Incidental Findings from Cone Beam Computed Tomography of the Maxillofacial Region: a Descriptive Retrospective Study

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INCIDENTAL FINDINGS FROM CONE BEAM COMPUTED TOMOGRAPHY OF THE MAXILLOFACIAL REGION: A DESCRIPTIVE RETROSPECTIVE STUDY

Khin L.Thaw, BDS

A thesis submitted to the faculty of the University of North Carolina at Chapel Hill in partial

fulfillment of the requirements for the degree of Master of Science in the Department of

Diagnostic Sciences and General Dentistry of the School of Dentistry, (Oral and

maxillofacial radiology).

Chapel Hill

2010

Approved by:

Dr. Donald Tyndall

Dr. John Ludlow

Dr. Ricardo Padilla

ABSTRACT

KHIN L. THAW: Incidental Findings from Cone Beam Computed Tomography of the

Maxillofacial Region: A Descriptive Retrospective Study

(Under the direction of Dr. Donald Tyndall)

Objectives: To evaluate type and prevalence of incidental findings from cone beam computed tomography (CBCT) of the maxillofacial region. Findings are divided into those that required 1) intervention/referral 2) monitoring and 3) no further evaluation.

Methods: 300 consecutive CBCT scans conducted in the School of Dentistry Oral and

Maxillofacial Radiology Clinic, from January 1 to August 31, 2008 were retrospectively reviewed. Findings were grouped into categories: airway, soft tissue calcifications, bone,

TMJ, endodontic, dental developmental, and pathological.

Results: 90.7% revealed a total of 881 incidental findings (3.2 findings/scan). The most prevalent was airway findings (35.0%), followed by soft tissue calcifications (20.0%), bone

(17.5%), TMJ (15.4%), endodontic (11.3%), dental developmental (0.7%) and pathological

(0.1%). 16.1% required intervention/referral, 15.6% required monitoring, and the remainder required neither.

Conclusion: This study underscores the need to thoroughly search for clinically significant lesions within and beyond the region of interest for all CBCT volumes of data.

ACKNOWLEDGEMENTS

I would like to express my heart-felt thanks and gratitude to my faculty without whose help, encouragement, and continuous support, this project would not have been possible. I would like to extend my special thanks to my colleagues in the oral and maxillofacial radiology program whose constructive advice, support, and friendship have made this a worthwhile and rewarding endeavor.

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TABLE OF CONTENTS

I. LIST OF FIGURES ...... v

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

III. LIST OF ABBREVIATIONS ...... viii

A) INTRODUCTION ...... 1

B) MATERIALS AND METHODS ...... 5

C) RESULTS ...... 8

D) DISCUSSION ...... 12

E) CONCLUSION ...... 26

IV. APPENDICES ...... 48

V. REFERENCES ...... 152

LIST OF FIGURES

Fig. 1. Age distribution of patients ...... 27

Fig. 2. Indications of the CBCT scans ...... 28

Fig. 3. Frequency distribution of incidental findings………………………………………...29

Fig. 4. Clinical significance of the incidental findings ...... 30

Fig. 5. CBCT images demonstrate a generalized mucosal thickening of bilateral maxillary sinuses ...... 31

Fig. 6. CBCT images demonstrate thickening of the floor of the maxillary sinus mucosa in the left antrum ...... 32

Fig. 7. CBCT images demonstrate pansinusitis involving mucosal thickening of sinusitis involving sphenoid, ethmoid and maxillary sinusitis ...... 33

Fig. 8. CBCT images demonstrate oro-antral fistula present in the floor of the sunus in the tooth No. 14……………………………………………………………………………….…34

Fig. 9. CBCT images demonstrate a mild generalized thickening of the mucosa lining the inferior portion of the left maxillary sinus associated with an antrolith ...... 35

Fig. 10. CBCT images demonstrate sialoliths in the right submandibular gland...... 36

Fig. 11. CBCT images demonstrate bilateral calcified carotid atheroma ...... 37

Fig. 12. Sirona Galileos three-dimentional CBCT images depict osteoma in the right ethmoid sinus ...... 38

Fig. 13. TMJ views of CBCT images depict signs of severe degenerative joint disease of temporomandibular joints ...... 39

Fig. 14. TMJ views of CBCT images depict signs of degenerative joint disease of temporomandibular joints ...... 40

Fig. 15. CBCT images demonstrate the periapical lesions associated with tooth No. 15 and No. 16 ...... 41

Fig. 16. CBCT images demonstrate a case of perforation or fracture associated with the post in a tooth...... 42

Fig. 17. Sirona Galileos three-dimensional CBCT images depict a case of root fracture associated with upper right central incisor...... 43

Fig. 18. CBCT images demonstrate the two supernumerary microdonts just palatal to the root of maxillary right central incisor ...... 44

Fig. 19. Sirona Galileos three-dimensional CBCT images depict the two supernumerary teeth: Each buccal to the maxillary third molars bilaterally...... 45

Fig. 20. Panoramic reconstructed image from CBCT scan depicts florid cemento-osseous dysplasia ...... 45

LIST OF TABLES

Table I. Descriptive analysis and frequency of the incidental findings ...... 46

Table II. Number of patients having incidental findings under general categories ...... 47

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LIST OF ABBREVIATIONS

3D (Three Dimentional)……………………...………………………………….………….....1

CBCT (Cone Beam Computed Tomography) ...... 1

CT (Computed Tomography).……..…………..……………………...…….....…………...... 1

2D (Two Dimentional) ...... 1

TMJs (Temporomandibular Joints)……………………………………………………...….....3

UNC (University of North Carolina).…………………………………………………...….....5

IRB (Institutional Review Board)..……………………………………………………...….....5

DICOM (Digital Imaging and Communications in Medicine) ...... 6

FCOD (Florid Cemento-osseous Dysplasia…………………………………………...... 11

ENT (Ear-Nose-Throat)………….……………………………………………………...... 13

C3-C4 (Cervical Spine Numbers 3 and 4) ...... 17

MDCT (Multidetector Computed Tomography) ………….………………….…….....….....18

IAN (Inferior Alveolar Nerve)………….………..……………………………………...…...21

DJD (Degenerative Joint Disease) ………….………..………………………………....…...22

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INTRODUCTION

Three-dimensional (3D) cone beam computed tomography (CBCT) was developed from conventional computed tomography in the 1990s. The ﬁrst commercial CBCT unit, the

NewTom 9000 (Quantitative Radiology, Verona, Italy), was described in 1998.1Since then new and improved CBCT systems have been developed. CBCT is well suited to dentistry because it provides excellent images of high-contrasting structures such as maxillofacial bony anatomy and teeth while not as expensive as the conventional computed tomography

(CT).

Unlike the fan-shaped X-ray used in conventional CT, CBCT uses a conical or pyramidal X-ray beam to acquire a large volume of data via a flat detector. In CBCT imaging, a conical X-ray beam which circles in a single or partial rotation about the patient to generate multiple two-dimensional (2D) projections. By using reconstruction algorithms, the acquired 2D images are converted to a three-dimensional data set that can be viewed in the axial, sagittal and coronal planes. Using functionalities such as magnification and visual enhancements (e.g. grey scale, brightness and contrast level); the CBCT gives clinicians a powerful tool for diagnosis of various pathologies and dental treatment planning.

Compared to CT, CBCT technology offers a comparable diagnostic value for various indications while allowing for lower radiation dose, lower cost, and a faster, easier image acquisition and display.

While the radiation dose in CBCT is higher than that from the conventional radiographs routinely used in dentistry,2, 3 3D CBCT has advantages over 2D conventional radiographs in that it depicts a more accurate three dimensional relationship between anatomic structures, thus eliminating two major problems that usually plague conventional radiographs: geometric distortion and superimposition of surrounding anatomical structures.

Marmulla et al.4 reported that a major advantage of CBCT is its three-dimensional geometric accuracy compared with conventional radiographs.

CBCT can reveal hidden anatomy as well as occult pathology, reducing the possibility of missing a clinically relevant disease. Nakata et al.5 found that CBCT may detect the presence of previously undiagnosed periapical disease where prior clinical evaluation and conventional radiographic findings failed to reveal the pathology. It has also been suggested that CBCT may detect periapical findings earlier and more accurately than conventional radiographs.6, 10 Asymptomatic or occult pathology may lead to delayed diagnosis, which may adversely affect treatment strategy and outcome. Early detection, prevention, and improved diagnostic accuracy are essential for ensuring improved patient care and treatment outcomes. It can also reduce treatment time, complexity, complications, and costs.

The role of CBCT is rapidly emerging in the fields of dental implantology7, orthodontic treatment8, endodontic evaluations9, 10, and oral surgery11. It has also found applications in the evaluation of pathology12, assessment of the temporomandibular joints

(TMJs) 13, and airway analysis14. It has been used in the precise localization of impacted ectopic canines15, supernumerary teeth16, and foreign bodies17. It is also being used in

2 assessment of third molar relationship18, dental trauma19, and root fracture20. Moreover,

CBCT is useful for localizing anatomy, pathoses, developmental anomalies and the extent of trauma within the oral and maxillofacial region.

Despite the advantages, CBCT is known to have its limitations that include poor soft tissue contrast21 and image noise due to scatter radiation. CBCT cannot be used with any reliability on the typical patient at high risk for caries due to the presence of false positive lesions resulting from the presence of metallic restorations.22

CBCT is a useful tool for detecting incidental oral and maxillofacial abnormalities.

The large CBCT volume covering the entire maxillofacial area allows one to detect abnormal pathology that exists outside the specific region of interest. While reviewing CBCT scans, it is important to analyze the entire image volume and not just limit evaluation to the region of interest. Careful and thorough evaluation permits detection of incidental findings with clinical significance.

Incidental findings in CBCT examinations are well documented. The exact frequency of incidental findings vary widely from study to study depending on the age groups, population studied, and category of findings. Miles 23 reported an average of two reportable findings per CBCT. Many of those findings resulted in referrals to other specialists. In the same study, periapical lesions that were missed during conventional radiographic examination were later detected on CBCT images. Cha et al. 24 found that the overall rate of maxillofacial incidental findings in CBCT images of 500 consecutive patients was 24.6%, and that the highest rate of incidental findings was in the airway area. Nair et al.25 incidentally found an intracranial aneurysm during the CBCT evaluation of a mandibular

3 lesion. Popat et al.26 also described an incidental finding of mid-line clefts of the cervical vertebrae arising from CBCT of a dental patient. Arnheiter et al.27 found that patients that were 40-49 years old had the largest percentage of reportable incidental findings (70%), while patients that were 20–29 years old showed the lowest percentage of secondary diagnoses (40%).

The purpose of the study was to evaluate the type and prevalence of incidental findings in the maxillofacial region from CBCT scans obtained for specific dental diagnostic purposes. It also attempts to stratify the clinical significance of incidental findings. A better understanding of the incidental findings revealed by CBCT images may help practitioners to identify clinically significant lesions while at the same time minimizing unnecessary further diagnostic tests and evaluation for lesions that require no intervention or treatment.

MATERIALS AND METHODS

Thesis project protocol was reviewed and approved by the UNC-Chapel Hill

Institutional Review Board (IRB) of Human Subjects Research. CBCT scans of 300 consecutive patients conducted by the radiology department of the University Of North

Carolina School Of Dentistry from January 1, 2008 to August 31, 2008 were retrospectively evaluated for incidental findings. Incidental findings are defined as findings that are unrelated to the primary purpose of the scan.

The patients’ demographic data, indication for imaging, and CBCT unit used were recorded. The patients’ mean age was 49.3 years, (range 9-80 years). The distribution of the total sample by age is given in Fig. 1. Most of the patients who visited were between the ages of 60 years and 69 years. There was a slight predominance of women (n=165 or 56.3%). The patients having CBCT scans for an orthodontics and orthognathic surgery were excluded because they underwent CBCT with a larger 12-inch field of view.

The incidental findings to be assessed were divided into seven general categories: airway findings, soft tissue calcifications, bone findings, TMJ findings, endodontic findings, dental developmental findings and pathological findings. Radiographic criteria used for the recording of incidental findings were modified from the textbook: ―Oral Radiology:

Principles and Interpretation‖, 6th edition by White and Pharaoh28 (Appendix A). The findings such as dental caries, missing teeth, altered tooth morphology, eruption disturbances and periodontal bone loss were not recorded. Findings directly related to the primary indications of CBCT scans were excluded.

The imaging equipment used in this study were the: 1). NewTom 3G (AFP Imaging,

Elmsford, NY) using a 6 or 9 inch field of view and with 110 kV, 1-15 mA and 2). Sirona

Galileos 3D Comfort (Sirona Dental Systems, Charlotte, NC) using a 6 inch field of view and with 85 kV, 5-7 mA and 21-42 mAs.

To facilitate image retrieval, the raw volume data sets of NewTom CBCT scans that were already saved in a computer hard drive were converted/exported into DICOM (Digital

Imaging and Communications in Medicine) format. The DICOM data was uploaded and viewed with 3rd party software, In-Vivo Dental software (Anatomage, Inc. San Jose, CA).

The latter provides more flexibility in viewing volumes. In this method, the volume was viewed in correlated orthogonal planes (axial, coronal and sagittal views). Custom sections were also viewed when suspected variation or pathology was found. A 15 mm panoramic image layer encompassing the dentate area of the jaws and the TMJs was reconstructed.

Cross-sections perpendicular to this panoramic arc were viewed in order to visualize details.

Volume rendering was used for some soft tissue calcifications and impacted teeth.

For Galileos CBCT scans, images were viewed using the manufacturer’s proprietary software, Galaxis/Galileos Implant software (Sirona Dental Systems, Charlotte, NC). The volume was viewed with the Radiology module of the software, which provides orthogonal views (axial, coronal and sagittal planes). A panoramic image layer that closely resembles a conventional dental panoramic radiograph was also viewed using the panorama module of the software. The region of interest is selected using an approximately 7 cm H x 5 cm W

Slicing Window which can be moved over the panoramic view. The relevant sagittal, coronal

6 and axial slices of the area where the window is positioned are produced. Magnification and brightness and contrast level adjustments were employed on all the images reviewed.

