Glasses and Glass Ceramics for Medical Applications Emad El-Meliegy  Richard van Noort Glasses and Glass Ceramics for Medical Applications Emad El-Meliegy Department of Biomaterials National Research centre Dokki Cairo, Egypt emadmeliegy@hotmail.com Richard van Noort Department of Adult Dental Care School of Clinical Dentistry Sheffi eld University Claremont Crescent Sheffi eld, UK r.vannoort@sheffi eld.ac.uk ISBN 978-1-4614-1227-4 e-ISBN 978-1-4614-1228-1 DOI 10.1007/978-1-4614-1228-1 Springer New York Dordrecht Heidelberg London Library of Congress Control Number: 2011939570 © Springer Science+Business Media, LLC 2012 All rights reserved. This work may not be translated or copied in whole or in part without the written permission of the publisher (Springer Science+Business Media, LLC, 233 Spring Street, New York, NY 10013, USA), except for brief excerpts in connection with reviews or scholarly analysis. Use in connection with any form of information storage and retrieval, electronic adaptation, computer software, or by similar or dissimilar methodology now known or hereafter developed is forbidden. The use in this publication of trade names, trademarks, service marks, and similar terms, even if they are not identifi ed as such, is not to be taken as an expression of opinion as to whether or not they are subject to proprietary rights. Printed on acid-free paper Springer is part of Springer Science+Business Media (www.springer.com) v Glass-ceramics are a special group of materials whereby a base glass can crystallize under carefully controlled conditions. Glass-ceramics consist of at least one crystalline phase dispersed in at least one glassy phase created through the controlled crystallization of a base glass. Examples of glass-ceramics include the machinable glass-ceramics resulting from mica crystallization, the low thermal expansion glass-ceramics resulting from β-eucryptite and β-spodumene crystallization, high toughness glass-ceramics resulting from enstatite crystallization, high mechanical strength resulting from canasite crystallization or the high chemical resistance glass-ceramic resulting from mullite crystallization. These materials can provide a wide range of surprising combinations of physical and mechanical properties as they are able to embrace a combination of the unique properties of sintered ceramics and the distinctive characteristics of glasses. The properties of glass-ceramics principally depend on the characteristics of the fi nely dispersed crystalline phases and the residual glassy phases, which can be controlled by the composition of the base glass, the content and type of mineralizers and heat treatment schedules. By precipitating crystal phases within the base glasses, exceptional novel characteristics can be achieved and/or other properties can be improved. In this way, a limitless variety of glass-ceramics can be prepared with various combinations of different crystalline and residual glassy phases. With the appropriate knowledge on the right way to modify the chemical compositions and the heat treatment schedules, one can effectively control the phase contents, scale the developed properties and control the fi nal product qualities. Consequently, a skilled glass-ceramist is able to play with the constituting chemical elements and their contents in the composition to regulate the different ceramic properties. Admittedly, the success in controlling functional properties is much more diffi cult if opposing properties such as high hardness and good machineability are desired. Similarly, achieving good chemical resistance in the presence of high content of alkalis and alkaline earths or rendering inactive glass ceramics into bioactive glass ceramics through composition modifi cation are diffi cult to reconcile. Thus there are some real challenges and some serious limitations to what can be achieved. Preface vi Preface This book includes fi ve parts. The fi rst part provides the context in which the classifi cation and selection criteria of glass and glass ceramics for medical and dental applications are observed. This part starts with an introduction to medical glasses and glass ceramics, their classifi cation and the specifi c criteria for various applications in order to show the clinical context in which the materials are being asked to perform. The grouping and arrangements of ions in silicate based glasses and glass ceramics are considered. The second part deals with the manufacturing, design and formulation of medical glasses and provides a detailed description of theoretical and practical aspects of the preparation and properties of glasses. This part explains theoretically and practically how it is possible to predict fi nal glass properties such as density, thermal expansion coeffi cient and refractive index from the starting chemical compositions. Next this part focuses on the manufacturing of the glasses and shows how to calculate and for- mulate the