Applied Dental Materials E-Book

• Herausgeber: John Wiley & Sons
• Kategorie: Fachliteratur
• Sprache: Englisch

Seitenzahl: 814

Veröffentlichungsjahr: 2013

Beschreibung

This textbook covers all aspects of materials science relevant to the practice of dentistry. It is aimed primarily at undergraduate dental students, although it will also be useful for practising dentists, dental technicians and dental assistants.

The 9th edition has been extensively revised to include the many advances in dental materials and their use that have occurred during the past nine years. The chapters on Resin-based filling materials and Adhesive restorative materials have been expanded significantly with new coverage of fibre reinforcement of composite structures and polymerisable luting agents. A brand new chapter has been added on endodontic materials.

Leseprobe

Contents

Preface

1 Science of Dental Materials

1.1 Introduction

1.2 Selection of dental materials

1.3 Evaluation of dental materials

2 Properties used to Characterise Materials

2.1 Introduction

2.2 Mechanical properties

2.3 Rheological properties

2.4 Thermal properties

2.5 Adhesion

2.6 Miscellaneous physical properties

2.7 Chemical properties

2.8 Biological properties

2.9 Suggested further reading

3 Gypsum Products for Dental Casts

3.1 Introduction

3.2 Requirements of dental cast materials

3.3 Composition

3.4 Manipulation and setting characteristics

3.5 Properties of the set material

3.6 Applications

3.7 Advantages and disadvantages

3.8 Suggested further reading

4 Waxes

4.1 Introduction

4.2 Requirements of wax-pattern materials

4.3 Composition of waxes

4.4 Properties of dental waxes

4.5 Applications

4.6 Suggested further reading

5 Investments and Refractory Dies

5.1 Introduction

5.2 Requirements of investments for alloy casting procedures

5.3 Available materials

5.4 Properties of investment materials

5.5 Applications

5.6 Suggested further reading

6 Metals and Alloys

6.1 Introduction

6.2 Structure and properties of metals

6.3 Structure and properties of alloys

6.4 Cooling curves

6.5 Phase diagrams

6.6 Suggested further reading

7 Gold and Alloys of Noble Metals

7.1 Introduction

7.2 Pure gold fillings (cohesive gold)

7.3 Traditional casting gold alloys

7.4 Hardening heat treatments (theoretical considerations)

7.5 Heat treatments (practical considerations)

7.6 Alloys with noble metal content of at least 25% but less than 75%

7.7 Soldering and brazing materials for noble metals

7.8 Noble alloys for metal-bonded ceramic restorations

7.9 Biocompatibility

7.10 Suggested further reading

8 Base Metal Casting Alloys

8.1 Introduction

8.2 Composition

8.3 Manipulation of base metal casting alloys

8.4 Properties

8.5 Comparison with casting gold alloys

8.6 Biocompatibility

8.7 Metals and alloys for implants

8.8 Suggested further reading

9 Casting

9.1 Introduction

9.2 Investment mould

9.3 Casting machines

9.4 Faults in castings

9.5 Suggested further reading

10 Steel and Wrought Alloys

10.1 Introduction

10.2 Steel

10.3 Stainless steel

10.4 Stainless steel denture bases

10.5 Wires

10.6 Suggested further reading

11 Ceramics and Porcelain Fused to Metal (PFM)

11.1 Introduction

11.2 Composition of traditional dental porcelain

11.3 Compaction and firing

11.4 Properties of porcelain

11.5 Alumina inserts and aluminous porcelain

11.6 Sintered alumina core ceramics

11.7 Injection moulded and pressed ceramics

11.8 Cast glass and polycrystalline ceramics

11.9 CAD-CAM restorations

11.10 Porcelain veneers

11.11 Porcelain fused to metal (PFM)

11.12 Capillary technology

11.13 Bonded platinum foil

11.14 Suggested further reading

12 Synthetic Polymers

12.1 Introduction

12.2 Polymerisation

12.3 Physical changes occurring during polymerisation

12.4 Structure and properties

12.5 Methods of fabricating polymers

12.6 Suggested further reading

13 Denture Base Polymers

13.1 Introduction

13.2 Requirements of denture base polymers

13.3 Acrylic denture base materials

