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McLean: The Science and Art of Dental Ceramics
McLean, John W.

The Science and Art of Dental Ceramics
Volume 1: The Nature of Dental Ceramics and their Clinical Use

1. Auflage 1979
Hardcover, 331 Seiten, 302 Abbildungen (56 farbig, 246 schwarz/weiss)
Sprache: Englisch
Fachgebiet: Prothetik

Artikelnr.: 15011
ISBN 978-0-93138-604-6
Quintessence Publishing, Deutschland

Die gedruckte Ausgabe ist vergriffen.
Bestellen Sie das E-Book über die Partner-Links.

There is a no more rewarding experience in restorative dentistry than to duplicate to perfection the colour, texture and surface anatomy of the human tooth. Dental porcelain is the closest match to tooth enamel of all our restorative materials but is perhaps the most difficult to use in dental practice.

A study of the science of dental porcelain will enable the dentist or technician to perfect his art since it develops an increasing awareness of the fundamental problems in construction.

Preparation design, the stresses developing in porcelain restorations, the influence of opaque backgrounds on colour, surface reflectivity and light transmission in crowns are some of the complex factors that influence the success of a porcelain veneer restoration.

A survey of new metals, bonding systems, cements and impression materials will enable the clinician to select his materials with greater confidence. New research on the shoulder preparation for the veneer crown also sheds light on the controversy of the bevel versus the butt joint. The author has attempted to rationalise the use of both metal and alumina reinforced ceramics and to show how no ingle system can be applied universally if optimum aesthetics is to be achieved.

