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.
- AI agents deliver results – but do they reason scientifically?A research team co-led by Kevin Maik Jablonka from the Helmholtz Institute for Polymers in Energy Applications Jena (HIPOLE Jena) and N. M. Anoop Krishnan from the Indian Institute of Technology Delhi has developed Corral, a new benchmark for AI agents in science. The preprint “AI scientists produce results without reasoning scientifically” has been published on arXiv (https://doi.org/10.48550/arXiv.2604.18805). The analysis shows that current systems can execute scientific workflows and deliver results; however, they often do not follow the basic principles of scientific testing and reasoning.
- Magnetic field during catalyst synthesis triples ammonia yieldApplying an external magnetic field during the synthesis of CoFe₂O₄ electrocatalysts triples the ammonia yield during electrocatalytic conversion. The magnetic field alters the surface states of the spinel oxide thin films, making catalytically active sites more accessible. In the journal 'Advanced Functional Materials', a team led by Marcel Risch at HZB and Sanjay Mathur at University of Cologne demonstrates a scalable strategy for developing next-generation electrocatalysts for efficient and sustainable chemical production.
- Materials chemistry shapes the future of catalysisThe synthesis of materials can serve as a tool for developing smart, adaptive electrocatalysts. This rapidly evolving field of research involves in-situ analytics, data-driven discoveries and autonomous robotics. These new approaches could accelerate the discovery of long-lasting and efficient catalysts for future energy conversion and the decarbonisation of the chemical industry. A recent article by Dr Prashanth Menezes and his team in the renowned journal Angewandte Chemie provides an overview of this research.