The sequential examination of the CBCT volume was made from the superior to inferior aspects of the volume and then back to the superior using the axial views of the scan.

Anatomic regions which were specifically identified and evaluated included paranasal sinuses (frontal, maxillary, ethmoid, sphenoid) and nasal airways, then followed by nasopharyngeal airway, carotid space, calcified tissues of the head and the neck and submandibular areas, gnathic structures, TMJ areas, temporal bone (external, middle and inner ear, internal auditory canal), intracranial carotid pathway and middle cranial fossa.

Each CBCT scan was reviewed three times on separate occasions for thoroughness and accuracy. Diagnoses were based entirely on radiographic appearance and its consistency with classic radiographic findings. All diagnoses were based on CBCT findings, and no other additional clinical, radiographic or histologic information was used. The scans were analyzed by the author, and in doubtful cases, consultations were undertaken with the committee members of this study who are board certified radiologists with extensive experience in reading CBCT scans.

In the first portion of the study, all 300 CBCT scans were studied, and the type and prevalence of incidental findings detected in maxillofacial region in the CBCT scans were evaluated. In the second part of the study, these findings were divided into 1). findings that require definitive intervention 2). findings that require monitoring, and 3). findings that require no further work-up. Descriptive data including patient demographics (gender, age) and indications for the CBCT scan were collected.

RESULTS

The predominant reason for CBCT scans was dental implant treatment planning.

Seventy three percent (n=218) patients were referred for dental implant treatment planning,

11% (n=33) for TMJ analyses, 7% (n=21) for suspected oral and dental pathologies, 5%

(n=15) for orthodontic applications, 3% (n=10) for impacted teeth, and 1% (n=3) for a combination of diagnostic tasks. Frequency distribution of the total sample referred for

CBCT scans is illustrated in Fig. 2 and Appendix B.

Of the 300 CBCT scans reviewed, 272 (90.7%) scans revealed 881 incidental findings

(3.2 findings per scan) which were unrelated to the primary indications of the CBCT scan, while 28 (8.3%) scans showed no incidental findings. The most prevalent incidental findings were airway findings (35.0%), followed by soft tissue calcifications (20.0%), bone (17.5%),

TMJ (15.4%), endodontic (11.3%), dental developmental (0.7%) and pathological findings

(0.1%) in Fig. 3. Table I further subdivides those categories into more specific pathological or anatomic findings. Table II shows the numbers of patients having incidental findings under general categories.

I. Airway findings

As stated, airway findings represented the most frequent incidental findings. Of the

308 air way findings in 188 patients, there were 125 instances of sinusitis (14.2%) in 83 patients: 91 in maxillary sinus, 8 in spehnoid sinus, and 26 in ethmoid sinus. There were 7 instances of pansinusitis (0.8%), 51 instances (5.8%) of mucous retention pseudocysts in 44 patients, 46 instances (5.2%) of antral polyps in 44 patients, 65 instances (7.4%) of concha

8 bullosom, 9 instances (1.0%) of oroantral fistula in 8 patients, and 5 instances (0.6%) of antroliths in 5 patients.

II. Soft tissue calcifications

The over-all incidence of soft tissue calcifications was 176 (20.0%) in a total of 138 patients. For all findings under this category, a collection of calcifications whether single or bilaterally evident in a patient were counted as one instance. Of 176 soft tissue calcifications, there were two sialoliths, 13 carotid artery calcifications, 4 intracranial calcifications of the internal carotid artery, 80 ossifications of stylohyoid ligaments, 43 tonsilloliths and 34 calcified thyroid cartilage and/or triticeous cartilage.

III. Bone findings

Bone findings accounted for 154 (17.5%) of the total incidental findings in 111 patients. In this category, a collection of bone density radiopaque masses was counted as one instance. Of this category, 59 (6.7% of the entire group of findings) represented dense bone islands (idiopathic osteosclerosis or enostoses), 45 (5.1%) torus palatinus, 39 (4.5%) mandibular tori, 9 (1.0%) exostoses, 1 (0.1%) osteoma and 1 (0.1%) Stafne bone defect.

Of the 59 instances of dense bone islands, there were 46 idiopathic osteosclerosis and

13 enostoses. Total of 45 torus palatinus and 39 mandibular tori existed. 13 patients demonstrated both torus palatinus and mandibular tori. Nine exostoses (9 patients) were detected. All were located on either buccal or lingual surfaces of posterior maxillary alveolus. One instance of osteoma was found in the left ethmoid sinus. A developmental

9 submandibular salivary gland depression (Stafne bone defect) was located classically in the left submandibular fossa below the inferior alveolar canal.

IV. TMJ findings

In this category, TMJ findings accounted 136 instances (15.4%) in 45 patients. Each finding of TMJ such as condyle flattening, subchondral sclerosis, condyle erosion, subchondral pseudocyst, osteophyte formation and condyle appearance was counted as one instance. We detected 50 instances of condlyle flattening in 33 patients, 10 instances of subchondral sclerosis in 8 patients, 34 instances of condyle erosion in 24 patients, 24 instances of subchondral pseudocysts in 17 patients, 17 instances of osteophytes in 12 patients, and 1 bifid condyle.

V. Endodontic findings

Endodontic findings accounted for 100 (11.3%) of the total incidental findings in 69 patients. Endodontic findings represented periapical inflammatory lesions such as rarefying osteitis, sclerosing osteitis those with both features and root fracture. Of the periapical findings, the vast majority were the rarefying osteitis type: 50 findings (5.7%) in 38 patients.

We also detected 30 instances (3.4%) of rarefying and sclerosing osteitis type in 25 patients and 18 instances (2.0%) of apical sclerosing osteitis in 16 patients. Two cases (2 patients) of root fracture were detected. Both cases were associated with a maxillary central incisor. In one case, root perforation or fracture was associated with the post in a tooth.

VI. Dental developmental findings

Dental developmental findings accounted for six or 0.7% of the total findings, all representing supernumerary teeth in a total of four patients. The three supernumerary teeth

(microdonts) were impacted palatally to the upper central incisors in two patients, and another one was impacted in an inverted position in the edentulous upper central incisor region in a patient. The two geminated-molar-like supernumeraries (microdonts) occurred distal to the maxillary third molars in a patient (bilaterally).

VII. Pathological findings

Only 1 (0.1%) pathological finding was detected in this study. This was a case of florid cemento-osseous dysplasia (FCOD). Occurrences of findings such as dentigerous cyst, nasopalatine duct cyst, residual cyst, or odontoma were not detected.

Clinical significance of the incidental findings

As the second part of the study, the incidental findings were divided into: 1) those that required definitive intervention, 2) those that require monitoring, and 3) those that require no intervention or monitoring.

A substantial portion of the incidental findings 142 (16.1%) required definitive intervention or referral, while 137 (15.6%) required monitoring, and 602 (68.3%) did not require either (Appendix C).

