Contribution of micropores in porous zirconia spheres to high optical transparency of dental resin composites

Abstract

Transparency to UV-Vis light and radiopacity of dental resin composites containing zirconia (ZrO₂) fillers were investigated. The transparency of the resin composite containing porous ZrO₂ spheres was much higher than that containing irregularly shaped ZrO₂ particles. Calcination of the porous ZrO₂ spheres at high temperatures led to dramatically reduced specific surface areas and pore volumes. The transparency of the resin composite containing the calcined porous ZrO₂ spheres drastically decreased as the calcination temperature increased. Then, the enhanced UV-Vis transmittance of the resin composite containing porous ZrO₂ spheres is attributed to the concentration and physical characteristics of the pores. The radiopacity of the resin composites containing porous ZrO₂ spheres increased slightly with increasing calcination temperature. This study revealed that the internal structure of the ZrO₂ fillers mainly influenced in the UV-Vis light transmittance of the resin composites.