Effect of blood and saliva contamination on shear bond strength of brackets bonded with 4 different adhesives

The purpose of this study was to assess the effect of blood and saliva contamination on the shear bond strength and failure site of 4 different orthodontic adhesives (Transbond XT primer, Transbond plus Self-Etching Primer, Assure hydrophilic primer and Smartbond cyanoacrylate adhesive).In this study integral based stainless steel maxillary central-incisor brackets were bonded to 120 bovine permanent mandibular incisors. The teeth were randomly divided into 12 groups; each group contained 10 specimens. Each primer-adhesive combination was tested under a different enamel condition: dry, blood and saliva contamination after priming.Shear forces were applied gingivo-occluzal direction to the samples by Zwick Universal test machine. Bond strengths were measured in megapascals, and bond failure was analyzed by using the adhesive remnant index. When the results were statistically evaluated shear bond strengths of Smartbond cyanoacrylate adhesive group were significantly lower than all other groups, however it was the only adhesive that was not affected by contamination conditions. Saliva and blood contamination results in a significant drop in shear bond strengths of Transbond XT and Assure groups. Transbond Plus Self-Etching Primer is also affected by blood contamination even though it was a suitable adhesive for bonding in presence of saliva contamination.The comparison of the adhesive remnant index scores indicated that there was significantly less residual adhesive remaining on the teeth under blood and saliva contamination except the group treated with Smartbond cyanoacrylate adhesive.