Comparison of the push-out shear bond strength of four types of glass ionomers when used to bond amalgam: An in vitro study

Background : Dental amalgam is the primary direct posterior restorative material used worldwide, but it have certain shortcomings due to the lack of adhesiveness to the cavity. The introduction of the concept of bonded amalgam helped improve the use of amalgam as a restorative material. Aim : Evaluation of the comparative push-out shear bond strength of four types of conventional glass ionomers used to bond amalgam to tooth in simulated class I situations. Materials and Methods : Four chemical cure glass ionomers are used: GC Fuji I, GC Fuji II, GC Fuji III and GC Fuji VII, and are compared with unbonded amalgam. The push-out bond strength was tested using the Instron Universal Testing Machine at a crosshead speed of 0.5 mm/min. Statistical Analysis : One-way ANOVA and post hoc Bonferroni tests were used to analyze the data. Results : The results showed that the use of glass ionomer to bond amalgam resulted in an increase in the bond strength of amalgam. The Type VII glass ionomer showed the highest bond strength in comparison with the other glass ionomers. Conclusions : Conventional glass ionomer bonds to amalgam and shows a beneficial increase in the bond strength of the restoration in comparison with unbonded amalgam.