Aims: To evaluate the effect of different surface treatments and ceramic primers on the shear bond strength (SBS) of self-adhesive resin cement to zirconia ceramic.
Materials and methods: A total of 40 zirconia discs (10 mm in diameter and 3 mm in height; StarCeram Z-Med, H.C. Starck, Selb, Germany) were prepared from pre-sintered zirconia blocks. Discs were divided into two groups according to surface treatment: (a) airborne particle abrasion (sandblasting) with 50-μm Al2O3 particles and (b) 9.5% hydrofluoric acid etching. Each of these groups was subdivided into two groups according to the type of primer applied: (a) Z-Prime Plus primer and (b) Clearfil Ceramic Primer. A self-adhesive resin cement (Multilink Speed, Ivoclar Vivadent, Schaan, Liechtenstein) was used to bond with polyethylene molds. All specimens were tested at thermocycled (5000 cycles at 5-55°C for 30 s) conditions. The SBS of the luting cement to the ceramic was measured in a universal testing machine (1 mm/min).
Results: The sandblasted groups showed significantly higher SBS values than the acid-etched groups for both primers (P = 0.0001). Independent of the surface treatment, the Z-Prime Plus primer groups showed higher SBS values than the Clearfil Ceramic Primer groups (P = 0.0001).
Conclusions: Sandblasting is a more effective method to increase bond strength on zirconia ceramics than hydrofluoric acid etching, and the application of Z-Prime Plus primer increases SBS better than Clearfil Ceramic Primer.
Keywords: Acid etching; ceramic primer; surface conditioning; zirconia ceramics.