Fundamentals of Oral and Maxillofacial Radiology

About the author J. Sean Hubar, DMD, MS, is Professor in the Department of Diagnostic Sciences at Louisiana State University School of Dentistry in New Orleans, Louisiana, USA.

Acknowledgments ix

About the Companion Website x

Part One: Fundamentals 1

A. Introduction 3

What is dental radiology? 3

What are x rays? 3

What’s the big deal about x‐ray images? 5

B. History 6

Discovery of x rays 6

Who took the world’s first “dental” radiograph? 8

Dr. C. E. Kells, Jr., a New Orleans dentist and the early days of dental radiography 8

C. Generation of X Rays 11

D. Exposure Controls 13

Voltage (V) 13

Amperage (A) 13

Exposure timer 14

E. Radiation Dosimetry 15

Exposure 15

Absorbed dose 15

Equivalent dose 15

Effective dose 16

F. Radiation Biology 17

What happens to the dental x‐ray photons that are directed at a patient? 18

Determinants of biologic damage from x‐radiation exposure 19

G. Radiation Protection 22

1. Radiation protection: Patient 22

Protective apron 23

Collimation 24

Filtration 25

Digital versus analog 26

Exposure settings 26

Operator technique 26

2. Radiation protection: Office personnel 27

How much occupational radiation exposure is permitted? 29

H. Patient Selection Criteria 30

I. Film versus Digital Imaging 32

Film 32

Digital imaging 33

Imaging software 36

J. What do Dental X‐ray Images Reveal? 38

Alterations to the dentition 38

Periodontal disease 39

Growth and development 39

Alterations to periapical tissues 40

Osseous pathology 40

Temporomandibular joint disorder 40

Implant assessment (pre‐ and post‐placement) 40

Identification of a foreign body 40

K. Intraoral Imaging Techniques 41

1. Paralleling technique 42

Maxillary incisors paralleling projection 45

Maxillary cuspid paralleling projection 45

Maxillary bicuspid paralleling projection 46

Maxillary molar paralleling projection 46

Mandibular incisor paralleling projection 47

Mandibular cuspid paralleling projection 48

Mandibular bicuspid paralleling projection 48

Mandibular molar paralleling projection 49

2. Bisecting angle technique 50

Maxillary incisor bisecting angle projection 51

Maxillary cuspid bisecting angle projection 51

Maxillary bicuspid bisecting angle projection 52

Maxillary molar bisecting angle projection 52

Mandibular incisor bisecting angle projection 53

Mandibular cuspid bisecting angle projection 53

Mandibular bicuspid bisecting angle projection 54

Mandibular molar bisecting angle projection 54

3. Bitewing technique 55

Bicuspid bitewing 56

Molar bitewing 56

Anterior bitewing projection 56

4. Distal oblique technique 57

5. Occlusal imaging technique 58

Maxillary occlusal projection 59

Mandibular occlusal projection 60

L. Intraoral Technique Errors 61

Cone‐cut 61

Apex missing 62

Elongation 63

Foreshortening 63

Overlapped contacts 64

Missing contacts 64

Overexposure and underexposure 65

Motion artifact 66

Foreign object 66

M. Extraoral Imaging Techniques 68

1. Panoramic imaging 68

Positioning the patient 69

Exposure settings 71

Advantages and disadvantages 71

Technique errors 74

Anatomic landmarks 84

2. Lateral cephalograph imaging 85

3. Cone beam computed tomography 86

Introduction 86

Anatomic landmarks 89

N. Quality Assurance 96

O. Infection Control 97

Excerpt from “CDC

Guidelines for Infection Control in Dental Health‐Care Settings” 97

General instructions for cleaning and disinfecting a solid‐state receptor (courtesy of Sirona™) 98

P. Occupational Radiation Exposure Monitoring 100

Q. Hand‐held X‐ray Systems 102

Dental radiographic examinations: recommendations for patient selection and limiting radiation exposure 102

Commentary 102

Part Two: Interpretation 105

R. Localization of Objects (SLOB Rule) 107

S. Recommendations for Interpreting Images 111

T. X‐ray Puzzles: Spot the Differences 113

U. Radiographic Anatomy 124

1. Dental anatomy 124

2. Anatomic landmarks of the maxillary region 126

Radiopaque landmarks 126

Radiolucent landmarks 129

3. Anatomic landmarks of the mandibular region 133

Radiopaque landmarks 133

Radiolucent landmarks 136

V. Dental Caries 141

Limitations to visualizing caries on x‐ray images 141

Classification of caries 143

W. Dental Anomalies 149

Number 149

Size 149

Shape 151

Developmental factors 157

Environmental factors 161

X. Osseous Pathology (Alphabetic) 170

Y. Lagniappe (Miscellaneous Oddities) 188

Part Three: Appendices 195

Appendix 1: FDA Recommendations for Prescribing Dental X‐ray Images 197

Appendix 2: X‐radiation Concerns of Patients: Question and Answer Format 200

1. How often should I get x rays taken? 200

2. How much radiation am I receiving from dental x rays? 200

3. Can I get cancer from dental x rays? 201

4. Why do I need to wear a protective apron for dental x rays and why does the assistant leave the room before taking my x rays, if dental x rays are so safe? 201

5. Your protective apron does not have a thyroid collar, why not? 201

6. I am pregnant, should I get dental x rays taken? 201

7. When should my child first get dental x rays taken? 201

8. Will I glow in the dark after all of the x rays that I received at the dental office? 202

9. What are 3‐D x rays? 202

10. Why does the dentist require additional 3‐D x rays before placing my dental implant? 202

Appendix 3: Helpful Tips for Difficult Patients 203

1. Hypersensitive gag reflex 203

2. Small mouth/shallow palate/ constricted arch/torus 204

3. Large frenulum 205

4. Trismus 205

5. Cuspid superimposition 205

6. Rubber dam 206

7. Third molar imaging 206

Appendix 4: Deficiencies of X‐ray Imaging Terminology 207

Survey results 207

Appendix 5: Tools for Differential Diagnosis 210

1. Number 210

2. Location 210

3. Density 211

4. Shape 211

5. Size 211

6. Borders 212

7. Changes to surrounding anatomic structures 212

Appendix 6: Table of Radiation Units 213

Appendix 7: Table of Anatomic Landmarks 214

Tooth 214

Tooth‐related structures 214

Landmarks associated with the maxilla 214

Landmarks associated with the mandible 214

Appendix 8: Table of Dental Anomalies 216

Number 216

Size 216

Shape 216

Developmental defects 216

Environmental effects 216

Appendix 9: Table of Osseous Pathology 217

Radiolucent anomalies in the maxilla and mandible 217

Radiopaque anomalies in the maxilla and mandible 217

Mixed (radiolucent–radiopaque) anomalies in the maxilla and mandible 218

Appendix 10: Common Abbreviations and Acronyms 219

Appendix 11: Glossary of Terms 221

Suggested Reading 238

Index 251