Enhancing the bond of a resin-based sealer to root dentine.

AIM To evaluate whether application of a total-etch/separate adhesive layer can enhance the bond of a UDMA-based sealer to dentine. METHODOLOGY The root canals of 20 decoronated maxillary premolar teeth with two canals were prepared to size 35-45, 0.04 taper using rotary NiTi instruments. The canals of each tooth were treated with application of either a total-etch/separate adhesive or the manufacturer-recommended primer, before root filling with sealer plus matching master cone using warm vertical compaction. After setting, roots were sectioned perpendicular to the long axis to obtain 1-mm-thick slices, and the root filling was subjected to the push-out test using a plunger closely matched to canal diameter. The roots of another 15 single-rooted premolars were sectioned in a bucco-lingual direction, and the cut surfaces were ground flat for microshear bond strength testing. One-half of the specimens were coated with a separate total-etch/adhesive layer, and then, a cylinder of sealer cement 1 mm diameter × 1.5 mm high was bonded to the prepared surface of all specimens. Microshear bond strength was measured in a universal testing machine after 48 h. Data were analysed using anova and paired t-tests, with significance set at P < 0.05. RESULTS Use of a separate total-etch/adhesive markedly increased both microshear bond strength and push-out strengths compared with standard primer (P < 0.001). CONCLUSION Application of a separate adhesive layer significantly increases bond strength of UDMA-based sealers to root dentine.