Abstract: Objective: To evaluate the effect of the application mode of etch-and-rinse adhesives on the push-out bond strength (PBS) and nanoleakage (NL) of fiber posts in the root canal. Methods: The roots of human premolars were endodontically prepared and divided into 2 groups according to the application mode (manual or sonic). The posts were cemented and the PBS tested at 0.5 mm/min. The NL was evaluated by scanning electron microscopy after the immersion of specimens in 50% silver nitrate. Root third was also considered in the statistical evaluation. Data were analyzed by t and chi-square tests. Results: Under sonic application, the PBS increased, whereas NL decreased significantly in the middle and apical thirds (P<0.05). Conclusion: The application of simplified adhesives by sonic mode in the root canal is a feasible tool to increase the fiber post bond to root canals.

Key words: Fiber posts, Sonic application, Push-out bond strength, Nanoleakage