Prefabricated veneers - bond strengths and ultramorphological analyses

To measure the microshear bond strengths (μSBS) of composite resin to the intaglio surface of prefabricated indirect veneers and analyze the FE-SEM ultramorphology of the pretreated intaglio surfaces as well as the fracture modes.

Three veneer systems (veneer and respective luting material) were used in this study: two prefabricated veneer types, Cerinate One-hour (CER, DenMat) and Componeer (CMP, Coltene), and a laboratory- made veneer, IPS e.max Press (IPS, Ivoclar Vivadent) used as the control. For each group, 10 veneers were used. After delimitation of the bonding area with a double-faced adhesive tape, 0.8-mm-diameter cylinders of composite luting material were bonded to the pretreated intaglio surface. After polymerization, the specimens were fractured in shear mode using the wire-loop method in a universal testing machine. The pretreated intaglio surface of two extra veneers and four fractured specimens per group were morphologically characterized using FE-SEM.

CER resulted in statistically lower mean μSBS (7.1 ± 1.2 MPa) than the other two veneer systems, CMP (15.2 ± 2.5 MPa) and IPS (14.7 ± 1.7 MPa) at p < 0.0001. As seen with the FE-SEM, the intaglio surface of CMP did not display microretentive features, while multiple microretentions were observed in both CER and IPS after HF etching.

Within the limitations of this in vitro study, the CMP and IPS veneer systems resulted in greater bond strengths than those of the CER veneer system.