Methods: In total, 75 crowns of each all-ceramic material used (Vita Mark II, Ivoclar Empress CAD, Ivoclar e.max CAD) were milled using a CAD/CAM system (Sirona inLab). The inner surfaces of the crowns were etched and bonded. The implant abutments were fixed on implant analogs. The exterior surfaces of the implant abutments were sandblasted (50 µm), degreased, and bonded. Adjacent crowns were cemented on implant abutments using five different luting systems (Multilink Implant (A), Variolink II (B), RelyX Unicem (C), FujiCEM (D), and Panavia 2.0 (E)). After thermocycling, the crowns were removed using a universal testing machine. Statistical analyses were performed using analysis of variance (ANOVA) at the 5% level of significance.
Results: The retentive strengths [N] of the crowns were as follows: Vita Mark II ceramic (mean/SD/min/max), A) (685/142/310/885), B) (652/146/430/995), C) (728/148/489/976), D) (759/134/552/1010), E) (715/144/485/946); Ivoclar Empress CAD ceramic, A) (364/159/163/706), B) (774/89/642/925), C) (749/175/536/1198), D) (748/98/579/935), E) (822/131/635/1068); Ivoclar e.max CAD ceramic, A) (842/176/438/1147), B) (859/109/691/1052), C) (1044/173/825/1310), D) (970/135/740/1137), E) (784/133/458/945). For Vita Mark II, no significant difference was found between the luting systems. Using Ivoclar Empress CAD, luting system A had a significantly lower retentive strength than the other luting systems. With Ivoclar e.max CAD, luting system C had a significantly higher mean retentive strength.
Conclusion: Within the limitations of this study, all of the luting systems had the same retentive quality for the ceramic material Vita Mark II. Using Ivoclar Empress, luting system A had a lower retentive strength than the other luting systems. Luting system C had the highest retentive strength for Ivoclar e.max CAD.