Shear bond strengths of polymethyl methacrylate to cast titanium and cobalt-chromium frameworks using five metal primers

Statement Of Problem. Poor chemical bonding of a denture base resin to cast titanium frameworks often introduces adhesive failure and increases microleakage. Purpose. This study examined the shear bond strengths of a denture base resin to cast pure titanium, Ti-6Al-4V, and a cobalt-chromium alloy using various adhesive primers. Material And Methods. Disks (6.0 mm diameter, 2.5 mm thick) were cast of the 3 alloys. The disk surfaces were grit-blasted with 50 μm alumina and treated with 5 different metal primers (Metal Primer II [MP]; Cesead Opaque primer [OP]; Meta Base [MB]; experimental primer [EP]; Siloc bonding system [SI]). A denture base resin (Palapress Vario) was then applied on the disks with hole-punched sticky tape (bonding area of 5.0 mm) and a Teflon (PTFE, New Age Industries Inc, Willow Grove, Pa.) ring (6.0 mm diameter × 2.0 mm thick). Specimens without primer were also prepared as controls. All specimens were immersed in 37°C water and thermocycled up to 2000 cycles. Shear bond strength values were determined at a crosshead speed of 0.5 mm/min. Data were statistically analyzed using 3-way ANOVA, followed by 1-way ANOVA and the Scheffé multiple range test. Results. Primers significantly ( P