Post retention strength of apical and conventional coating obturation method using bioceramic sealer: A laboratory investigation.

Abstract

Abstract Objectives Bioceramic sealer (BCS) occupied dentinal tubules have been shown to reduce fibre post retention strength. Coating gutta percha with BCS only on apical portion leaving middle and coronal part of the canal unsmeared by BCS may improve post retention strength due to increased retention strength between dentin and resin cement interface. The purpose of the study was to test if this was the case. Materials and Methods Twenty seven extracted human mandibular premolars were instrumented and randomly assigned to three obturation methods: conventional coating (CC), non coating (NC), and apical coating (AC). After post cementation, two samples were prepared at apical, middle, and coronal root level (one for scanning electron microscope (SEM) study and another push out bond strength (PBS) test). After PBS test, failure modes were determined by stereo microscope: dentine-cement (DC), post-cement (PC) and mixed. PBS data were analysed by One way ANOVA for the specific effects of obturation methods. Repeated ANOVA was used for the specific effects of root levels on PBS in different obturation methods. Results PBS of CC at the middle 1/3 was significantly higher than the apical 1/3. PBS of AC and NC was significantly higher than CC group at apical 1/3 and coronal 1/3 level. DC was found most in CC group while PC was found most in NC and AC group. Conclusions and Clinical Relevance Apical coating obturation method under operating microscope had significantly higher PBS than conventional coating method. This may reduce the chance of fibre post dislodgement.