Bond strength values: should they be considered in material selection?

This study determined shear bond strengths of 4 glass ionomer cements under standardized conditions and compared the results with data derived from the product manufacturers. Flat dentine planes were prepared on the buccal surfaces of 40, unerupted, surgically removed, human third molars. Ten cylinders of Fuji II LC (FII), Aqua Ionofil (AI), Variglass VLC (VA) and Vitremer (VI) were bonded to dentine surfaces. The specimens were stored in distilled water for 96 hours and their shear bond strengths were then determined using an Instron testing machine. FII LC achieved the highest (15 MPa) and VA the lowest (2 MPa) mean shear bond strength values and those for Aqua Ionofil and Vitremer were 5 to 6 MPa. The manufacturers have reported lower bond strengths for FII and AI and higher values for VI and VA. This study showed that in view of differences in test methods bond strength test values are not comparable and we recommend that they should not be used as the only criterion for material selection.