals.