Research focus

The investigations focus on the methods of mechanical and morphological material testing. In addition to the material, the choice of methods is strongly oriented towards the biomedical issue and the relevant standards and guidelines. 

Polymers are subject to different ageing mechanisms, which often occur in combination. A distinction is made between mechanical, chemical, thermal, biological and radiation-induced ageing. The resulting degradation can be intentional, e.g. in the case of degradable or resorbable biomaterials. The aim here is to adapt the rate of degradation to the ambient environment by influencing the material. However, degradation can also occur undesirably and is controlled by the physiological parameters. This can be mechanical abrasion (abrasion, tribology), but also chemical and even biological degradation through exposure of the biomaterial to body fluids, tissues or microorganisms (oxidation/hydrolysis/enzymatically catalyzed hydrolysis). Polymer degradation can be simulated experimentally in vitro and results in statements on mechanical, physicochemical and morphological ageing. We investigate unfilled and highly filled polymers and their areas of application in biomedical engineering. From this, new strategies for material synthesis can be derived.

Metals and their alloys are subject to electrochemical corrosion when they come into contact with an electrolyte. Physiological solutions in the body, such as saliva or blood, act as electrolytes. As a result, the implant surface begins to corrode. This can lead to the dissolution of the metal with the accompanying release of ions. However, metal compounds can also form and protect the surface from corrosive attacks, known as (re)passivation.

Our current focus is on investigating the corrosion behavior of dental alloys using examples from prosthetics and orthodontics. The composition of the alloy plays a role here, but also the fact that material pairings of different alloy compositions (galvanic element) frequently occur in the oral cavity. Another aspect is the joining techniques [(laser) welding, soldering] used in the manufacture and repair of dental restorations. In addition to the joining technique, the influence of heat also leads to changes in the microstructure.

We investigate these issues using current density potential measurements (linear polarization) on various alloys and their material pairings and the subsequent analysis of characteristic parameters such as the resting potential, the corrosion potential, the corrosion resistance and the corrosion rate through to the breakthrough potential. In the case of iron-free alloys, the repassivation behaviour can also be investigated using cyclic polarization.

The electrochemical measurement is accompanied by morphological characterization (light and electron microscopy) as well as qualitative element analysis (EDX) and quantitative ion analysis (ICP-MS).

In dentistry, modern procedures for digital intraoral impressions are now available. The data records are immediately available to the treating dentist for further treatment. Time and costs are saved. Nevertheless, it is still of interest how intraoral impressions compare to conventional procedures. Quality and accuracy in the impression taking of complex situations is required and is being investigated by us in comparative studies.

Additive manufacturing processes have become an integral part of patient care in dental clinics. Digital data sets and the planning of patient care based on them are already possible in many situations. We are investigating the integration of the digital workflow into the clinical situation. In addition to material examinations and their functionality, this also includes the establishment of new workflows for dental treatments in cooperation with the Dental School at University Medical Centre Rostock.

Hard tissue in the form of bone (cortical bone and cancellous bone) and teeth (enamel and dentin) differs in chemical composition and is subject to hierarchical organizational principles, which are expressed in the morphology. This also results in gradients of mechanical properties such as modulus of elasticity, strength, elongation and microhardness. The investigation of this structure-property correlation explains the morphological and mechanical correlations in hard tissue on the one hand and enables the targeted development of biomaterials and the design of implants on the other.

Furthermore, together with our cooperation partners, we also investigate these correlations in the context of pathologies such as osteoporosis and hormone balance. In addition to the mechanical and morphological characterization of hard tissue, we are developing new methods of hard tissue preparation for electron microscopy together with the Electron Microscopy Center of the University Medical Center Rostock .