DISCUSSION

3D CBCT finds applications in many aspects of dentistry for various maxillofacial diagnostic purposes. It can provide valuable diagnostic information beyond the region of interest. For example, the CBCT volume can reveal incidental findings in maxillofacial areas including gnathic structures as well as extragnathic structures.

This study recorded incidental findings from CBCT scans. These findings vary in their importance, from common benign lesions to significant pathological findings that may have an important impact on health of the patient. Those findings include normal anatomy variants, the age-related findings, developmental findings, and occult pathological findings.

Of the 300 CBCT scans reviewed, a remarkable 90.7% (272) of the scans revealed a total 881 incidental findings (3.2 findings per scan) which were unrelated to primary indications for the CBCT scan. The majority of the findings represent benign findings that do not require specific intervention. However, a substantial portion of the incidental findings

(142 or 16.1%) required definitive intervention or referral. This reinforces the fact that, a careful and thorough interpretation of the CBCT images beyond the region of interest is necessary to avoid overlooking occult pathology which can have health consequences for the patient. An example of this is an incidental finding of a calcified carotid atheroma which put the patient at high risk of developing a cerebrovascular accident. A knowledgeable and competent analysis of CBCT scan is also required to avoid unnecessary procedures (e.g. in the case of a benign mimic of a serious pathology), and to identify pathology early so as to reduce treatment time, complexity, complications and costs.

The most prevalent incidental findings were airway findings (35.0%), followed by soft tissue calcifications (20.0%), bone (17.5%), TMJ (15.4%), endodontic (11.3%), dental developmental (0.7%), and pathological findings (0.1%). The exact frequency of incidental findings on CBCT vary widely from study to study in the dental radiology literature. This is due to differences in age groups, population studied, and category of findings that are examined.

Airway findings

CBCT images are helpful in identifying sinusitis, mucous retention pseudocysts, antral polyps, concha bullosa (pneumatization of concha), antroliths and oroantral fistula. In this study, airway findings represented the most frequent incidental findings 308 (35.0%) in

188 patients. Cha et al.24 found that the overall rate of maxillofacial incidental findings in

CBCT images of 500 consecutive patients was 24.6%, and that the highest rate of incidental findings was in the airway area (18.2%). Other similar studies noted incidental ﬁndings in paranasal sinuses in 35%- 45% of CT scans of asymptomatic patients.29, 30

Of the airway findings in our study, there were 125 instances of sinusitis (14.2%) in

83 patients (Fig. 5). Sinusitis may be caused by an allergen, bacteria, fungus or a virus.

Odontogenic etiology was responsible for approximately of 10% of inflammatory episodes of the maxillary sinuses owing to anatomic proximity of the maxillary sinus28 (Fig. 6). In our study, we did not review the patients’ symptoms and the sources of sinusitis (as it is not the intent of the study). Diseases of the sinus and odontogenic diseases can mimic each other.28

Therefore diagnosis requires a thorough dental and clinical evaluation including radiographs and clinical symptoms.31 Patients should not be referred to an Ear-Nose-Throat (ENT)

13 specialist in every case of sinusitis. On the other hand, the dental practitioner should not ignore conditions that may benefit from referral and management.

We detected 7 cases of pansinusitis (Fig. 7). Three of those had concomitant oroantral fistulas. Four patients with pansinusitis were undergoing dental implant planning.

In those patients, if the implant is to be placed in the maxilla and a sinus augmentation procedure anticipated, the paranasal sinusitis needs to be thoroughly treated before the surgery is performed.

We found 9 instances (1.0%) of oroantral fistula in 8 implant patients (Fig. 8).

Oroantral communication is a relatively common complication of dental surgery and one of the possible causes of maxillary sinusitis.32, 33 As stated previously, three of those patients had concomitant pansinusitis. If an oroantral communication is suspected, prompt surgical management is recommended to reduce the likelihood of complications including sinusitis.

In our study fifty-one instances (5.8%) of mucous retention pseudocysts were detected in 44 patients. Mucous retention cysts are a result of enlargement of a mucous gland caused by blockage of a mucous gland duct in the floor of the maxillary sinus. There is no bony cortex around the well-defined rounded radiopacity. They rarely cause any signs and symptoms and are not related to extractions or associated with periapical disease.28, 34 Due to its self-limited nature, it is generally agreed that no treatment is required. Some antral pseudocysts remain the same for a long time, some increase gradually, and others disappear spontaneously.

Forty six instances (5.2%) of antral polyp were detected in 44 patients. Polyp is a mucosal thickening of chronically inflamed sinus that forms into irregular folds. It appears as a diffuse, polypoid radiopacity along the sinus margins. They could be solitary or multiple and pedunculated or more irregularly shaped than mucus retention pesudocysts. No treatment is required unless the symptoms are present. The dental practitioner should not ignore the conditions because benign or malignant neoplasms can mimic antral polyps. In the case of malignant neoplasm, a radiographic image of the bone displacement and destruction may be found. Odontogenic infections also mimic antral polyps, and should be suspected if symptoms of infection are present.35

We found 5 cases (0.57%) of antroliths in 5 patients. Four were in maxillary sinus and one in ethmoid sinus. All except one had concomitant sinusitis (Fig. 9). Nass Duce et al.36 found 3 patients with antroliths out of 1957 sinus CTs reviewed. All three were associated with sinusitis. Antroliths are calciﬁed bodies as a result of mineral salt deposition around an endogenous or exogenous nidus within the nasal cavity. Endogenous sources include structures of dental origin, blood, mucus, and bone fragments.37 Exogenous sources are the foreign bodies introduced into the sinus cavities. Smaller antroliths are usually asymptomatic and are discovered as incidental findings on radiographic examination. If they continue to grow, however, the patient may have symptoms such as sinusitis, facial pain, purulent or bloody nasal discharge, or nasal obstruction.28 Referral or further investigation may then be recommended depending on location, size and symptoms present.

Concha bullosa is a common anatomic variation of the sinonasal anatomy. It is most commonly encountered in the middle turbinate. We found 65 concha bullosa in 65 patients.

They are either unilateral or bilateral. Comparative studies have reported that the concha bullosa was more frequently encountered in patients with sinusitis although no consensus was achieved regarding the casual association.38, 39 No treatment is required.

Soft tissue calcifications

The over-all incidence of soft tissue calcifications accounted 176 instances (20.0%) in

138 patients. Soft tissue calcifications in the maxillofacial and cervical areas can be pathological, age-related or idiopathic. It is sometimes difficult to interpret calcifications that are adjacent to the bone. It is important to know their anatomic location, distribution, and morphology to interpret correctly and to familiarize the practitioners with their CBCT imaging appearance.

We detected two sialoliths; one in the right submandibular gland (Fig. 10) and one in sublingual gland. Patients with sialoliths may be asymptomatic but they usually have a history of pain and swelling around the sialoliths involved. Sialoliths can be distinguished from other soft tissue calcifications such as calcified lymph nodes by the presence or absence of symptoms and their number, morphology and location. Sialolith has a smooth outline whereas a calcified lymph node is usually irregular and sometimes lobulated. Patients with sialoliths need referral for further investigation or treatment.

