Transcript
Page 1: Incidental findings on cone beam computed tomography

University of IowaIowa Research Online

Theses and Dissertations

Spring 2009

Incidental findings on cone beam computedtomographyVeeratrishul AllareddyUniversity of Iowa

Copyright 2009 Veeratrishul Allareddy

This thesis is available at Iowa Research Online: https://ir.uiowa.edu/etd/457

Follow this and additional works at: https://ir.uiowa.edu/etd

Part of the Other Dentistry Commons

Recommended CitationAllareddy, Veeratrishul. "Incidental findings on cone beam computed tomography." MS (Master of Science) thesis, University of Iowa,2009.https://doi.org/10.17077/etd.8ed7q3af

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INCIDENTAL FINDINGS ON CONE BEAM COMPUTED TOMOGRAPHY

by

Veeratrishul Allareddy

A thesis submitted in partial fulfillment of the requirements for the Master of

Science degree in Stomatology in the Graduate College of

The University of Iowa

May 2009

Thesis Supervisor: Professor Axel Ruprecht

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Copyright by

VEERATRISHUL ALLAREDDY

2009

All Rights Reserved

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Graduate College The University of Iowa

Iowa City, Iowa

CERTIFICATE OF APPROVAL

_______________________

MASTER'S THESIS

_______________

This is to certify that the Master's thesis of

Veeratrishul Allareddy

has been approved by the Examining Committee for the thesis requirement for the Master of Science degree in Stomatology at the May 2009 graduation.

Thesis Committee: ___________________________________ Axel Ruprecht, Thesis Supervisor

___________________________________ John Hellstein

___________________________________ Steven Vincent

___________________________________ Wendy Smoker

___________________________________ Fang Qian

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I would like to dedicate this work to my wife Sindhura for whom no amount of words can do justice for all her love, support and constant caring for me

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ACKNOWLEDGMENTS

I would like to express my sincere gratitude and thanks to Dr. Axel Ruprecht who

had to spend an enormous amount of time and energy to help me get this project done,

Dr. Hellstein for his constant encouragement and ideas to do things more efficiently, Dr.

Steve Vincent for his support to help me finish the project, Dr. Wendy Smoker who has

been a tremendous source of support and advice, Fang Qian who has graciously accepted

to look at the results of the project, Mark Palmer CEO and President, 360imaging for

allowing me to use the data for the study, Ryan Roosekrans and Adam Van Pelt for their

help in organizing and helping me with the data for the study. I would like to thank all

my co-residents and staff for their friendship during my time in the Department of Oral

Pathology, Radiology and Medicine.

I would like to especially thank my parents, brothers and wife for their constant

support all through my life.

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TABLE OF CONTENTS

LIST OF TABLES ............................................................................................................ vii

LIST OF FIGURES ........................................................................................................... ix

CHAPTER 1 INTRODUCTION ........................................................................................1 Cone Beam Computed Tomography Image Acquisition ..................................2 Cone Beam Computed Tomography in Dentistry ............................................2 Aim ...................................................................................................................3

CHAPTER 2 MATERIALS AND METHODS ..................................................................4 Source of the scans ...........................................................................................4 Field of View of the scans ................................................................................4 Time of exposure to acquire the scan ...............................................................4 Age and Sex distribution of subjects ................................................................5 Interpretation and review of the scans ..............................................................6

CHAPTER 3 RESULTS ......................................................................................................7

CHAPTER 4 DISCUSSION ..............................................................................................33 CBCT image production .................................................................................33

Acquisition configuration and setup ........................................................33 Image detection .......................................................................................34 Image reconstruction ...............................................................................34 Image display ...........................................................................................35

Findings inside/outside the areas of interest ...................................................43 Periapical/parapical/peridental findings in the subjects ..........................43

Cementoblastoma .............................................................................43 Rarefying osteitis and sclerosing osteitis .........................................44

Rarefying osteitis ......................................................................44 Radicular cyst ............................................................................44

Sclerosing osteitis .............................................................................46 Hypercementosis ..............................................................................47 Enostosis ...........................................................................................48 Alveolo-osseous induction effect .....................................................48 Osteosclerosis ...................................................................................49 Root fragments .................................................................................50 External resorption ...........................................................................51 Dentigerous cyst ...............................................................................51 Residual cyst ....................................................................................52 Odontogenic Keratocyst ...................................................................53 Simple bone cyst ..............................................................................54 Nasopalatine canal cyst ....................................................................55 Reactive hyperplastic osteitis ...........................................................57 Oroantral fistulas ..............................................................................58 Restorative material in the apical regions of teeth ...........................59 Cemento-osseous dysplasia ..............................................................60 Giant cell lesion ................................................................................61 Impacted teeth ..................................................................................62 Graft material and sclerotic healing .................................................63

Pathosis/anatomical variants in the paranasal sinuses .............................64

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Mucositis ..........................................................................................64 Sinusitis ............................................................................................65 Polyps ...............................................................................................66 Surgical changes in the sinuses and adjacent structures ..................66 Hypoplastic sinuses ..........................................................................67 Osteoma ............................................................................................67

Findings in the cervical vertebrae region: ...............................................69 Degenerative joint disease in cervical vertebrae ..............................69 Screws in cervical vertebrae .............................................................70 Fusion of C2-3 cervical vertebrae ....................................................71 Nonsegmentatation of vertebrae .......................................................72

Findings in the TMJ regions/associated structures ..................................72 Osteoarthrosis in the osseous components of the TMJ ....................72 Coronoid hyperplasia .......................................................................73 Condylar hyperplasia ........................................................................74 Condylar hypoplasia .........................................................................75

Calcifications found in the volume ..........................................................76 Calcifications in blood vessels .........................................................76 Carotid artery calcifications .............................................................76 Vertebral artery calcification ............................................................77 Pineal gland calcifications ................................................................78 Tonsilliths .........................................................................................79 Sialoliths ...........................................................................................80 Dystrophic calcifications ..................................................................81

Other findings ..........................................................................................83 Osteopenia ........................................................................................83 Osteomyelitis, radioosteonecrosis and chemoosteonecrosis ............84 Amelogenesis imperfecta .................................................................86 Dentin dysplasia ...............................................................................87 Dentinogenesis imperfecta with osteogenesis imperfecta ................87 Taurodontism ...................................................................................89 Supernumerary teeth ........................................................................89 Oligodontia .......................................................................................92 Transposition ....................................................................................93 Gemination .......................................................................................93 Microdontia ......................................................................................94 Macrodontia .....................................................................................95 Odontomas .......................................................................................95 Surgical drain in the soft tissue of brain ...........................................97 Surgical staples in the neck ..............................................................98 Retained suture material ...................................................................98 Adenoidal hyperplasia ......................................................................99 Soft tissue swellings in the airway region ......................................100 Fibrous dysplasia ............................................................................100 Torus ...............................................................................................102 Mandibular hemihyperplasia ..........................................................103 Osteoma cutis .................................................................................103 Cleft Palate .....................................................................................104 Salivary Gland Inclusion (Stafne) defects ......................................105 Nut Notch .......................................................................................106 Implant impinging on borders of the inferior alveolar canal..........107 Previous unhealed fracture .............................................................108 Shot gun wound ..............................................................................109 Hearing aids ....................................................................................110

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Earrings ..........................................................................................111 Nose ring ........................................................................................111

CHAPTER 5 CONCLUSION..........................................................................................112

REFERENCES ................................................................................................................113

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LIST OF TABLES

Table 1. Age and Sex distribution of subjects .....................................................................5

Table 2. Reason of scan for the subjects ..............................................................................6

Table 3. Variations in size, shape and number of teeth .......................................................7

Table 4. Periapical/parapical/peridental findings ................................................................8

Table 5. Other periapical/parapical/peridental findings......................................................9

Table 6. Pathosis/anatomical variants in the paranasal sinuses ...........................................9

Table 7. Findings in the cervical vertebrae region .............................................................10

Table 8. Findings in the TMJ region/associated structures................................................10

Table 9. Calcifications visualized in the volume ...............................................................11

Table 10. Other findings ....................................................................................................12

Table 11. Supernumerary teeth ..........................................................................................13

Table 12. Oligodontia ........................................................................................................14

Table 13. Rarefying osteitis ...............................................................................................15

Table 14. Enostosis ............................................................................................................16

Table 15. Root fragments ...................................................................................................17

Table 16. External resorption - physiological and pathological ........................................18

Table 17. Restorative material in the apices of the teeth ...................................................19

Table 18. Impacted teeth not including third molars .........................................................20

Table 19. Graft material and sclerotic healing ...................................................................21

Table 20. Mucositis/sinusitis/mucous retention pseudocyst ..............................................22

Table 21. Hypoplastic sinuses............................................................................................23

Table 22. Surgical changes in the sinuses ..........................................................................24

Table 23. Osteoarthrosis of vertebrae ................................................................................25

Table 24. Osteoarthrosis of TMJs ......................................................................................26

Table 25. Coronoid hyperplasia .........................................................................................27

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Table 26. Carotid artery calcifications ...............................................................................28

Table 27. Pineal gland calcifications (physiologic) ...........................................................29

Table 28. Tonsilliths ..........................................................................................................30

Table 29. Osteoma cutis .....................................................................................................31

Table 30. Adenoidal hyperplasia .......................................................................................32

Table 31. Findings in paranasal sinuses. ............................................................................69

Table 32. Degenerative joint disease in the cervical vertebrae. .........................................70

Table 33. Degenerative joint disease in the osseous components of the TMJs. ................73

Table 34. Dystrophic calcifications. ..................................................................................81

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LIST OF FIGURES

Figure 1. An axial view through the body of the mandible (M). ......................................36

Figure 2. A coronal view of the skull, showing the maxillary sinuses (A), orbits (B), nasal conchae (C) and mandible (D) at approximately the depth of the premolars. .................................................................................................................37

Figure 3. A sagittal view of the facial region and the cervical vertebrae (A) near the midline showing Sphenoid Sinus (SS), Ethmoid air cells (EAC), Inferior(I) and Middle (M) Conchae and hard palate (H) and mandible(Ma) . ........38

Figure 4. Example of a panoramic image. .........................................................................39

Figure 5. Orthoradial images in the maxillary anterior region. .........................................40

Figure 6. A 3D reconstruction showing the osseous structures of the middle and lower face, as well as the cervical vertebrae. ............................................................41

Figure 7. A maximum intensity projection in the panoramic mode. .................................42

Figure 8. A panoramic image showing a cementoblastoma (C) attached to the root of the mandibular right first premolar.......................................................................43

Figure 9. A panoramic image showing rarefying osteitis(R) in the periapical regions of the mandibular right first molar and external resorption(X) of the tooth. .........................................................................................................................45

Figure 10. A coronal view showing rarefying osteitis(R) with external resorption(X) and a draining sinus tract (ST). ..........................................................46

