Ultrasonic activation of different self-etch adhesive systems – Dentin tubule penetration and push-out bond strength of fiber posts

Objectives: The objective of this study was to evaluate the dentin tubule penetration of three self-etching adhesive systems and the bond strength of fiber post cementation using standard protocols and ultrasonic activation of the adhesive system. Materials and Methods: Sixty extracted bovine teeth samples had their canals prepared and the apical thirds filled. Six groups were selected from the total sample. Clearfil SE, Prime and Bond, and Single Bond Universal adhesive systems were applied in two groups each. The standard adhesive application protocol was executed in one group, and ultrasonic activation of the adhesive system was executed in one group for each adhesive system. Afterward, fiber posts were cemented in all canals using resin cement (RelyX ARC). The samples were prepared and analyzed under confocal laser scanning microscopy and submitted to a push-out test to observe the adhesive's dentin tubule penetration and evaluate the bond strength values of the posts, respectively. Results: The dentin tubule penetration of the adhesives was more visible on the ultrasonic-activated adhesive groups. Using the standard adhesive protocol, Prime and Bond Universal presented the lowest bond strength values on the apical and cervical thirds and mean value (<i>P</i> < 0.05). Clearfil SE presented the highest bond strength values among ultrasonic-activated adhesive system groups (<i>P</i> < 0.05). Conclusions: Ultrasonic activation improved self-etch adhesive dentinal tubule penetration and bond strength of Clearfil SE and Prime and Bond Universal. Ultrasonic activation of self-etch adhesive systems influenced the prevalence of adhesive failure patterns.