Investigation of Monoclinic Content on Clinically Retrieved Zirconia Heads

The monoclinic zirconia content in clinically failed ceramic heads was investigated in order to identify the cause of the failure. High percentages of the monoclinic zirconia were associated with the fractured surface. In vitro, accelerated aging of some components shows that the monoclinic transformation is site related: the closer to the bore, the more the monoclinic transformation. This phenomenon may be associated with the composition and the manufacturing process.