Shear bond strength of zirconia post to root dentin with two different cements and comparison with fiber posts

In the recent years, the demand for esthetic restoration led to developement of tooth colored post. The establishment of reliable retention between post and root canal is an important factor. Current prefabricated tooth-colored posts are fiber and zirconia posts. Loss of fitness in these posts reduces the post retention; therefore, there is a need for fabricating a tooth colored post that may be fitted in the root canal. The aim of this study was to compare the bond strength of fiber posts and custom made zirconia posts with two cement types (resin cement and zinc phosphate) to root dentin. Thirty-two single root extracted teeth were prepared and endodontically treated. They were divided into two groups (fiber post, zirconia post); in each group two cement subgroups (zincphosphate and panavia F2) were used for cementation. Bond strength was measured with the push-out method. Failure modes were observed under a stereomicroscope (20x). Data were analyzed with the two way ANOVA test. In both post groups, bond strengths of panavia F2 were higher than zinc phosphate. The least bond strength was for fiber post/zinc phosphate group (4.60MPa) and the highest bond strength was for zirconia/Panavia F2(14.92 MPa). Most of the failures were at the post-cement interface. Higher bond strength may be achieved with custom made zirconia post and resin cement than fiber posts. So, fitness is a critical factor in post retention and we should not rely only on the bonding ability of resin cement for post retention.