Effect of Primers on the Shear Bond Strength of Two Types of Acrylic Resin to Co-cr Partial Denture Alloy

The absence or poor chemical bonding of acrylic resin to Cobalt-Chromium metal frameworks, often introduces microleakage and bond failure at the interface. The aim of this study was to compare the shear bond strength of sandblasted cast and ingot cobaltchromium alloy to heat-cured and self-cured acrylic resins primed with four different metal primers. Fifty Co-Cr Ingot and fifty cast specimens were fabricated and embedded in resin. Their surfaces were sandblasted and primed with four primers except for the control group. 4 x 5 mm discs of self-cure and heat-cured resins were processed against the alloy and stored in distilled water for 24 hours. Specimens were de-bonded in shear using a Universal testing machine The data were analyzed statistically using ANOVA, and Fisher’s PLSD test. In general, primed alloy specimens showed greater bond strength than the non-primed controls and heat-cured resin bonded better than the auto-polymerized resin. ZP primer demonstrated the highest bond strength regardless of type of alloy and resin. Monobond P demonstrated the lowest bond strength. The bond strength of primed specimens improved significantly compared to the control group. Within the limitation of this study, it is shown that primers enhanced the bond strength of acrylic resin and cast Co-Cr alloy. Therefore, metal primers such as ZP Primer and SR Primer are recommended for routine use in the process of fabrication of removable partial denture to increase its longevity.