Plastics in Dentistry and Estrogenicity (eBook)

Theodore Eliades graduated from the School of Dentistry, University of Athens, Greece, completed the Orthodontic postgraduate program of the Ohio State University, and earned a Master’s from Ohio State, a doctorate from the University of Athens, School of Medicine, and a PhD from the University of Manchester. His research has generated 90 papers and 15 book chapters, which elucidated the in vivo ageing pattern of orthodontic materials and resultant clinical implications, receiving 800 citations. He has co-edited books on ageing of biomaterials (Quintessence), bonding to dental tissues (Springer), orthodontic materials (Thieme), orthodontic practice risk management (Quintessence), and self-ligating brackets (Wiley-Blackwell), some translated into 3 languages. A Fellow of the Institute of Materials, Minerals and Mining, and member of the Royal Society of Chemistry and the Institute of Physics, Dr. Eliades is affiliated with Universities in the US (Texas-Houston and Marquette) and EU (Manchester and Bonn), is an Associate Editor of the European Journal of Orthodontics, and the American Journal of Orthodontics and Dentofacial Orthopedics, Editorial Board member in 5 and reviewer in 22 periodicals.Gottfried Schmalz: Since 1986 President of various national and international organizations, (CED-IADR, Pan-European Federation, Pulp Biology and Regeneration Group of IADR). German Representative in the Advisory Committee of the EU for Dental Education, Honorary member of several scientific organizations, 2007 Distinguished Scientist Award of IADR. Member of the German Academy of Sciences (Leopoldina). Editor-in-Chief of our journal Clinical Oral Investigations.

Foreword 6
Contents 8
Part I:Introduction and Overview 9
Chapter 1: Endocrine Disruptors (Xenoestrogens): An Overview 10
1.1 Introduction 10
1.2 Mechanism of Action of Estrogens and Xenoestrogens 14
1.2.1 Estrogen Receptor Signalling Pathway 14
1.2.2 Cytochrome P (CYP) Induction 20
1.3 Effects 21
1.3.1 Effects on Female Genital System 22
1.3.2 Effects on Male Genital System 23
1.3.3 Breast Cancer 24
1.3.4 Obesity 26
1.3.5 Diabetes 27
1.3.6 Neurologic Defects 27
1.3.7 Immunologic Effects 29
1.3.8 Effects on Bones 30
1.3.9 Exposure In Utero and During Lactation 30
1.3.10 Risk Assessment 32
1.4 Importance of Identification of Compounds with Estrogenic Activity 33
References 34
Part II:Methodology of Measuring BPA and Its Effects 56
Chapter 2: Analytical Methods for Determination of Bisphenol A 57
2.1 Introduction 57
2.2 Sampling and Storage 59
2.3 Extraction Techniques 59
2.4 Analytical Techniques 71
2.4.1 Gas Chromatography-Mass Spectrometry 71
2.4.2 Liquid Chromatography 73
2.4.2.1 Liquid Chromatography-Ultraviolet Detection 73
2.4.2.2 Liquid Chromatography-Fluorescence Detection 73
2.4.2.3 Liquid Chromatography-Electrochemical Detection 73
2.4.2.4 Liquid Chromatography-Mass Spectrometry 74
2.5 Immunoassays 74
2.6 Quality Assurance and Quality Control 74
2.7 Sources and Occurrence of Bisphenol A 76
2.7.1 Dental Restorative Materials 76
2.7.2 Environmental Samples 77
2.7.3 Food Samples 77
2.7.4 Biological Samples 78
References 78
Chapter 3: In Vitro Assay Systems for the Assessment of Oestrogenicity 84
3.1 Cell-Free Assay Systems 85
3.2 Yeast Assay Systems 86
3.3 Mammalian Cell Assay Systems 87
3.4 Conclusion 89
References 89
Chapter 4: BPA Effects In Vivo: Evidence from Animal Studies 93
4.1 Introduction 93
4.2 Part I: Issues on Experimental Design 94
4.2.1 Route of Exposure 95
4.2.2 Pharmacokinetics 95
4.2.3 Dosage 96
4.2.4 Timing and Duration of Exposure 97
4.2.5 Choice of Rodent Species 97
4.2.6 Choice of Sex to Study 98
4.2.7 Appropriate Controls 99
4.3 Part II: Evidence from Low-Exposure Studies 99
4.3.1 General 99
4.3.2 Effects in the Reproductive System 100
4.3.3 Effects in the Accessory Reproductive Organs 101
4.3.4 Effects in the Central Nervous System 102
4.3.4.1 Effects on Brain Structure 104
4.3.4.2 Effects on Brain Physiology 105
Changes in Steroidogenesis and Synaptic Plasticity 105
Changes in Neurotransmission 106
Changes in Nuclear Receptors’ Levels 106
Changes in the Stress Response System 107
4.3.4.3 Effects on Behaviour and Cognition 108
4.3.5 Effects on Other Systems 110
4.3.5.1 Effects in Metabolism 110
4.3.5.2 Epigenetic Changes 111
4.4 Concluding Remarks 111
References 113
Part III:Bisphenol-A in Dental Polymers 119
Chapter 5: BPA and Dental Materials 120
5.1 Introduction and Historical Perspective 120
5.2 What Is the Current “Safe” Level of Exposure? 121
5.3 Where Can We Get BPA Exposure from Dental Materials? 121
5.4 Is BPA from Dental Material Sources Significant When Compared to Overall Exposure Levels? 122
5.5 What Effects Have Been Reported from Dental Material-Derived BPA? 122
5.6 What Is the Current Impact of BPA on the Dental Profession? 123
5.7 What Can We Do in the Future? 125
References 125
Chapter 6: Bisphenol A and Orthodontic Materials 128
6.1 Introduction 128
6.2 Orthodontic Adhesives 129
6.3 Orthodontic Adhesives: In Vitro BPA Release 130
6.4 Orthodontic Adhesives: In Vitro Estrogenicity 131
6.5 Orthodontic Adhesives: In Vivo BPA Release and Estrogenicity 133
6.6 Polycarbonate Brackets: In Vitro BPA Release 134
6.7 Polycarbonate Brackets: In Vivo BPA Release and Estrogenicity 135
6.8 Aligners 135
6.9 Conclusions 136
References 137
Index 141