Push-out strength of resin cements to radicular dentin

Debonding is the main failure factor related to the use of resin cements for luting fiber posts. Objectives: This in vitro study assessed the bond strength of resin cement/fiber post systems to the radicular dentin, regarding different radicular thirds, after one and nine months. Methods: Forty single-rooted human teeth were randomly assigned to 4 groups (n=10), according to variables under study: storage time (1 and 9 months) and resin cement (RelyX ARC/3M-ESPE and UNICEM/3M-ESPE). Conic-shape and smooth surface glass fiber posts (DC White Post/FGM) were luted to the roots and covered with a coat of resin composite TPH (Dentsply) to seal the cervical surface. Specimens were stored inside a light-proof container in humid sponge at 37°C during one (G1 and G2) or nine months (G3 and G4). Roots were transversally sectioned in 3 slices (2mm thick), corresponding to the cervical, medium and apical thirds used for the push-out test at 1mm/min at Kratos Universal Testing Machine. Data were submitted to statistical analysis by Kruskal-Wallis and Friedman test (p<0.05). Results: There was no difference among thirds within the same group (p>0.05). There was significant statistical difference between both cements but regarding period of storage (p>0.05). At one month, the cervical (p>0.05) third was similar for both materials; the best outcomes were achieved by UNICEM at medium (p=0.013) and apical (p=0.006) thirds. At nine months, UNICEM showed higher outcome than ARC in all thirds, i.e. cervical (p=0.019), medium (p=0.0007) and apical (p=0.0006). Conclusions: The Self-Adhesive Universal Resin Cement (UNICEM) showed higher bond strength to push-out test when compared to Adhesive Resin Cement (RelyX ARC) and their bond strength were not influenced by the storage time.

FUNDECT/CNPq 02/2006PPP - # 23/200-084/2007