Effect of a Hydrophilic Bonding Agent on Shear Bond Strength to Water and Saliva Contaminated Enamel

The purpose 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. The introduction of composite resin in direct bonding has improved the clinical practice of orthodontics. Moisture contamination after etching is one of the principle causes of early bond failure, and is an inherent problem all orthodontists encounter when using these conventional bonding agents. Recently, a hydrophilic ethanol-based primer (Transbond MIP Moisture Insensitive Primer) has been developed and may show improvements to conventional resin adhesives in moisture contaminated conditions. Sixty extracted human premolar teeth were randomly assigned into four groups of 15. In Group A, conventional primer/adhesive resin were applied to non-contaminated specimens as a control. Group B specimens were contaminated with fresh whole human saliva; MIP primer/adhesive resin were applied according to manufacture\u27s 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 were 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. Based on the results of this study, the followings conclusions are drawn: 1. When optimal bond load is needed on etched and dried enamel, conventional composite primer remains the material of choice and careful isolation is still the foundation of successful bracket bonding. 2. Contrary to what the manufacturer has claimed, significantly lower shear bond loads were achieved when Transbond MIP primer was used on dry etched enamel or under water/saliva contaminated conditions. 3. The results of this study indicate that when Transbond MIP primer was used on dry etched enamel or in the presence of water/saliva, it can provide sufficient shear bond load that is able to withstand routine orthodontic and masticatory forces. 4. When placing brackets in areas where isolation is difficult and access is limited, Transbond MIP primer with conventional composite is an acceptable alternative in case of inadvertent salivary or water contamination