Article

Journal of Materials Science: Materials in Medicine

, Volume 23, Issue 3, pp 677-685

Qualitative assessment of microstructure and Hertzian indentation failure in biocompatible glass ionomer cements

  • Kun V. TianAffiliated withMaterials Science Research Institute, Faculty of Dentistry, Semmelweis UniversityGlobal Institute of Computational Molecular and Materials Science (GIOCOMMS)Global Institute of Computational Molecular and Materials Science (GIOCOMMS)Global Institute of Computational Molecular and Materials Science (GIOCOMMS)
  • , Peter M. NagyAffiliated withMaterials Science Research Institute, Faculty of Dentistry, Semmelweis University
  • , Gregory A. ChassAffiliated withGlobal Institute of Computational Molecular and Materials Science (GIOCOMMS)Global Institute of Computational Molecular and Materials Science (GIOCOMMS)Global Institute of Computational Molecular and Materials Science (GIOCOMMS)Department of Biological and Chemical Sciences, Queen Mary University of London
  • , Pal FejerdyAffiliated withDepartment of Prosthetic Dentistry, Faculty of Dentistry, Semmelweis University
  • , John W. NicholsonAffiliated withSchool of Science, University of Greenwich, Medway Campus
  • , Imre G. CsizmadiaAffiliated withMaterials Science Research Institute, Faculty of Dentistry, Semmelweis UniversityGlobal Institute of Computational Molecular and Materials Science (GIOCOMMS)Global Institute of Computational Molecular and Materials Science (GIOCOMMS)Global Institute of Computational Molecular and Materials Science (GIOCOMMS)Department of Chemistry, University of Toronto
  • , Csaba Dobó-NagyAffiliated withMaterials Science Research Institute, Faculty of Dentistry, Semmelweis University Email author 

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Abstract

Discs of biocompatible glass ionomer cements were prepared for Hertzian indentation and subsequent fracture analyses. Specifically, 2 × 10 mm samples for reproducing bottom-initiated radial fracture, complemented by 0.2 × 1 mm samples for optimal resolution with X-ray micro tomography (μCT), maintaining dimensional ratio. The latter allowed for accurate determination of volumetric-porosity of the fully cured material, fracture-branching through three Cartesian axes and incomplete bottom-initiated cracking. Nanocomputed tomography analyses supported the reliability of the μCT results. Complementary 2-dimensional fractographic investigation was carried out by optical and scanning electron microscopies on the larger samples, identifying fracture characteristics. The combined 3-D qualitative assessment of microstructure and fractures, complemented by 2-D methods, provided an increased understanding of the mechanism of mechanical failure in these cements. Specifically, cracks grew to link pores while propagating along glass-matrix interfaces. The methodological development herein is exploitable on related biomaterials and represents a new tool for the rational characterisation, optimisation and design of novel materials for clinical service.