The effect of saliva on shear bond strengths of hydrophilic bonding systems

Failure of orthodontic bonded attachments and brackets is mostly attributed to contamination of the enamel surface. To overcome this problem, material s have been developed that purportedly overcome the moisture and contaminan ts present in the oral environment. This study compared the shear bond stre ngths of 2 light-cured hydrophilic bonding systems, Transbond XT with MIP ( 3M/Unitek, Monrovia, Calif) and Assure (Reliance Orthodontics, Itasca, III) with a hydrophobic bonding system, Transbond XT with XT primer (3M/Unitek) . Comparison tests were conducted under 4 enamel surface conditions: (I) et ched and dried; (2) etched and moistened with artificial saliva; (3) etched , primed, and moistened with artificial saliva; and (4) etched, primed, moi stened with artificial saliva, and reprimed. In addition, an adhesive remna nt index score was used to determine the amount of adhesive remaining on th e tooth. Stainless steel brackets with mesh-backed pads (n = 144) were bond ed to bovine teeth. Bond strength was then tested in shear using an Instron mechanical testing instrument. There were significant differences in the b ond strengths among the products (P < .05), within surface treatments (P < .05), and among the different bonding materials in combination with various surface treatments (P < .05). Treatments 1 and 4 showed the highest mean b ond strengths adhesive remnant index scores, whereas treatments 2 and 3 sho wed the lowest mean bond strengths and scores.