Bonding effectiveness and sealing ability of fiber-post bonding

To evaluate the push-out bond strength and the sealing ability of five adhesive cements routinely used for fiber-post bonding.

Fifty extracted single-rooted teeth were randomly divided in five groups and restored using Parapost FiberLux and the following luting agents: Panavia 21 (PAN), Clearfil Esthetic Cement (CLF), Variolink II (VAR), RelyX Unicem (UNI) and experimental GC self-adhesive cement (EGC). After 1 week of water storage at 37 degrees C, three sections (coronal, middle and apical) of 2mm thickness were prepared from each specimen. Sealing ability was quantified with a fluid-filtration system (Flodec) during 10 min, after which the push-out bond strength was immediately measured. Data were analyzed with ANOVA (push-out) and Kruskal-Wallis (sealing ability).

The push-out bond strength and sealing ability were not significantly different among the coronal, middle and apical sections for each luting agent. The highest push-out bond strength was measured for CLF (14.60+/-3.63 MPa), which was not significantly different from PAN (12.57+/-2.45 MPa), but significantly higher than VAR (11.09+/-4.09 MPa), UNI (11.29+/-4.31 MPa) and EGC (7.65+/-4.79 MPa). When evaluating the sealing ability, significant differences were not found among PAN, CLF and VAR, and between UNI and EGC. The latter luting agents scored significantly lower than the former ones. The push-out bond strength was correlated to the sealing ability (p<0.001).

The self-etching MDP-based cements presented the highest push-out bond strength. Although the bonding effectiveness of self-adhesive cements appears promising, their interaction with root dentin might be too weak to minimize microleakage at the post-cement-dentin interface.