An Overview of Biomedical Implants

Preface xiii

Acknowledgments xiv

1 Biomaterials for Dental Implants 1

1.1 Introduction: Dental Implants and Current Materials 1

1.1.1 The Need for Better Dental Implants 1

1.1.2 Various Approaches and Biomaterials to Improve Dental Implants 3

1.1.3 Working at the Nanoscale to Improve Dental Implants 6

1.2 Ceramic Dental Implants 8

1.2.1 Zirconia 8

1.2.1.1 Surface Roughness Optimization of Zirconia-Based Implants 9

1.2.1.2 Coating Alternatives for Zirconia-Based Implants 9

1.2.1.3 Using Nanotechnology to Modify Zirconia-Based Implants 10

1.2.1.4 Disadvantages and Advantages of Zirconia-Based Implants 11

1.2.2 Hydroxyapatite 12

1.2.2.1 Antimicrobial Properties of Hydroxyapatite-Containing Materials 12

1.2.2.2 Combination Dental Materials Using Hydroxyapatite 13

1.2.2.3 Nano-Hydroxyapatite 14

1.2.2.4 Disadvantages and Advantages of HA-based Biomaterials 15

1.3 Polyetheretherketone (PEEK) 15

1.3.1 PEEK Composites to Improve Mechanical Properties 16

1.3.2 PEEK Bioactivity 17

1.3.3 Working at the Nanoscale and With Composites to Enhance PEEK Bioactivity 17

1.3.4 Disadvantages and Advantages of PEEK 20

1.4 Peptide Coatings for Dental Implants 20

1.5 Functionally Graded Dental Implants 22

1.5.1 Biological Responses to Functionally Graded Dental Implants 24

1.5.2 Radially Designed FGMs for Dental Implants 25

1.5.3 Disadvantages and Advantages of FGMs 26

1.6 Looking to the Future: State-of-the-Art Biomaterials for Dental Implants 26

1.7 Conclusion 28

References 29

2.1 Biomaterials for Total Hip Implants 35

2.1.1 Introduction 35

2.1.2 History of THA Development 36

2.1.3 Metallic Materials 36

2.1.3.1 Stainless Steel 36

2.1.3.2 Cobalt-Chromium Alloys 37

2.1.3.3 Titanium Alloys 37

2.1.3.4 Alloy Surface Modifications 37

2.1.4 Exploited Materials for Bearing Surface 38

2.1.4.1 Polymers 38

2.1.4.1.1 Ultrahigh Molecular Weight Polyethylene (UHMWPE) 38

2.1.4.1.2 High Cross-Linked UHMWPE (XLPE) 38

2.1.4.1.3 Antioxidant-Doped PE 38

2.1.4.1.4 Poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC) 39

2.1.4.2 Ceramics 39

2.1.4.2.1 Alumina 39

2.1.4.2.2 Zirconia 39

2.1.4.2.3 Alumina-Zirconia Composites 40

2.1.4.2.4 Silicon Nitride 40

2.1.4.2.5 Hybrid Design of Oxide Ceramic Layer on Metal (Oxinium(TM)) 40

2.1.4.2.6 Ultra-Hard Coatings on Metals 41

2.1.4.2.7 Clinical Aspects of Bearing Surface 41

2.1.4.3 MoP Articulation 42

2.1.4.3.1 Advantages 42

2.1.4.3.2 Disadvantages 42

2.1.4.3.3 Wear Mechanism 42

2.1.4.4 MoM Articulation 42

2.1.4.4.1 Advantages 42

2.1.4.4.2 Disadvantages 43

2.1.4.4.3 Wear Mechanism 43

2.1.4.5 CoC Articulation 43

2.1.4.5.1 Advantages 43

2.1.4.5.2 Disadvantages 44

2.1.4.5.3 Wear Mechanism 45

2.1.4.6 CoP Articulation 45

2.1.4.6.1 Advantages 45

2.1.4.6.2 Disadvantages 45

2.1.4.6.3 Wear Mechanism 45

2.1.5 Orthopedic Wear Debris 46

2.1.6 Conclusion 47

References 47

2.2 Biomaterials for Total Knee Replacement (TKR) and Total Hip Replacement (THR) and Next-Generation Advancements 57

2.2.1 Introduction 57

2.2.2 Ultra-High Molecular Weight Polyethylene (UHMWPE) and Polyethylene (PE) 61

2.2.3 Polyetheretherketone (PEEK) 62

2.2.4 Polymethylmethacrylate (PMMA) 65

2.2.5 Metal Implants 68

2.2.5.1 Metal Implants: Titanium (Ti) Alloys and Cobalt-Chromium (Co-Cr) and Surface Treatments 68

2.2.5.2 Metal Implants: Stainless Steel and Next Generation Surface Treatments 71

2.2.5.3 Porous Coatings 73

2.2.6 Ceramics and New Generation Surface Treatments 76

