Effect of Adhesive Strategy on the Push-out Bond Strength of Anatomical Fibre Posts in Flared Root Canals: An in vitro Study

Abstract

Background: Flared root canals present a restorative challenge because prefabricated fibre posts may fit inadequately, resulting in a thick and irregular resin-cement layer that can compromise retention. Anatomically relined fibre posts can improve adaptation to canal walls; however, the influence of different dentine adhesive strategies used with self-adhesive resin cement on push-out bond strength remains uncertain. Aims: To compare the push-out bond strength of anatomically relined fibre posts in flared root canals using RelyX U200 with no separate dentine adhesive, an etch-and-rinse adhesive, or a universal adhesive in self-etch mode. Study Design: Three-group in vitro comparative study. Place and Duration of Study: Department of Conservative Dentistry and Endodontics, KVG Dental College and Hospital, Sullia, India. Methodology: Twenty-four extracted single-rooted human teeth were prepared to simulate flared canals and allocated equally among three protocols (n = 8). Composite-relined fibre posts were cemented with RelyX U200. One 3-mm slice from each coronal, middle, and apical third was subjected to push-out testing after 24 hours. The tooth was the experimental unit, and root third was treated as a repeated measure. Results: Overall effects of adhesive strategy (P = .036) and root third (P = .039) were reported. The etch-and-rinse group had the highest mean values in the middle (11.8 ± 4.81 MPa) and apical (12.0 ± 4.51 MPa) thirds. Within-group comparisons across thirds were not significant (all P > .05). The interaction and adjusted pairwise comparisons were unavailable, so superiority of any one strategy over another cannot be established. Conclusion: Bond strength varied with dentine treatment and root third under the tested laboratory conditions. Additional adhesive steps with a self-adhesive cement require further evaluation with full statistical output and ageing before clinical recommendations can be made.