Effect of a Bonding Agent on Shear Bond Strength to Contaminated Enamel

The objective of this study was to compare the shear debond loads of a new commercially available hydrophilic enamel bonding agent to that of a standard hydrophobic enamel bonding agent, and to measure the effects of water and saliva contamination on shear bond load. Sixty extracted human premolar teeth were randomly assigned into four groups of fifteen. In Group A, conventional primer/adhesive resin (3M Unitek, Corp) was applied to non-contaminated specimens as a control. Group B specimens were contaminated with fresh whole human saliva; Transbond Moisture Insensitive Primer (MIP) primer/adhesive resin (3M Unitek, Corp) were applied according to manufacturer’s instructions. Group C samples were contaminated with water prior to application of MIP primer/adhesive resin. Group D specimens were not contaminated; MIP primer/adhesive resin was applied. A custom fabricated mounting jig was used to align the bracket slot perpendicular to the bottom of the mold. Specimens were stored in water for 48 hours at room temperature prior to testing. An Instron testing unit was utilized to produce a shear force at the bracket-tooth interface. The shear bond loads were recorded and the sites of bond failure were evaluated under a dissecting microscope. The results of the analysis of variance (ANOVA) that compared the shear debonding loads for the various experimental groups indicated that there was a significant difference among the four groups. The Significance level was p<0.5 or the 95th confidence level. The means of the various groups were compared with the Ryan-Einot-Gabriel-Welsch range test at a 5% level of significance. Although results indicate that significantly lower shear bond loads were achieved in-groups B, C and D, it can still provide sufficient shear bond load to withstand routine orthodontic and masticatory forces.