Figure 11. A panoramic image showing hypercementosis (H) on the maxillary left third molar and possibly the maxillary right third molar. .........................................47

Figure 12. A panoramic image showing enostosis (E) in the bone in the periapical regions of the maxillary left premolars. ....................................................................48

Figure 13. A panoramic image showing alveolo-osseous induction effect (A) in periapical regions of the mandibular right second molar. ........................................49

Figure 14. A panoramic image showing osteosclerosis (O) in the periapical regions of the mandibular right first molar. ...........................................................................49

Figure 15. A panoramic image showing multiple retained root fragments in the maxillae and one in the mandible .............................................................................50

Figure 16. A panoramic image showing external resorption (X) of the maxillary incisors and the mandibular incisors .........................................................................51

Figure 17. A panoramic image showing a dentigerous cyst (D) associated with the impacted mandibular left third molar (T). ................................................................52

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Figure 18. Orthoradial slices showing a residual cyst (RC) in the maxillary left central incisor region. ...............................................................................................53

Figure 19. A panoramic image showing multiple odontogenic keratocysts (OKC),a microdont (Mi), taurodonts(T) and impacted teeth(I) in a patient with nevoid basal cell carcinoma syndrome. ................................................................................54

Figure 20. A panoramic image showing a simple bone cyst (SBC) in the left side body of the mandible. ...............................................................................................55

Figure 21. A coronal image showing a nasopalatine canal cyst (N) with minimal evidence of inferior (I) or superior (S) borders.........................................................56

Figure 22. A sagittal image showing the same nasopalatine canal cyst (N) with minimal evidence of inferior or superior borders. ....................................................57

Figure 23. A panoramic image showing reactive hyperplastic osteitis (O) under the bridge in the mandibular left first molar region. .......................................................58

Figure 24. A sagittal image shows an oroantral fistula (O) in the floor of the right maxillary sinus which has sinusitis (S). ....................................................................59

Figure 25. A sagittal image showing restorative material (RM) extruded into the periapical regions of the maxillary right canine. ......................................................59

Figure 26. Florid cemento-osseous dysplasia is seen in the periapical regions of most of the teeth in the maxillae and the mandible on this panoramic image. .........60

Figure 27. A panoramic image showing a giant cell lesion (GCL) in the left side of the mandible. There is resorption of the premolars and the molars and the mandibular left third molar is displaced. ..................................................................61

Figure 28. The same giant cell lesion (GCL) in the left side of the mandible with a break in the cortex due to a biopsy (B) in the area seen on this coronal image. .......62

Figure 29. The permanent maxillary canines (IC) are impacted in this 36-year-old female can be seen on this panoramic image. ...........................................................62

Figure 30. This coronal image shows graft material (GM) in the left maxillary alveolar ridge and the floor of the left maxillary sinus. ............................................63

Figure 31. A chin graft (CG) with a pin is seen on this sagittal image. .............................64

Figure 32. Mucositis (M) in the maxillary sinuses seen on this coronal image. ................65

Figure 33. Sinusitis (S) in the maxillary sinuses and the ethmoidal air cells seen on this coronal image. Subject had pansinusitis. ...........................................................65

Figure 34. A coronal image showing polyps (P) in the maxillary sinuses. .......................66

Figure 35. A coronal image showing surgical (S) changes, that is absence of part of the walls of the sinuses and the conchae...................................................................66

Figure 36. Both the maxillary sinuses (MS) in this coronal image are hypoplastic. .........67

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Figure 37. An osteoma (O) can be seen on this coronal image in the right frontal sinus. .........................................................................................................................68

Figure 38. An osteoma (O) in the right ethmoidal air cell is seen in this coronal image. ........................................................................................................................68

Figure 39. Degenerative disease (OA) with anterior and posterior osteophyte formation is seen on this sagittal image. ...................................................................70

Figure 40. A sagittal image showing an osseous screw (OS) in the body of the fourth cervical vertebrae (V).....................................................................................71

Figure 41. Partial fusion (PF) of the C2-3 cervical vertebrae is seen on these coronal and sagittal images. ......................................................................................71

Figure 42. Partial nonsegmentation (NS) of C3-4 cervical vertebrae seen on this sagittal image. ...........................................................................................................72

Figure 43. There is bilateral osteoarthrosis (OA) with reduction of disc space on the left side and hypoplastic condyle on the right side on this coronal view. ................73

Figure 44. A hyperplastic coronoid process(H) is seen on this sagittal view. ...................74

Figure 45. The right condyle (CH) is markedly hyperplastic compared to the left in this coronal image. ....................................................................................................75

Figure 46. Hypoplastic condyles (HC) are seen bilaterally on this coronal view..............75

Figure 47. Carotid artery calcifications (CAC) are seen bilaterally on this axial image. ........................................................................................................................77

Figure 48. A calcification in the left vertebral artery (VAC) at the C3-4 level is seen on this coronal image. ...............................................................................................78

Figure 49. Pineal gland calcification (P) seen in the midline on this axial image. ............79

Figure 50. Tonsilliths (T) are seen in the region of the tonsils on this coronal image. .....80

Figure 51. A sialolith (S) is seen in the Warton’s duct on this axial image. ......................81

Figure 52. A calcification is seen in the region of the adenoids (CA) region in this image. ........................................................................................................................82

Figure 53. A calcification in the epiglottis region (CE) is seen on this sagittal image. ........................................................................................................................82

Figure 54. A calcification in the temporal region (CT) seen on this axial image. .............83

Figure 55. Generalized osteopenia is seen on this sagittal image. .....................................84

Figure 56. Osteomyelitis (OM) can be seen on this axial image in the right side of the mandible. There is an ossifying periosteal reaction (PR) on the lingual side. ...........................................................................................................................85

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Figure 57. Radioosteonecrosis (RON) and post surgical changes (S) are seen on this panoramic image. ......................................................................................................85

Figure 58. Chemoosteonecrosis (CN) seen on an axial image on the right side of the mandible....................................................................................................................86

Figure 59. A panoramic image shows a hypomineralized form of amelogenesis imperfecta. ................................................................................................................86

Figure 60. Dentin dysplasia can be seen on this panoramic image. ..................................87

Figure 61. Dentinogenesis imperfecta seen on this panoramic image in a subject with osteogenesis imperfecta. ...................................................................................88

Figure 62. Taurodonts, multiple odontogenic keratocysts, microdonts and impacted teeth in a patient with nevoid basal cell carcinoma syndrome are seen on a panoramic image . .....................................................................................................89

Figure 63. A 3D reconstruction shows a mesiodens and an impacted maxillary right central incisor. ...........................................................................................................90

Figure 64. A mesiodens (MD) is seen on this sagittal image on the palatal aspect of the central incisor. .....................................................................................................91

Figure 65. A distodens (DD) distal to the maxillary left third molar is seen on this panoramic image. ......................................................................................................91

Figure 66. Peridentes (PD) are seen bilaterally in the mandible and in the left maxilla on this coronal image. ..................................................................................92

Figure 67. Transposition of the maxillary left canine (C) and first premolar (PM) is seen on this panoramic image. ..................................................................................93

Figure 68. Gemination (G) of the maxillary left lateral incisor is seen on this panoramic image. ......................................................................................................94

Figure 69. A microdont (Mi) can be seen distal to the maxillary right second molar on this panoramic image. ..........................................................................................94

Figure 70. Generalized macrodontia is seen on this panoramic image. .............................95

Figure 71. A compound odontoma (CO) can be seen in the body of the mandible on this sagittal image. ....................................................................................................96

Figure 72. A compound odontoma (CO) can be seen in the body of the mandible on this axial image .........................................................................................................97

Figure 73. A radiopaque tubular structure (D) can be seen on these coronal and sagittal images...........................................................................................................97

Figure 74. Surgical staples (SS) are seen on these multi-planar reconstruction image. ........................................................................................................................98

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Figure 75. Suture material (S) is seen on the lateral walls of the orbits bilaterally on this coronal image .....................................................................................................99

Figure 76. Marked adenoidal hyperplasia (AH) in a 16 year-old female which is obstructing the airway can be seen on this sagittal section. ....................................100

Figure 77. Fibrous dysplasia (FD) seen on this axial image in the right side of the mandible..................................................................................................................101

Figure 78. Fibrous dysplasia (FD) is seen on this coronal image in the right side of the mandible. ...........................................................................................................102

Figure 79. A palatal torus (P) is seen on this sagittal image ............................................102

Figure 80. Mandibular hemihyperplasia is seen on this panoramic image on the right side of the mandible .......................................................................................103

Figure 81. Osteoma cutis (OC) is seen bilaterally on this axial image. ...........................104

Figure 82. A cleft palate (CP) is seen on the right side in the maxillae on this axial image. ......................................................................................................................104

Figure 83. A Stafne defect (ASD) is seen on this axial image on the right side of the lingual aspect of the mandible. ...............................................................................105

Figure 84. A 3D reconstruction showing an anterior Stafne defect (ASD). ....................106

Figure 85. A posterior submandibular Stafne defect (PSD) is seen on this panoramic image inferior to the roots of the mandibular right second molar. .......106

Figure 86. A 3D reconstruction shows a nut notch in the maxillary left central incisor......................................................................................................................107

Figure 87. Orthoradials show an implant (I) impinging on the borders of the inferior alveolar nerve canal (IAN) ........................................................................107

Figure 88. A discontinuity in the mandible representing incomplete healing in the region is seen on this 3D reconstruction. ................................................................108

Figure 89. A shot gun wound and surgical changes are seen on this 3D reconstruction..........................................................................................................109

Figure 90. Hearing aids (HA) can be seen bilaterally in this coronal view. ....................110

Figure 91. Earrings (ER) can be seen bilaterally on this coronal view ............................111

Figure 92. A nose ring (NR) on this axial image of the ala of the left side of the nose. ........................................................................................................................111

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CHAPTER 1

INTRODUCTION

The development of panoramic radiography in the 1950s and its commercial

introduction in 1965 led to the widespread adoption and use of the technology which has

continued until now. Although widely used, these images have the same inherent

limitations as other 2D projections, namely magnification and minifaction of structures,

superimposition of anatomical and/or pathological entities and misrepresentation of

structures. However panoramic radiography is efficient at providing an overview of oral

and maxillofacial hard tissues, including teeth, and may reveal associated pathoses of the

jaws. To overcome some of the above limitations cone beam computed tomography

(CBCT) for the jaws was developed in the 1990s, and has gained widespread acceptance

in dentistry, especially in the last 5 years.

Cone beam computed tomography was initially developed for angiography and is

also popularly used for radiotherapy guidance and mammography1. It was developed as

an alternative to conventional fan beam helical computed tomography (CT) machines to

provide more rapid acquisition of a dataset of the entire field of view.

One advantage is that rapid acquisition has led to less patient motion artifact. In

addition, the radiation dose to the patient is markedly reduced when compared to that of

conventional CT machines and CBCT machines are markedly less expensive than

conventional CT machines.

