Fundamentals of Oral and Maxillofacial Radiology

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 (TM)) 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