Elsayed A, et al. – In the present study, the bond strength and durability after artificial aging of so–called universal primers and universal multimode adhesives to lithium disilicate or zirconia ceramics were tested. The results showed that the bond strength to lithium disilicate and zirconia ceramic was significantly affected by the bonding system used. Using a separate primer containg silane and phosphate monomer gives more durable bonding than do silanes incorporated in universal multimode adhesives. The findings suggested that only 1 of 5 so–called universal primers and adhesives provided durable bonding to lithium disilicate and zirconia ceramic.