However, there are certain disadvantages. The field of view is usually smaller

than that of standard CT and there is a lack of differentiation among various soft tissues.

Cone beam CT scanners have been commercially available for craniofacial

imaging since 1999 in Europe and more recently since 2001 in the United States2. Cone

beam CT scanners were first introduced in 1997 in Italy3.

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Cone Beam Computed Tomography Image Acquisition

Depending on the unit, in current CBCT units patients can be scanned in sitting,

standing or supine positions. The machines which scan patients in a supine position are

predominantly the earlier generation of CBCT machines. They have a large footprint and

are relatively difficult for patients with physical disabilities. The machines that scan

patients in standing positions may make it difficult to accommodate patients who are

relatively tall, short or obese. The latter often results in the machine hitting the patient’s

shoulders during the process of image acquisition. The machines that scan patients in

sitting positions are generally the most comfortable for patients.

Cone Beam Computed Tomography in Dentistry

The use of CBCT has gained widespread acceptance in dentistry for a variety of

applications such as:

Evaluation of pathosis in the jaws,

Evaluation of bone for implants,

Orthodontic assessments, and

TMJ assessments

This imaging modality is mainly for assessment of the osseous and dental

components of the maxillofacial complex. Unlike conventional CT scans, imaging of soft

tissue is not indicated with dental CBCT examinations.

However, most dentists who are not radiologists, are not familiar with

interpretation of anatomical structures and/or pathosis outside their area of primary

interest. This may not be within the scope of training for a person without advanced

education in interpretation techniques in radiology. This study was undertaken to

determine the prevalence and nature of unusual findings in and around the maxillofacial

complex encountered in CBCT studies.

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Aim

To assess whether the number of incidental findings on a cone beam computer

tomography scan is high in both the primary area of interest as well as outside the

primary area of interest, thereby emphasizing the importance of interpretation of all areas

visualized on the scan.

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CHAPTER 2

MATERIALS AND METHODS

Source of the scans

The CBCT scans used in the study were acquired on an i-CAT machine (Imaging

Sciences International, Hatfield, PA) at a private imaging company (360imaging in

Atlanta, Georgia). To assess the feasibility of this study, a pilot survey was carried out on

a continuous series of 100 subjects scanned at the imaging company. Institutional Review

Board approval to use the information on the scans for the study was obtained at The

University of Iowa. Once the data obtained from the initial 100 subjects showed the

feasibility and importance of a comprehensive study, a series of 1000 subjects imaged at

the same company was analyzed comprehensively. Consent was obtained from all

subjects as well as the private imaging company to use and share the information from

the scans for purposes of education, including teaching and research.

Field of View of the scans

All the scans used for this study were acquired at a field of view of 13cm and a

0.3mm thickness.

Time of exposure to acquire the scan

The time of exposure to acquire the scan was uniform at 8.5 seconds for 843

subjects and 20 seconds for 157 subjects after acquiring the scout image to assess and

adjust for proper positioning of the subject to include the region of interest on the scan.

The field of view and thickness of the slices remained the same in both sets of subjects

despite the change in time of the scan from 20 seconds to 8.5 seconds. The decrease in

time of acquisition was due to the increased image acquisition speed of a new sensor.

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Age and Sex distribution of subjects

The age of the youngest subject included in the study was 5 years and 11 months

and the oldest was 87 years.

Table 1. Age and Sex distribution of subjects

Age group Number of Subjects

Males Females Total

5years and 11 months - 10 12 13 25

11-20 78 101 179

21-30 21 30 51

31-40 29 62 91

41-50 53 94 147

51-60 86 134 220

61-70 64 133 197

71-80 35 44 79

81-87 4 7 11

Total 382 618 1000

The subjects scanned presented for a variety of reasons given in table 2.

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Table 2. Reason of scan for the subjects

Reason for Scan No of Subjects

Impaction localization 110

Supernumerary teeth localization 31

Other possible pathosis 46

Implants/Bone evaluation for implants 678

Evaluation of graft in the sinus area/bone

assessment for implants

40

Sinus evaluation prior to implants 17

TMJ assessment 11

Orthodontic records 67

Total 1000

Interpretation and review of the scans

The images were reviewed by an Oral and Maxillofacial Radiologist (VA), using

the proprietary i-CAT viewer software version 3.034.

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CHAPTER 3

RESULTS

Tables 3, 4, 5, 6, 7, 8, 9 and 10 shows the prevalence of the pathologic entities

and or anatomic variants found on scans inside and out of the primary region of interest.

Table 3. Variations in size, shape and number of teeth

Findings visualized Male Female Total

Amelogenesis imperfecta 1 0 1

Dentin dysplasia 1 1 2

Dentinogenesis imperfecta with

osteogenesis imperfecta

0 1 1

Taurodontism 1 0 1

Compound odontoma 0 4 4

Supernumerary teeth 19 12 31

Oligodontia 16 22 38

Transposition 2 3 5

Gemination 1 0 1

Microdontia 3 1 4

Macrodontia 1 0 1

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Table 4. Periapical/parapical/peridental findings

Findings visualized Male Female Total

Rarefying osteitis 114 167 281

Sclerosing osteitis 6 11 17

Hypercementosis 5 8 13

Cementoblastoma 2 2 4

Enostosis 54 82 136

Alveolo-osseous induction effect 3 5 8

Osteosclerosis 2 3 5

Root fragments 45 55 100

External resorption 22 20 42

Residual cyst 3 4 7

Nasopalatine canal cyst 3 0 3

Dentigerous cyst 4 2 6

Hyperplastic dental follicle 3 5 8

Reactive hyperplastic osteitis 0 2 2

Oroantral fistulas 6 8 14

Restorative material in the periapical regions

of teeth

22 37 59

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Table 5. Other periapical/parapical/peridental findings

Findings visualized Male Female Total

Cemento-osseous dysplasia 1 9 10

Giant cell lesion 1 0 1

Simple bone cyst 3 4 7

Odontogenic keratocyst 1 1 2

Impactions (not including third molars) 29 37 66

Graft material and sclerotic healing 35 73 109

Osteomyelitis 1 1 2

Radioosteonecrosis 0 1 1

Chemoosteonecrosis 0 1 1

Fibrous dysplasia 4 4 8

Table 6. Pathosis/anatomical variants in the paranasal sinuses

Findings visualized Male Female Total

Mucositis/Sinusitis/Mucous retention

pseudocysts

246 305 551

Hypoplastic sinuses 8 13 21

Surgical changes in the sinuses 13 16 29

Osteoma 1 3 4

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Table 7. Findings in the cervical vertebrae region

Findings visualized Male Female Total

Osteoarthrosis 90 150 240

Osseous screws in vertebrae 1 2 3

Fusion of C2-3 Cervical vertebrae 1 0 1

Nonsegmentatation of C2-3 vertebrae 1 0 1

Table 8. Findings in the TMJ region/associated structures

Findings visualized Male Female Total

Osteoarthrosis 42 116 158

Coronoid hyperplasia 8 9 17

Condylar hyperplasia 1 2 3

Condylar hypoplasia 2 0 2

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Table 9. Calcifications visualized in the volume

Findings visualized Male Female Total

Carotid artery calcifications 28 29 57

Pineal gland calcifications 43 104 147

Vertebral artery calcification 0 1 1

Tonsilliths 53 39 92

Sialoliths 1 3 4

Calcifications in adenoids 1 1 2

Calcifications in epiglottis 1 1 2

Calcifications in temporal regions 1 2 3

Osteoma cutis 9 14 23

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Table 10. Other findings

Findings visualized Male Female Total

Unhealed fracture 1 0 1

Osteopenia 1 3 4

Surgical drain in the soft tissue of brain 1 0 1

Surgical staples in the neck 1 0 1

Retained suture material 2 2 4

Adenoidal hyperplasia 44 63 107

Soft tissue swellings in the airway region 2 7 9

Palatal tori 1 7 8

Mandibular hemihyperplasia 2 0 2

Cleft Palate 4 1 5

Stafne defect 2 1 3

Nut Notch 1 0 1

Implant impinging on borders of the inferior

alveolar canal

3 3 6

Shot gun wound 1 0 1

Hair artifacts 0 4 4

Hearing aids 1 3 4

Nose ring 0 3 3

Earrings 0 3 3

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Table 11. Supernumerary teeth

Age group Male Female Total

5-11 months-10 years 2 3 5

11-20 years 11 8 19

21-30 years 4 1 5

31-40 years 0 0 0

41-50 years 1 0 1

51-60 years 1 0 1

61-70 years 0 0 0

71-80 years 0 0 0

81-87 years 0 0 0

Total 19 12 31

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Table 12. Oligodontia

Age group Male Female Total

5-11 months-10 years 3 2 5

11-20 years 11 16 27

21-30 years 1 4 5

31-40 years 0 0 0

41-50 years 0 0 0

51-60 years 0 0 0

61-70 years 0 0 0

71-80 years 0 0 0

81-87 years 0 0 0

Total 16 22 38

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Table 13. Rarefying osteitis

Age group Male Female Total

5-11 months-10 years 1 2 3

11-20 years 11 15 26

21-30 years 7 8 15

31-40 years 7 11 18

41-50 years 18 33 51

51-60 years 33 41 74

61-70 years 24 30 54

71-80 years 11 26 37

81-87 years 2 1 3

Total 114 167 281

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Table 14. Enostosis

Age group Male Female Total

5-11 months-10 years 2 5 7

11-20 years 11 17 28

21-30 years 3 6 9

31-40 years 3 4 7

41-50 years 12 8 20

51-60 years 15 21 36

61-70 years 4 18 22

71-80 years 2 2 4

81-87 years 2 1 3

Total 54 82 136

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Table 15. Root fragments

Age group Male Female Total

5-11 months-10 years 0 1 1

11-20 years 12 17 29

21-30 years 4 6 10

31-40 years 3 2 5

41-50 years 2 4 6

51-60 years 10 11 21

61-70 years 7 9 16

71-80 years 7 5 12

81-87 years 0 0 0

Total 45 55 100

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Table 16. External resorption - physiological and pathological

Age group Male Female Total

5-11 months-10 years 2 4 6

11-20 years 9 11 20

21-30 years 5 3 8

31-40 years 3 1 4

41-50 years 2 1 3

51-60 years 1 0 1

61-70 years 0 0 0

71-80 years 0 0 0

81-87 years 0 0 0

Total 22 20 42

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Table 17. Restorative material in the apices of the teeth

Age group Male Female Total

5-11 months-10 years 0 0 0

11-20 years 2 1 3

21-30 years 4 0 4

31-40 years 2 2 4

41-50 years 4 6 10

51-60 years 7 13 20

61-70 years 3 11 14

71-80 years 0 3 3

81-87 years 0 1 1

Total 22 37 59

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Table 18. Impacted teeth not including third molars

