Shear bond strength of resin luting cement to all-ceramic materials

Objectives: The aim of this study was to evaluate the shear bond strength of one resin luting agent (Rely-X, 3M, ESPE) to two all-ceramic materials IPS-Empress 2 (Ivoclar) and In-Ceram Zirconia (Vita). Methods: Samples of both systems (n=18) were embedded in autopolymerizing acrylic resin JET (Artigos Odontológicos Clássico), submitted to a polishing in Metaserv Grinder/Polisher (Buehler) machine. Composite cylinders (4.0 mm x 5.0 mm) of Z-100 (3M-ESPE) were bonded to treated surfaces of ceramics according to manufacturers' instructions with the resin luting cement. Shear bond strength test was performed using a Universal Testing Machine MTS 810 at a cross-head speed of 0.5 mm/min with a 10-kN load cell. The failed specimens were examined after immersion in dye. Results: Mann-Whitney test (a=.05) showed higher shear bond strength (P<.05) for IPS-Empress 2 (18.46 ± 5.22 MPa) than In-Ceram Zirconia (14.05 ± 4.93 MPa). For IPS-Empress 2, failure modes were cohesive (72.22%) and cohesive/adhesive (27.78%). In-Ceram Zirconia specimens revealed an average of 33.33% cohesive, 61.11% cohesive/adhesive and 5.56% adhesive failure modes. Conclusions: The shear bond strength of the two all-ceramic materials was influenced by both composition and surface treatments (IPS-Empress 2: lithium disilicate/ hydrofluoric acid etching and In-Ceram Zirconia: zirconium oxide/sandblasting with Al₂O₃ - 50µm).