CD Laboratory for Photopolymers in digital and restorative dentistry

Photopolymers are plastics that harden under the influence of light. In modern dentistry, they are used for fillings, temporary restorations, inlays and crowns. The basic properties of the materials are being researched with the aim of improving quality, for example in terms of curing speed, shrinkage and removability.

The laboratory's approach is very broad and covers the entire development spectrum of new photocurable materials: From chemical synthesis, production and processing to process development and material characterisation. This is also reflected in the management of the laboratory: two scientists from different fields - synthetic chemistry and materials science - work together to develop new materials.

The aims of the research activities are, on the one hand, more durable and easier to process materials for restorative purposes (i.e. fillings) and materials that have to be customised for specific patients in order to be able to produce crowns and bridges, for example. Ceramic-based materials are being developed for patient-specific moulding, which can be processed using pioneering 3D printers. The aim is to be able to offer materials and processes for aesthetically sophisticated restorations in digital dentistry.

One of the major problems with regard to restorative applications is the limited photoreactivity and curing depth. Traditionally, photopolymers are cured with UV light - in dentistry, however, this could damage surrounding tissue, which is why visible light must be used. As a result, the materials harden less deeply and processing takes longer. The scientists at the laboratory are therefore researching substances that can absorb light efficiently at wavelengths above 450 nm and trigger cross-linking reactions. This requires very detailed knowledge of the photochemical properties of the substances.

Another goal of the research work is materials that shrink less during curing than previous materials. This shrinkage can lead to the formation of micro-cavities and micro-cracks and favour the formation of edge gaps.

Finally, certain materials, such as adhesives for brackets on braces, should also be able to be removed when they are no longer needed. We are looking for new ways to thermally and photochemically loosen such bonds to the teeth.