Age group Male Female Total

5-11 months-10 years 5 8 13

11-20 years 19 24 43

21-30 years 3 2 5

31-40 years 0 0 0

41-50 years 1 1 2

51-60 years 1 0 1

61-70 years 0 1 1

71-80 years 0 1 1

81-87 years 0 0 0

Total 29 37 66

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Table 19. Graft material and sclerotic healing

Age group Male Female Total

5-11 months-10 years 0 0 0

11-20 years 1 2 3

21-30 years 2 4 6

31-40 years 5 7 12

41-50 years 7 11 18

51-60 years 13 25 38

61-70 years 4 19 23

71-80 years 2 3 5

81-87 years 1 2 3

Total 35 73 108

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Table 20. Mucositis/sinusitis/mucous retention pseudocyst

Age group Male Female Total

5-11 months-10 years 7 9 16

11-20 years 44 57 101

21-30 years 15 17 32

31-40 years 19 31 50

41-50 years 31 43 74

51-60 years 54 63 117

61-70 years 51 54 105

71-80 years 23 27 50

81-87 years 2 4 6

Total 246 305 551

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Table 21. Hypoplastic sinuses

Age group Male Female Total

5-11 months-10 years 1 1 2

11-20 years 3 3 6

21-30 years 1 3 4

31-40 years 0 1 1

41-50 years 2 2 4

51-60 years 1 1 2

61-70 years 0 2 2

71-80 years 0 0 0

81-87 years 0 0 0

Total 8 13 21

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Table 22. Surgical changes in the sinuses

Age group Male Female Total

5-11 months-10 years 0 0 0

11-20 years 0 0 0

21-30 years 0 1 1

31-40 years 2 3 5

41-50 years 3 5 8

51-60 years 5 5 10

61-70 years 3 1 4

71-80 years 0 1 1

81-87 years 0 0 0

Total 13 16 29

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Table 23. Osteoarthrosis of vertebrae

Age group Male Female Total

5-11 months-10 years 0 0 0

11-20 years 0 0 0

21-30 years 0 0 0

31-40 years 0 1 1

41-50 years 6 10 16

51-60 years 23 37 60

61-70 years 32 51 83

71-80 years 19 31 50

81-87 years 4 7 11

Total 84 137 221

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Table 24. Osteoarthrosis of TMJs

Age group Male Female Total

5-11 months-10 years 0 0 0

11-20 years 0 0 0

21-30 years 1 2 3

31-40 years 1 4 5

41-50 years 4 28 32

51-60 years 13 39 52

61-70 years 17 33 50

71-80 years 4 8 12

81-87 years 2 2 4

Total 42 116 158

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Table 25. Coronoid hyperplasia

Age group Male Female Total

5-11 months-10 years 0 0 0

11-20 years 2 3 5

21-30 years 1 1 2

31-40 years 1 1 2

41-50 years 2 1 3

51-60 years 1 1 2

61-70 years 1 2 3

71-80 years 0 0 0

81-87 years 0 0 0

Total 8 9 17

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Table 26. Carotid artery calcifications

Age group Male Female Total

5-11 months-10 years 0 0 0

11-20 years 0 0 0

21-30 years 0 0 0

31-40 years 0 0 0

41-50 years 1 1 2

51-60 years 9 8 17

61-70 years 11 13 24

71-80 years 5 6 11

81-87 years 2 1 3

Total 28 29 57

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Table 27. Pineal gland calcifications (physiologic)

Age group Male Female Total

5-11 months-10 years 0 0 0

11-20 years 3 9 12

21-30 years 2 4 6

31-40 years 2 7 9

41-50 years 6 13 19

51-60 years 11 24 35

61-70 years 13 23 36

71-80 years 5 22 27

81-87 years 1 2 3

Total 43 104 147

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Table 28. Tonsilliths

Age group Male Female Total

5-11 months-10 years 0 0 0

11-20 years 4 3 7

21-30 years 1 0 1

31-40 years 3 0 3

41-50 years 9 11 20

51-60 years 11 9 20

61-70 years 14 7 21

71-80 years 9 7 16

81-87 years 2 2 4

Total 53 39 92

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Table 29. Osteoma cutis

Age group Male Female Total

5-11 months-10 years 0 0 0

11-20 years 0 0 0

21-30 years 0 0 0

31-40 years 1 2 3

41-50 years 2 5 7

51-60 years 2 5 7

61-70 years 3 1 4

71-80 years 1 0 1

81-87 years 0 0 0

Total 9 13 22

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Table 30. Adenoidal hyperplasia

Age group Male Female Total

5-11 months-10 years 6 14 20

11-20 years 38 19 87

21-30 years 0 0 0

31-40 years 0 0 0

41-50 years 0 0 0

51-60 years 0 0 0

61-70 years 0 0 0

71-80 years 0 0 0

81-87 years 0 0 0

Total 44 63 107

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CHAPTER 4

DISCUSSION

CBCT image production

The basic components in CBCT image production are acquisition configuration,

image detection, image reconstruction and image display.

Acquisition configuration and setup

The subject is seated in the i-CAT CBCT unit with the head positioned between

the source of radiation and the receptor. Accurate positioning is achieved by aligning the

subject with red laser lines. A scout view is obtained making sure the subject’s head is in

the desired position. Once properly positioned, the patient is scanned. A single partial or

full rotation of the x-ray source takes place while a reciprocating area detector moves

synchronously with the source around a fixed point based on the subject’s alignment in

the unit. During this rotation of the unit, each projection image is made by a sequential

single image capture of the attenuated x-ray beam by the detector. In the newer

generation CBCT machines, pulsed x-ray beam exposures enable a marked reduction in

the patient dose.

The field of view that can be acquired varies (3cm-23 cm) with different units and

depends on detector size and shape, and ability to collimate the beam. Collimation of the

primary x-ray beam helps reduce the radiation dose to the patient. An extended field of

view may be achieved with one of the current units which uses two rotational scans to

produce a single volume with a 23cm height (iCAT new generation scanner).

During the process of the scan, single exposures are made at certain degree

intervals, producing the “raw,” “frame,” or “basis” images which are similar to lateral,

postero-anterior and angled cephalometric images. These are combined to produce a

single data volume. From the whole data set, referred to as the projection data, image

slice data sets are reconstructed. This data set is either fixed or variable and is based on

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the trajectory arch and number of rotations. The more images in the data set, the more

information is available for reconstruction. However, the greater the number of images

the more the radiation dose is increased.

Image detection

Image detectors in current units are one of the following: image intensifier tube/

charged-couple combination devices (IIT/CD), or flat-panel imagers. “The IIT/CCD

configuration comprises an x-ray IIT coupled to a CCD by way of a fiber optic coupling.

Flat-panel imaging consists of detection of x rays using an ‘indirect’’ detector based on a

large-area solid-state sensor panel coupled to an x-ray scintillator layer. Flat-panel

detector arrays provide a greater dynamic range and greater performance than the II/CCD

technology. Image intensifiers may create geometric distortions that must be addressed in

the data processing software, whereas flat-panel detectors do not suffer from this

problem. This disadvantage could potentially reduce the measurement accuracy of CBCT

units using this configuration. IIT/CCD systems also introduce additional artifacts”.

The image detector in the current i-CAT machine is an amorphous silicon flat

panel imager. The dimension of this detector is 20cm X 25cm.

Image reconstruction

After the raw data has been acquired and the data set has been obtained, the

images are reconstructed. Depending on the specific unit, the data set may contain

anywhere from 100 to 650 raw images. The reconstruction process usually takes from

less than a minute to about six minutes. The time is based on the acquisition parameters

(voxel size, field of view and number of projections), hardware (processing speed of the

computers used) and software (reconstruction algorithms).

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Image display

The reconstructed data can be presented in various planes including multi-planar

images (in many orientations such as, but not limited to, axial (Figure 1), coronal (Figure

2) and sagittal (Figure 3)), panoramic (Figure 4), orthoradial (Figure 5) and tangential

views. These are the basic views found in almost all CBCTs but, depending on the

software, additional views can be made of the region of interest. Some of the other

common images that may be obtained from the CBCT volume are 3D reconstructions and

maximum intensity projections.

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Figure 1. An axial view through the body of the mandible (M).

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Figure 2. A coronal view of the skull, showing the maxillary sinuses (A), orbits (B), nasal conchae (C) and mandible (D) at approximately the depth of the premolars.

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Figure 3. A sagittal view of the facial region and the cervical vertebrae (A) near the midline showing Sphenoid Sinus (SS), Ethmoid air cells (EAC), Inferior(I) and Middle (M) Conchae and hard palate (H) and mandible(Ma) .

The slice thickness for axial, coronal and sagittal views can vary from 0.125mm

to .4mm. The thickness most often used is .3mm. Because the voxels from which these

images are reconstructed are isotropic in the current generation of CBCT units, that is, all

three sides are equal, the images can be created in any plane in the data volume,

depending upon the software.

Also, depending upon the CBCT software, a panoramic image can be obtained

from the CBCT data set, either by the software itself, or by the operator plotting along the

arch of the mandible and/or maxillae and then reconstructing the image along the plotted

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curve. The slice thickness of this image is selected to ensure that that it covers the width

of the corresponding jaw bone.

Figure 4. Example of a panoramic image.

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Orthoradial images are reconstructed at right angles (orthogonally) to the line of

the panoramic view.

Figure 5. Orthoradial images in the maxillary anterior region.

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A three dimensional rendering of the volume can be obtained by using algorithms

based on the inherent windows and leveling of different structures in the CBCT volume.

Figure 6. A 3D reconstruction showing the osseous structures of the middle and lower face, as well as the cervical vertebrae.

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A maximum intensity projection, one that shows the structure with the most

attenuation in the selected direction, is obtained from algorithms based on the attenuation

co-efficient of the structures in the CBCT volume.

Figure 7. A maximum intensity projection in the panoramic mode.

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Findings inside/outside the areas of interest

Periapical/parapical/peridental findings in the subjects

Cementoblastoma

A cementoblastoma is a slow-growing odontogenic neoplasm composed

primarily of cementum-like tissue. Found predominantly in the

mandible,cementoblastomas are seen as bulbous attachments to the resorbed roots of

premolars or molars. Pain and swelling may be associated with two thirds of the

cementoblastomas.

Radiographically the cementoblastoma appears as a radiopaque mass that is fused

to the resorbed roots of a tooth and is surrounded by a thin radiolucent line which in turn,

is surrounded by a thin radiopaque line. This is a relatively rare benign neoplasm.

Figure 8. A panoramic image showing a cementoblastoma (C) attached to the root of the mandibular right first premolar.

A cementoblastoma was found in 4 subjects. The relatively high prevalence in

this study was probably a referral phenomenon. That is, there was evidence of such an

entity on plain film radiographs and the subjects were referred for a CBCT.

