Fast-Setting Tooth Fillings
When treating teeth with cavities (caries), the diseased tooth material is removed first. Next, the dentist fills the clean cavity with a suitable material. Among others, so-called composite materials consisting of about 80% inorganic substances such as glass, ceramic or quartz particles find use. Organic compounds account for the remaining 20% of composite fillings. Usually, these are special methacrylates that cure on exposure to light. This involves the use of polymerization lamps that generate light having a wavelength between 300 and 500 nm.
Until now, these composites had to be applied in several individual layers that cured successively in the case of severe caries damage. One of the reasons for this is that the light does not penetrate deep enough into the material to cure the entire filling. Researchers at the Institute for Applied Synthetic Chemistry at Vienna University of Technology have now solved this problem with the aid of a germanium compound.
The molecule splits into two parts on exposure to light, creating radicals that trigger a chain reaction: the acrylates combine into polymers and the material cures. Using the new material, it was possible to increase the depth at which curing occurs from 2 mm to 4 mm. This reduces the treatment time considerably. Although the germanium compound is very expensive, only very small quantities are needed, which means that it is not a significant cost factor for the dental treatment. The compound makes up only 0.03% of the filling material.