Effect of Micromechanical Surface Treatment on the Failure of Y-TZP

Objectives: Surface damage and bonding strength difference after micromechanical treatment of Y-TZP surface are not studied enough yet. The aim of this study was to evaluate the difference of fracture resistance and bonding strength between more surface-damaged group from higher air-blasting particle size and pressure, and less damaged group.
Methods: Disk shape Y-TZP (LAVA^TM) specimens were air-blasted with 30μm particle size (Cojet), under 2.8 bar for 15s, 110μm particle size (Rocatec), under 2.8 bar for 15s, and 110μm particle size (Rocatec), under 3.8 bar for 30s, respectively. Biaxial flexure test and bonding failure load test were performed serially (n=10 per group). For bonding test, specimens were bonded on the base material having similar modulus of elasticity of dentin with 200μm-thick resin cement to simulate tension of damged surface. Failure load of bonding was detected with acoustic emission (AE) sensor.
Results: There were no significant differences between groups both in the biaxial flexure test and bonding failure load test (p> .05). Sub-surface cracks were all radial cracks except for two specimens.
Conclusions: Within the limitations of no aging under monotonic load test, surface damage from higher air-blasting particle size and pressure was not significant. Evaluation of failure load with bonded zirconia disks was clinically relevant modality to investigate the effect of surface damage on bonding strength.