New inorganic components for dental filling composites

Dental composite filling materials are improved by incorporating nanofillers. They impart increased hardness and wear resistance to composites. In addition, they produce better polishing results than macrofillers. If the particles are sufficiently small, transparent composite pastes are obtainable, independent of the refractive index of the polymerisable monomers. In this context, organosols, non-agglomerated nanoparticles in organic liquid media, are especially interesting. Some of our own results on organosols are presented in this paper. Their relatively low viscosity enables the preparation of composites with a high filler load, thus reducing the shrinkage of the dental composite during polymerisation and improving themechanical properties. Inorganic - organic hybrids are an attractive class of materials for dental fillings. The synthesis of different polymerisable ormocers for dental composites is reviewed in the second part. Ormocers can be applied as a polymerisable matrix, improving biocompatibility and wear resistance. Their use as inorganic fillers improves the thermodynamic compatibility of the filler with the matrix and enhances the polishability. Functionalised inorganic clusters used as new additives combine the properties of very small nanoparticulate fillers and well-designed highly functional monomers with high crosslinking capabilities. Xerogel colour pigments are advantageous alternative additives to conventional pigments. 3-D structural colour pigments, which are obtained by the self-assembly of monodisperse spherical particles, produce an opalescent effect resembling that of the natural enamel in highly aesthetic composites.