We found 43 tonsilloliths (43 patients) were detected in the present study.

Aspestrand and Kolbenstvedt found 16 patients had tonsilloliths on the scans of 100 consecutive patients referred for CT examinations that included the oropharynx.40

Tonsilloliths can be single, multiple, unilateral or bilateral. Four cases in this study had

16 bilateral and multiple involvement. Small calcifications are usually asymptomatic and are frequently discovered incidentally on dental or soft tissue radiographs. Those attaining large sizes can result in halitosis, sore throat, dysphagia or a foreign body sensation.41 No treatment is required for most tonsillar calcifications. However, treatment may be considered in elderly patients with immunosuppression because of the risk of aspiration pneumonia.28

Thirteen patients had calcified carotid artery atheroma. These calcifications could be an indicator of potential stroke or metabolic disease.28, 42 They are usually multiple, irregular, nodular heterogeneous radiopacities with radiolucent voids independent of the hyoid bone and epiglottis. They are adjacent to the cervical vertebra in a vertical linear orientation at, above, or below the C3-C4 intervertebral disc level.

It is important to differentiate between carotid calcifications and other calcifications found in the head and neck region. Other soft tissue calcifications include salivary gland stones, tonsilloliths, calcified triticeous, cricoids, and thyroid cartilages, calcified acne scars or lymph nodes, ossification of stylohyoid ligaments, phleboliths and myositis ossificans. It is important to know the possible size, shape and location of carotid atheroma to avoid erroneous diagnoses. CBCT provides accurate 3 D localization of soft tissue calcifications including carotid atheroma (Fig. 11).43 It is important to carefully evaluate the entire imaged volume in detail and not just the region of interest so as not to overlook such clinically significant calcifications. Referral for further investigation may be required.

Atherosclerotic calcifications can be present not only in the extracranial carotid artery bifurcation but also in the intracranial part of the internal carotid artery. In our study, four patients had intracranial calcifications in the region of the internal carotid artery. Weert

17 et al.44 found no association between intracranial internal carotid artery calcifications and the presence of ischemic cerebrovascular disease on 406 patients with ischemic cerebrovascular symptoms who underwent multidetector CT (MDCT) angiography of the carotid arteries for assessment of possible carotid artery stenosis. However, Nair et al. presented an incidental finding of a potentially life-threatening large aneurysm of the internal carotid artery in a patient who reported with complaints of the presence of a radiolucent lesion in the mandible that was diagnosed as an odontogenic keratocyst.25 It is important to be aware of other calcification patterns associated with vascular pathology, such as vascular malformations and aneurysms. In this study, the pattern of calcifications we found did not suggest vascular malformations or aneurysms so that no referral or intervention was needed.

In the present study, ossification of stylohyoid ligament was noted in eighty patients.

It does not cause significant signs or symptoms, and is detected fairly commonly as an incidental feature. It commonly occurs bilaterally. No treatment is required. However, atypical neurofacial pain, known as Eagle’s syndrome, has been attributed to the calcification of this ligament which may resemble stylo-hyoid ossicles.45

Calcified thyroid and/or triticeous cartilages were noted in thirty-four patients.

Thyroid cartilage is part of the upper laryngeal skeleton and the triticeous cartilage is located in the thyrohyoid ligaments. They are bilateral ovoid structures. They consist of hyaline cartilage, which has a tendency to calcify or ossify with advancing age and are incidental findings with no clinical symptoms. No treatment is needed. Calcified triticeous cartilage may be mistaken for atheromatous plaque. Therefore, careful attention to the differences in

18 morphology and location to distinguish between calcified triticeous cartilage and calcified carotid atheroma.

Bone findings

We found 59 instances of dense bone island/idiopathic osteosclerosis: 13 cases of enostosis and 46 cases of central osteosclerosis in a total 59 patients. Conventional radiographs cannot differentiate dense bone islands into idiopathic osteosclerosis (central) or enostosis. On computed tomography images, however, the two types are distinguishable.

Yonetsu et al studied the panoramic radiographs of 64 patients and found that 6.1% of subjects exhibited idiopathic osteosclerosis. They also found two enostosis and six central scleroses in 11 patients on CT examination.46 One study found that CBCT can diagnose the location and the extent of enostosis with which the conventional radiography cannot accomplish.47 In the present study, most of bone findings are found to be of little clinical relevance. In clinical practice, most of them are asymptomatic and usually discovered incidentally during a routine clinical exam.

Dense bone islands are considered to be asymptomatic and non-expansile. They are localized intrabony radiopaque lesions that are not the sequela of infection or systemic disease. Etiology of dense bone island is unknown. Idiopathic osteosclerosis should be distinguished from other radiopaque lesions such as sclerosing osteitis of dental inflammatory origin, or other bone-related radiopacities such as periapical cemental dysplasia.48, 49 No treatment is required. In rare instances, it is located periapical to a tooth root and is associated with external root resorption.28

In the present study we found 9 exostoses (9 patients). Both tori and exostosis exist together. Buccal and palatal exostoses occur less frequently than tori.50 We found 3 exostoses in persons with both torus palatinus and torus mandibularis, 3 extostoes in patients with torus palatinus, 1 exostosis in subjects with mandibular tori, and 2 exostoses exit in subjects with no both tori.

We found 45 torus palatinus and 39 torus mandibularis. Thirteen subjects demonstrated both torus palatinus and torus mandibularis. Of the 45 persons with torus palatinius, 6 exhibited exostosis. Of 39 persons with torus mandibularis, 4 exhibited exostosis. Of 13 subjects with both torus palatinus and mandibularis, 3 exhibited extosis. One patient exhibited tori (torus palatinus and mandibular tori) and multiple exostoses in buccal and lingual aspects of maxilla and buccal aspects of mandible. Jainkittivong and group51 reported that coexistence of multiple exostoses and tori represented a general multiple exostoses syndrome. Tori and exostoses usually do not require treatment but may be require removal for prosthetic reasons and for the use as biomaterial in periodontology and implantology.

We detected one instance of osteoma in the left ethmoid sinus (Fig. 12). Diagnosis is based on a well-circumscribed, radiopaque bony mass occupying the paranasal sinus on radiographs or computed tomography scans. Osteomas are slow-growing and the most common benign tumors of the paranasal sinuses. They are asymptomatic and thus usually detected as an incidental finding. However, they can cause symptoms depending on their sizes and location. They can increase in size slowly and extend into the neighboring structures, causing mild to serious complications.52, 53 Treatment is not recommended in

20 asymptomatic cases. However, periodic radiographic imaging should be used to follow up the changes in size. Alexander and group reported that multiple osteomas can be a manifestation of Gardner’s syndrome, called familial multiple polyposis syndromes, characterized by intestinal polyps, pigmented skin lesions, multiple osteomas and multiple dense bone islands.54

In the present study, a Stafne bone defect was detected in a 67-year-old male patient who had CBCT scan for implant planning. CBCT scan revealed a well-deﬁned radiolucency with dense corticated margin measured about 11 mm x 6 mm x 2 mm proximate and inferior to the inferior alveolar nerve (IAN) canal in the lingual aspect of left mandibular molar region. Stafne bone cavity is considered to be a developmental anomaly. It is usually asymptomatic and discovered during routine radiographic examination. The posterior variant of Stafne bone defect called submandibular gland defect is associated with submandibular glands and anterior variant, called sublingual gland defect is associated with sublingual gland. The variant of the ascending ramus of mandible is associated with the parotid gland.

