Surface Modified Nanoparticle Fillers for Dental Polymer-Particle Composites

OBJECTIVES: Dental composites are limited in durability due to polymerization shrinkage and stress and their effects on adhesion and strength. We are attempting to develop a dental composite having low polymerization stress and shrinkage, high in strength, and having low toxicity. Fillers, as high performance additives, play an important role in polymer composite applications, including dental composites. METHODS: This work synthesized metal oxide nanorods/nanofibers by a simple hydrothermal process. The particles' surface composition was then chemically altered, for improvement in polymer-composite properties. Surface modified and unmodified filler particles were characterized and their effect on composite properties by incorporating the neat and modified particles into BisGMA-TEGDMA (control) radical and Silmix (®3M-ESPE) cationic light-curable dental composites. RESULTS: Surface modifications to covalently attach reactive groups to the particle surface had two functions: Organic groups provided enhanced dispersion while reactive groups enhanced the interfacial bond strength and cohesive strength without introducing toxicity. CONCLUSIONS: Surface-modified particles can be of particular interest for their ability to promote strength but also reduce polymerization stress. This work was supported in part by NIH-NIDCR grant R-21DEO18336.