Physico-mechanical Characterisation of a Novel and Commercial CAD/CAM Composite Blocks

Abstract

Ceramics and resin composites have been used in dentistry as restorative materials for over fifty years ago, and meanwhile their properties have been substantially improved. Recently a new class of restorative materials known as ‘polymer infiltrated ceramic network-PICN’ materials has been introduced as CAD/CAM materials, and to optimise the performance of ceramic and composite materials by combining them into a single material. The aim of the present research was to assess PICN in comparison to conventional materials with respect to their composition, structure, physical and mechanical properties. A new polycrystalline based PICN material was fabricated and assessed in this study. Alumina discs were fabricated and sintered at different temperatures followed by silanaisation and UDMA-TEGDMA resin polymer infiltration. The density, optical properties and biaxial flexural strength were assessed and the microstructure was examined using a scanning electron microscope. It was found that polymer infiltration significantly improved the density% of ceramic samples. An increase in sintering temperature results in a significant improvement in the optical properties but not the biaxial flexural strength. The effect of sintering temperature, the quality and the quantity of ceramic compositions on the mechanical coherence of PICN materials and other restorative materials were assessed and compared at different microstructural dimensions: macro, micro and nano. Materials showed variable results and micro hardness and nano hardness of the studied materials increased systematically with an increase in filler loading. Mechanical properties of PICN ceramic were significantly influenced by the sintering temperatures of their ceramic matrices. The elastic modulus values showed bimodal distribution and associated with the various phases present which were able to be distinguished at nano level. Sorption and solubility were assessed after 7 months of water storage. Water sorption of CAD/CAM composite blocks are material-dependent and are affected by the filler weight percentage. Commercial and model PICN ceramics showed hydrolytic stability between resin composite and conventional ceramic, reflecting its microstructural components. Sintering temperature appears to have a significant effect on the hydrolytic stability of PICN