Influence of Drying Protocol with Isopropyl Alcohol on the Bond Strength of Resin-based Sealers to the Root Dentin

Introduction

This study compared the bond strength, interfacial ultrastructure, and tag penetration of resin-based sealers applied to smear-free radicular dentin using 70% isopropyl alcohol as the active final rinse.

Methods

Eighty root canals were prepared and assigned to 2 groups (n = 40) according to the drying protocol: paper points or 70% isopropyl alcohol. Then, roots were divided into 4 subgroups (n = 10) with respect to the sealer and obturation material: AH Plus (Dentsply De Trey GmbH, Konstanz, Germany) and gutta-percha (AH/GP), Hybrid Root SEAL (Sun Medical, Tokyo, Japan) and gutta-percha (HR/GP), Epiphany SE (Pentron Clinical Technologies, Wallingford, CT) and gutta-percha (EP/GP), and Epiphany SE and Resilon (EP/RS). Roots were sectioned, and the push-out test was performed. Failure modes were examined under stereomicroscopy and sealer penetration into the dentinal tubules under scanning electron microscopy. Data were statistically analyzed by 2-way analysis of variance post hoc Tukey tests with a significant level of 5%.

Results

Overall, canals dried with isopropyl alcohol showed significantly higher bond strength values (2.11 ± 1.74 MPa) than with paper points (1.81 ± 1.73 MPa) (P < .05). The HR/GP group showed lower bond strength than the AH/GP group (P < .05) but higher than the EP/GP and EP/RS groups (P < .05). The most frequent type of failure was cohesive in the AH/GP and HR/GP groups and adhesive in the EP/GP and EP/RS groups. Scanning electron microscopic evaluation revealed better adaptation of the adhesive interface in the AH/GP and HR/GP groups in comparison with the EP/GP and EP/RS groups.

Conclusions

A final rinse with EDTA and 70% isopropyl alcohol improved the bond strength and penetration of the sealers into dentinal tubules of the root.