Bond Strengths of Four Self-adhesive Resin Cements to Zirconia Ceramic

Objectives: This study evaluated the shear bond strengths of four auto-mixing self-adhesive resin cements {Maxcem (Kerr), Multilink Sprint (Ivoclar Vivadent), New Resin Cement (SAC-A, Kuraray), and RelyX Unicem Clicker (3M ESPE)} between partially-stabilized zirconia ceramic (Shinagawa Fine Ceramics) and dual-cured resin composite for core build-up (UniFil Core, GC). Methods: Zirconia disk specimens were air-abraded with 50 µm alumina particles, treated with phosphoric acid gel (Kuraray) for 5 s, rinsed, and then air-dried. Composite disk specimens were sanded with grit #600 silicon carbide paper, and then treated as same manner as zirconia specimens. Zirconia and composite disks were bonded together with each self-adhesive resin cement, and then photo-polymerized with a visible-light-curing unit for 80 s. Specimens were stored in water at 37ºC for 24 hrs and/or performed thermal cycling (4°C and 60°C with a dwell time of 1 min at each bath) of 20,000 times before shear bond strength testing. Means and SDs (in parenthesis) of shear bond strength (MPa) are listed in Table. Data were analyzed by two-way ANOVA and identical letters were not significantly different by Tukey-Kramer test (p>0.05, n=5). Results: The bond strength of four self-adhesive resin cements between resin composite and zirconia showed over 28 MPa before thermal cycling. However, after thermal cycling, one of four resin cements showed significantly decrease of bond strength. Most of specimens showed adhesive failure at the zirconia-resin cement interface. Conclusion: These results suggest that bond durability is different between brands and an effective primer for zirconia ceramic appears to be necessary for bonding of zirconia to resin composite for core build-up with self-adhesive resin cement.

Self-adhesive	Thermal Cycling
Resin Cement	0	20,000
Maxcem	32.2 (2.7)b,c	2.8 (2.5)a
Multilink Sprint	37.3 (3.5)c,d	41.4 (4.8)d
New Resin Cement	36.8 (3.8)c,d	43.1 (2.1)d
RelyX Unicem Clicker	28.4 (3.9)b	35.6 (4.8)b,c,d