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Poster Pitch

Interfaces in Dental Enamel and Implications for Mechanical Properties

Monday (16.03.2020)
17:10 - 17:13
Part of:


Dental enamel is a hierarchically structured material consisting of hydroxyapatite crystallites with a diameter of around 50 nm and a length of several micrometers [1]. These crystallites are then bundled together and form prisms (with a diameter of around 5 µm) and interprismatic matrix that can be arranged in numerous ways. It has been the subject of a large number of studies in the last decades with an effort to understand the structure-property relation. However, the focus has been the role of prism arrangement and organization whereas the nature of the interfaces is poorly investigated. Literature often suggests that enamel crystallites are glued together by protein [2] and that prisms are surrounded by organic sheaths [1], [3]. A high resolution structural analysis revealed the local geometrical structure of the crystallite interfaces with a resolution ≤ 1 nm. Within this resolution the enamel prisms are surrounded by an interface that is discontinuous with frequent mineral to mineral contact separated by gaps. This contact manifests either by crystallites bridging the boundary between prismatic and interprismatic enamel or continuous crystallites curving and bridging the interprismatic enamel to the prisms. Contrary to existing structural descriptions of dental enamel structure in materials science literature, here the crystallites themselves are shown to be either in direct contact with each other, fusing together or are separated by gaps. These structural features contribute important understanding to both the architecture and mechanical properties of this biological material. A new structural model is proposed and the implications for the mechanical properties of dental enamel are discussed. In addition nanoindentation and micro-bending experiments for different sample conditions (chemical deproteination, heat treatment and wet/ dry) are conducted to investigate the influence of these conditions on the mechanical response.

References

[1] A.R. TenCate, A. Nanci, Ten Cate's oral histology, 7th ed., Mosby/Elsevier., St. Louis, Mo., 2008.

[2] M.C. Maas, E.R. Dumont, Built to last: The structure, function, and evolution of primate dental enamel, Evol. Anthropol. 8 (1999) 133–152. DOI: 10.1002/(SICI)1520-6505(1999)8:4<133::AID-EVAN4>3.0.CO;2-F

[3] L.H. He, M.V. Swain, Understanding the mechanical behaviour of human enamel from its structural and compositional characteristics, J. Mech. Behav. Biomed. 1 (2008) 18–29. DOI:10.1016/j.jmbbm.2007.05.001

Speaker:
Jasmin Koldehoff
Hamburg University of Technology
Additional Authors:
  • Prof. Dr. Michael V. Swain
    University of Sydney
  • Prof. Dr. Gerold A. Schneider
    Hamburg University of Technology