Requirements for dental filling materials
Materials for filling composites should feature tooth-like properties (appropriate hardness, elasticity and thermal expansion behavior), but they must also be easy to use by the dentist, i.e. they should penetrate easily into the cavity and harden quickly under the effect of UV light. The material should also feature minimum shrinkage, be non-toxic and sufficiently non-transparent to X-rays.
Traditional filling composites
Plastic fillings have been used for dental restorations for quite a long time. However, problems arose in connection with long-term adhesion (abrasion, marginal fissures etc.), a high degree of polymerization shrinkage (marginal fissure) and a high content of residual monomers.
Sol-gel technology as a key to improving properties
The dual character of the ORMOCER®s as inorganic-organic copolymers is the key for improving the properties of filling composites. The organic, reactive monomers are bound in the sol-gel process by the formation of an inorganic network. In the subsequent curing process, the polymerization takes place with less shrinkage. Abrasion resistance, in particular, is significantly enhanced by the existing inorganic Si-O-Si structure.
Two filling composites based on dental ORMOCER®s (Definite® and Admira®) are available. The single-component, specifically designed
dentine-enamel bonding used in Admira® (developed in cooperation with VOCO) uses a special adhesive ORMOCER®, which makes this product especially advantageous.
Apart from the actual filling composites, light-curable ionomer cements based on ORMOCER®s are also developed as part of a BMBF project. By combining the ORMOCER® and glass ionomer technologies, a biocompatible, cost-efficient alternative to amalgam will be developed. Monodisperse nano fillers with a high degree of X-ray opacity, which allows a high packaging density and a modified refractive index, are also a focal point in these developments.