13.4 Modified acrylic materials

13.5 Alternative polymers

13.6 Suggested further reading

14 Denture Lining Materials

14.1 Introduction

14.2 Hard reline materials

14.3 Tissue conditioners

14.4 Temporary soft lining materials

14.5 Permanent soft lining materials

14.6 Self-administered relining materials

14.7 Suggested further reading

15 Artificial Teeth

15.1 Introduction

15.2 Requirements

15.3 Available materials

15.4 Properties

15.5 Suggested further reading

16 Impression Materials: Classification and Requirements

16.1 Introduction

16.2 Classification of impression materials

16.3 Requirements

16.4 Clinical considerations

16.5 Suggested further reading

17 Non-elastic Impression Materials

17.1 Introduction

17.2. Impression plaster

17.3 Impression compound

17.4 Impression waxes

17.5 Zinc oxide/eugenol impression pastes

18 Elastic Impression Materials: Hydrocolloids

18.1 Introduction

18.2 Reversible hydrocolloids (agar)

18.3 Irreversible hydrocolloids (alginates)

18.4 Combined reversible/irreversible techniques

18.5 Modified alginates

18.6 Suggested further reading

19 Elastic Impression Materials: Synthetic Elastomers

19.1 Introduction

19.2 Polysulphides

19.3 Silicone rubbers (condensation curing)

19.4 Silicone rubbers (addition curing)

19.5 Polyethers

19.6 Comparison of the properties of elastomers

19.7 Suggested further reading

20 Requirements of Direct Filling Materials and Historical Perspectives

20.1 Introduction

20.2 Appearance

20.3 Rheological properties and setting characteristics

20.4 Chemical properties

20.5 Thermal properties

20.6 Mechanical properties

20.7 Adhesion

20.8 Biological properties

20.9 Historical

21 Dental Amalgam

21.1 Introduction

21.2 Composition

21.3 Setting reactions

21.4 Properties

21.5 Clinical handling notes for dental amalgam

21.6 Manipulative variables

21.7 Suggested further reading

22 Resin-based Filling Materials

22.1 Introduction

22.2 Acrylic resins

22.3 Composite materials – introduction

22.4 Classification and composition of composites

22.5 Properties of composites

22.6 Fibre reinforcement of composite structures

22.7 Clinical handling notes for composites

22.8 Applications of composites 223; 22.9 Suggested further reading

23 Adhesive Restorative Materials: Bonding of Resin-based Materials

23.1 Introduction

23.2 Acid-etch systems for bonding to enamel

23.3 Applications of the acid-etch technique

23.4 Bonding to dentine – background

23.5 Dentine conditioning – the smear layer

23.6 Priming and bonding

23.7 Current concepts in dentine bonding – the hybrid layer

23.8 Classification of dentine bonding systems

23.9 Bonding to alloys, amalgam and ceramics

23.10 Bond strength and leakage measurements

23.11 Polymerizable luting agents

23.12 Suggested further reading

24 Glass Ionomer Restorative Materials (Polyalkenoates)

24.1 Introduction

24.2 Composition

24.3 Setting reaction

24.4 Properties

24.5 Cermets

24.6 Applications and clinical handling notes

24.7 Suggested further reading

25 Resin-modified Glass Ionomers and Related Materials

25.1 Introduction

25.2 Composition and classification

25.3 Setting characteristics

25.4 Dimensional change and dimensional stability

25.5 Mechanical properties

25.6 Adhesive characteristics

25.7 Fluoride release

25.8 Clinical handling notes

25.9 Suggested further reading

26 Temporary Crown and Bridge Resins

26.1 Introduction

26.2 Requirements

26.3 Available materials

26.4 Properties

27 Requirements of Dental Cements for Lining, Base and Luting Applications

27.1 Introduction

27.2 Requirements of cavity lining materials

27.3 Requirements of luting materials

27.4 Requirements of endodontic cements

27.5 Requirements of orthodontic cements

27.6 Suggested further reading

28 Cements Based on Phosphoric Acid

28.1 Introduction

28.2 Zinc phosphate cements

28.3 Silicophosphate cements

28.4 Copper cements

28.5 Suggested further reading

29 Cements Based on Organometallic Chelate Compounds

