Effect of delayed application on shear bond strength of four fifth-generation bonding systems

This study compared the shear bond strength of four adhesives dispensed 10 minutes prior to use to immediate dispensing and use. For half (40) of the specimens (n = 10), four different dentin bonding agents (One Coat, Bisco One Step, Prime & Bond 2.1 and 3M Single Bond) were used to bond a column of composite resin (Z100 Restorative Resin) to the dentin surface following manufacturers' directions and using the dentin bonding agent immediately after dispensing. For the remaining specimens, the same procedure was followed except that the dentin-bonding agent was dispensed 10 minutes prior to use. All specimens were tested two weeks after bonding on a MTS machine. The data obtained was subjected to Two-factor ANOVA and Tukey-B post-hoc tests. The statistical analysis showed that there was no significant difference between the control groups and the experimental groups, although the dentin bonding agents containing acetone showed a trend toward lower bond strengths when not used immediately after dispensing.