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Rarefying osteitis and sclerosing osteitis

Periapical inflammatory lesions often result in a local reaction in the bone

surrounding the tooth with necrotic pulp, and are thought to be in reaction to the release

of cellular breakdown products from these pulps.

Rarefying osteitis

When the inflammatory reaction described above is acute, there is often removal

of the bone of the lamina dura of the alveolus and the surrounding trabecular bone. The

radiographic features vary depending on the nature and duration of the lesion. An early

lesion may not show any radiographic features or may show slight increase in the width

of the periodontal ligament space at the apex of the tooth. After one or two weeks there is

destruction of the lamina dura and removal of the surrounding bone, seen as a radiolucent

area around the apex of a tooth. This is referred to radiologically as rarefying osteitis.

The term rarefying osteitis encompasses three entities: abscess, cyst and/or

granuloma. It is often not possible to differentiate one entity from the other radiologically

because of the similarity in the radiographic features.

Rarefying osteitis or radiolucent healing post endodontic treatment was found in

the apex of at least one tooth in 281 subjects. (114 males and 167 females)

At times the inflammatory process takes on a specific appearance. The shape

becomes more circular, referred to a hydraulic appearance, and there is development of a

thin radiopaque border. At this point the appearance is consistent with a cyst (a

pathologic cavity lined by epithelium containing a fluid, a semi-fluid or a semisolid).

Radicular cyst

When a cyst is associated with the root, it is referred to as a radicular cyst. The

radicular cyst is the most common cyst in the jaws. It arises in response to non-vital pulp,

like the more generic rarefying osteitis. The cyst epithelium originates from the rests of

epithelial cells in the periodontal ligament which are stimulated by the breakdown

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products from the non-vital pulp. The cells then proliferate and undergo cystic

degeneration.

Radiographically, a radicular cyst may have a well-defined corticated border and

a hydraulic appearance. The radicular cyst is most often associated with roots of a

cariously broken down tooth. If a radicular cyst becomes secondarily infected, the intact

cortical borders may be lost.

Considering the range of entities rarefying osteitis encompasses, and the number

of teeth it may affect, it is difficult to determine the exact prevalence of these findings in

the literature, but it is common.

Figure 9. A panoramic image showing rarefying osteitis(R) in the periapical regions of the mandibular right first molar and external resorption(X) of the tooth.

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Figure 10. A coronal view showing rarefying osteitis(R) with external resorption(X) and a draining sinus tract (ST).

Sclerosing osteitis

Sclerosing osteitis refers to an inflammatory process, most often periapical,

wherein the primary reaction of bone is the deposition of more bone, rather than removal

as with rarefying osteitis. It is seen in the presence of low-grade inflammation, most often

chronic.

Radiographically, sclerosing osteitis usually manifests as an area of bone

deposition around the apex of a tooth with a non-vital pulp. This area may present as a

completely sclerotic (osseous) area or be seen around the margins of an area of rarefying

osteitis. In the current study, if both rarefying osteitis and sclerosing osteitis were present

it was included under rarefying osteitis.

Sclerosing osteitis was found at the apex of at least one tooth in 17 subjects (6

males and 11 females). There is no literature showing the exact prevalence of sclerosing

osteitis.

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Hypercementosis

Hypercementosis is defined as excess deposition of cementum on the roots of

teeth.

The radiographic appearance of a tooth with hypercementosis is that of an

enlarged root. Idiopathic hypercementosis is bordered by a thin radiolucent line (the

periodontal ligament space) which, in turn, is surrounded by a thin radiopaque line (intact

lamina dura). Hypercementosis may be isolated or may be generalized. The frequency of

this entity increases with age. Paget disease of bone can have multiple teeth with

hypercementosis. Hypercementosis can also be seen in association with chronic

inflammation in the periapical regions of a tooth. In such cases, the periodontal ligament

space and the lamina dura are absent, as with rarefying osteitis.

Figure 11. A panoramic image showing hypercementosis (H) on the maxillary left third molar and possibly the maxillary right third molar.

Hypercementosis was found in at least one tooth in 13 subjects. (5 males and 8

females)

The exact prevalence of hypercementosis is not clear in the literature.

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Enostosis

Enostosis is a small dense bone island within the normal bone, or a projection,

like a peninsula, from the inner surface of the cortex. The latter is the internal counterpart

of exostosis.

Figure 12. A panoramic image showing enostosis (E) in the bone in the periapical regions of the maxillary left premolars.

Alveolo-osseous induction effect

Alveolo-osseous induction effect appears as an area of increased bone along the

inner (osseous) surface of the lamina dura of the root of a tooth. This entity, idiopathic

bone deposition, is thought to be the result of stimulation of osteoblasts from the

periodontal ligament.

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Figure 13. A panoramic image showing alveolo-osseous induction effect (A) in periapical regions of the mandibular right second molar.

Osteosclerosis Osteosclerosis is an increased deposition of the bone as a result of excessive

osteoblastic activity in the area probably as a result of inflammation in the area. It is

commonly associated with the resorbed roots of heavily restored mandibular premolars

and molars. There is bone deposition to such an extent that the bone marrow spaces are a

fraction of what they are in normal bone.

Figure 14. A panoramic image showing osteosclerosis (O) in the periapical regions of the mandibular right first molar.

It is not always possible to differentiate enostosis, alveolo-osseous induction

effect or osteosclerosis from each other. These entities do not require any treatment.

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At least one area of enostosis was found in 136 subjects. (54 males and 82

females). Alveolo-osseous induction effect was found associated with a root of a tooth in

eight subjects. Osteosclerosis was found in five subjects (2 males and 3 females). No

exact prevalence rates are noted for these radiopaque entities in the jaws in the literature.

Although these entities appear to show a relatively high prevalence rate it may be due to

the ability to visualize these entities better on CBCT scans when compared to traditional

radiographs.

Root fragments

Root fragments are often found in radiographs of the jaws. A root fragment may

be either from a deciduous tooth which has not completely resorbed, which is most often

seen in the premolar regions of the mandible, or a permanent tooth as the remains of a

cariously broken down tooth or from an incomplete extraction.

Figure 15. A panoramic image showing multiple retained root fragments in the maxillae and one in the mandible

It is important to recognize the presence of root fragments as they may interfere

with implant placement.

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A retained root fragment (deciduous and/or permanent) was found in at least one

area in 100 subjects (45 males and 55 females). No exact prevalence rates are noted for

the presence of root fragments in the literature.

External resorption

External resorption is the removal of a tooth surface from the external aspect and

it may be either pathologic or physiologic. External resorption is often seen as an

incidental finding and the etiology is unknown. In some cases it is associated with an

inflammatory periapical lesion or due to pressure from an impacted tooth, neoplasm or

cyst.

Figure 16. A panoramic image showing external resorption (X) of the maxillary incisors and the mandibular incisors

External resorption was found in at least one tooth in 42 subjects (22 Males and

20 Females) and was physiologic in 30 cases and pathologic in 12. In the latter it was

associated with a dentigerous cyst in one subject, a giant cell lesion in one subject and

associated with rarefying osteitis in 10 subjects. The prevalence of external resorption in

teeth in this study is 4.2% and in other studies it about 3.7%4,5,6.

Dentigerous cyst

A dentigerous cyst is an odontogenic cyst that forms around the coronal portion of

an impacted/unerupted tooth.

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As with any classic cyst, the radiographic features of this entity include a well-

defined radiolucent area with thin corticated borders. As stated above, it is around all or

part of an impacted/unerupted tooth and does not extend apically beyond the cemento-

enamel junction. It may cause expansion of bone.

Figure 17. A panoramic image showing a dentigerous cyst (D) associated with the impacted mandibular left third molar (T).

Dentigerous cysts were found associated with one tooth in six subjects (4 males

and 2 females) and with two different teeth in one subject (1 male). The prevalence of

dentigerous cyst in this study is 0.6% and in another study it is 0.14%7.

Residual cyst

A residual cyst is a cyst that remains after removal of the associated tooth, most

often a radicular or a dentigerous cyst.

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Figure 18. Orthoradial slices showing a residual cyst (RC) in the maxillary left central incisor region.

Radiographically a residual cyst usually appears as a well defined hydraulic

radiolucent area with corticated borders in an area where there was a tooth present

previously.

A residual cyst was found in one area in seven subjects (3 males and 4 females).

The prevalence of radicular cysts in this study is 0.7%.

Odontogenic Keratocyst

Odontogenic keratocyst (OKC) also known as keratocystic odontogenic tumor is,

as its name implies is another distinctive form of odontogenic cysts. This cystic lesion is

now classified as a neoplasm on the basis of its tumor like characteristics. Odontogenic

keratocysts are found from infancy to old age. A small odontogenic keratocyst is usually

found as an incidental finding on radiographs made for other purposes. Although an

odontogenic keratocyst can occur almost anywhere in the jaws, it most often found in the

posterior body and the rami of the mandible.

Radiographically, an odontogenic keratocyst is a well defined radiolucent entity

with corticated borders. The lesion may be unilocular or the borders may be scalloped,

giving the cyst a multilocular appearance. It usually grows along the long axis of the

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mandible causing minimal expansion. Multiple odontogenic keratocysts may be found in

patients with nevoid basal cell carcinoma syndrome.

Figure 19. A panoramic image showing multiple odontogenic keratocysts (OKC),a microdont (Mi), taurodonts(T) and impacted teeth(I) in a patient with nevoid basal cell carcinoma syndrome.

At least one odontogenic keratocyst was found in four subjects (2 males and 2

females). One subject was confirmed to have nevoid basal cell carcinoma syndrome. The

nevoid basal cell carcinoma syndrome has a prevalence of 1 in 57000 to 1/2560008,9,10

and odontogenic keratocysts account for 17% of all cysts submitted for histopathological

analysis.

Simple bone cyst

A simple bone cyst is a cavity within bone lined by connective tissue, which may

be empty or may contain some fluid. A simple bone cyst is more commonly found in the

mandible but it can also develop in the maxilla.

Radiographically, a simple bone cyst has well defined to ill defined delicate

cortical borders that blend into the surrounding bone. The entity in many cases appears

to evaginate between the roots of the teeth without causing any effect on the teeth. It

usually grows along the long axis of the bone causing minimal to no expansion of the

bone, but in some cases it may cause marked expansion.

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Figure 20. A panoramic image showing a simple bone cyst (SBC) in the left side body of the mandible.

A simple bone cyst was found in seven subjects (3 males and 4 females). There is

no exact prevalence data for this condition. However, it is found in the age group of 6-45

years (mean 26.5 years)11.

Nasopalatine canal cyst

The nasopalatine canal cyst is a non odontogenic cyst found in the nasopalatine

canal. The nasopalatine canal cyst accounts for about 10 percent of the jaw cysts

submitted for histopathological analysis. A nasopalatine canal cyst, which is usually

asymptomatic is often found as an incidental finding on radiographs made for other

purposes. Occasionally, the patient may have a swelling which is -defined and is

posterior to the incisive papilla region.