2.2.7 Advancements in Biomedicine and Nanotechnology: Titanium, Silver Nanoparticles, and More 78

2.2.8 Summary and Conclusion 81

References 83

2.3 Biomaterials for Shoulder Implants 91

2.3.1 Introduction 91

2.3.2 Titanium Alloys 95

2.3.3 Cobalt-Chrome Alloys 95

2.3.4 Ceramics 96

2.3.5 Pyrolytic Carbon 96

2.3.6 Comparison of Shoulder Implants with Different Class Materials 97

2.3.7 Conclusion 97

References 98

3 Biomaterials for Spinal Implants 103

3.1 Introduction 103

3.2 Overview of Implants and Corresponding Material Design Requirements 104

3.2.1 Spinal Cages 104

3.2.2 Spinal Rods 104

3.2.3 Pedicle Screws 105

3.2.4 Plates 105

3.2.5 Disc Replacements 105

3.3 Metals 106

3.3.1 Titanium and its Alloys 106

3.3.2 Stainless Steel 108

3.3.3 Cobalt-Chromium and its Alloys 108

3.3.4 Nitinol 108

3.3.5 Tantalum 109

3.4 Ceramics 109

3.4.1 Silicon Nitride 109

3.5 Polymers 112

3.5.1 Peek 112

3.6 3D-Printed Spinal Implants: Applications and Relevant Materials 118

3.7 Degradable Implants 118

3.8 Discussion 119

3.9 Conclusion 120

References 120

4 Biomaterials in Cochlear Implants 123

4.1 Introduction 123

4.2 Biological Requirements 125

4.3 Electrical Requirements 126

4.4 Mechanical Requirements 126

4.5 New Electrode Biomaterials 127

4.5.1 Dexamethasone (DEX) 127

4.6 Nanoscale Coatings 129

4.7 New Potential Implant Materials 134

4.8 Drug Delivery 135

4.9 Summary and Conclusion 136

References 138

5 Biomaterials for Cardiovascular Implants 141

5.1 Introduction 141

5.2 Different Applications 143

5.2.1 Stents 143

5.2.1.1 Balloon Expandable Stents 144

5.2.1.2 Self-Expandable Stents 146

5.2.1.3 Drug-Eluting Stents 148

5.2.1.4 Biodegradable Stents 150

5.2.1.5 Latest Stent Inventions 152

5.2.2 Prosthetic Heart Valves 153

5.2.2.1 Mechanical Valves 155

5.2.2.2 Bioprosthetic Valves 160

5.2.2.3 Latest Valves Advancements 161

5.3 Summary and Conclusions 162

References 164

6 Biomaterials for Liver and Kidney Implants 173

6.1 Introduction 173

6.2 Liver Biomaterials 175

6.2.1 General View 175

6.2.2 Biomaterials and Structures 177

6.2.2.1 Natural Polymers 178

6.2.2.2 Synthetic Material 179

6.2.2.3 Decellularized Matrix 181

6.2.3 Conventional Therapy and Future 184

6.3 Kidney Biomaterials 186

6.3.1 A General View 186

6.3.2 Biomaterials and Structure 188

6.3.3 Conventional Therapy and Future 190

6.4 Conclusions 193

References 194

7 Biomaterials for Brain Implants 199

7.1 Introduction 199

7.2 Brain Implants Classification 201

7.2.1 Brain Implants for Recording 201

7.2.1.1 Electrocorticography (ECoG) 201

7.2.1.2 Multielectrode Arrays (MEAs) 202

7.2.2 Brain Stimulator Implants 202

7.2.3 Brain Regenerative Medicine 206

7.3 Causes of Failure 207

7.4 Materials for Neural Electrodes 210

7.4.1 Neural Electrodes 210

7.4.2 Materials for Microelectrode Fabrication 211

7.4.2.1 Conductive Polymers 212

7.4.2.2 Carbon Nanotubes 213

7.4.2.3 Graphene 214

7.4.2.4 Hybrid Nanomaterials 216

7.5 Conclusions 217

References 218

8 Biomaterials for Bionic Implants 225

8.1 Introduction 225

8.2 Biomaterials in Bionic Eye and Neural Systems 227

8.2.1 Implant Package 227

8.2.2 Electrodes 229

8.2.2.1 Diamond Electrodes 229

8.2.2.2 Organic Polymer Electrode Coating 233

8.3 Biomaterials in Bionic Limbs 234

8.3.1 Upper Limb 235

8.3.1.1 Electrodes 235

8.3.1.2 Electrode Packaging and Encapsulation 237

8.3.1.3 Arms 238

8.3.2 Lower Limb 239

8.4 Summary Conclusion 241

References 241

9 Final Remarks 249

Index 251