ABSTRACT
The purpose of this study was to investigate the effect of immediate and delayed activation of two different self etching primer adhesives [One Up Bond-F and AdheSE] on bond strength to enamel. Sixty freshly extracted human maxillary premolars were used in this study. The enamel of the buccal surfaces of the teeth were ground flat to create a 2-mm flat buccal enamel surfaces. After creation of the flat enamel surfaces, the teeth were divided equally into six groups [10 each]. In groups. 1 and 4. The sell etching primer adhesives were applied passively undisturbed. In groups, 2 and 5, the sell etching primer adhesives were applied with immediate active application. While in groups 3 and 6, the self etching primer adhesives were applied with delayed activation. After 48 hours the teeth were subjected to shear bond strength testing. The results of this study showed that, immediate and delayed activation reduced significantly the bond strength of One Up Bond-F to enamel. On other hand, although immediate and delayed activation reduced the bond strength of AdheSE to enamel, the results were not of statistical significance. The bond strength of the two steps self etching primer adhesive was more superior then the one step sell etching primer adhesive. Strict Manufacturer instruct ions should be followed to achieve optimum bond strength result