Primary study of synthesis and dispersion of zirconia and silica nanoparticles for post-endodontic composite

Zirconia and silica-based composite are introduced as an alternative to post-core systems due to their high elastic modulus. The cast metal post-core systems in the application of dental material can cause stress concentration within the surrounding radicular dentin, resulting in root fractures. These materials provide more esthetical appealing and biocompatible restorations. However, the use of zirconia and silica nanoparticles as fillers tends to agglomerate in an organic solvent. The objective of the present report is to synthesize zirconia and silica nanoparticles by sol-gel method and subsequently, disperse them in an organic solvent by beads milling methods. The particle size distribution and stability were observed correspondingly using the particles size analyzer (PSA) and zeta potential. The initial average sizes of silica and zirconia particles in organic media were correspondingly 2.7 mm and 191 nm, respectively. After beads milling for 5 hours, silica and zirconia nanoparticles successfully were dispersed with average particles size of 91.5 nm and 124 nm, respectively. The zeta potentials of silica and zirconia suspensions were -21.1 and -10.6 mV, respectively. The SEM image for both particles showed spherical morphology with agglomerated particles having primary particle sizes below 100 nm. Therefore, it was concluded that both particles can be applied as filler for a post-endodontic composite with an additional surfactant before polymerization.