Immediate and 24-hour evaluation of the interfacial strengths of fiber posts

This study examined the contribution of testing time on the interfacial strengths of fiber posts to radicular dentin. Twenty-five fiber posts were luted to root segments with resin cements and a zinc phosphate cement. Immediately upon setting of the materials, the roots were sectioned into slices and randomly divided into two subgroups, depending on testing time (immediate vs. 24-hours), for push-out test. The results showed an improvement on the interfacial strength after 24 hours of storage. When data were pooled for each cement, the interfacial strengths (MPa) were: Optibond Solo Plus/Nexus: 10.3 ± 3.8a; zinc phosphate cement: 10.1 ± 2.7a; Multilink: 9.6 ± 3.8ab; RelyX Unicem: 7.1 ± 4.9bc; AllBond 2/Duolink: 6.7 ± 3.5c (groups with same superscript letter were not statistically significant). It is concluded that bond strength can increase during the first 24 hours and that the interfacial strength is predominantly contributed by frictional retention. © 2006 American Association of Endodontists.