New Method for Absorption Correction to Improve Dental Fillings
The micro-XRF composite image for the Ca (white/tooth), Yb (magenta/filling) and Zn (red/sealer) distribution in a treated human tooth shows Zn diffusion from the sealer material into the tooth. © Leona Bauer (TU Berlin/HZB)
A research team led by Dr. Ioanna Mantouvalou has developed a method to more accurately depict the elemental distributions in dental materials than previously possible. The used confocal micro-X-ray fluorescence (micro-XRF) analysis provides three-dimensional elemental images that contain distortions. These distortions occur when X-rays pass through materials of different densities and compositions. By utilizing micro-CT data, which provides detailed 3D images of the material structure, and chemical information from X-ray absorption spectroscopy (XAS) experiments conducted in the laboratory (BLiX, TU Berlin) and at the synchrotron light source BESSY II, the researchers have improved the method.
"We can now conduct more accurate measurements," says Ioanna Mantouvalou. "The absorption correction with micro-CT and XAS takes into account how strongly different materials absorb X-rays." This has been made possible through a combination of laboratory infrastructures at BAM (Federal Institute for Materials Research and Testing) and the HZB SyncLab laboratory in combination with the BESSY II synchrotron light source. BESSY II provided tunable X-rays over a wide energy range (200 eV to 32 keV) necessary for detailed compositional analysis. The micro-CT and confocal micro-XRF investigations were then facilitated using laboratory setups that utilize X-ray tubes as sources.
One of the materials investigated by Mantouvalou's team is dentin—a mineralized tissue that makes up most of the tooth, lies beneath the enamel, and plays a crucial role in transmitting sensations such as cold and heat. Its analysis is important for dentistry because, with dental fillings, elements often diffuse from the filling material into the dentin. "Our results enable detailed studies of such diffusion processes," says Leona Bauer, a doctoral student at HZB and TU Berlin and the study's first author. They are important for improving the durability and biocompatibility of dental fillings and reducing the risk of secondary caries and other dental problems.
In addition to investigating materials for dentistry, the method offers applications in other areas where precise 3D elemental distributions are required. These include the analysis of biological tissues, the investigation of catalyst materials, and the study of materials in environmental science. The versatility of the measurement method could thus have a positive impact on various research fields.
- 3D magnetic field experiment at BESSY II takes spintronics a step further(Fe0.63Ni0.3Pd0.07)3P or FNPP is a magnetic material that exhibits complex magnetic structures even at room temperature. This makes the material of interest for spintronics, a field that could enable data processing with significantly lower energy consumption. One potential application is novel magnetic memory devices. However, generating and modifying the desired structures in a controlled manner remains a challenge to date. A new study led by HZB has now taken a step forward in this regard. They demonstrated at the worldwide unique VEKMAG-Station at BESSY II, that a tiny external B-field in the plane of the magnetic patterns is sufficient to change them.
- Thin nickel films boost green hydrogen productionUltra-thin nickel oxide coatings can significantly improve the performance of anion exchange membrane (AEM) water electrolysers, a promising technology for producing green hydrogen. This was demonstrated by a team led by HZB scientist Dr. Michelle Browne. The results show that a nickel oxide film only 10 nanometres thick outperformed conventional nickel oxide powder electrodes while using less than 1% of the catalyst material. The study is published in the Journal of Materials Chemistry A,
- Confirmed figures for the first time: Investments in BESSY are worthwhile for Berlin and GermanyAn impact analysis by DIW Econ demonstrates the scientific and economic value of BESSY II. Every euro invested yields three euros for Germany and as much as ten euros for the State of Berlin. Furthermore, the study provides an economic forecast for the construction of BESSY III.
The impact analysis was presented on 3 September 2026 to Dr Henry Marx, State Secretary for Science and Research in the Berlin Senate. He supports the investment and is a strong advocate for BESSY III.