Hydrofluoric acid etching of dental zirconia. Part 2: effect on flexural strength and ageing behavior

Among the diverse treatments proposed to promote the osseointegration of zirconia dental implants, hydrofluoric acid (HF) etching appears to be a good candidate. However little is known on the effect of this process on the mechanical properties and long-term reliability. In this work, the surface integrity, the flexural strength and the ageing sensitivity of yttria-stabilized zirconia were assessed after etching in HF 40%. Results show that etching induces an increase of monoclinic phase content and a decrease in flexural strength. The strength decrease is limited to 15% for etching times below 60 min, whereas it reaches 29% after 120 min because of the formation of large etching pits. No substantial change in the ageing sensitivity was evidenced. Within the limits of this study, HF 40% etched zirconia appears to be reliable for long-term implantation provided that the etching duration does not exceed 60 min.