28, 55 Our finding was the posterior variant, submandibular salivary gland defect. No intervention or referral was recommended.

TMJ findings

In this study, we examined changes of TMJ condylar heads such as flattening, sclerosis, erosion, subcondylar pseudocysts, osteophytes, and bifid condyle which is presumed to be a developmental anomaly. TMJ condylar head changes occurred in 136 instances (15.4%) in a total of 46 patients. Most changes demonstrated radiographic signs of remodeling and/ or degenerative changes (Fig. 13 – 14). Radiographically, the signs of mild

21 degenerative joint disease (DJD) are identical to those associated with joint remodeling.

Remodeling is a physiologic process that adapts the TMJ structure to the mechanical forces applied to the joint. TMJ flattening and sclerosis are signs of remodeling process.28

Degenerative join disease is the most common pathological condition of the TMJ.

TMJ erosions and osteophytes are significant radiographic hallmarks of DJD.28, 56 It may occur at any age but it is usually an age-related disorder. Mie Wiese et al.57 reported that age, gender, and coarse crepitus were associated with increased risk of degenerative findings on

TMJ tomograms. Yet, TMJ disease is not confined to older patients. Stewart et al.58 found

26% incidence of TMJ DJD in 346 patients under age 19 who were referred for jaw disorders.

DJD of the TMJ detected on radiographic examination may be incidental and may not be responsible for TMJ dysfunction or symptoms. Many patients with mild to moderate DJD of the TMJ observed on radiographs may have no symptoms. Patient history, clinical findings and symptoms help in the determination of disease activity. Patients with symptoms such as pain and limitation of oral opening need referral or intervention, otherwise, no treatment but monitoring is required.

A case of unilateral (left) mesiolateral bifid condyle was detected in a sixty year old patient who had a CBCT scan for implant treatment planning. The bifid condyle is a rare anomaly and may be unilateral or bilateral and anterioposterior or mediolateral. Etiology is not fully understood but evidence suggests traumatic or developmental etiology. Bifid mandibular condyles were reported as incidental findings on radiographic examination in

22 asymptomatic patients.59 They are also found in association with TMJ ankylosis.60, 61

Treatment was not indicated for our patient.

Endodontic findings

We detected 100 endodontic findings in 69 patients. The vast majority were periapical rarefying osteitis type: 50 findings (5.7% of total incidental findings) in 38 patients. We also detected 30 instances (3.4% of all findings) of rarefying and sclerosing osteitis type in 25 patients and 18 instances (2.0% of all findings) of apical sclerosing osteitis in 16 patients. Two cases of horizontal root fracture were detected in two patients.

Periapical inflammatory lesions can represent acute apical periodontitis, chronic apical periodontitis, periapical abscess, periapical granuloma, and periapical cyst (radicular cyst). It is difﬁcult to differentiate periapical granulomas from periapical cysts by radiological examinations (Fig. 15). Prior endodontic treatment or apical surgery can leave a dense fibrous scar which appears as periapical radiolucency and can look like periapical rarefying osteitis. Thus, in such cases, diagnosis cannot be made on radiographic grounds alone, the clinical signs and symptoms should be taken into account. In our study we did not correlate radiographic features and clinical symptoms. Thus we could not sort out the periapical inflammatory lesions.

Patel et al.10 found CBCT to be clinically superior to periapical radiography for the detection of periapical lesions in a literature review of CBCT applications to endodontics.

Nakata et al.5 found that CBCT may detect the presence of previously undiagnosed periapical disease where prior clinical evaluation and conventional radiographic findings failed to

23 reveal the pathology. It has also been suggested that three-dimensional CBCT may detect periapical findings earlier and more accurately than conventional radiographs.6 Periapical findings require management. Timely intervention could prevent and reduce spread of infection. Referral for intervention or at least further investigation such as pulp testing was recommended for our cases.

Two cases of root fracture were detected in two patients. Both cases were associated with the upper left central incisor (Fig. 16 and 17). In one case, root perforation or fracture was associated with the post in a tooth (Fig. 16). Most root fractures occur in the maxillary central incisor. Early detection and treatment is essential in order to minimize the risk of complications resulting from root fractures.62

Dental developmental findings

In the present study, developmental findings accounted for 6 (0.7%) of the total findings in four patients, all representing supernumerary teeth. We found four impacted microdonts in the maxillary central incisor regions in three patients and two microdonts distal to the third molars bilaterally (distodens) in a patient (Fig. 18 and 19). This is an unusual case of bilateral involvement.

In the literature, the majority of the supernumerary impacted teeth lay palatal to the central incisors.63 In our study, the three microdonts were located palatally in two patients, and another one in an edentulous area. The most common location is the maxillary anterior region, followed by the maxillary premolar region, mandibular premolar region, maxillary molar region, mandibular molar region, and mandibular anterior region.

Complications associated with supernumerary teeth such as mesiodens include dental impactions, delayed or ectopic eruption of adjacent teeth, crowding or alteration of the position of teeth, malocclusion and disruption in tooth spacing, external root resorption and the formation of follicular cysts (dentigerous formation). 63-65

Treatment of supernumerary teeth depends on their type and position, and their effect on adjacent teeth. Early diagnosis and early treatment are important to minimize the risk of complications.65

Pathological findings

We found one case of a fibro-osseous lesion (0.1%) in a 39 year old female who underwent the CBCT imaging for dental implant planning (Fig. 20). Florid cemento-osseous dysplasia (FCOD) involved three quadrants of her jaws. Diagnosis was made based on radiographic findings of CBCT imaging. Radiographic imaging such as computed tomography accurately depicts the features of the fibro-osseous and cementum-containing lesions.66 It rarely produces symptoms and is found incidentally during a radiographic examination.28 Under normal circumstances, FCOD does not require treatment. However, regular follow-up with consecutive radiographs is recommended to see the changes of radiographic features.28, 67 No other pathological findings such as dentigerous cyst, nasopalatine duct cyst, residual cyst and odontoma were detected.

The limitation of this study is that there is no independent review of the scans by a second reader. All CBCT scans were analyzed by the author who is a third year oral maxillofacial radiology resident. However, board certified oral maxillofacial radiologists that

25 comprise the study committee were consulted for doubtful cases. In order to improve accuracy and thoroughness, each CBCT scan was reviewed three different times on separate occasions. Another limitation is that no prior clinical, radiographic or histologic information was obtained or reviewed to determine whether the CBCT findings had already been diagnosed or detected in those prior evaluations. However, this comparative analysis was outside the scope of this study. Future studies may be designed to explore this aspect. Finally, there were no clinical correlations of the CBCT findings as this study exclusively evaluated the images, and did not include clinical encounters.

