Good day! As far as I can understand, incorporation of zirconia particles mostly increase the flexural strength of PMMA. While the concentration of zirconia influences PMMA, the type of acrylic resin, size, and silanization of zirconia particles do not influence the results. Thus, the addition of zirconia particles shows a positive effect on PMMA. Please, refer the following links:
Article Influence of addition of zirconia on PMMA: A systematic review