In-vitro evaluation of the retention of different prefabricated posts luted with different cements

Abstract

The aim of this study was to assess and compare the mechanical resistance and the retentive force of metal and composite post systems cemented with different types of cements. Three different designs of prefabricated titanium alloy posts were used in the study, i.e., active, passive and combined, as well as AgPd cast posts and two different fibre-reinforced composite post systems. In accordance with the experimental design these posts were cemented with zinc phosphate, self-curing composite resin or self-adhesive, self-etching, luting agent. Comparing the results between the different metal post designs, cemented with zinc phosphate, a statistically significant difference in the retention was found between all the analysed posts. The best results with the pull-out test were obtained with the active posts, then the passive, followed by the combined posts. The metal cast posts cemented conventionally with Zn-phosphate demonstrated the lowest retentive force value, based on all the measurements. The bond strengths between the post and the root dentine were influenced statistically by the post design (active, passive, combined or cast) and material, metal vs. composite. The active Ti posts showed significantly superior retention in combination with all the cements. The Ti alloy posts achieved higher retentive force values than the composite posts, in general. The composite cements compared to the Zn-phosphate ensure a better retentive strength for all the posts, including individually cast posts.