Methods: zirconia specimens (125) were cut from cylinders of Y-TZP Kavo Everest ZS-Blanks and sintered overnight. After sandblasting (50 μm Al2O3) and simulated firing cycles the specimens were divided into five groups of 25. Group 1 was the sandblasted control. Specimens were coated with, Group 2: hydroxyapatite/glaze, Group 3: IPS-Empress 2 glass-ceramic powder/glaze, Group 4: IPS-Empress 2 glass (20%)/glaze, Group 5: IPS-Empress 2 glass (30%)/glaze. All groups were glaze fired and etched using 5% HF (Groups 3-5) for 2 mins or 37% H3PO4 (Group 2) for 60 secs. All groups (1-5) were subjected to the same bonding protocol. A single layer of Monobond-S was applied to each glazed-ceramic surface and composite cylinders (Variolink II, Ivoclar-Vivadent) light cured to the specimen surface before water storage for 7 days. Specimens were tested using the shear bond strength (SBS) test at a crosshead speed of 0.5 mm/min. DTA, XRD and SEM was carried out.
Results: Group 3 mean SBS was statistical different to the control group 1 and group 2 (p<0.05). Groups 4 and 5 SBS were significantly different to group 2. There was no statistical difference (p>0.05) between groups 1 and 2, or between groups 4 and 5. Groups 4 and 5 were not different to group 1 (p>0.05). Weibull regression analysis was also reported. XRD of the IPS-Empress 2 glass-ceramic powder revealed a major lithium disilicate phase and a minor lithium orthophosphate phase. High temperature XRD of IPS-Empress 2 glass at 614oC, revealed a lithium metasilicate phase, whereas at 795oC, lithium disilicate and lithium orthophosphate phases were present.
Conclusions: IPS-Empress 2 glass-ceramic/glaze produced a coating that could be etched to increase the SBS between zirconium oxide ceramics and resin cements, when compared with a control group.