Journal of Indian Academy of Oral Medicine and Radiology

: 2018  |  Volume : 30  |  Issue : 3  |  Page : 223--229

Unintended and unexpected incidental findings on cone beam computed tomography: A retrospective study of 1500 scans

Shalu Rai, Deepankar Misra, Mukul Prabhat, Mansi Khatri, Priyank Mallick, Ayush Dhawan 
 Department of Oral Medicine and Radiology, Institute of Dental Studies and Technologies, Ghaziabad, Uttar Pradesh, India

Correspondence Address:
Dr. Shalu Rai
Department of Oral Medicine and Radiology, Institute of Dental Studies and Technologies, Kadrabad, Modinagar, Ghaziabad - 201 201, Uttar Pradesh


Introduction: Cone beam computed tomography (CBCT) has revolutionized the field of oral radiology. With the detailed three-dimensional views of dental tissues, incidental findings which were once considered abnormalities present outside the area of interest can now be recognized. Here, we report various incidental findings found on CBCT. Materials and Methods: This retrospective study consisted of 1500 CBCT scans. Different fields-of-view ranging from 5 × 5 to 11 × 13 were selected. Age group of the subjects included in the study was 5 to 89 years. All incidental findings were categorized in seven groups according to the area and nature of pathology – dento-alveolar region, cysts and tumors, nasal and sinus pathologies, supernumerary and impacted teeth, artifacts, temporomandibular joint (TMJ) region, and miscellaneous. Results: Out of 1500 patients, 723 (48.2%) were males and 777 (51.8%) were females. Mean age of patients referred for CBCT was 47.08 years. Most frequently referred patient age group was 60–69 years (19.75%). Eighty-nine percent of the subjects showed incidental findings. Total number of incidental findings was 2734. The most common area showing incidental findings was dento-alveolar area (44.3%), the least number of findings were seen in the TMJ area (0.4%). Most common finding was mucositis/mucous retention cyst (83.4%) whereas the least finding found was odontogenic keratocyst cyst and coronoid hyperplasia (0.6%). Conclusion: The full CBCT dataset should be fully examined and interpreted by Oral Maxillofacial Radiologists. Correct identification of various potentially pathological lesions outside the area of interest on CBCT scan should be reported and documented.

How to cite this article:
Rai S, Misra D, Prabhat M, Khatri M, Mallick P, Dhawan A. Unintended and unexpected incidental findings on cone beam computed tomography: A retrospective study of 1500 scans.J Indian Acad Oral Med Radiol 2018;30:223-229

How to cite this URL:
Rai S, Misra D, Prabhat M, Khatri M, Mallick P, Dhawan A. Unintended and unexpected incidental findings on cone beam computed tomography: A retrospective study of 1500 scans. J Indian Acad Oral Med Radiol [serial online] 2018 [cited 2021 Nov 30 ];30:223-229
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Full Text


Cone beam computed tomography (CBCT) in recent years has gained popularity among dental practitioners and has become a preferred three-dimensional, diagnostic imaging modality in the maxillofacial region.[1],[2] Unlike traditional two-dimensional radiographic techniques, structural superimpositions, image enlargement, and distortions are absent in CBCT.[3],[4],[5] Moreover, CBCT allows precise three-dimensional visualization of maxillofacial structures at a lower radiation dose in comparison to computed tomography (CT).[6],[7] It has a wide array of applications in different specialties of dentistry, and has many advantages over other two-dimensional and three-dimensional imaging modalities. With the increase in field-of-view (FOV), incidental findings have increased considerably.[8],[9] Incidental findings were defined as abnormal findings that exist outside the specific region of interest and are detected by CBCT covering the entire skull.[10] They are also defined as findings that are unrelated to the present illness and are discovered unintentionally.[11] According to Cha et al.,[12] incidental findings are defined as any and all discovered finding detected by CT, magnetic resonance imaging (MRI), CBCT, or any other imaging modalities that are unrelated to the clinical indication for the imaging being performed.

The presence of these incidental findings may raise concerns about the need for further diagnostic tests or referral to other specialists. According to the American Academy of Oral and Maxillofacial Radiology (AAOMR) and the the European Academy of Dento-Maxillofacial Radiology (EADMFR), a clinician needs to fully examine and interpret the whole CBCT dataset. If the clinician is not an expert in interpreting the entire dataset, a referral is required for a review by oral and maxillofacial radiologists.[3]

This retrospective study aimed to determine the prevalence of incidental findings in a large sample of CBCT scans with a large FOV, thereby emphasizing the importance of interpretation of all areas visualized on the scan.

 Materials and Methods

Source of the scans: The research was carried out on 1500 randomly selected CBCT scans from a private imaging centre. Scans were taken using New Tom Giano extended volume CBCT machine. Specifications of the CBCT machine were 60–90 kV (max), pulsed mode was used for three-dimensional modality, Current was 2–15 mA (max), focal spot size was 0.5 mm, Gray scale was 16 bits, and voxel size was 100–200 μm voxel. NNT Software version 6.1 (installation package:6.1.0) QR Sri Company, Verona, Italy was used for the study.

Institutional review and ethical board approval was taken for the use of information on the scans for the study. Consent was obtained from all the subjects as well as the private imaging company to use and share the information from the scan for purposes of education, including teaching and research.

FOV and time of the scans: The scans had different FOVs according to their indication for which the scan was obtained. The scan time also varied with the size of the FOVs. It ranged from 5 × 5 to 11 × 13. Slice thickness was constant at 0.3 mm.

