Dental materials with comparable aesthetic effects and mechanical response to that of natural human enamel and dentin are in demand. Ceramic systems, particularly those with veneer porcelains, suffer a relatively high failure rate, due to brittleness of the veneering layer. It shortens their time in-service compared to polymer-ceramic and metal-ceramic restorations. However, the hardness of veneering materials may cause excessive wear on the opposing teeth, causing undesirable sensitivity and occlusal imbalance. Ceramic restorations are usually manufactured by either soft- or hard-milling processes. However, 3D-printing technology permits the desired assembly easily and, depending on the scaffold configuration, it can also be used to control the mechanical stability of the parts by combining different materials (ceramic–polymer, ceramic–metal, metal–polymer) and different geometries.
 
The aim of this work was to prepare a polymer–ceramic composite for dental applications, and determine the mechanical properties at sub-micrometric scale. For this purpose, the robocasting process was combined with the infiltration of biocompatible Bis-GMA/TEGDMA copolymer (Bis-GMA, bisphenol A-glycidyl methacrylate; and TEGDMA, triethyleneglycol dimethacrylate) inside porosity of yttria-doped zirconia. This approach should allow the reduction in Young’s modulus of zirconia to values closer to dentin, without the loss of adaptive modulation to teeth. Yttria-doped zirconia scaffolds with 50% porosity were prepared by Direct Ink Writing, and sintered at high temperature (1450ºC). The proper scaffolds were studied by means of X-Ray Computed Microtomography and Field Emission Scanning Electron Microscopy (FESEM). The final polymer-zirconia composite was obtained by infiltrating the scaffold with the diluted copolymer solution. Then the polymer infiltrated samples were cured into an oven. After their processing, the samples were characterized using complementary techniques, such as FESEM, Raman Spectroscopy, and X-Ray Diffraction (XRD), among others. Finally, the mechanical properties, such as elastic modulus and hardness, of polymer-zirconia composite at sub-micrometric scale were determined using Nanoindentation technique.