Foreword 5
Preface 7
Acknowledgements 9
Introduction 19
Monograph I:
The Nature of Dental Ceramics
Crystalline Ceramics 23
Extraction of Alumina 25
Fabrication of Alumina Components 25
Sintering of Alumina 25
Translucent Alumina 26
Effect of Debasing Alumina 27
Colouring Alumina 28
Dental Alumina 28
Physical Properties 28
The Nature of Glasses 29
Glass Formation 29
Formulation of Dental Porcelain 30
The Role of Fluxes 30
Intermediate Oxides 32
Boric Oxide Fluxes 33
Chemical Composition of Dental Porcelain 33
Devitrification and Thermal Expansion 34
Fritting 35
Alternative Additives to Dental Porcelain 35
Felspathic Porcelain 35
Nepheline Syenite 36
Colouring and Opacifying Dental Porcelain 37
Colour Pigments 37
Opacifying Agents 37
Stains and Colour Modifiers 38
Fluorescence 38
Glazes and Add-on Porcelain 39
Classification of Dental Porcelains 39
Porcelains Used in Tooth Manufacture 40
Condensation of Dental Porcelain 40
Volume Porosity of Powders 40
Condensation 42
Surface Tension 42
The Wet Brush Technique 42
Sintering of Dental Porcelains 44
Air Firing Porcelain 44
Particle Size and Translucency 47
Vacuum-firing-Porcelains 47
Diffusible Gas Firing Process 48
Pressure Cooling Process 48
Classification of Stages of Maturity 49
Glazing and Thermal Shock Prevention 49
Thermal Shock 49
Solubility 50
References 51
Monograph II:
The Strengthening of Dental Porcelain
Crack Propagation in Dental Porcelain 55
Mechanical Testing 57
Testing Ground Porcelain Specimens 58
Testing Glazed Specimens 59
Strength of Glazed and Surface Ground Porcelain 59
Influence of Condensation Techniques on Mechanical Strength 59
Methods of Strengthening Dental Porcelain 61
Enamelling of Metals 63
Types of Metal-Ceramic Systems 63
Noble-Metal Alloy Systems 63
Base-Metal Alloy Systems 63
Gold-Platinum-Palladium Alloys 63
Gold-Platinum-Palladium Alloys - Mechanical Strength and Heat Treatment 64
Gold Bonding Agents 66
Alternative Alloy Systems 66
Gold-Platinum-Tungsten Alloys 67
Gold-Palladium-Silver Alloys 67
Palladium-Silver Alloys 68
Mechanical properties of the noble-metal alloys 69
Nature of the Porcelains used in Metal-Ceramic Systems 69
The Nature of the Metal-Ceramic Bond 71
Methods of Testing Bond Strength 72
Choice of Test Piece Design 75
Results of Testing Bond Strengths 76
Technical Considerations 79
Noble-Metal Alloy Systems 79
Base Metal Alloy/Porcelain Systems 79
Bond Strength of Base Metal Alloy/ Porcelain Systems 82
Types of Metal/ Porcelain Failure 82
1. Metal-Porcelain 82
2. Metal Oxide-Porcelain 82
3. Metal-Metal Oxide 85
4. Metal Oxide-Metal Oxide 85
5. Cohesive within Metal 85
6. Cohesive within Porcelain 85
Effect of the Degree of Oxidation and Cooling Rate on the STrength of the Bond 85
Technical Considerations-Base-Metal Alloy Systems 87
Evaluation of Metal-Ceramic Systems 88
Oxide Formation 88
Strength and Castability 89
1. Yield Strength 89
2. Modulus of Elasticity 89
3. Creep or "sag-resistance" 89
4. Hardness 89
5. Burnishability 89
Gold-platinum-palladium alloys 89
Gold-palladium-silver alloys 90
Palladium-silver alloys 90
Base-metals Nickel-chromium alloys 90
Bonding of Porcelain to Precious Metals Using Tin Oxide Coatings 92
The Platinum Bonded Alumina Crown Cementation 95
Dispersion Strengthening of Glasses 95
Types of Reinforcing Crystals 97
Types of Alumina 97
Calcined Alumina 98
Fused Alumina 98
Types of Glass used with Alumina 99
Aluminous Porcelain 99
Aluminous Porcelain Core Powders 99
Influence of Grain Size on Opacity and Strength 100
Influence of Alumina Crystal Concentration on Strength 102
Crack-propagation in ALuminous Porcelain 102
Sintering Aluminous Porcelain 104
Effect of Sintering Time on the Strength of Aluminous Porcelain 104
Dispersion Strengthening of Glass with Alumina Whiskers 105
Enamelling of High Strength Crystalline Ceramics 106
Strength of Alumina-Enamel Laminates 107
Bonding of Aluminous Porcelain to High Alumina 108
Controlled Crystallisation of Glasses 109
Production of Pre-stressed Surface Layers in Dental Porcelain via Ion-exchange 109
Technical Considerations 111
Aluminous Porcelains 111
References 112
Monograph III:
Aesthetics of Dental Porcelain
The Nature of Light 118
Primary Colours 120
The Three Dimensions of Colour 120
Hue 120
Chroma 120
Value 121
Colour Measurement 121
Complimentary Colours 121
Optical Properties 122
Reflection 122
Regular or Specular Reflection 122
Diffuse Reflection 122
Refractive index and dispersion 122
