The role of Y2O3 in the bioactivity of YSZ/PLLA composites

Yttria stabilized zirconia, one of the most common ceramics in the field of dentistry and in particular dental implantology, for decades has been wrongly considered to be completely bio-inert. In this work, we investigate the role of yttria on the bioactivity of yttria stabilized zirconia formulations, proving that the composite ceramic is actually bioactive, do not affect the cell adhesion and can stimulate cell proliferation, in vitro. To reduce to minimum the number of variables, yttria stabilized zirconia particles with different contents of yttria but similar average size and morphology have been used to reinforce an electrospun poly-l-lactide (PLLA) fibers. Characterization of both the ceramic particulates and the scaffolds confirmed the morphological and structural similarities between the samples, which were then tested in vitro using a human fetal osteoblasts model. The results showed that cell proliferation is enhanced by the presence of the composite ceramic additive, with higher contents of yttria being overall more effective. These results confirm that yttria plays a key role in the biocompatibility and bioactivity of ceramics and can be used to improve the chances for a positive outcome in the osteo-integration of dental implants and/or biomedical scaffolds.