Methods: The surface of commercially stainless steel plates (10 mm in diam. and 2.5 mm in thickness) were blasted with 50 mm alumina particles (0.48 MPa). Four adhesive primers [Alloy primer (Kurare, Japan), Metal primer II (GC, Japan), Metafast (San medical Japan), and Metal link (Shofu, Japan)] were applied to the blasted surface using a brush-on technique. An auto-polymerized polymethyl methacrylate denture base resin (ParaXpress, Heraeus Kulzer) was poured into a Teflon ring (a 3.0 mm circular hole) on the primed surface and polymerized according to the manufacturer's instructions. As a control, bonding specimens without priming were also prepared. After storing in distilled water for 48 hours, the shear bond strengths were measured on an autography (Instron 5565) at a crosshead speed of 0.5 mm/min. Obtained data (n=5) were analyzed using a one-way ANOVA and Tukey's Multiple Comparison Test (a=0.05).
Result: The highest bond strengths were obtained with the Alloy primer (23.8 MPa) followed by Metal link (20.0 MPa), Metafast (17.3 MPa), Metal primer II (12.2 MPa), and the control (5.3 MPa). The Alloy primer exhibited significantly higher strengths than Metafast, Metal primer II, and the control (p> 0.05).
Conclusion: The primed specimens significantly improved the bond strengths of denture acrylic resin to stainless steel. When stainless steel reinforcement wires are used for acrylic dentures, an Alloy primer should be applied. This research was partially supported by a research grant from the Japan Dental Association.