Radiographically a nasopalatine canal cyst has a well-defined corticated border

and is circular or oval in shape. The border may not be seen on the superior and inferior

aspects. The entity should be greater than 10mm in its horizontal dimension to be

considered as a cyst.

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Figure 21. A coronal image showing a nasopalatine canal cyst (N) with minimal evidence of inferior (I) or superior (S) borders.

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Figure 22. A sagittal image showing the same nasopalatine canal cyst (N) with minimal evidence of inferior or superior borders.

A nasopalatine canal cyst was found in three subjects (3 males). The prevalence

of nasopalatine canal cyst is about 1percent of all cysts sent for histopathological

analysis12.

Reactive hyperplastic osteitis

Occasionally under fixed prosthodontic appliances in the jaws, there is increased

bone deposition due to the constant stimulation of the bone by the appliance which is

referred to as reactive hyperplastic osteitis.

Radiographically, reactive hyperplastic osteitis is seen as a radiopaque area

having a normal bone pattern or bone deposited in layers under the prosthodontic

appliance.

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Figure 23. A panoramic image showing reactive hyperplastic osteitis (O) under the bridge in the mandibular left first molar region.

Reactive hyperplastic osteitis was found in two subjects (2 females).

Oroantral fistulas

An oroantral fistula is a communication between the oral cavity and the maxillary

sinus. Radiographically this condition is seen as discontinuity in the floor of the maxillary

sinus, usually with associated sinusitis.

Such a discontinuity was found in 14 subjects (6 males and 8 females).

A clinical examination was recommended to evaluate for the presence of

discontinuity in these subjects.

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Figure 24. A sagittal image shows an oroantral fistula (O) in the floor of the right maxillary sinus which has sinusitis (S).

Restorative material in the apical regions of teeth

Restorative material (endodontic restorative material and amalgam fragments)

was found in at least one region at least in 59 subjects (22 males and 37 females).

Figure 25. A sagittal image showing restorative material (RM) extruded into the periapical regions of the maxillary right canine.

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Cemento-osseous dysplasia

Cemento-osseous dysplasia is a bone dysplasia arising from localized changes in

the normal bone turnover which results in replacement of normal bone with fibrous and

cementum-like tissue. This condition typically occurs in middle-aged African American

females.

Radiographically, the periapical form of cemento-osseous dysplasia is seen as a

radiolucent area in the periapical regions of teeth with well-defined borders but the area

may be irregularly shaped. Depending on the stage of dysplasia, it may have variations in

the amount of radiopaque structures (cemento-osseous components) within the

radiolucent area. This entity may cause expansion of bone and may displace adjacent

structures if it is large. It is not always possible to differentiate this entity from rarefying

osteitis radiographically in the radiolucent stage of the condition. The vitality of the pulp

is not related to this condition. Based on its location and size it has been sub-classified

into periapical, florid and focal cemento-osseous dysplasia, which share similar

radiographic features.

Figure 26. Florid cemento-osseous dysplasia is seen in the periapical regions of most of the teeth in the maxillae and the mandible on this panoramic image.

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Cemento-osseous dysplasia was found in at least one area in 10 subjects (1 male

and 9 females). Of these, seven were of the florid type. The age group in which this

condition was found was consistent with that in the literature in that most of them are

incidentally found in black females in the age group of 30 to 50 years.

Giant cell lesion

A giant cell lesion is thought to be a reactive lesion of unknown origin. This entity

is typically seen in people under the age of 20 and most often in the mandible. The entity

usually manifests as a painless swelling which may be tender to palpation. This entity is

slow growing.

Radiographically, a giant cell lesion shows well-defined margins with no

cortication. The internal structure may show thin wispy septae that are at right angles to

the periphery of the lesion. Occasionally there may be calcification within this lesion. At

times the presence of septae and the scalloped margins gives it a multilocular appearance.

Figure 27. A panoramic image showing a giant cell lesion (GCL) in the left side of the mandible. There is resorption of the premolars and the molars and the mandibular left third molar is displaced.

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Figure 28. The same giant cell lesion (GCL) in the left side of the mandible with a break in the cortex due to a biopsy (B) in the area seen on this coronal image.

A giant cell lesion was found in one subject (1 male).

Impacted teeth

A tooth which fails to erupt into the oral cavity at the appropriate chronological

age is said to be impacted. Sixty six subjects (29 males and 37 females) had at least one

impacted tooth other than the third molars.

Figure 29. The permanent maxillary canines (IC) are impacted in this 36-year-old female can be seen on this panoramic image.

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Graft material and sclerotic healing

Graft material can be placed to enhance the quantity of bone in the area in patients

who would wish to have implants but have insufficient bone.

Radiographically graft material can be seen as a radiopaque area with excess bone

not expected to be otherwise present. Correlation with history would always confirm the

same.

Figure 30. This coronal image shows graft material (GM) in the left maxillary alveolar ridge and the floor of the left maxillary sinus.

One hundred and eight subjects (35 males and 73 females) had either graft

material or sclerotic healing in areas of extracted teeth. It was not always possible to tell

these entities apart.

Two subjects (2 females) had a chin graft for cosmetic purposes which were

incidental findings. One male subject had a mandible replaced by a rib graft.

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Figure 31. A chin graft (CG) with a pin is seen on this sagittal image.

Pathosis/anatomical variants in the paranasal sinuses

The most common incidental findings seen in 605 subjects (268 males and 337

females) were mucosal thickening which included sinusitis or mucositis in one of the

paranasal sinuses, surgical changes in the walls of the maxilla, polyps and mucous

retention pseudocysts. In 548 subjects these were incidental findings, the subjects were

not scanned specifically for any pathosis of the sinuses.

Mucositis

The mucosa lining the sinus can become inflamed, from either an infectious or

allergic process and becomes thickened 10 to 15 times. This may be seen on radiographs

and is referred to mucositis.

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Figure 32. Mucositis (M) in the maxillary sinuses seen on this coronal image.

Sinusitis

Sinusitis is defined as generalized inflammation of the mucosa of a paranasal

sinus that may be caused by allergens or a bacterial infection. When all, or most of, the

sinuses are involved, it is called pansinusitis.

Figure 33. Sinusitis (S) in the maxillary sinuses and the ethmoidal air cells seen on this coronal image. Subject had pansinusitis.

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Polyps

The thickened mucous membrane of a chronically inflamed sinus frequently

forms into irregular folds called polyps.

Figure 34. A coronal image showing polyps (P) in the maxillary sinuses.

Surgical changes in the sinuses and adjacent structures

Surgical changes, as the name implies, are those changes where there has been an

alteration in the paranasal sinuses due to previous surgery.

Figure 35. A coronal image showing surgical (S) changes, that is absence of part of the walls of the sinuses and the conchae.

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Surgical changes were found as incidental findings in 29 subjects (13 males and

16 females).

Hypoplastic sinuses

When a sinus is not as well-aerated as expected, the sinus is referred to as

hypoplastic.

At least one of the paranasal sinuses was hypoplastic in 21 subjects (8 males and

13 females).

Figure 36. Both the maxillary sinuses (MS) in this coronal image are hypoplastic.

Osteoma

An osteoma is a benign neoplasm of the bone. It can form from membranous

bones of the skull. Osteomas can be single or multiple. An osteoma originates from the

periosteum and may occur either outside, of or within, the paranasal sinuses. It is more

common in the frontal sinuses and ethmoidal air cells.

Radiographically, an osteoma is seen as a well-defined uniform radiopaque entity

with evidence of trabeculae.

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Figure 37. An osteoma (O) can be seen on this coronal image in the right frontal sinus.

Figure 38. An osteoma (O) in the right ethmoidal air cell is seen in this coronal image.

An osteoma was found in four subjects (3 males and 1 female). Of these, three

were in the ethmoid sinuses and one was in the frontal sinus.

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Table 31. Findings in paranasal sinuses.

Findings in paranasal

sinuses in subjects

Males (268) Females (337)

Mucositis/sinusitis/mucous

retention pseudocyst

246 305

Hypoplastic sinuses 8 13

Surgical changes 13 16

Osteoma 1 3

Findings in the cervical vertebrae region:

Degenerative joint disease in cervical vertebrae

Degenerative joint disease (osteoarthrosis) is a common finding in older patients.

Degenerative joint disease (DJD) is a noninfectious progressive disorder and is an

aging process.

In DJD there is usually wear and tear of articular cartilages accompanied by an

overgrowth of bone (osteophytes), narrowing of the joint spaces, sclerosis or hardening of

bone at the joint surface, and deformity in joints.

Degenerative joint disease in the cervical vertebrae in subjects above 50 years of

age was common and was found in 221 subjects (84 Males and 137 Females) of 507

subjects and in 17 subjects (6 Males and 11 Females) below the age of 50 years of age of

493 subjects. Findings included small subchondral cysts in the vertebrae, osteophyte

formation, marked reduction of disc space and osteoporotic bone marrow defects.

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Table 32. Degenerative joint disease in the cervical vertebrae.

Age group of patients Male Female

Age > 50 years 84 137

Age < 50 years 6 13

Figure 39. Degenerative disease (OA) with anterior and posterior osteophyte formation is seen on this sagittal image.

Screws in cervical vertebrae

Osseous screws are sometimes placed in the vertebrae. These are seen as

incidental findings on CBCTs made for other purposes.

A screw in the cervical vertebrae was found in three subjects (1 male and 2

females).

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Figure 40. A sagittal image showing an osseous screw (OS) in the body of the fourth cervical vertebrae (V).

Fusion of C2-3 cervical vertebrae

Fusion in the cervical vertebrae is when two vertebrae previously not continuous

have joined either partially or completely.

Cervical vertebrae C2-3 was partially fused (post surgery from history) in one

subject (1 male).

Figure 41. Partial fusion (PF) of the C2-3 cervical vertebrae is seen on these coronal and sagittal images.

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Nonsegmentatation of vertebrae

Nonsegmentation is the failure of two vertebrae to separate completely during the

process of development. It is most commonly seen between the second and third cervical

vertebrae but it can occur between any vertebrae. It may be complete or partial.

Figure 42. Partial nonsegmentation (NS) of C3-4 cervical vertebrae seen on this sagittal image.

Partial nonsegmentation was found in one subject (1 male).

Findings in the TMJ regions/associated structures

Osteoarthrosis in the osseous components of the TMJ

Degenerative changes were found in the osseous components of the TMJs in 152

of subjects ( 40 males and 112 females) scanned for reasons not related to TMJ joint

disorders and in six subjects (2 males and 4 females) of 11 in whom the areas of interest

were the temporomandibular joints.

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Figure 43. There is bilateral osteoarthrosis (OA) with reduction of disc space on the left side and hypoplastic condyle on the right side on this coronal view.

Table 33. Degenerative joint disease in the osseous components of the TMJs.

