Effect of lubricant substances on the bond strength of relined posts to root canals

The aim of this study was evaluate the influence of the substance used as root canal lubricant during relining and the cleaning protocol on the bond strength of relined posts to root dentin. Eighty single canal mandibular bovine incisors were used in the study. The root canals were endodontically treated and allocated into four groups (n?=?20) according to the lubricant material and the root canal cleaning protocol: petroleum jelly/no cleaning; petroleum jelly/cleaning with paper points; hydrosoluble gel/no cleaning; hydrosoluble gel/water rinse and drying with paper points. All posts were relined with resin composite and luted to the root canals with regular resin cement. Specimens were cross-sectioned to obtain root slices producing 1.5?mm thick slices. The push-out test was performed at a crosshead speed of 0.5?mm/min until post dislodgement occurred. The failure mode was verified using a stereomicroscope. Data were analyzed by two-way ANOVA followed by Tukey post hoc test (push-out) with α?=?0.05. A statistically significant difference was found considering the type of lubricant (p?<?0.001). The hydrosoluble gel/water rinse group showed the highest mean bond strength value (11.0?±?3.7?MPa). The most frequent pattern of failure was adhesive between the root canal walls and resin cement. The use of a hydrosoluble gel as lubricant substance seems to be adequate for the relining post technique.