29.1 Introduction

29.2 Zinc oxide/eugenol cements

29.3 Ortho-ethoxybenzoic acid (EBA) cements

29.4 Calcium hydroxide cements

29.5 Suggested further reading

30 Polycarboxylates, Glass Ionomers and Resin-modified Glass Ionomers for Luting and Lining

30.1 Introduction

30.2 Polycarboxylate cements

30.3 Glass ionomer cements

30.4 Resin-modified glass ionomers and compomers

30.5 Suggested further reading

31 Endodontic Materials

31.1 Introduction

31.2 Irrigants and lubricants

31.3 Intra-canal medicaments

31.4 Endodontic obturation materials

31.5 Historical materials

31.6 Contemporary materials

31.7 Clinical handling;

31.8 Suggested further reading

Appendix 1

Index

© 2008 by Blackwell Publishing Ltd

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First published 1956. Second edition 1961. Third edition 1967. Fourth edition 1972.

Fifth edition 1976. Sixth edition 1985. Seventh edition 1990. Eighth edition 1998.

Ninth edition published 2008 by Blackwell Publishing Ltd

ISBN-13: 978-1-4051-3961-8

Library of Congress Cataloging-in-Publication Data

McCabe, J.F. (John F.)

Applied dental materials. – 9th ed. / J.F. McCabe, A.W.G. Walls.

p. ; cm.

Includes bibliographical references and index.

ISBN: 978-1-4051-3961-8 (pbk. : alk. paper)

1. Dental materials. I. Walls, Angus. II. Title.

[DNLM: 1. Dental Materials. WU 190 M477a 2008]

RK652.5.A55 2008

617.6′95–dc22

2007044377

A catalogue record for this title is available from the British Library

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Preface

In producing this ninth edition of Applied Dental Materials we have updated the text in both content and appearance. We hope that the book will remain helpful to students and teachers of the science of dental materials alike by remaining true to the core principles and developing them into a more comprehensive text which covers a wide spectrum of materials falling within the scope of ‘dental materials’. Hence, there are more references to practical issues like handling and clinical performance of materials, whilst maintaining a strong link to quality issues encompassed within newly developed ISO standards. Some areas, such as adhesion, ceramics, light activation technology, CAD-CAM have been developed and expanded significantly from the eighth edition, reflecting significant changes or developments in these areas. There is a new chapter on endodontic materials. All areas have benefited from a fresh approach to the use of drawings and photographs including the use of colour for the first time.

John McCabe

Angus Walls

Chapter 1

Science of Dental Materials

1.1 Introduction

The science of dental materials involves a study of the composition and properties of materials and the way in which they interact with the environment in which they are placed. The selection of materials for any given application can thus be undertaken with confidence and sound judgement.

The dentist spends much of his professional career handling materials and the success or failure of many forms of treatment depends upon the correct selection of materials possessing adequate properties, combined with careful manipulation.

It is no exaggeration to state that the dentist and dental technician have a wider variety of materials at their disposal than any other profession. Rigid polymers, elastomers, metals, alloys, ceramics, inorganic salts and composite materials are all commonly encountered. Some examples are given in Fig. 1.1 along with some of their uses in dentistry.

This classification of materials embodies an enormous variation in material properties from hard, rigid materials at one extreme to soft, flexible products at the other.

Many dental materials are fixed permanently into the patient’s mouth or are removed only intermittently for cleaning. Such materials have to withstand the effects of a most hazardous environment. Temperature variations, wide variations in acidity or alkalinity and high stresses all have an effect on the durability of materials.