CONCLUSION

This study confirms the frequent presence of incidental findings in maxillofacial

CBCT scans. This finding underscores the need for general dental practitioners and oral and maxillofacial radiologists to search for clinically significant lesions (outside of the primary indication) that require interventions, monitoring, or a referral to other specialists in all

CBCT scans. Correct identification of incidental findings will reduce unnecessary further diagnostic tests and evaluation for lesions that require no intervention or treatment. A careful and thorough interpretation of the CBCT images beyond the region of interest is necessary to avoid overlooking occult pathology which can have health consequences for the patient.

FIGURES

90 79 80

60 57

50 47

40 31 29 28 30

Number of patients patients of Number 23 20

10 5 1 0 Below (10-19) (20-29) (30-39) (40-49) (50-59) (60-69) (70-79) (80-89) 10 yrs yrs yrs yrs yrs yrs yrs yrs yrs

Fig. 1. Age distribution of patients

Impacted teeth Orthodontic 3% A combination applications 5% of diagnostic Pathology tasks 1% 7%

TMJ analyses Implant 11% treatment planning 73%

Fig. 2. Indications of the CBCT scans

40.0% 35.0% 35.0%

30.0%

25.0% 20.0% 20.0% 17.5% 15.4% 15.0% 11.3% 10.0%

5.0%

Percentage of incidental findings incidental of Percentage 0.7% 0.1% 0.0%

Fig. 3. Frequency distribution of incidental findings

16%

Definitive Intervention or Referral 16% Monitoring

No intervention or referral

68%

Fig. 4. Clinical significance of the incidental findings

Fig. 5. CBCT images (correlated orthogonal planes-axial, coronal, sagittal and custom section) demonstrate a generalized mucosal thickening of bilateral maxillary sinuses.

Fig. 6. CBCT images (correlated orthogonal planes - axial, coronal, sagittal and custom section) demonstrate thickening of the floor of maxillary sinus mucosa in the left antrum. This correlates with a widened apical periodontal ligament space of the distal buccal root of tooth No. 14. Further investigation such as pulp testing of this tooth was recommended.

Fig. 7. CBCT images (correlated orthogonal planes- axial, coronal, sagittal) demonstrate pansinusitis involving mucosal thickening of sinuses involving sphenoid, ethmoid and maxillary sinuses.

Fig. 8. CBCT images (correlated orthogonal planes-axial, coronal, sagittal and custom section) demonstrate oro-antral osseous fistula present in the floor of the sinus in tooth No. 14 area.

Fig. 9. CBCT images (correlated orthogonal planes - axial, coronal, sagittal and custom section) demonstrate a mild generalized thickening of the mucosal lining the inferior portion of the left maxillary sinus associated with an antrolith.

Fig. 10. CBCT images (correlated orthogonal planes - axial, coronal, sagittal and custom section) demonstrate sialoliths in the right submandibular gland.

Fig. 11. CBCT images (correlated orthogonal planes - axial, coronal, sagittal and volume rendering) demonstrate bilateral calcified carotid atheroma. Bilateral irregular calcifications at the C3-C4 level of the carotid space are consistent with calcified cartotid atheroma. This finding should be shared with the patient’s physician for assessment of carotid artery stenosis and possible need for intervention to reduce stroke risk.

Fig. 12. Sirona Galileos three-dimensional CBCT depiction of osteoma in the right ethmoid sinus.

Fig. 13. TMJ views of CBCT images depict signs of severe denegerative joint disease of the temporomandibular joints. (Upper panel shows parasagittal slices of the right TMJ, the middle panel shows parasagittal slices of the left TMJ, and the lower panel shows axial slice in the center). This patient obtained CBCT for dental implant planning. Signs of TMJ degenerative disease include flattening, sclerosis, erosion, osteophytes, and subcondylar pseudocysts.

Fig. 14. TMJ views of CBCT images depict signs of denegerative joint disease of temporomandibular joints: flattening, erosion, subcondylar pseudocyst and osteophytes.

Fig. 15. CBCT images (correlated orthogonal planes - axial, coronal and sagittal) demonstrate the periapical lesions associated with tooth No. 15 and No. 16.

Fig. 16. CBCT images (axial and cross-sectional views and cropped reconstructed panoramic x-ray) demonstrate a case of root perforation or fracture associated with the post in a tooth.

Fig. 17. Sirona Galileos three-dimensional CBCT depiction of a case of root fracture associated with upper right central incisor.

Fig. 18. CBCT images (correlated orthogonal planes - axial, coronal and sagittal) demonstrate the two supernumerary microdont teeth just palatal to the root of maxillary right central incisor.

Fig. 19. Sirona Galileos three-dimensional CBCT depiction of the two supernumerary teeth: one buccal to the right maxillary third molar and one buccal to the left maxillary third molar.

Fig. 20. Panoramic reconstructed image from CBCT scan depicts florid cemento-osseous dysplasia.

TABLES

Table I. Descriptive analysis and frequency of the incidental findings from 300 CBCT scans

General Incidental findings No. (%) of No. of patients category incidental with incidental findings findings I Airway Sinusitis 125 (14.2) 83 Pansinusits 7 (0.8) 7 Mucous retention pseudocyst 51 (5.8) 44 Antral polyps 46 (5.2) 44 Concha bullosa 65 (7.4) 65 Oroantral fistula 9 (1.0) 8 Antrolith 5 (0.6) 5 II Soft Tissue Sialoliths 2 (0.2) 2 Calcifications Carotid artery calcifications 13 (1.5) 13 Intracranial calcifications of the internal 4 (0.5) 4 carotid artery Ossification of stylohyoid ligament 80 (9.0) 80 Tonsilloliths 43 (4.9) 43 Calcified thyroid cartilages/Triticeous 34 (3.9) 34 cartilage III Bone Idiopathic osteosclerosis/Enostoses 59 (6.7) 59 Torus palatinus 45 (5.1) 45 Mandibular Tori 39 (4.5) 39 Exostoses 9 (1.0) 9 Osteoma 1 (0.1) 1 Stafne bone defect 1 (0.1) 1 IV TMJ TMJ condyle flattening 50 (5.7) 33 TMJ subchondral sclerosis 10 (1.1) 8 TMJ condyle erosion 34 (3.9) 24 Subchondral pseudocyst 24 (2.7) 17 Osteophyte 17 (1.9) 12 Bifid condyle 1 (0.1) 1 V Endodontic Periapical rarefying osteitis 50 (5.7) 38 Periapical rarefying and sclerosing osteitis 30 (3.4) 25 Periapical sclerosing osteitis 18 (2.0) 16 Root fracture 2 (0.2) 2 VI Dental Supernumerary teeth 6 (0.7) 4 developmental VII Pathological Pericoronal radiolucency presumed 0 (0) 0 dentigerous cyst Radiolucency at nasopalatine canal 0 (0) 0 presumed nasopalatine duct cyst Residual radiolucency presumed residual 0 (0) 0 cyst Odontoma 0 (0) 0 Florid cemento-osseous dysplasia 1 (0.1) 1

