Material aging abutting restorations: predicting dentine sclerosis

• Applicants: Dr. Ioanna Mantouvalou; Professor Dr. Paul Zaslansky
• Subject Area: Biomaterials ; Dentistry, Oral Surgery
• Term: since 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 396127899

Dentine sclerosis is an enigmatic term, used to describe an altered but non-carious state (or process of transition) of the tubule-containing bulk-forming tissue of teeth. Whereas some material researchers consider sclerotic dentine synonymous with blocked tubules, others identify important aging changes in the matrix of mineralized-collagen-fibers in intertubular dentine (ITD). Sclerosis can develop in a physiological process with age, but is also develops in dentine tissue adjacent to fillings – possibly an effect of chemical leaching from the used materials. From a clinical point of view sclerosis is on the one hand detrimental because it negatively influences the durability of tooth bonded fillings, it complicates root canal treatment, and it may decrease the effectiveness of disinfection procedures. On the other hand, the reduced permeability may increase the resistance to bacterial penetration. In this InterDent project we will study filling-related time evolving changes to permeability, properties and chemical integrity of the natural ingredients of dentine, taking a closer look at the biocomposite outside of the tubules. To achieve this, we need to better understand diffusion across the ITD, to be able to separate between interzone impregnation versus flow along the tubules. More concretely, we aim to measure chemical composition changes within the ITD surrounding tubules at increasing distances along the interzone between dentine and fillings as a function of time and storage. This will be complemented with the mechanical characterisation of the ITD in sclerotic dentine, relating deformation responses of the nanocrystals to nano-mechanical testing. We will explore diffusion and divalent leaching elements (Zn, Sr) as marker for studying diffusion between restorations and dentine. And last, we will characterize Zn distributions in naturally-growing pulp-stones in virgin teeth, and elucidate correlations between such excessive pulp mineralization and sclerotic dentine. These objectives will be tackled using a multi-length-scale imaging approach spanning from mm to nm using methods such as confocal µXRF, (PCE-)µCT, FTIR and FIB-SEM. With this multitude of analytical techniques the investigation of different characteristics such as elemental distributions, mineral density, residual stress or structure in the hierarchical bio-nanocomposite dentine will become feasible.

• DFG Programme: Research Units
• Subproject of: FOR 2804: The Materials Science of Teeth in Function: Principles of Durable, Dynamic Dental Interphases
• International Connection: Jordan
• Cooperation Partner: Dr.-Ing. Gianluca Iori