glass batches, melt, and cast glasses. The part also explains how to predict the right annealing point, transition point, and glass softening temperature of the base glasses. The third part presents the manufacturing and methodology, the assessment of physical and chemical properties and the development of colour and fl uorescence in medical glasses and glass ceramics. In addition, the microstructural optimization which is responsible for most of the valuable ceramic properties is considered. This part also explains how to optimize the microstructure so as to reach a uniform microcrystalline glass ceramic microstructure and gives examples of practical opti- mization such as mica and leucite-mica glass ceramics. The last chapter of this part deals with the selection of the glass compositions such that the materials can develop the correct colour and have the desired fl uorescence. It also provides the ways for the development of colours and fl orescence in UV and visible light regions and a reliable quantitative measurement of colour and fl uorescence in dental glasses and glass ceramics. The fourth part presents a detailed description of the most prevalent clinically used examples of dental glass ceramics namely; leucite, mica and lithium disilicate glass ceramics, together with the encountered scientifi c and technical problems. This part explores in details the chemical composition, developed crystalline phases and the criteria for choosing the right chemical composition for different applica- tions as veneering ceramics for coating metal alloys and glass ceramics for CAD/ CAM applications. Appropriate solutions for common scientifi c and technical prob- lems encountered with their industry and applications are discussed. The part also explores how to control and modify the chemical, thermal, mechanical, optical and microstructural properties of glass ceramic systems. The fi fth part provides a brief description of the chemical compositions, bioactivity and properties of bioactive glasses and glass ceramics for medical applications. This part also discusses different models of bioactive glass ceramics such as apatite, apatite–wollastonite, apatite–fl uorophlogopite, apatite–mullite, potassium fl uorrichterite and fl uorcanasite glass ceramics. The primary function of this book is to provide anybody with an interest in medical and dental glasses and glass ceramics with the wherewithal to start making their own vii Preface glasses and glass-ceramics. Even if that is not their ambition then this book provides the reader with a greater understanding of the delicate interplay between the various factors that control the fi nal properties of medical and dental glasses and glass-ceramics. This book is a valuable source of information for scientists, clinicians, engineers, ceramists, glazers, dental research students and dental technicians in the fi eld of glasses and glass ceramics, and appeals to various other related medical and industrial applications. Sheffi eld, UK Emad El-Meliegy Richard van Noort ix Part I Introduction to Medical Ceramics 1 History, Market and Classifi cation of Bioceramics 3 1.1 Bioceramics 3 1.2 Classifi cation of Bioceramics 6 1.2.1 Biopassive (Bioinert) and Bioactive Materials 6 1.3 Mechanisms of Bioactivity 7 1.3.1 Formation of a Silica-Rich Surface Layer 8 1.3.2 Direct Precipitation of Apatite 8 1.3.3 Protein Mediation 8 1.4 Biopassive Ceramics 8 1.5 Bioactive Ceramics 10 1.6 Resorbable Bioceramics 11 1.7 Currently Used Glasses and Glass Ceramics 11 1.7.1 Bioactive Glasses 11 1.7.2 Glass–Ceramics 13 1.7.3 Dental Ceramics 14 2 Selection Criteria of Ceramics for Medical Applications 19 2.1 Biocompatibility 19 2.2 Radioactivity 20 2.3 Esthetics 20 2.4 Refractive Index 21 2.5 Chemical Solubility 22 2.6 Mechanical Properties 24 2.6.1 Tensile Strength 25 2.6.2 Flexural Strength 26 2.6.3 Biaxial Flexural Strength 27 2.6.4 Fracture Toughness 28 2.6.5 Microhardness 29 2.6.6 Machinability 31 Contents x Contents 2.7 Thermal Behavior 32 2.7.1 Thermal Expansion 33 2.7.2 Differential Thermal Analysis 35 3 Grouping of Ions in Ceramic Solids 37 3.1 Ceramic Solids 37 3.2 The Structure of the Atom 38 3.3 Formation of Ions and Ionic Compounds 38 3.4 The Ionic Size 39 3.5 Coordination Number 40 3.6 Electronegativity 41 3.7 Bonding of Ions in Ceramic Solids 41 3.8 The Ionic Bond Strength 42 3.9 Prediction of the Ionic Packing Structure 42 3.10 Stability of the Coordination Structure 45 3.11 Solid Solutions 46 3.12 Model of Solid Solutions 48 3.13 The Feldspar Solid Solution Using Rules of Ions Grouping 49 3.14 The Basic Structural Units of Silicates 49 3.14.1 Neosilicates (Single Tetrahedra) 50 3.14.2 Sorosilicates (Double Tetrahedra) 51 3.14.3 Cyclosilicates (Ring Silicates) 51 3.14.4 Inosilicates (Chain Structure Silicates) 52 3.14.5 Phyllosilicates (Sheet Structure Silicates) 52 3.14.6 Tectosilicates (Framework Silicates) 53 Further Reading 54 Part II Manufacturing of Medical Glasses 4 Formulation of Medical Glasses 57 4.1 Glass Chemical Compositions 57 4.2 The Glass Stoichiometry 58 4.3 Factors Affecting the Glass Stoichiometry 59 4.4 Industrial Factors Affecting Glass Stoichiometry 60 4.5 Replacement of Oxygen by Fluorine in Glass Chemical Compositions 61 4.6 Information Needed for Glass Calculations 62 4.7 Calculation of Glass Chemical Compositions 63 4.8 Glass Chemical Composition in wt% (Weight Composition) 63 4.8.1 Information Needed for Calculation 63 4.8.2 Steps of Calculation of the Glass Chemical Composition in wt% 64 [...]