Shear bond strength of several new core materials

This study compared the shear bond strengths of three core materials: a light activated glass-ionomer cement (VariGlass VLC), a fluoride-release dual cure composite resin (Fluoro Core), and a conventional silver-reinforced glass-ionomer cement (Miracle Mix) when cured to dentin. Fifty-four noncarious molar teeth were extracted, cleaned, mounted in acrylic resin, and sectioned horizontally to expose the dentin surface. Each material was mixed according to manufacturer's instructions, applied in a premade mold to the exposed dentin, and then cured. The specimens were randomized into three group (six teeth from each material) and stored (37 degrees C, 100% humidity) for 15 minutes, 24 hours, and 24 hours and were then thermocycled (5 degrees to 55 degrees C) for 125 cycles. The specimens were tested for shear bond strength with the Instron universal testing machine. The differences among time groups were not statistically significant except for Miracle Mix and VariGlass VLC cements, which showed a greater improvement with thermocycling. This study indicated that the FluoroCore resin exhibited the greatest shear bond strength of the core materials and that VariGlass VLC cement had greater bond strength than Miracle Mix cement except after thermocycling, when VariGlass VLC cement and FluoroCore resin were not significantly different.