Fundamentals and applications of biophotonics in dentistry

341 Pages·2007·16.45 MB·English

by  Anil Kishen

Fundamentals and Applications of
Biophotonics in Dentistry
Anil Kishen
Anand Asundi
Imperial College Press
Vol.4
Series on Biomaterials and Bioengineering
Fundamentals and Applications of
Biophotonics in Dentistry
SERIES ON BIOMATERIALS AND BIOENGINEERING
Series Editors: A W Batchelor (Monash Univ. Sunway Campus Malaysia Sdn Bhd)
J R Batchelor (UK)
Margam Chandrasekaran (Singapore Institute of Manufacturing
Technology, Singapore)
Vol. 1: An Introduction to Biocomposites
by Seeram Ramakrishna (National University of Singapore, Singapore),
Zheng-Ming Huang (Tongji University, China),
Ganesh V Kumar (National University of Singapore, Singapore),
A W Batchelor (Monash University Malaysia, Malaysia)
Joerg Mayer (TECIM, Switzerland)
Vol. 2: Life-Enhancing Plastics: Plastics and Other Materials in Medical Applications
by Anthony Holmes-Walker (Biolnteractions Ltd, UK)
Vol. 3: Service Characteristics of Biomedical Materials and Implants
by Andrew W Batchelor (Monash University Malaysia, Malaysia) and
Margam Chandrasekaran (Singapore Institute of Manufacturing Technology,
Singapore)
Vol.4
Series on Biomaterials and Bioengineering
Fundamentals and Applications of
Biophotonics in Dentistry
Anil Kishen
National University of Singapore, Singapore
Anand Asundi
Nanyang Technological University, Singapore
Imperial College Press
Jft^
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British Library Cataloguing-in-Publication Data
A catalogue record for this book is available from the British Library.
FUNDAMENTALS AND APPLICATIONS OF BIOPHOTONICS IN DENTISTRY
Series on Biomaterials and Bioengineering — Vol. 4
Copyright © 2007 by Imperial College Press
All rights reserved. This book, or parts thereof, may not be reproduced in any form or by any means,
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PREFACE
Biophotonics is revolutionizing the field of medicine, biology and
chemistry and creating a new breed of medical engineers while at the
same time getting engineers a taste of medicine. From an engineer's
perspective, biophotonics is the application of photonics - the technology
of generating and harnessing packet of light energy called photons - to
image, detect and manipulate biological materials. In biology the
understanding of molecular mechanisms, function of proteins and
molecules has seen great new advances. In biomedical engineering
detection, diagnoses and treatment targeting both macro-objects like the
teeth or bone as well as micro-objects such as bacteria have seen better
understanding through the development of new tools. There is another
school of thought, albeit much smaller that defines biophotons as a
quantum of light that is permanently and continuously emitted by all
living systems. For example, humans emit radiation similar to a
blackbody with maximum power being emitted at a wavelength of about
10 um.
Regardless of definition, biophotonics is a multi-disciplinary field that
bridges engineering, the sciences and medical fields. This diversity of
sciences and technologies usually makes for challenging and interesting
projects - that could be driven by engineers and clinicians alike.
However, there is still the need that clinicians understand some concepts
in photonics while engineers get a feel for medical and bio-chemical
sciences. Towards this end, this book is written by persons from different
fields such as engineering, sciences and medical field.
The book is roughly divided into two sections - the first introduces
the readers to some basic concepts in the field of biophotomechanics. As
the name suggests, this topic looks at the use of optical methods (photo)
for the study of mechanical behaviour (mechanics) of biological objects
v
VI Preface
in the macro-scale such as teeth and bone. The next chapter introduces
some recent techniques on bioimaging such as fluorescence microscopy
and optical coherence tomography amongst others. Chapter 4 introduces
