Seminar - Human dental tissues - Nature's hierarchically structured materials by Professor Alexander M. Korsunsky
日期：2018 年 03 月 13 日 ( 星期二)
Time：11:00 am – 12:00 pm
Human dental tissues are hydrated biological mineral composites of hydroxyapatite crystallites within an organic matrix. Dentine and enamel have a hierarchical structure that delivers their versatile mechanical properties. These composites demonstrate superb thermo-mechanical stability, but suffer biological and chemical degradation (decay) due to one of the most widespread diseases, human dental caries, that arises as a consequence of modern sugar-rich diet, and proceeds through the proliferation of acid-producing bacteria residing in the biofilm known as plaque.
A strong and durable bond between dentine and enamel is formed by the dentine enamel junction (DEJ), an important biological interface that resists failure under long-term harsh thermal and mechanical conditions in the mouth. Understanding the underlying reasons for this remarkable combination of strength and toughness remains an important challenge, both in the context of dentistry, and from the point of view of pursuing biomimetic advanced materials engineering.
Residual strain develops in the vicinity of the DEJ during odontogenesis (tooth formation). The experimental and interpretational challenges that could not be overcome until recently presented an obstacle to the evaluation of residual stress in the vicinity of the DEJ at the appropriate spatial resolution. We used the recently developed FIB-DIC micro-ring-core method to determine the residual elastic strain at micron resolution. The residual strain profiling across the transition from dentine to enamel are correlated with the study of internal architecture using X-ray scattering (SAXS/WAXS). We illustrate how this provides improved insight into the origins of the remarkable performance of the DEJ.
Further discussion will be devoted to enamel and dentine erosion due to acid attack during caries.
Prof AM Korsunsky is a world-leader in engineering microscopy of materials systems and structures for optimization of design, durability and performance. He leads the Centre for In situ Processing Science (CIPS) at Research Complex, Harwell. He consults Rolls-Royce plc on matters of residual stress and structural integrity, and is Editor-in-Chief of Materials & Design, a major Elsevier journal with the IF of 4.364. He has degree of Doctor of Philosophy (DPhil) from Merton College, Oxford, and undergraduate education in theoretical physics. He was Junior Research Fellow at Fitzwilliam College, Cambridge, and Lecturer at Newcastle University, before moving to his current position at Oxford. Each year he gives several keynote and plenary lectures at major international conferences on engineering and materials. He has extensive international links that included visiting appointments in Italy (Roma Tre), France (ENSICAEN) and Singapore (NUS, NTU, A*Star). Prof Korsunsky’s research interests concern improved understanding of integrity and reliability of engineered and natural structures and systems, from high-performance metallic alloys to polycrystalline ceramics to natural hard tissue such as human dentin and seashell nacre. He co-authored books on fracture mechanics (Springer) and elasticity (CUP), and published ~350 papers in scholarly periodicals on subjects ranging from multi-modal microscopy, neutron and synchrotron X-ray analysis, contact mechanics and structural integrity to micro-cantilever bio-sensors, size effects and scaling transitions. His h-index is 33, and his top paper has about 600 citations. Support for Prof Korsunsky’s research comes from EPSRC and STFC (major UK Research Councils, over £2M current funding) and the EU (~€6M project iStress), as well as from Rolls-Royce (~£0.5M current funding), Oxford Instruments, the Royal Society, Royal Academy of Engineering (RAEng), NRF (South Africa), DFG (Germany), etc. He is member of editorial boards of Journal of Strain Analysis, FFEMS, TAML.