Additive Manufacturing Technologies (AMT)
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Christian Doppler Laboratory for Photopolymers in Digital and restorative dentistry

Photopolymers are plastics that harden on exposure to light. In modern dentistry, they are used for fillings, restoratives, inlays and crowns. This project will explore the underlying properties of these materials with the aim of improving performance, for example in relation to curing, shrinkage and controlled removability.

The approach of the laboratory is very broad and covers the entire R&D spectrum of new photo-curing materials: from chemical synthesis, production and processing to process development and material characterization. This breadth is also reflected in the management of the laboratory: Two scientists with different specialties - synthetic chemistry and materials science - working together to develop new materials.

Objectives of the research activities are on the one hand more durable and easier to process materials for restorative purposes (i.e. fillings) as well as materials that have to be made ​​specifically for the patient such as crowns and bridges. For patient-specific contouring, ceramic-based materials are being developed that can be processed with advanced 3D printers. The objective here is to offer materials and processes for esthetic restorations in digital dentistry.

 One of the major problems in relation to restorative applications is limited photoreactivity, which effects material strength and depth of cure. Classically, photopolymers are cured with ultraviolet light; however, UV light is potentially harmful both to the patient and the dentist, which necessitates the use of visible light. The scientists of the laboratory therefore investigate photoinitiators that efficiently absorb at or even beyond 450 nm. The detailed knowledge of the photochemical properties of the initiators and of crosslinking kinetics ensures better performing materials.

Another aim of the project is the development of materials that during curing shrink less than currently used materials. This shrinkage may in fact lead to the formation of microvoids and microcracks and promote the formation of marginal gaps.

Finally, emphasis is placed on improved adhesives for braces, where the material should be easily removed when they are no longer needed. Investigations are being made in both thermal and photochemical methods for controllably debonding the adhesive from the tooth.

Contact: Prof. R. Liska, Prof. J. Stampfl

Funding: Christian Doppler Research Society