Reflection and Refraction 122
Light Scattering 123
Opacity 123
Paint-on-Opaques 125
Translucency 125
Surface Gloss 127
Effect of Metal Surface Treatment on the Masking Power of Opaque Porcelain 129
Ultra-Violet Radiation and Fluorescence 129
Radio-active compounds in dental porcelain 130
Radiation hazards 131
Colour Blending 131
Colour Production in Natural Teeth 132
Incisal Third 133
Middle Third 133
Cervical Third 133
Types of Porcelain Crowns 134
Felspathic Crown - air-fired 134
Felspathic crown - vacuum-fired 135
The Metal-Ceramic Crown 136
Metamerism 137
The Aluminous Porcelain Crown 138
The Role of Opaque Porcelains in Obtaining Aesthetics 140
Requirements for a Tooth Shade Guide 143
The Munsell Colour Order System 143
The Adams Co-ordinate System 144
Colour of Natural Teeth related to Modern Shade Guides 144
Shade Matching 146
The Custom-Built Shade Guide 146
The Custom-Built Metal-Ceramic Shade Guide 147
Vacuum-Fired Porcelain Tooth Shade Guides 148
The Eye and Colour Perception 149
Recommended Procedures for Shade Matching 149
Determining Hue 150
Determining Chroma 151
Determining Value 152
Determining Metameric Effects 152
Blending of Colours 152
Custom staining 154
The Study Cast 154
The Influence of Tooth Contour on Aesthetics 156
Vertical correction 156
Horizontal correction 157
Instanding and Outstanding Teeth 157
Rotated Teeth 161
Significance of intra-arch space 161
Spaced teeth 163
Mesial or distal inclination of teeth 163
Outline form and size 163
Making a tooth look wider or narrower 164
Making a tooth look shorter or longer 164
Orthodontic Correction 164
Reproducing Tooth Anatomy in Dental Porcelain 164
Common faults in porcelain tooth anatomy 168
The Central incisors 168
Lateral Incisors 168
The Canine Teeth 168
The Posterior Teeth 170
Full Mouth Reconstruction 170
The repeated ratio 170
Front-to-back progression 170
Horizontal and Vertical space allocation 177
Refernces 181
Selected Reading 182
Monograph IV:
Porcelain as a Restorative Material
Plaque Accumulation on Restorative Materials 185
Marginal Fit 187
Mikro-leakage under Porcelain Crowns 187
Occlusion and Dental Porcelain 190
Gold versus Porcelain Occlusion 197
Indications for use 197
Indications for Use of Porcelain Jacket Crowns 199
Contra-Indications for Use of the Porcelain Jacket Crown 199
Indications for use of the Metal-Ceramic Crown 200
Contra-Indications for use of the Metal-Ceramic Crown 200
Aluminous Porcelain Compared with Metal-Ceramics 200
Aluminous Porcelain 200
Metal-Ceramics 200
The Platinum bonded Alumina Crown 201
Indications for use of the Bonded Alumina Crown 202
Contra-indications 202
Clinical Cases 202
The Complete Porcelain Veneer Crown and the Platinum Bonded Alumina Crown 213
Aesthetics 213
Strength 213
Periodontal Health and Occlusion 213
Health of the Pulp 213
Preserving Pulp Vitality 214
The Devitalised Tooth 215
The Preparation 215
The Typical Preparation 215
Design Factors 217
Application to the Metal-Ceramic Crown 217
The Porcelain Veneer Crown 218
Stress Analysis and Design Factors 218
Cervical area and shoulder requirements - Maxillary central incisor 218
Design Factor - Cervical and Shoulder Area - Maxillary central incisor 219
The lingual and labial surfaces and length of preparation - Maxillary central incisor 220
Design Factor - Lingual and labial surfaces - Maxillary central incisor 223
Approximal axial walls - Maxillary central incisor 223
Application to the Metal-Ceramic Crown 225
Design factor - Approximal Axial Walls - Maxillary central incisor 225
Shoulder geometry 225
Definitions 225
Design factor - Shoulder geometry 226
Retention 226
Design factor - Retention 227
Cement film thickness 227
The Bonded Alumina Crown and the Complete Porcelain Veneer Crown or Aluminous Porcelain Crown 228
Recommended dimensions for tooth preparation 228
Stress Analysis of the Posterior Molar Crown 232
The Premolar Porcelain Veneer Crown 233
The Molar Porcelain Veneer Crown 234
The Atypical Preparation 236
Class 1: Crowns larger than the anatomical average 237
Class 2: Crowns smaller than the anatomical average 237
Class 3: Crowns wich show marked anatomical deviations from normal 239
Class 4: Crowns with loss of enamel and dentine on either the mesial or distal surfaces 241
Class 5: Crowns with loss of enamel and dentine on both the mesial and distal surfaces 242
Class 6: Crown with loss of enamel and dentine at the incisal edge 243
Class 7: Crowns with loss of enamel and dentine at the cervical margins 243
