Improvement of 3Y-TZP zirconia by salt infiltration of CeO2

Tetragonal polycrystalline zirconia stabilized with 3% mol of yttria (3Y-TZP) is a popular biocompatible ceramic which has the highest mechanical properties of any single oxide ceramic. Its application in recent years to dental restorations and implants has raised concerns about to its resistance to low temperature degradation (LTD), because in orthopedics it has been shown that femoral heads used in hip-joint arthroplasty may be vulnerable to LTD. Femoral heads explanted after several years in vivo have been thoroughly studied and now there is overwhelming evidence that low temperature degradation is an important issue in vivo for 3Y-TZP, at least in this application. Some recent publications devoted to dental zirconia have already underlined the need to remember that zirconia is susceptible to suffer LTD if exact processing conditions are not followed. Despite this, the problem of LTD in dental zirconia seems to be underemphasized so far. In the present work, a strategy is presented to increase resistance to LTD with the purpose to increase the long-term reliability of dental implants. A new method is proposed which is based in small changes in the standard processing steps for 3Y-TZP that significantly enhance the resistance to LTD while maintaining its good mechanical properties. This has been demonstrated by producing specimens under usual manufacturing practice in dental labs but introducing a tetravalent Cerium ion by infiltrating with a cerium salt solution in either water or ethanol in the pre-sintering stage and finally sintering at different temperatures. The developed methodology has been assessed by studying the resistance to LTD and the mechanical characterization after each processing condition.Incomin