Effect of Nanoparticles on Wear Resistance and Surface Hardness of a Dental Glass-ionomer Cement

We have studied the effect of nanoparticles on wear resistance and surface hardness of a dental glass-ionomer cement. The effects of composition, loading ratio, and surface modification of the nanoparticles as well as particle size were investigated as well. Commercially available spherical nanoparticles were incorporated into a commercial dental cement Fuji II. One of the nanoparticles was surface-modified with poly(acrylic acid) via surface-initiated atom-transfer radical polymerization. All the cements were conditioned in distilled water at 37°C for 24 h prior to testing. The results showed that all the particles incorporated (either nano-, micro-, or surface-modified) increased the resistance to attrition of Fuji II by approximately 50% but slightly decreased the resistance to abrasion. Most of the modified cements showed increased surface hardness values as compared to Fuji II. Surface modification significantly increased the loading of the nanoparticles into Fuji II from 10% to 30% as compared to the unmodified ones (only 10% at the maximum). Within the limitations of this study, it seems that incorporation of 1-3% spherical silica nanoparticles can effectively improve both resistance to attrition and surface hardness of Fuji II cement.