Bond Strength of Resin Cements to Leucite-Reinforced Ceramics

Objective: The aim of this study was to evaluate the shear bond strength (SBS) of four leucite-reinforced ceramics and two resin cements. Methods: Forty ceramic blocks (4 mm wide, 14 mm length and 2 mm thick) were used and the samples abraded with aluminum oxide (90 µm). The samples were randomly divided into eight groups (n=5). Two resin cements (RelyX ARC conventional and RelyX U100 self-adhesive, both 3M ESPE) were bonded to ceramics Creapress (CRE-Creation/Klema), Finesse All-Ceramic (FIN-Dentsply/Ceramco), IPS Empress Esthetic (IPS-Ivoclar Vivadent) and Vita PM9 (PM9-Vita). For all groups and in each ceramic block, after application of the 10% hydrofluoric acid (for 1 min) and the silane, 3 Tygon tubings were positioned over ceramics and filled in with the resin cements (cured for 40 s). The tubing molds were removed to expose the specimens in format of cylinders (area: 0.38 mm2), which were stored relative humidity at 24±2°C for one week. After this period, each sample was attached to an universal testing machine and the specimens were tested in shear (applied at the base of the specimen/cement cylinder with a thin wire - 0.2 mm) at speed of 0.5 mm/min, until failure. The results were analyzed by 2-way ANOVA (resin cements and ceramic systems) and Tukey test (p<0.05). Results: The means (SD) were (in MPa): ARC+CRE=32.1±4.3; ARC+FIN=28.3±3.7; ARC+IPS=25.9±4.4; ARC+PM9=22.2±2.1; U100+CRE=38.0±5.2; U100+FIN=36.9±2.8; U100+IPS=38.4±2.9; U100+PM9=34.3 ±7.3. The self-adhesive resin cement showed higher SBS to ceramics than RelyX ARC. The RelyX U100 had higher SBS when applied on IPS ceramic than on PM9. For the RelyX ARC, the SBS obtained with CRE was higher than with IPS and PM9. Conclusions: The RelyX U100 can provide higher SBS to leucite-reinforced ceramics than conventional resin cement. The resin cements applied on the PM9 ceramic surface resulted in lower SBS.