Class 8: Crowns with generalised loss of surface enamel 245
Class 9: Length of clinical crown greater than the anatomical crown 245
Crown-Root ratio 246
Summary of the requirements of the Atypical Preparation 247
The Typical Maxillary Central Incisor Preparation 248
Registration of surface characterisations of tooth 248
Shade Determination 248
Elimination of gingival trauma 248
Depth of Shoulder 249
The Preparation 250
Theoretical Considerations 250
Cervical approach 250
Measurements required for establishing the design of preparation 252
The stages in preparation 253
Operative technique 253
Instrumentation 253
Vario-air coupling ( Kavo Super-torque) 255
Labial and Lingual Depth Cuts 255
Reduction of the Labial Surface 258
Relationship of the shoulder to the interdental papilla 261
Creation of the Labial Sub-Gingival Shoulder 261
Reduction of Incisal Edge 263
Monitoring the Depth of the Preparation by Using a Temporary Crown as a Master Template 263
The Epimine Resin Temporary Crown 264
Construction of an Epimine Resin Temporary Crown 264
Finishing the Typical Maxillary Central Incisor Preparation 268
Micro-diamond finishing 269
Tungsten-Carbide Finishing "Stones" 270
Polishing the Preparation 271
Pre-packing of the gingiva 271
Common causes of Fracture in Porcelain Jacket Crowns 271
The Metal-Ceramic Veneer Crown 273
Reduction of stress and creep in the metal porcelain combination 273
The Labial Shoulder 276
Optimising the aesthetics and maintaining the marginal fit on the labial and buccal porcelain 276
The shoulder versus the bevel 276
Effect of burnishing 276
The gold collar and bevel 278
The shoulder and Chamfer Preparation 279
Influence of Shoulder design on Metal Creep 279
The Approximal and Lingual Shoulders 280
Recommended Designs for the Preparation and Metal Coping in Metal-Ceramic Crowns 282
Labial Shoulder 282
Chamfer with bevel 283
Lingual Shoulder 285
Recommended designs for the preparations and metal coping 285
The Metal-Ceramic Crown 285
Typical Maxillary Central incisor Preparation. Operative Procedures 285
Typical Maxillary Premolar Preparation for Full Porcelain Veneer Coverage 290
Preparation of the Typical Maxillary Premolar for Partial Porcelain Veneer Coverage 292
Improving Retention of Metal-Ceramic Crowns 296
Advantages of Partial Veneer Coverage of Porcelain over Full Veneer Coverage 296
Disadvantages of Partial Veneer Coverage over Full Veneer Coverage 296
Preparation for the periodontally involved tooth 296
Common Faults in Preparation 298
Biological Considerations 298
The Impression 299
Relationship of the gingival tissue to the crown or margin 300
Selection of Impression Materials and Techniques 301
The Copper Tube Impression 301
The Transfer Coping 301
The Elastic Impression 302
Surface Reproduction 303
Compatibility with Model Materials 304
Dimensional Stability 304
Coefficient of Thermal Expansion 304
Elasticity 304
Tearing Energy 305
Cost 305
Types of Elastic Impression Material 305
Reversible Hydrocolloid 306
Polysulphide Rubber 307
Silicone Rubber (Organo tin catalysts) 307
Silicone Rubber (Chloroplatinic acid catalyst) 307
Polyether Rubber 307
Evaluation of Elastic impression Materials 308
Clinical Recommendations 309
Procedures for taking Polysulphide or Polyether Elastomeric Impressions 310
Requirements for a Custom-Built Tray 310
Preparation of the Gingival Tissue 310
Mechanical Retraction 311
Mechanical-chemical Retraction 312
Technical considerations 312
Gingival packing instrument 313
Preparation of Shoulder areas 317
Surgical Retraction 317
Steel scalpel and electrosurgical cutting on gingival tissues and alveolar bone 317
Factors governing optimal electrosurgical cutting 318
Impression Technique 319
Choice of syringe 319
Alternative methods 324
Common Causes of Failure in Elastomeric Impression Materials 324
Surface Defects 324
Dimensional Instability 324
Cementation of Porcelain and Metal-Ceramic Crowns 325
Recommended clinical use for dental cements 328
Cementation of crowns with good retentive form and where pulpal damage may occur 328
Cementation of crowns with moderate retentive form and where pulpal damage may occur 328
Cementation of crowns where no possible damage of the pulp can occur 328
Cementation of complete porcelain crowns 328
Cementation of post crowns, facings or crowns on metal substructures 328
Cementation of fixed splints or bridgework 329
Clinical Manipulation 329
References 330
Appendix 333