spectroscopy - a erstwhile tool in biophotonics while chapter five deals
with lasers and laser tissue interaction. Finally Chapter 6 provides an
introduction to Photodynamic therapy a growing technology for targeted
application of photonic radiations.
The second half of the book applies some of these basic concepts to
the field of dentistry to highlight some of the features and adaptation of
photonics in this area. Dental photomechanics provides an understanding
of mechanical and thermal characteristics of dentine and permits a better
understanding of the causes of damage and failure of certain treatments.
Chapter 8 uses spectroscopic methods specifically Micro-Raman
spectroscopy for a better understanding of the materials aspects of
dentine and adhesives. The next chapter on Dental and Oral Optics
describes tools and techniques for imaging and optical properties of
dentine and enamel. The final chapter on fiber optic sensors explores
new sensor development for effective and fast ways of detecting and
diagnosing oral bacteria.
We, as editors, feel that the book would be just as informative for
final year undergraduate, graduate students in bioengineering as it would
to clinicians and dental surgeons to gain a better understanding of a
process or treatment.
Anil Kishen and Anand Asundi
CONTENTS
Preface
FUNDAMENTALS
Chapter 1 Introduction
1.1. Introduction 1
1.2. Definition and Significance 2
1.3. Classification of Biophotonics in Dentistry 3
1.3.1. Diagnostic 3
1.3.2. Therapeutic 4
1.3.3. Research 5
1.4. Future Opportunities 7
1.5. Scope of this Book 8
Chapter 2 Photomechanics
2.1. Introduction to Mechanics 9
2.1.1. Force and Stress 10
2.1.2. Deformation and Strain 13
2.1.3. Stress-Strain Equations 16
2.2. Basic Optical Engineering 16
2.2.1. Geometric Optics 17
2.2.2. Physical (Wave) Optics 19
2.2.3. Photonics 27
2.3.. Photomechanics 30
2.3.1. Moire and Grid Methods 31
2.3.2. Speckle Methods 40
2.3.3. Photoelasticity 46
2.3.4. Holography 54
2.3.5. Digital Photomechanics 58
2.4. Concluding Remarks 60
VI!
Vlll Contents
Chapter 3 Biomedical Imaging
3.1. Introduction 64
3.2. Non-Linear Optical Microscopy (NLOM): 65
Multiphoton Excited Fluorescence (MPEF)
and Second Harmonic Generation (SGH)
3.2.1. Principles of NLOM 66
3.2.2. Development and Applications 69
of NLOM
3.2.3. NLOM in Dentistry 72
3.3. Optical Coherence Tomography (OCT) 73
3.3.1. Principles of OCT 74
3.3.2. Developments and Applications 75
of OCT
3.3.3. OCT in Dentistry 80
3.4. Coherent Anti-Stokes Raman Scattering 82
(CARS) and Modulated Imaging (MI)
3.5. Fluorescence Contrast Enhancement 85
3.6. Concluding Remarks 87
Chapter 4 Spectroscopy
4.1. Introduction 93
4.2. Molecular Orbitals and Transitions 94
4.3. Transition Dipole Moment 99
4.4. Spin Selection Rule 100
4.5. Franck-Condon Principle 102
4.6. Jablonski Diagram 104
4.7. Stokes Shift 107
4.8. Spectrophotometry 108
4.9. Fluorescence Intensity and Lifetime 110
4.10. Spectrofluorimetry 112
4.11. Fluorescence Quenching 115
4.12. Fluorescence Resonance Energy Transfer 116
(FRET)
4.13. Fourier Transform Infrared (FTIR) 117
Spectroscopy
4.14. Concluding Remarks 120
Contents IX
Chapter 5 Lasers and Laser Tissue Interaction
5.1. Introduction 123
5.2. Laser Basics 124
5.2.1. Characteristics of Lasers 126
5.3. Light Propagation in Tissue 128
5.4. Optical Imaging and Diagnosis 131
5.4.1. Optical Imaging 131
5.4.2. Optical Spectroscopic Diagnosis 133
5.5. Optical Processing of Tissue 141
5.5.1. Photothermal Effects 142
5.5.2. Photomechanical Effects 144
5.5.3. Photochemical Effects 144
5.5.4. Applications of Laser Processing 145
of Tissue
5.6. Concluding Remarks 148
Chapter 6 Mechanisms and Applications of Photodynamic
Therapy
6.1. Historical Background 154
6.2. Photosensitizers 155
6.3. Light Applicators 156
6.4. PDT Mechanisms 161
6.4.1. Photophysics and Photochemistry 161
6.4.2. Biological Effect 162
6.5. PDT Dosimetry 166
6.6. Progress in Clinical Application 167
6.6.1. Non-Malignant Diseases 168
6.6.2. Malignant Diseases 169
6.7. PDT in Dentistry 175
6.7.1. Technical Challenges 175
6.7.2. Current Status 176
6.8. Concluding Remarks 177