Normal temperature variations in the oral cavity lie between 32°C and 37°C depending on whether the mouth is open or closed. The ingestion of hot or cold food or drink however, extends this temperature range from 0°C up to 70°C. The acidity or alkalinity of fluids in the oral cavity as measured by pH varies from around pH 4 to pH 8.5, whilst the intake of acid fruit juices or alkaline medicaments can extend this range from pH 2 to pH 11.

The load on 1 mm2 of tooth or restorative material can reach levels as high as many kilograms indicating the demanding mechanical property requirements of some materials.

Many products, for example direct filling materials, are handled entirely by the dentist and their chairside assistant and are rarely encountered by the dental technician. Other materials are generally associated with the work of the dental laboratory and in this case both technician and dentist require a thorough knowledge of the materials in order that they may communicate about selection, manipulation and any problems which arise. A third group of materials link the dental surgery and the laboratory. The most obvious example of such products is the impression materials. Whilst the latter are under the direct control of the dentist it is essential that the dental technician also has a sound knowledge of such materials.

1.2 Selection of dental materials

The process of materials selection should ideally follow a logical sequence involving (1) analysis of the problem, (2) consideration of requirements, (3) consideration of available materials and their properties, leading to (4) choice of material. Evaluation of the success or failure of a material may be used to influence future decisions on materials’ selection. This selection process is illustrated in Fig. 1.2. Many experienced practitioners carry out this sequence with no apparent effort since they are able to call upon a wealth of clinical experience. However, when presented with new or modified materials even the most experienced dentist should return to a more formal type of selection process based on the criteria mentioned.

Fig. 1.1 Diagram indicating the wide variety of materials used in dentistry and some of their applications.

Analysis: The analysis of the situation requiring selection of a material may seem obvious but it is of paramount importance in some circumstances. An incorrect decision may cause failure of the restoration or appliance. For example, when considering the selection of a filling material it is important to decide whether the restoration is to be placed in an area of high stress. Will it be visible when the patient smiles? Is the cavity deep or shallow? These factors and many more must be evaluated before attempting materials’ selection.

Requirements: Having completed a thorough analysis of the situation it is possible to develop a list of requirements for a material to meet the needs of that situation. For the example mentioned in the previous section, it may be decided that a filling material which matches tooth colour and is able to withstand moderately high stresses without fracture is required. Some tooth cavities are caused by toothbrush/toothpaste abrasion. In this special case the restorative material used should naturally possess adequate resistance to dentifrice abrasion. Hence, it is possible to build a profile of the ideal properties required for the application being considered.

Fig. 1.2 Flow chart indicating a logical method of material selection.

Available materials: The consideration of available materials, their properties and how these compare with the requirements is carried out at two levels. The dentist, faced with the immediate problem of restoring the tooth of a patient in his surgery, must choose from those materials on hand at the time. Previous experience with materials in similar circumstances will be a major factor which influences selection. On a wider scale, the practitioner is able to consider the use of alternative materials or newly developed products where these appear to offer a solution to cases which have proved difficult with his existing armoury of products. It is of paramount importance that the practitioner keeps up to date with developments in materials whilst taking a conservative approach towards adopting new products for regular use in his surgery until they are properly tested.

Choice of material: Having compared the properties of the available materials with the requirement, it is possible to narrow the choice to a given generic group of products. The final choice of material brand is often a matter of personal preference on the part of the dentist. Factors such as ease of handling, availability and cost may play a part at this stage of the selection process.

1.3 Evaluation of materials

As the number of available materials increases, it becomes more and more important for the dentist to be protected from unsuitable products or materials which have not been thoroughly evaluated. It should be emphasized, however, that most manufacturers of dental materials operate an extensive quality assurance programme and materials are thoroughly tested before being released to the general practitioner.

Standard specifications: Many standard specification tests, of both national and international standards organizations, are now available which effectively maintain quality levels for some dental materials. Such specifications normally give details for the testing of certain products, the method of calculating the results of the minimum permissible result which is acceptable. Although such specifications play a useful part they should not be seen as indicating total suitability since the tests carried out often do not cover critical aspects of the use of a material. For example, many materials fail by a fatigue mechanism in practice, but few specifications involve fatigue testing.

