Introduction: zirconia represents a valuable material that combines both color acceptance and ability to withstand high loads. It had been reported that sintering of zirconia followed by air-borne particle abrasion affect its strength. The effect of air-borne particle abrasion/sintering sequence on shear bond strength of resin cements to zirconia was found non-significant; however the effect of sequence on the flexural strength has not been reported. The Ivoclare Vivadent manufacturer recommendation is to sinter the zirconia before subjecting it to air-borne particle abrasion.
Aim of the study: to evaluate the effect of air-borne particle abrasion/sintering sequence on the flexural strength of zirconia.
Materials and Method: forty bars of dimensions (26 × 6 × 1.5 millimeter) were fabricated from IPS e-max zircad. The specimens was divided into two equal groups (A and B). Group A (AS) were subjected to air-borne particle abrasion followed by sintering. However specimens of group B (SA) were sintered before air-borne particle abrasion. Specimens of each group were subjected to X-Ray Diffraction to show monoclinic-tetragonal phases percentage. Three-point loading was applied to all specimens to measure the flexural strength using a Universal Testing Machine.
Results: At statistically significant level p ≤ 0.05. Group SA has showed significantly higher flexural strength compared to group AS. Air-borne particle abraded surface of group SA showed the highest amount of monoclinic phase crystals after X-Ray Diffraction analysis.
Conclusion: Air-borne particle abrasion/sintering sequence affects zirconia' flexural strength. And air-borne particle abrasion surface treatment induces tetragonal to monoclinic phase transformation in fully sintered zirconia.