... Bioactive Glasses 13.3 Properties of Bioactive Glasses 13.4 Bioactivity of Bioactive Glasses Further Reading 221 221 222 224 225 227 14 Models of Bioactive Glass Ceramics 14.1 Apatite Glass Ceramics 14.2 Apatite–Wollastonite Glass- Ceramics 14.3 Apatite–Fluorophlogopite Glass- Ceramics 14.4 Apatite-Mullite Glass- Ceramics 14.5 Fluorocanasite Glass Ceramics. .. need of bioceramics is that bone is especially susceptible to E El-Meliegy and R van Noort, Glasses and Glass Ceramics for Medical Applications, DOI 10.1007/978-1-4614-1228-1_1, © Springer Science+Business Media, LLC 2012 3 4 1 History, Market and Classification of Bioceramics Biomaterials Synthetic Medical ceramics Glass & Glass CERAMICS Dental ceramic Natural Metals Polymers PHOSPHATE CERAMICS Composites... Bioactive glasses, glass ceramics, alumina, partially stabilized zirconia Dental implants Alumina, hydroxyapatite, bioactive glasses Temporary bone space fillers Tricalcium phosphate Alveolar ridge Bioactive glass ceramics, alumina Spinal surgery Bioactive glass ceramics, hydroxyapatite Maxillofacial reconstruction Bioactive glasses, glass ceramics 600 500 400 300 200 100 0 2004 2005 Glass, glass- ceramics and. .. Other Glass Raw Materials 6.3 Melting of Glass Batches 6.4 The Glass Structure and Conditions of Glass Formation 6.5 Glass Shaping into Block as Glass Ceramic Precursors 6.6 Transformation Range of Glass and Annealing of Glass Blocks References Part III 7 95 95 96 97 98 99 99 101 101 104 105 106 Manufacturing of Medical Glass Ceramics Design of Medical. .. as the demands on strength are not too high 1.7 1.7.1 Currently Used Glasses and Glass Ceramics Bioactive Glasses Bioactive glasses are a group of surface reactive glasses that release ions into the local environment, which can then trigger a range of biological responses The most desirable response is for the glass to stimulate the formation of new bone by the release of sodium, calcium, and phosphate... the surface of the implant and the new bone However, the 1.7 Currently Used Glasses and Glass Ceramics 11 Table 1.4 Types of tissue attachment for bioactive ceramics Bioceramic-tissue attachment Bioceramics Porous implants attachment by bone in-growth Porous hydroxyapatite (biological fixation) Attach by chemical bonding with the bone (bioactive Bioactive glasses and glass ceramics fixation) time dependence,... PhaseI Bioglass 4555 Glass ceramic Ceravital Table 1.5 Composition and properties of a range of bioactive ceramics, after L Hench (1998) 12 History, Market and Classification of Bioceramics 1.7 Currently Used Glasses and Glass Ceramics 13 Table 1.6 Composition of different grades of Bioglass® [after Hench (1972)] Component SiO2 CaO Na2O P 2 O5 CaF2 45S5 bioglass 45 24.5 24.5 6 – 45S5.4F bioglass 45... Leucite–Fluorophlogopite Glass Ceramics 8.6 Fluorcanasite Dental Glass Ceramics Further Reading 9 Development of Colour and Fluorescence in Medical Glass Ceramics 9.1 Coloured Glasses 9.2 Coloured Glass Ceramics 9.3 Colourants Based on Spinel Structure 9.4 Fluorescing Oxide Additives 9.4.1 Uranium Oxides 9.4.2 Cerium and Terbium Oxides... Low Fusion Leucite Ceramics 10.12 Classification of Leucite Dental Glass- Ceramics 10.13 Glass- Ceramic Veneers for Metal or Ceramic Substructures 10.13.1 Low Fusion Leucite Glass- Ceramics for Coating Gold Alloys 10.14 Yellow Coloration in the Leucite Ceramics References 11 12 Machinable Mica Dental Glass- Ceramics 11.1 Mica Glass- Ceramics 11.2... of Medical Glass- Ceramics 7.1 Glass Ceramic Fabrication 7.2 Mechanisms of Nucleation and Crystallization 7.2.1 Bulk/Volume Nucleation 7.2.2 Surface Nucleation and Crystallization 7.3 Selection of Glass Compositions for Glass Ceramics Processing 7.4 Optimum Heat Treatment Conditions 7.5 Prediction of the Proper Glass Heat Treatment Schedule 7.5.1 Glasses Crystallizing . Glasses and Glass Ceramics for Medical Applications Emad El-Meliegy  Richard van Noort Glasses and Glass Ceramics for Medical Applications Emad El-Meliegy Department. classifi cation and selection criteria of glass and glass ceramics for medical and dental applications are observed. This part starts with an introduction to medical glasses and glass ceramics, their. Biopassive Ceramics 8 1.5 Bioactive Ceramics 10 1.6 Resorbable Bioceramics 11 1.7 Currently Used Glasses and Glass Ceramics 11 1.7.1 Bioactive Glasses 11 1.7.2 Glass Ceramics 13 1.7.3 Dental Ceramics