A new photoactive material could make visits to the dentist a more tolerable experience. Scientists from the Vienna University of Technology (TU Vienna) in Austria in collaboration with dental company Ivoclar Vivadent have developed a new generation of Germanium-based materials for use in tooth fillings, which could considerably reduce the duration of the often dreaded procedure.
In modern dentistry, amalgam fillings have become unpopular. Instead, white composite materials are more commonly used, which at first glance can hardly be distinguished from the tooth. The majority of these composites are based on photoactive materials that harden when they are exposed to light.
However, as the light does not penetrate very deeply into the material, the patients often have to endure a cumbersome procedure in which the fillings are applied and hardened in several steps.
The penetration depth of the light depends on its wavelength. ‘Usually, light in the violet and ultraviolet region is used,’ said Professor Robert Liska from the TU Vienna Liska. It is also possible to use light with longer wavelengths, which penetrates deeper into the material, but then the polymerisation process is less efficient. If the filling cannot be hardened in one step, the procedure has to be repeated several times. If the cavity is large, this can be rather uncomfortable.
This problem can now be solved with the new Germanium-based molecule, which makes up 0.04 per cent of the composite material. The molecule is split into two parts by blue light to create radicals, which initiate a chain reaction: molecular compounds, which are already present in the filling, react to form polymers, and the material hardens.
The Germanium-based photo initiator was created at the TU Vienna and then extensively tested by Ivoclar Vivadent. At Graz University of Technology in Austria, the physicochemical mechanism was investigated further. Using this new compound, the hardening depth could be increased from two to four millimetres, which significantly reduces the duration of the medical procedure.
Based on positive results, the TU Vienna and Ivoclar Vivadent have made additional strides to further extend their collective research interests in dental materials. In 2012, the University's Institute for Applied Synthetic Chemistry together with the Institute for Materials Science and Technology, with collective funding from Ivoclar Vivadent and the Christian Doppler Research Association, established a Laboratory for ‘Photopolymers in digital and restorative dentistry’.
Since its inception the laboratory has Goals for the laboratory include the development of improved photosensitive substances for dentistry with additional research efforts placed on 3D-printing of ceramic implants.