Kandil M, De Souza G, Alkumru H, El-Mowafy O. Microtensile bond strength of self-adhesive resin cements to e-Max crowns. Paper accepted for presentation at IADR in Seattle, March 2013
Purpose: To determine microtensile bond strength (μTBS) of two CAD-CAM crown materials when bonded to dentin or composite-resin substrate using two self-adhesive, an etch-and-rinse and a self-etch resin system; and to compare the effect of two surface treatments of the ceramic crown material on μTBS.
Methods: Lithium disilicate ceramic (IPS e.max CAD, Ivoclar-Vivadent ) (EMX)and composite-resin (Paradigm MZ-100, 3M/ESPE) (PZ) blocks, and custom-made composite-resin (Z100 restorative, 3M/ESPE ) block were sectioned into rods 1mm2 ± 0.1 mm2 in cross-section. Similar dentin specimens were obtained from coronal portion of freshly-extracted molars. EMX rods were either grit-etched (50μm Al2O3) or etched with HF acid and silanated. PZ rods were only grit-etched and silanated. EMX and PZ specimens were then bonded to either dentin or composite rods using four cements (RelyX-ARC, 3M/ESPE, Multilink Automix, Ivoclar-Vivadent, Clearfil Sa, Kurary, RelyX-Unicem,3M/ESPE) using a specially-made device (n=10). A static load of 146 g was maintained until initial setting of cement. Specimens were stored in water (37°C) for 24 h, thermocycled (500 cycles, 5- 55°C), then subjected to μTBS. test. Means and SDs were calculated in MPa and data statistically-analyzed by factorial ANOVA test (α=0.05).
Results: For composite substrate, highest mean μTBS (32.7(2)) was obtained when RelyX-ARC was used with PZ, while lowest mean μTBS (11.6(1.3)) when Rely-X Unicem was used with EMX. For dentin highest mean μTBS (28.8(2.3)) when Rely-X-ARC was used with PZ, while lowest mean μTBS (8.61(1.3)) was obtained when Clearfil-SA was used with EMX. ANOVA revealed significant differences among the groups (P<.05).
Conclusions: In overall Rely-X-ARC and Multilink-Automix resulted in significantly higher mean μTBS irrespective of the substrate material. Whereas Rely-X-Unicem and Clearfil-SA (Self-adhesive cements) resulted in significantly lower mean μTBS irrespective of the substrate. For EMX HF-treatment resulted in significantly-higher mean μTBS as compared to grit-etching.
Acknowledgements: 3M/ESPE, Ivoclar/Vivadent, Kuraray.