Area of interest Male Female

Outside area of interest 40 112

The area of interest 2 4

Coronoid hyperplasia

Coronoid process hyperplasia is the elongation of the coronoid process which can

be either acquired or developmental. The developmental variant is typically bilateral

whereas the acquired type is usually unilateral, but can also be bilateral and can result in

false ankylosis.

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Figure 44. A hyperplastic coronoid process(H) is seen on this sagittal view.

To be considered hyperplastic, the coronoid process should be at least 1 cm above

the inferior rim of the zygomatic arch.

Coronoid hyperplasia was seen in 17 subjects (males and females) of whom only

one subject was requested to be scanned for a TMJ assessment as he had trismus.

Condylar hyperplasia

Condylar hyperplasia is a developmental abnormality that results in an

enlargement and occasionally, a deformity of the condylar head. This may result in a

secondary effect on the glenoid fossa to accommodate the large condylar head. There

may be mandibular asymmetry associated with condylar hyperplasia.

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Figure 45. The right condyle (CH) is markedly hyperplastic compared to the left in this coronal image.

Condylar hyperplasia was seen in three subjects (1 male and 2 females) of whom

two subjects were primarily scanned for TMJ assessments.

Condylar hypoplasia

Condylar hypoplasia is the failure of the condyle to attain its normal size because

of developmental alterations or acquired conditions that may result in altered growth of

the condyle. The condyle is small but normal in morphology.

Figure 46. Hypoplastic condyles (HC) are seen bilaterally on this coronal view.

Condylar hypoplasia was seen in two subjects (2 males) as an incidental finding.

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Calcifications found in the volume

Calcifications in blood vessels

Calcifications in the blood vessels can be due to arteriosclerosis or calcified

atherosclerotic plaque. In arteriosclerosis there is fragmentation, degeneration, and

eventual loss of elastic fibers, followed by deposition of calcium within the medial layer

of the blood vessel. Radiographically, arteriosclerosis is seen as calcific deposits along

the outline of the artery. Atherosclerotic plaque is the dystrophic calcification that occurs

within the inner layer of the blood vessel. Radiographically, calcified atherosclerotic

plaque is seen as multiple and irregularly shaped calcifications that may be vertical in

orientation and can be easily distinguished from the adjacent soft tissue. It is important to

recognize these entities on radiographs as they can significantly increase the patient’s

morbidity and mortality13.

Carotid artery calcifications

Carotid artery calcifications were found in 57 of the 504 patients above the age of

40 (28 males and 29 females). The ability to recognize these calcifications is far superior

on CBCT when compared to a similar study on pantomographs designed to visualize

these calcifications in the carotid artery14. This points out that great care must be taken

during the interpretation of CBCT scans to ensure that these calcifications are recognized

as they may significantly increase patient morbidity and mortality. There may have been

a greater percentage of subjects with carotid artery calcifications than found in this study

as, in many subjects, the entire carotid artery regions may not have been inside the

volume. These calcifications must also be differentiated from other structures, such as

triticeal cartilage and the superior horn of the thyroid cartilage, which may also undergo

calcification and ossification.

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Figure 47. Carotid artery calcifications (CAC) are seen bilaterally on this axial image.

Vertebral artery calcification

Occasionally there may be calcifications in the vertebral artery. It is important to

recognize these entities on CBCT images as the presence of these entities may increase

patient mortality and morbidity 13. Vertebral artery calcification was found in one subject

(1 female).

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Figure 48. A calcification in the left vertebral artery (VAC) at the C3-4 level is seen on this coronal image.

Pineal gland calcifications

The pineal glands show propensity to undergo calcification physiologically with

increase in age. Physiologic calcifications of the pineal gland are manifested on

radiographs as small radiopaque entities in the region of the pineal gland.

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Figure 49. Pineal gland calcification (P) seen in the midline on this axial image.

Pineal gland calcifications were seen as incidental findings in 147 subjects (43

males and 104 females). However, this is not representative of the prevalence of pineal

gland calcification in the population as many times the field of view did not cover the

area of the pineal gland. The overall prevalence rate of pineal gland calcifications is

20%15 and about 46% in patients over the age of 40.

Tonsilliths

Tonsilliths are calcifications in the regions of the tonsils. Tonsilliths are seen on

radiographs as radiopaque entities in the regions of the tonsils. Tonsilliths were found in

92 subjects (53 males and 39 females), which correspond to the study which showed a

prevalence rate of approximately 10.3 percent on pantomographs carried out at the

University of Iowa, College of Dentistry16.

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Figure 50. Tonsilliths (T) are seen in the region of the tonsils on this coronal image.

Sialoliths

Sialoliths are calcifications in the salivary glands and associated ducts. They may

be symptomatic with swelling in the glands causing pain before meal times, due to the

inhibited saliva flow or they may be asymptomatic. Although they may be seen as

radiopaque masses in any of the salivary glands, they are most commonly found in the

submandibular salivary gland or duct. Sialoliths are seen as radiopaque entities in the

region of the salivary glands or their associated ducts.

A sialolith was found in four subjects (1 male and 3 females). All sialoliths were

associated with the submandibular salivary glands. All sialoliths found in this study were

incidental findings.

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Figure 51. A sialolith (S) is seen in the Warton’s duct on this axial image.

Dystrophic calcifications

Dystrophic calcifications are calcifications occurring in degenerated or necrotic

tissues.

Dystrophic calcifications were found in 7 subjects (3 males and 4 females). This

does not include osteoma cutis.

Table 34. Dystrophic calcifications.

Regions showing

dystrophic calcifications

Males Females

Adenoids 1 1

Epiglottis 1 1

Temporal regions 1 2

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Figure 52. A calcification is seen in the region of the adenoids (CA) region in this image.

Figure 53. A calcification in the epiglottis region (CE) is seen on this sagittal image.

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Figure 54. A calcification in the temporal region (CT) seen on this axial image.

Other findings

Osteopenia

Osteopenia is a condition where bone mineral density is lower than normal.

Osteopenia occurs more frequently in post-menopausal women as a result of the loss of

estrogen. It can also be exacerbated by lifestyle factors such as lack of exercise, excess

consumption of alcohol, smoking or prolonged use of glucocorticoid medications. It is

also associated with normal aging.

Although CBCT scans are not ideal for measuring bone mineral density, it was

very clear that four subjects had marked osteopenia (1 male and 3 females).

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Figure 55. Generalized osteopenia is seen on this sagittal image.

Osteomyelitis, radioosteonecrosis and chemoosteonecrosis

Osteomyelitis is inflammation of the bone, usually due to non-localized infection.

The inflammatory process may spread through bone to involve bone marrow, cortical and

cancellous bone and the periosteum.

Radiographically, it can manifest as loss of the normal trabeculation and bone

destruction resulting in mixed radiopaque radiolucent areas scattered throughout affected

area. Sequestra, which are areas of dead bone may be present. These appear as

radiopaque areas separated from the normal bone.

Radiographically, osteomyelitis can be difficult to distinguish from

radioosteonecrosis and chemoosteonecrosis in the absence of relevant clinical history.

Osteomyelitis was found in two subjects (1 male and 1 female).

Radioosteonecrosis was found in one subject (1 female).

Chemoosteonecrosis was found in one subject (1 female).

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Figure 56. Osteomyelitis (OM) can be seen on this axial image in the right side of the mandible. There is an ossifying periosteal reaction (PR) on the lingual side.

Figure 57. Radioosteonecrosis (RON) and post surgical changes (S) are seen on this panoramic image.

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Figure 58. Chemoosteonecrosis (CN) seen on an axial image on the right side of the mandible.

Amelogenesis imperfecta

Amelogenesis imperfecta is a genetic anomaly arising from mutations that may

affect one of the genes that play a role in enamel formation. Amelogenesis imperfecta can

be of four major types and there are at least 14 variants of the condition.

Figure 59. A panoramic image shows a hypomineralized form of amelogenesis imperfecta.

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Amelogenesis imperfecta was found in one subject (1 male). The original study

by Witkop et al17, based on a sample of 64,000 children from the State of Michigan,

reported that ‘‘enamel defects loosely classified as amelogenesis imperfecta occurred

once in 12,000 to 14,000’’ or 0.07 to 0.08 per 1,000. Two large Swedish

epidemiological1819 studies reported prevalence rates ranging from 0.025% to 0.14%. The

prevalence of one case found in this survey corresponds to the literature published18,19.

Dentin dysplasia

Dentin dysplasia is a developmental abnormality of the dentin. Four forms of type

I Dentin dysplasia and one form on type II20dentin dysplasia have been described. In type

I, the roots are short or abnormally shaped and the pulp chambers have demilune or

chevron symbol shape. The pulp chambers are obliterated. In type II, the roots are normal

but the crowns show obliteration of the pulp chambers.

Figure 60. Dentin dysplasia can be seen on this panoramic image.

In 2 subjects (1 male and 1 female) dentin dysplasia was found.

Dentinogenesis imperfecta with osteogenesis imperfecta

Dentinogenesis imperfecta is a genetic abnormality primarily involving the

dentin. Three types of dentinogenesis imperfecta are known to exist.

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In type I, the classical features are bulbous crowns with constriction of the teeth at

the cemento-enamel junction, short roots, reduced size of the pulp chamber and root

canals. In type II, the teeth have normal enamel thickness in association with extremely

thin dentin and enlarged pulps. The thin dentin may involve the entire tooth or be isolated

to the root. These teeth are referred to as “shell teeth”. The third type is a variant of the

type II and may have enlarged pulp chambers and was seen in the large Maryland

Brandywine isolate. Skeletal abnormalities may be associated with dentinogenesis

imperfecta.

Figure 61. Dentinogenesis imperfecta seen on this panoramic image in a subject with osteogenesis imperfecta.

Dentinogenesis imperfecta was found in one subject (1 female). From the history,

it was verified that the subject also had osteogenesis imperfecta.

Dentinogenesis imperfecta is reported to have a prevalence of 1 in 6,000 to 1 in

8,000, whereas dentin dysplasia has a prevalence of 1 in 10000021. Two cases of dentin

dysplasia and one case of dentinogenesis imperfecta with osteogenesis imperfecta were

found in this survey. The subject with dentinogenesis imperfecta and osteogenesis

imperfecta was sent in for bone evaluation for implants. Of the two subjects with dentin

dysplasia one was sent for evaluation of the disease and other was an incidental finding.

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Taurodontism

Taurodontism is a condition found in teeth where the body of the tooth and the

pulp chamber are enlarged. As a result, the floor of the pulp chamber and the furcation of

the tooth are moved. Taurodont teeth bodies appear elongated and the roots appear short.

Figure 62. Taurodonts, multiple odontogenic keratocysts, microdonts and impacted teeth in a patient with nevoid basal cell carcinoma syndrome are seen on a panoramic image .

