Bond strength and durability of porcelain bonding systems.

Because the most effective bonding system for ceramic restorations has not been documented, this study examined bond strength and durability of bonding systems joined to a feldspathic porcelain. Disks of porcelain specimens were fired on refractory investment materials and were air-abraded with alumina. The disks were then bonded with six combinations of five silane primers and six luting agents. Durability of the bond was evaluated by means of a thermocycling machine. Shear bond strengths were determined before and after thermocycling. The results showed that reduction in bond strengths after thermocycling was remarkable for five systems (p < 0.05). However, three systems exhibited shear bond strength greater than 20 MPa after 20,000 cycles.