Push-out bond strength of Resilon/Epiphany self-etch to intraradicular dentin after retreatment: a preliminary study

Retreatment procedures might affect the adhesion capability of refilling materials to dentinal walls. The purpose of this study was to compare the effect of different retreatment techniques on bond strength of Resilon (Resilon Research LLC, Madison, CT)/Epiphany (Pentron Clinical Technologies, LLC, Wallingford, CT) self-etch (SE) with radicular dentin after canal reobturation.

Sixty extracted single-rooted human teeth were prepared using Mtwo rotary files (VDW, Munich, Germany) and obturated with Resilon/Epiphany SE. The roots were randomly divided into four groups; in group 1, no retreatment procedure was done; group 2 was retreated using Mtwo R/Mtwo files; group 3 was retreated using Mtwo R/Mtwo combined with chloroform; and group 4 was retreated using Mtwo R/Mtwo combined with Endosolv R (Septodont, Paris, France). The root canals were then reobturated with Resilon/Epiphany SE. One-millimeter slices of midroot dentin were prepared for the push-out test (n=30 slices per group). Failure modes after the push-out test were examined under microscopy. The data were analyzed by using a one-way analysis of variance and the Dunnett post hoc test.

Group 3 showed significantly the lowest mean bond strength (p<0.02). No significant difference was found between the values of groups 1, 2, and 4 (p>0.26). The mode of bond failure was predominantly adhesive for all groups.

This study showed that the bond strength of Resilon/Epiphany SE after root canal retreatment using Mtwo files, either alone or combined with Endosolv R, was not significantly different from that of nonretreated specimens. Chloroform used for retreatment had an adverse effect on the bond strength of Resilon/Epiphany SE after root canal reobturation.