98 Effect of cements on bonding of abutments to the crown

Purpose The aim of this study was to evaluate the effect of different resin cements on bond strength of materials used for implant abutments to those generally used for full crown rehabilitation. Methods In order to simulate the crowns, specimens with a cylindrical shape were obtained from translucent Y-TZP zirconia (ZirkoM, Odontomega), LD - lithium disilicate (IPS E.max, Ivoclar), and CB - composite blocks (Grandio Blocs, Voco). Two different materials were used to simulate the implant abutments (titanium and opaque Y-TZP zirconia) and were compared to bovine dentin. The specimens were divided into 3 subgroups (n=10) according to the kind of cement applied: Multilink Hybrid Abutment (Ivoclar), Vita Adiva IA-CEM (VITA) and Bifix Hybrid Abutment (Voco). Different treatments were performed for the specimens simulating the abutments and crowns, following the manufacturer´s recommendations. The cements were applied over the treated surface of the cylinders simulating the crowns, which were placed over the abutment material. The specimens were submitted to shear stress using a universal testing machine at a speed of 1mm/min. The data were analyzed using three-way ANOVA and Tukey´s test. Results Significant differences were observed for the kind of abutment (p=0.001) and crown (p=0.001), but not for the kind of cement (p=0.1646). The results of Tukey´s test for the kind of abutment were: dentin-7.51(2.73)a; titanium-13.00(3.29)b; zirconia-20.75(7.46)c. The results for the kind of crown were: CB-10.72(4.33)a; LD-14.15(7.30)b; zirconia-16.38(8.66)c. The means for the cements were: Vita-13.14(7.01)a; Multilink-13.93(8.28)a; Bifix-14.18(6.72)a. Conclusion The bond strength to dentin was less than to titanium abutment, which was less than to zirconia abutment. Adhesion to zirconia crowns provided greater bond strength than to lithium disilicate and composite crowns. Non-significant effects were observed for the kind of cement.