Cytotoxicity and antimicrobial efficiency of ZrO2 nanoparticles reinforced 3D printed resins

The aim of this study was to investigate the potential antimicrobial and cytotoxic effect of modified 3D printed resin with ZrO2 nanoparticles, as long-term provisional restoration. In addition, the study involved artificial aging process for three months to observe stability of 3D printed resin.Functionalized ZrO2 nanoparticles with γ-MPS were characterized using transmission electron microscopy, scanning electron microscope and Fourier-transform infrared spectroscopy. Dental resin was incrementally impregnated with γ-MPS modified nanoparticles at different concentrations (0, 1, 3, and 5 wt%). Specimens were printed, post-cured and placed in artificial saliva at 37 oC for 48 h or aged for 3 months. Discrepancy in composition and roughness were monitored using FTIR and AFM, respectively. Biocompatibility was evaluated using human oral fibroblasts. Antimicrobials capacity and biofilm adhesion were measured with Streptococcus mutans and Candida albicans.The microscopic and spectroscopic analyses confirmed γ-MPS coating around ZrO2 nanoparticles. The addition of nanoparticles (>1 wt%) significantly increased the surface roughness. Cytotoxicity results were in agreement with the recommended range of oral biomaterials standard. Moreover, the antimicrobial activity significantly improved with increasing the filler concentration. Despite the decrease in antimicrobial efficacy after 3 months of aging, modified resin revealed a critical ability to dominate biofilm formation.The addition of ZrO2 nanoparticles showed significant antimicrobial capability of a 3D printed resin without inducing any cellular side effects. Thus, the modification of a 3D printed resin with ZrO2 nanoparticles has a promising future in the dental field for fabricating long-term provisional restorations.