Adhesion of resin-based sealers to dentine: an atomic force microscopy study

To evaluate the effect of several final irrigants on the adhesion force (Fad) between dentine and resin-based sealers by means of atomic force microscopy (AFM).

Twelve distal roots of mandibular molars were used. The roots were smoothened and cut to obtain 36 specimens. During chemomechanical preparation of the root canals, 5.25% NaOCl was used as the irrigant. The specimens were then divided into six groups according to the final irrigant used: control group - immersed in distilled water (DW) for 1 min; chlorhexidine (CHX) group - in 2% CHX for 1 min; NaOCl group - in 5.25% NaOCl for 1 min; EDTA group - in 17% EDTA for 5 min, EDTA/CHX group - in EDTA, followed by intermediate flushing with DW and then immersed in CHX; EDTA/NaOCl group - in EDTA, followed by intermediate flushing with DW and then immersed in NaOCl. After the treatments, all groups were washed with DW to remove all traces of the irrigants. Afterwards, the samples were dried and attached to a glass base. AFM tips containing AH Plus and Real Seal SE sealers were used to obtain force-distance curves with regard to dentine-treated surfaces. Data were analysed statistically using nonparametric tests with the significance level set at P < 0.05.

In the groups with smear layer, a final flush with CHX and NaOCl resulted in significantly higher Fad values than the control group for both sealers (P < 0.001). When smear layer was removed, the highest Fad values associated with AH Plus occurred with a final flush of NaOCl, whilst in Real Seal SE, the highest values were found with a final flush of CHX (all results significant at P < 0.001).

Irrigants had a positive effect on the adhesion of the resin-based sealers, AH Plus and Real Seal SE, to dentine.