incidental findings on cone beam computed tomography

of 131 /131
University of Iowa Iowa Research Online eses and Dissertations Spring 2009 Incidental findings on cone beam computed tomography Veeratrishul Allareddy University of Iowa Copyright 2009 Veeratrishul Allareddy is thesis is available at Iowa Research Online: hps://ir.uiowa.edu/etd/457 Follow this and additional works at: hps://ir.uiowa.edu/etd Part of the Other Dentistry Commons Recommended Citation Allareddy, Veeratrishul. "Incidental findings on cone beam computed tomography." MS (Master of Science) thesis, University of Iowa, 2009. hps://doi.org/10.17077/etd.8ed7q3af

Author: others

Post on 03-Feb-2022

2 views

Category:

Documents


0 download

Embed Size (px)

TRANSCRIPT

Incidental findings on cone beam computed tomographyTheses and Dissertations
Copyright 2009 Veeratrishul Allareddy
Follow this and additional works at: https://ir.uiowa.edu/etd
Part of the Other Dentistry Commons
Recommended Citation Allareddy, Veeratrishul. "Incidental findings on cone beam computed tomography." MS (Master of Science) thesis, University of Iowa, 2009. https://doi.org/10.17077/etd.8ed7q3af
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
2
Iowa City, Iowa
CERTIFICATE OF APPROVAL
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
ii
2
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
iii
3
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.
iv
4
v
5
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
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 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 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 23. Osteoarthrosis of vertebrae ................................................................................25
Table 24. Osteoarthrosis of TMJs ......................................................................................26
Table 25. Coronoid hyperplasia .........................................................................................27
Table 27. Pineal gland calcifications (physiologic) ...........................................................29
Table 28. Tonsilliths ..........................................................................................................30
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
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
x
10
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
xi
11
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
xii
12
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
xiii
13
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
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.
2
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 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.
3
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.
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.
5
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
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.
6
Reason for Scan No of Subjects
Impaction localization 110
Evaluation of graft in the sinus area/bone
assessment for implants
TMJ assessment 11
Orthodontic records 67
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.
7
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
Oligodontia 16 22 38
Transposition 2 3 5
Gemination 1 0 1
Microdontia 3 1 4
Macrodontia 1 0 1
Hypercementosis 5 8 13
Cementoblastoma 2 2 4
Enostosis 54 82 136
Osteosclerosis 2 3 5
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
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
Table 6. Pathosis/anatomical variants in the paranasal sinuses
Findings visualized Male Female Total
Mucositis/Sinusitis/Mucous retention
Surgical changes in the sinuses 13 16 29
Osteoma 1 3 4
Findings visualized Male Female Total
Osteoarthrosis 90 150 240
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
11
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 temporal regions 1 2 3
Osteoma cutis 9 14 23
12
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
Hair artifacts 0 4 4
Hearing aids 1 3 4
Nose ring 0 3 3
Earrings 0 3 3
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
34
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).
35
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.
36
Figure 1. An axial view through the body of the mandible (M).
37
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.
38
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
39
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.
40
Orthoradial images are reconstructed at right angles (orthogonally) to the line of
the panoramic view.
41
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.
42
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.
43
Periapical/parapical/peridental findings in the subjects
Cementoblastoma
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.
44
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
45
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.
46
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.
47
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.
48
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.
49
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.
50
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.
51
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.
52
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.
53
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
54
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.
55
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.
56
Figure 21. A coronal image showing a nasopalatine canal cyst (N) with minimal evidence of inferior (I) or superior (S) borders.
57
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.
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.
58
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.
59
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.
60
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.
61
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.
62
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.
63
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.
64
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.
65
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.
66
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.
67
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.
68
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.
69
Findings in paranasal
sinuses in subjects
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.
70
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).
71
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.
72
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.
73
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.
74
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.
75
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.
76
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.
77
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).
78
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.
79
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.
80
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.
81
Figure 51. A sialolith (S) is seen in the Warton’s duct on this axial image.
Dystrophic calcifications
tissues.
Dystrophic calcifications were found in 7 subjects (3 males and 4 females). This
does not include osteoma cutis.
Table 34. Dystrophic calcifications.
82
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.
83
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).
84
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).
85
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.
86
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.
87
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.
88
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.
89
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.
90
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.
91
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.
92
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.
93
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.
94
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.
95
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
96
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.
97
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
98
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.
99
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.
100
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).
101
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.
Fibrou