Effect of Different Surface Treatments on the Bond Strength of Different Monolithic Zirconia With Dentin

This study investigates the effects of different surface treatments on the microstructure, topography, and shear bond strength (SBS) of monolithic zirconia with varying yttria content (3Y and 5Y).

A total of 160 zirconia specimens underwent surface treatments, including air-particle abrasion (APA), hydrofluoric acid etching (HF), and hot hydrofluoric acid etching (HHF), with half receiving primer application prior to resin cement bonding. Scanning electron microscopy and X-ray diffraction analyses evaluated surface morphology and crystalline phase composition, while SBS was tested using a universal testing machine.

Scanning electron microscopy revealed distinct roughness patterns for each treatment, with APA producing microretentive grooves, HF creating shallow fissures, and HHF forming uniform, deeper grooves, particularly in 5Y zirconia. X-ray diffraction confirmed crystalline alterations due to treatments. SBS values were highest for APA (18.11 ± 10.02 MPa) and HHF (18.02 ± 9.95 MPa) treatments (P ˂ .0001), with primer application significantly enhancing SBS across all groups (P ˂ .0001). 5Y zirconia exhibited superior SBS (15.65 ± 9.05 MPa) compared to 3Y zirconia (13.76 ± 8.66 MPa) (P ˂ .0001). Failure modes transitioned from adhesive in controls to mixed in treated groups.

APA and HHF, combined with primer application, were effective methods to enhance the shear bond strength of 3Y and 5Y zirconia. Further research is needed to study their long-term stability under clinical conditions.