Effect of different primers on composite bond strength to zirconia

Objective: The objective of this study was to evaluate the effect of the application of two primers on the zirconia-to-resin cement shear bond strength (SBS).

Method: Zirconia blocks were treated with Z-Prime (ZP) and Signum Zirconia Bond (SZB). Non-primed specimens were considered as controls. Forty five specimens of Y-TZP (6mm x 6mm x 3mm) were produced and cylinders of resin cement were built on the ceramic surface and submitted to a shear bond strength test (at 0.5 mm/min). Three resin cements were tested: Multilink, SET and NX 3 and specimens were produced according to the design of the SDI SBS apparatus (bonding area of 9.62 mm²). Fractured surfaces were observed under stereomicroscopy to determine the failure mode, and bond strength mean values were analyzed by two-way ANOVA and Tukey’s test (a=0.05).

Result: The mean values of SBS obtained when SZB primer was applied were significantly higher than those of the control groups for all resin cements. ZP application resulted in statistically higher SBS values compared to the control group only for NX 3. All fractures were classified as adhesive failures.

	Multilink (Ivoclair)	SET (SDI)	NX 3 (Kerr)
Control	4.11 (0.55) C	3.90 (1.36) C	3.79 (1.03) C
Z-Prime (Bisco)	5.17 (0.80) C	6.03 (0.22) C	9.24(1.14) B
Signum Zirconia Bond (Heraeus)	9.58 (1.91) B	14.74 (1.68) A	12.71(2.61) A

Conclusion: Application of SZB is effective to increase the bond strength of resin cement to ceramic to Y-TZP.