Table II. Number of patients having incidental findings under general categories

General categories of incidental findings Number (%) of Number of patients with incidental findings incidental findings Airway 308 (35.0) 188 Soft tissue calcifications 176 (20.0) 138 Bone 154 (17.5) 111 TMJ 136 (15.4) 45 Endodontic 100 (11.3) 69 Dental developmental 6 (0.7) 4 Pathological 1 (0.1) 1

APPENDICES

Appendix A. Radiographic criteria used for recording of incidental findings (Modified from the textbook by White and Pharaoh)

General Incidental findings Criteria category I Airway Sinusitis Dense thickened mucosal lining along the sinus floor

Pansinusitis Inflammation of paranasal sinuses on one or both sides

Mucous retention Well-defined, non-corticated, smooth, dome- pseudocyst shaped radiopaque soft tissue mass in sinus

Antral polyps Polypoid thickening of mucous membrane in sinus

Concha bullosa Pneumatization of the nasal concha

Oroantral fistula Abnormal communication between the maxillary sinus and oral cavity

Antrolith A homogenous or heterogeneous radiopacity of calcified density in the maxillary sinuses

II Soft Tissue Sialoliths Radiopaque masses in the area of ducts of salivary Calcifications gland or the gland itself

Carotid artery Multiple and irregular radiopacities in the carotid calcifications space at the level of cervical vertebrae C3, C4

Intracranial Calcifications in intracranial internal carotid calcifications of the artery region internal carotid artery

Ossification of The linear ossification of stylohyoid or stylohyoid ligament stylomandibular ligaments

Calcified thyroid Calcifications of thyroid cartilage and the small cartilages/ Triticeous and paried triticeous cartilage located within the cartilage lateral thyrohyoid ligaments

Tonsilloliths Dystrophic calcification in the tonsillar crypts

III Endodontic Periapical rarefying Radiolucent appearance of bone at the apex of the osteitis tooth of inflammatory origin

Periapical rarefying and A mixture of sclerosis (radiopaque) and

sclerosing osteitis rarefaction (radiolucent) of bone in association with the apex of the tooth of inflammatory origin

Periapical sclerosing Sclerotic (radioapque) region of bone associated osteitis with the apex of the tooth of inflammatory origin

Root fracture A radiolucent line or lines on the image of a tooth

IV Bone Dense bone island Radiopaque change of bone, ie, condensation of (Periapical idiopathic trabecular bone that are not the sequelae of osteosclerosis) infection or systematic disease

Enostoses Thickening of inner surface of either the buccal or lingual cortical bone

Torus palatinus A protuberance (hyperostosis) in the middle third of the midline of the hard palate

Mandibular tori Hyperostosis from the lingual aspect of the mandibular alveolar process

Exostoses Small regions of osseous hyperplasia of cortical bone and occasionally cancellous bone on the surface of the alveolar process

Osteoma A radiopaque mass with well-defined border composed of compact and cancellous bone arising from walls of sinuses

Stafne bone defect A defined corticated radiolucency along the inferior cortex of the mandible below the inferior alveolar nerve (IAN) canal

V TMJ TMJ condyle flattening A flat bony contour deviating from the convex form

Subchondral sclerosis An area of increased density of cortical bone extending into the bone marrow

Subchondral pseudocyst Small, round, radiolucent areas with irregular margins surrounded by an area of increased density

TMJ condyle erosion Loss of cortex or erosions of the articulating surfaces of the condyle

Osteophyte Bony proliferation occurring at the periphery of the articulating surface

Bifid condyle TMJ condyle having a notich, or deep cleft resulting in the appearance of a bifid condylar 49

head

VI Dental Supernumerary teeth Teeth that develop in addition to the normal developmental complement

Mesiodens Supernumerary teeth found between the maxillary central incisors

Peridens Supernumerary teeth that develop in the premolar area

Distodens Supernumerary teeth that occur in the molar area

VII Pathological Pericoronal radiolucency Radiolucent zone of more than 5 mm with well- presumed dentigerous defined borders around the crown of an unerupted cyst tooth with margins at the cementoenamal junction

Radiolucency in the Radiolucency of cystic appearance in the nasopalatine duct nasopalatine canal or duct in the maxillary presumed nasopalatine midline duct cyst

Residual radiloucency Radiolucency of cystic appearance most presumed residual cyst commonly after extraction of a tooth

Odontoma A mixed density lesion radiographically characterized by the components of a tooth or irregular mass of calcified tissues in association with the crown of an unerupted tooth

Florid cemento-osseous A widespread form of mixed density lesions at the dysplasia apex of tooth affecting three or more quadrants in both jaws

Appendix B. Indications for the CBCT scans

Indications for the CBCT scans N (%) Dental implant treatment planning 218 (73%) TMJ analyses 33 (11%) Pathology 21 (7%) Orthodontics applications 15 (5%) Impacted teeth 10 (3%) A combination of diagnostic tasks 3 (1%)

Appendix C. Clinical significance of the incidental findings

General category of Incidental findings No. of No of incidental findings incidental patients findings (%) I) Intervention or Total 142 (16.1) referral Dental developmental Supernumerary teeth 6 (0.7) 4 Endodontic Periapical rarefying osteitis 50 (5.7) 38 Periapical rarefying and sclerosing osteitis 30 (3.4) 25 Peripaical sclerosing osteitis 18 (2.0) 16 Root fracture 2 (0.2) 2 Airway Antroliths 5 (0.6) 5 Oroantral fistula 9 (1.0) 8 Pansinusitis 7 (0.8) 7 Sialoliths 2 (0.2) 2 Calcifications Carotid artery calcification 13 (1.5) 13 Pathology Pericoronal radiolucency presumed 0 (0) 0 dentigerous cyst Radiolucency around nasopalatine canal 0 (0) 0 presumed nasopalatine duct cyst Periapical residual radiolucency presumed 0 (0) 0 residual cyst Odontoma 0 (0) 0 II) Monitoring Total 137 (15.6) Bone Osteoma 1 (0.1) 1 Pathology Florid cemento-osseous dysplasia 1 (0.1) 1 TMJ TMJ flattening 50 (5.7) 33 TMJ subchondral sclerosis 10 (1.1) 8 TMJ erosion 34 (3.9) 24 TMJ subchondral pseudocyst 24 (2.7) 17 TMJ osteophytes 17 (1.9) 12 III) No intervention or Total 602 (68.3) referral Bone Idiopathic osteosclerosis/Enostoses 59 (6.7) 59 Torus palatinus 45 (5.1) 45 Mandibular tori 39 (4.5) 39 Exostosis 9 (1.0) 9 Stafne bone defect 1 (0.1) 1 Airway Sinusitis 125 (14.2) 83 Mucous retention pseudocyst 51 (5.8) 44 Antral polyp 46 (5.2) 44 Concha bullosa 65 (7.4) 65 TMJ Bifid condyle 1 (0.1) 1 Calcifications Intracranial calcifications of the internal 4 (0.5) 4 carotid artery Ossification of stylohyoid ligament 80 (9.0) 80 Tonsilloliths 43 (4.9) 43 Calcified thyroid cartilage/Triticeous cartilage 34 (3.9) 34

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