Document Type : Original Articles

Abstract

Introduction: One of the complications of removable partial dentures is debonding of the acrylic resin from the cobalt-chromium framework. Several factors are involved in this chemical and physical bond. The aim of this study was to investigate the effect of applying primers and sandblasting on bond strength between the metal and the acrylic resin in mesh and ladder-like frameworks. Materials and Methods: In this in vitro study, 30 frameworks with ladder-like design (A) and 30 frameworks with mesh-like design (B) were fabricated. The mesh-like and ladder-like frameworks were each subdivided into three subgroups: 10 specimens in each subgroup were un-treated as the control group (A1 and B1); 10 specimens were sandblasted (A2 and B2), and 10 were both primed and sandblasted (A3 and B3). Then the acrylic resin base was bonded to metal surfaces and the metal‒resin bond strength was examined by an Instron testing machine and recorded in Newton. Data were analyzed using two-way ANOVA and Tukey test (α = 0.05). Results: There were significant differences between the three preparation techniques (p value < 0.001). There were no significant differences between the mean bond strength values of ladder (785.90 ± 207.24N) and mesh type (718.60 ± 216.83N) frameworks (p value = 0.133). Mean bond strength values of sandblasting and primer (947.38 ± 86.18 N) were significantly higher than those of sandblasting (749.5 ± 142.11 N) (p value < 0.001). Sandblasting resulted in a significantly higher bond strength values compared to the control group (539.47 ± 164.09 N) (p value < 0.001). Sandblasting alone resulted in a 38% increase in bond strength whereas applying primers with sandblasting increased bond strength by 75%. Conclusion: Sandblasting and primer significantly influence resin‒metal bond strength. Subjecting frameworks to a combination of priming and sandblasting produces the highest bond strength.   Key words: Acrylic resins, alloys, Removable partial denture