These studies revealed the role of residual porosity-acting as defects and thus detrimental to the mechanical properties-as well as the role of the mechanical properties of the polymer phase and its adhesion to the ceramic surface. Without a good adhesion (e.g., with epoxy), delamination occurs easily at the polymer/ceramic interface . A better control of the adhesion can be achieved with PMMA . However, in all these studies, the final composites are nearly dense, with a residual porosity of only a few percents.