Fracture resistance of amalgam/glass-polyalkenoate open sandwich Class II restorations: An in vitro study

Objective: To investigate the effect of two glass-polyalkenoate restorative materials used as root-dentin replacements on the fracture strength of Class II amalgam restorations. Materials and methods: Class II slot preparations extending 2 mm apical to the cemento-enamel junction were made in 30 teeth and randomly assigned to three groups. Group 1 (Control): restored entirely with amalgam (Tytin, Sybron Kerr, Orange, CA, USA). Group 2: The root-dentin area was restored with a viscous conventional glass-polyalkenoate restorative material (Fuji IX GP, GC America, Alsip, IL, USA), and the remainder of the preparation restored with amalgam. Group 3: The root-dentin area was restored with a resin-modified glass-polyalkenoate restorative material (Fuji II LC, GC America) and the remainder restored with amalgam. The amalgam restorations were loaded in compression to failure and the data analyzed using one-way ANOVA (α = 0.05). Results: No significant differences in fracture strength were found. Conclusion: Root-dentin replacement with the tested glass-polyalkenoate materials did not affect the fracture strength of Class II amalgam restorations.