Laboratory evaluations: Laboratory tests, some of which are used in standard specifications, can be used to indicate the suitability of certain materials. For example, a simple solubility test can indicate the stability of a material in aqueous media – a very important property for filling materials.

It is important that methods used to evaluate materials in the laboratory give results which can be correlated with clinical experience. For example, when upper dentures fracture along the midline they do so through bending. Hence a bending or transverse strength test is far more meaningful for denture base materials than a compression test.

Clinical trials: Although laboratory tests can provide important and useful data on materials the ultimate test is the randomised controlled clinical trial and the verdict of practitioners after a period of use in general practice. Many materials produce good results in the laboratory, only to be found lacking when subjected to clinical use. The majority of manufacturers carry out extensive clinical trials of new materials, normally in co-operation with a university or hospital department prior to releasing a product for use by general practitioners.

Chapter 2

Properties used to Characterise Materials

2.1 Introduction

Many factors must be taken into account when considering which properties are relevant to the successful performance of a material used in dentistry. The situation in which the material is to be used and the recommended technique for its manipulation define the properties which characterise the material. Laboratory tests used to evaluate materials often duplicate conditions which exist in situ. This is not always possible and sometimes not desirable since one aim of in vitro testing is to predict in a rapid laboratory test what may happen in the mouth over a number of months or years. Many tests used to evaluate dental materials involve the measurement of simple properties such as compressive strength or hardness which have been shown to correlate with clinical performance.

Many materials used in dentistry are supplied as two or more components which are mixed together and undergo a chemical reaction, during which the mechanical and physical properties may change dramatically. For example, many impression materials are supplied as fluid pastes which begin to set when mixed together. The set material may be a rigid solid or a flexible rubber depending upon the chemical nature of the product.

The acceptance of such a product by the dentist depends upon the properties of the unmixed paste, the properties during mixing and setting and the properties of the set material (Table 2.1). This classification of properties applies to virtually all groups of materials.

Properties of unmixed materials: Manufacturers formulate materials which give optimal performance as evaluated by their quality assurance programme and clinical trials. It is known however, that certain products deteriorate during storage and as a result may perform poorly. Such materials are said to have limited shelf life. Some materials have an extended shelf life if refrigerated during storage. One technique commonly employed to predict stability is to carry out accelerated ageing by storing samples at elevated temperature, commonly 60°C, followed by evaluation of material properties.

Containers used for materials generally have a batch number stamped or printed onto them from which the date of manufacture can be obtained. Thus, for materials with limited shelf life it is possible to ascertain the date at which one would expect the properties to deteriorate.

Properties of materials during mixing, manipulation and setting: Properties of materials during mixing, manipulation and setting are considered together since they mainly involve a consideration of rheological properties and the way in which these change as a function of time during setting.

For materials of two or more components which set by a chemical reaction, thorough mixing is essential in order to achieve homogeneous distribution of properties throughout the material. The ease of mixing depends on factors such as the chemical affinity of the components, the viscosity, both of the components and the mixed material, the ambient temperature, the method of dispensation and the method of mixing.

Several methods of dispensation exist among materials used in dentistry. Some involve the mixing of powder and liquid components, others the mixing of two pastes, while others involve paste and liquid components. When the mixing of two pastes is required, the manufacturer often gives a good colour contrast between the two pastes. The achievement of a thorough mix of the two components can be judged by the attainment of a homogeneous colour with no streaks. When powder and liquid or paste and liquid are mixed, the achievement of a thorough mix is less certain. The components are mixed for a recommended time and/or until a recommended consistency is reached.

Table 2.1 Illustrating the different requirements and associated tests used for materials at different stages during their storage and use.

Stage of use

Practical issues

Tests required

During storage Before use in surgery or laboratory.

Require material to keep fresh and last a long time. Wastage is minimised and bulk purchases can be made.

Shelf life, expiry date or date of manufacture given by manufacturer.Test that certain key properties are within acceptable limits after a period of storage.