Methods: RelyX Unicem (3M ESPE), Calibra (Dentsply) and Variolink (Ivoclar-Vivadent) were used as resin cements. They were bonded to machine milled feldspatic ceramic disks, which were pretreated in five different ways: [A]: no pretreatment of the ceramic; [B]: ceramic etched with HF; [C]: silanizing; [D]: ceramic etched and silanized; [E]:ceramic etched with HF, silanized and treated with Heliobond (Ivoclar-Vivadent). The shear bond strength of 10 specimens per material and per ceramic pretreatment were tested initially, after 5*103 thermocycles and after 104 thermocycles. Results: Mean values of shear bond strength in MPa:
| ceramic treatment | [A] | [B] | [C] | ||||||
| tested at: | initial | 5*103 | 104 | initial | 5*103 | 104 | initial | 5*103 | 104 |
| Calibra | 4,41 | ** | ** | 7,41 | 11,2 | 9,81 | 3,31,2 | ** | ** |
| Variolink | 5,4 | 6,1 | ** | 9,6 | 9,4 | 9,42 | 12,51 | 16,8 | 18,4 |
| Unicem | 6,71 | 5,9 | 8,3 | 9,91 | 13,8 | 15,11,2 | 12,22 | 15,6 | 12,4 |
| ceramic treatment | [D] | [E] | ||||
| tested at: | initial | 5*103 | 104 | initial | 5*103 | 104 |
| Calibra | 7,401,2 | 10,71,2 | 10,31,2 | 12,0 | 15,51 | 11,11,2 |
| Variolink | 17,61,3 | 15,11,3 | 18,61 | 16,8 | 24,81 | 25,01 |
| Unicem | 12,82,3 | 22,22,3 | 20,92 | 12,5 | 20,4 | 24,32 |
** = debonding during thermocycling
The superscript letters within the same column indicate a significant difference according to the U-test at p £ .05, (Bonferroni corrected).
Conclusion: Due to the results of this study a simplification of ceramic treatment in combination with Variolink and RelyX Unicem seems to be possible. For the Calibra material only the complete pretreatment procedure [E] should be used and lead to reliable adhesion values.