Taurodontism was found in one subject in multiple teeth (1 Male). Taurodontism

is reported to have a prevalence ranging from 4 -18 percent22, 23. The prevalence rate was

markedly lower in this study because, during the interpretation, unless the condition was

an obvious case of taurodontism, as found in the one patient it was not noted.

Supernumerary teeth

Supernumerary teeth are those teeth that develop in addition to the normal

complement of teeth. When supernumerary teeth have normal morphologic features of

other teeth in the same area they are referred to as supplemental teeth.

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Figure 63. A 3D reconstruction shows a mesiodens and an impacted maxillary right central incisor.

At least one supernumerary tooth was found in 31 subjects (19 males and 12

females). The prevalence of supernumerary teeth varies from 1-3% in most populations24.

The findings in this study correspond to a three percent incidence in supernumerary teeth.

They were found twice as often in males, which correspond to findings in the literature24.

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Figure 64. A mesiodens (MD) is seen on this sagittal image on the palatal aspect of the central incisor.

Figure 65. A distodens (DD) distal to the maxillary left third molar is seen on this panoramic image.

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Figure 66. Peridentes (PD) are seen bilaterally in the mandible and in the left maxilla on this coronal image.

Oligodontia

The developmental absence of teeth is referred to as oligodontia. A tooth is

considered to be developmentally missing when there is no history of either its presence

or extraction.

In 38 subjects (16 males and 22 females) there was definite history and\or

evidence of at least one tooth being developmentally missing.

Oligodontia is one of the most common developmental abnormalities with a

reported prevalence rate of 3.5 to 8.0% wherein at least one tooth was developmentally

missing, excluding third molars25. However, it should be noted that in many subjects, it

was not possible to determine if the teeth were developmentally absent or if they were

absent for other reasons.

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Transposition

The term transposition refers to a condition in which two adjacent teeth have

exchanged their positions in the jaws, i.e. erupted in the wrong positions.

Figure 67. Transposition of the maxillary left canine (C) and first premolar (PM) is seen on this panoramic image.

Transposition of teeth was found in five subjects (2 Males and 3 Females).

The prevalence of transposition is about 0.4%26. Five subjects had transposition of

the maxillary canines with either the premolar or the lateral incisor.

Gemination

Gemination is an anomaly of the tooth that arises as the result of a tooth bud

trying to divide. The result is a double tooth which have may have any part of the tooth

being duplicated. Complete gemination would result in a supernumerary tooth. In the

presence of a double tooth gemination, when it is counted as one, the number of teeth in

the arch remains the same.

Gemination was found in one subject (1 male). The prevalence of gemination is

about 0.1-0.2 percent27.

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Figure 68. Gemination (G) of the maxillary left lateral incisor is seen on this panoramic image.

Microdontia

Microdontia refers to the condition wherein teeth are smaller than normal.

Microdontia may involve all teeth or may affect one or just few teeth. Generalized

microdontia is rare.

Figure 69. A microdont (Mi) can be seen distal to the maxillary right second molar on this panoramic image.

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Microdonts were found in four subjects (3 males and 1 female).

The prevalence of microdontia ranges from 0.4 to 8.4 percent.28

Macrodontia

Macrodontia refers to the condition wherein the teeth are larger than normal. Most

often only a single tooth is affected but multiple teeth may be involved in the presence of

a vascular abnormality such as a hemangioma in the area.

Figure 70. Generalized macrodontia is seen on this panoramic image.

Generalized macrodontia was found in one subject (1 male).

The prevalence of macrodontia in different studies is about 0.2 percent19, 26.

Odontomas

Odontomas are classified as hamartomas. A hamartoma is a benign tumor-like

nodule composed of an overgrowth of mature cells and tissues that normally occur in the

affected part, but with disorganization and, often, with one element predominating. A

hamartoma is an abnormal arrangement of tissue normal to the area.

Radiographically, an odontoma is a radiopaque mass or masses surrounded by a

radiolucent line (band) surrounded by a radiopaque line. The tissue has the radiopacity of

dental tissues. Odontomas may be either of compound or complex types. The compound

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odontoma has multiple small tooth-like entities, all within the same crypt (radiolucent

line or band) surrounded by a thin radiopaque line. The complex odontoma is a

malformation in which all the dental tissues are represented, individual tissues being

mainly well-formed, but occurring in a more or less disorderly pattern

Figure 71. A compound odontoma (CO) can be seen in the body of the mandible on this sagittal image.

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Figure 72. A compound odontoma (CO) can be seen in the body of the mandible on this axial image

A compound odontoma was found in four subjects (4 females).

Surgical drain in the soft tissue of brain

A surgical drain was found in the soft tissue of the brain in one subject (1 female).

Figure 73. A radiopaque tubular structure (D) can be seen on these coronal and sagittal images

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Surgical staples in the neck

Surgical staples were found in the soft tissue of the neck in one subject (1 male)

Figure 74. Surgical staples (SS) are seen on these multi-planar reconstruction image.

Retained suture material

Suture material (apparently metallic) retained in either jaw was found in four

subjects (2 males and 1 female) and in the lateral walls of the orbit bilaterally in one male

subject.

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Figure 75. Suture material (S) is seen on the lateral walls of the orbits bilaterally on this coronal image

Adenoidal hyperplasia

Adenoidal hyperplasia is a common finding in patients under 20 years of age. The

adenoids, over a period of time, become smaller. However it is important to recognize

these areas on a CBCT scan as an older individual having hyperplasia in the adenoids

region may actually have potentially a neoplasm in the area or may have AIDS and not

just hyperplasia. Adenoid hyperplasia was found in the 107 subjects (44 males and 63

females). All subjects were under the ages of 20.

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Figure 76. Marked adenoidal hyperplasia (AH) in a 16 year-old female which is obstructing the airway can be seen on this sagittal section.

Soft tissue swellings in the airway region

Soft tissue swellings whose nature could not be determined were found in nine

subjects (2 males and 7 females). These soft tissue swellings did not include adenoidal

hyperplasia as in young subjects. All of these subject’s physicians were notified of the

same and were referred to an otolaryngologist.

Fibrous dysplasia

Fibrous dysplasia is a change in the bone, caused by abnormal bone turnover that

results in replacement of the components of normal bone by fibrous tissue containing

various amounts of abnormal appearing bone. Fibrous dysplasia may be monostotic

(affecting a single bone) or polyostotic (affecting more than one bone).

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Fibrous dysplasia has a variety of appearances radiographically. The radiographic

features may be radiolucent, usually “unilocular”, but may have septae, or may have a

radiopaque appearance described as ground glass on extraoral views or orange peel on

intraoral views.

Figure 77. Fibrous dysplasia (FD) seen on this axial image in the right side of the mandible.

Fibrous dysplasia was found in eight subjects (4 males and 4 females). There is no

literature showing the exact prevalence of fibrous dysplasia in the jaws. The prevalence

of fibrous dysplasia in this study appears to be somewhat higher than that encountered in

the general population which can be expected, considering the detail seen on CBCT scans

when compared to traditional radiographs.

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Figure 78. Fibrous dysplasia (FD) is seen on this coronal image in the right side of the mandible.

Torus

A torus is a bony protuberance often found in the jaw bones. Mandibular and

palatal tori were found in large number of patients. Here only the prevalence of large

palatal tori is noted.

A large palatal torus was seen in eight subjects (1 male and 7 females).

Figure 79. A palatal torus (P) is seen on this sagittal image

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Mandibular hemihyperplasia

Hemihyperplasia is a condition in which half of the face, including either one

maxilla or one half of the mandible, grows at an abnormal rate compared to the normal

side. Sometimes the condition may affect only the mandible and is then referred to as

mandibular hemihyperplasia.

Figure 80. Mandibular hemihyperplasia is seen on this panoramic image on the right side of the mandible

Mandibular hemihyperplasia was found in two subjects (2 males).

Osteoma cutis

The term osteoma cutis refers to small idiopathic calcifications in the soft tissue

of the face. Osteoma cutis is usually multiple in number.

Osteoma cutis was found in 23 subjects (9 males and 14 females).

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Figure 81. Osteoma cutis (OC) is seen bilaterally on this axial image.

Cleft Palate

A cleft palate is a discontinuity in the palate creating a communication between

the oral cavity and the nasal cavity.

Cleft palate was found in five subjects (4 males and 1 female). One male subject

had a bilateral cleft palate.

Figure 82. A cleft palate (CP) is seen on the right side in the maxillae on this axial image.

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Salivary Gland Inclusion (Stafne) defects

A Stafne defect is a depression in the lingual cortex of the mandible to

accommodate the salivary gland. The most common location is adjacent tothe

submandibular gland fossa close to the inferior border of the mandible but this type of

depression can also occur in the anterior region to accommodate the sublingual salivary

gland.

An anterior salivary gland inclusion defect was found in one subject (1 male) and

a posterior salivary gland inclusion defect was found in two subjects (1 male and 1

female).

Figure 83. A Stafne defect (ASD) is seen on this axial image on the right side of the lingual aspect of the mandible.

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Figure 84. A 3D reconstruction showing an anterior Stafne defect (ASD).

Figure 85. A posterior submandibular Stafne defect (PSD) is seen on this panoramic image inferior to the roots of the mandibular right second molar.

Nut Notch Variations in the size of teeth may be due to a variety of circumstances which

may be environmental or genetic. Sometimes, because of an abnormal habit a notch may

be formed in the teeth due to wearing of the tooth surface by this abnormal habit, such as

opening shells or seeds with the teeth. Such a pattern is referred to as a nut notch. This is

more frequently seen in patients having roots in the middle east countries.

A nut notch was found in one male subject.

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Figure 86. A 3D reconstruction shows a nut notch in the maxillary left central incisor.

Implant impinging on borders of the inferior alveolar canal

Six subjects had at least one implant impinging on the borders of the inferior

alveolar nerve canal.

Figure 87. Orthoradials show an implant (I) impinging on the borders of the inferior alveolar nerve canal (IAN)

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Previous unhealed fracture

One subject (1 male) had a prior fracture which showed fibrous healing.

Figure 88. A discontinuity in the mandible representing incomplete healing in the region is seen on this 3D reconstruction.

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Shot gun wound

A shot gun wound was found in one subject (1 Male).

Figure 89. A shot gun wound and surgical changes are seen on this 3D reconstruction.

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Hearing aids

Hearings aids were found in four subjects (1male and 3 females).

Figure 90. Hearing aids (HA) can be seen bilaterally in this coronal view.

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Earrings

Earrings were found in three subjects (3 Female).

Figure 91. Earrings (ER) can be seen bilaterally on this coronal view

Nose ring

A nose ring was found in three female subjects.

Figure 92. A nose ring (NR) on this axial image of the ala of the left side of the nose.

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CHAPTER 5

CONCLUSION

From the wide scope of findings noted on these scans, both inside and outside the

primary areas of interest in the 1000 subjects, it can be concluded that it is essential that a

person trained in advanced interpretation techniques in radiology interpret Cone Beam

Computed Tomography scans.

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