Age and reason for the scan

Subjects aged 5–89 years were included in the study. Scans indicated for evaluation of maxillary and mandibular pathology, temporomandibular pathologies, sinus pathologies, orthodontic treatment, implant assessment, and calcifications were enrolled in the study [Table 1].{Table 1}

Study design: 1500 CBCT scans were studied including dentulous, partially edentulous, and completely edentulous subjects of maxilla and mandible. Any pathologies or anatomical variant findings observed outside or inside the area of interest excluding the pathology, for which the scan was advised, was considered as an incidental finding. All incidental findings were taken twice by an experienced oral maxillofacial radiologist at an interval of 2 weeks. All the findings were divided into seven categories according to the area involved, namely, dento-alveolar region, cysts and tumors, nasal and sinus pathology, supernumerary and impacted teeth, artefact, temporomandibular joint (TMJ) region, and miscellaneous. Diagnosis of incidentally found diseases was made purely on the basis of radiographic features.


Out of 1500 patients, 723 (48.2%) were males and 777 (51.8%) were females. The mean age of patients referred for CBCT was 47.08 years. Most frequently referred patient age group was the 60–69-year age group (19.75%). Eight-nine percent of the subjects showed incidental findings. The total number of incidental findings was 2477. The most common area showing incidental findings was dento-alveolar area (48.9%), the least number of findings were seen in the TMJ area (0.4%). Most common finding was mucositis/sinusitis (83.4%) whereas the least common finding was odontogenic keratocyst cyst, antrolith, and coronoid hyperplasia (0.6%) [Table 2].{Table 2}


In this study, out of the 1500 CBCT scans reviewed, 89.34% subjects revealed a total of 2477 incidental findings, i.e., average of 1.7 findings per scan. In other studies, the rate of overall incidental findings varied from 24.6% to 92.8%.[1],[10],[11],[12] This is due to differences in age groups, demographics of patient studies, and categories of findings that were reported.

Our study is apparently the largest study examining incidental findings using 1500 subjects compared to the studies by Price et al.,[13] Cha et al.[12] and Pette et al.[3] Rheem et al.,[2] Barghan et al.,[14] Warhekar et al.[15] and Allareddy et al.[1] having sample size 300, 500, 318, 147, 400, 795, and, 1000 respectively. Large sample sizes justify the need to review incidental findings on CBCT, as some rare diseases and findings can be visualized when a large sample size is used. Some findings of our study are rare, but at the same time can be fatal. In our study, we included scans done for various indications [Table 1] with different FOV sizes to include large varieties of incidental findings among wide patient age groups compared to studies that have only taken scans done for one specific purpose (e.g., orthodontic purposes).[10],[16],[17]

The highest rate of incidental findings by Cha et al. was in the airway area (18.2%) followed by TMJ findings (3.4%), endodontic findings (1.8%), and others (1.2%).[12] However, the most frequent incidental finding in our study was dento-alveolar region (48.9%) followed by nasal and sinus pathologies (25.2%). The reasons for variations in the prevalence rates of different findings between this study and previous studies can be geographical variations and number of scans with different FOVs.

In previous studies, findings in dento-alveolar region varied from 6.29% to 34.01%.[3],[4],[13] Most of them are asymptomatic clinically, but some of them, e.g., root fragments, periapical abscess, etc. can become symptomatic in later stages. Hence, these incidental findings need monitoring and reporting[2] [Figure 1].{Figure 1}

In our study, findings of nasal and sinus region were the second most common group (28.3%). Other studies showed the prevalence of findings in nasal and sinus pathologies between 18% and 51.8%.[3],[4],[9],[12],[13] The most common finding was mucositis/mucous retention cyst (83.4%) [Figure 2]. Findings in this region are very critical when planning for an implant in the posterior maxillary region. Postoperative complications after implant placement as well as grafting procedures depend upon the patency of osteomeatal complex.[18] The presence of anatomical variations within the maxillary sinus, such as septa, has been reported to increase the risk of sinus membrane perforation during the surgical sinus elevation procedure. Findings such as deviated nasal septum and concha bullosa [Figure 3] can predispose patients to obstruction of sinuses, leading to chronic sinusitis.[19],[20] Calcifications of sinus that is antrolith [Figure 4] were also reported. It may increase the risk of complications following implant or any other surgical procedures done in sinus vicinity. Therefore, patients with nasal findings should be carefully reviewed for the presence or absence of sinusitis.[20]{Figure 2}{Figure 3}{Figure 4}

In our study, 7.4% findings were incidentally found cysts and tumors. Highest occurrence (55.9%) of periapical cyst was found. Rarest among all were dentigerous cyst [Figure 5] and stafne's bone cyst [Figure 6] with 1% incidence. Most common (23.9%) incidentally found tumor was odontoma [Figure 7]. These cysts and tumors can cause maxillary and mandibular resorption and expansion at a later date, hence, it is important to report. One case of unknown osteolytic lesion was also observed in the vicinity of an extracted tooth socket [Figure 8].{Figure 5}{Figure 6}{Figure 7}{Figure 8}

Prevalence of supernumerary/impacted tooth in our study was 7%. Incidence reported in the study of Fardi et al. was 13.7%.[21] Most commonly impacted teeth were maxillary and mandibular third molar (39.7%). In our study, we recorded one case with an impacted canine along with supernumerary tooth [Figure 9], and another case of a fourth molar present distal to the third molar reported as distomolar [Figure 10].{Figure 9}{Figure 10}

In our study, incidental findings occurring in the TMJ region was 0.4%. Previous studies reported it to be in the range of 2.6% to 26.5%.[3],[4] Patients showing any incidental pathological finding in TMJ region could be symptom free clinically and may not be experiencing any TMJ dysfunction. These patients must be educated and monitored by the clinician as they are showing incidental findings, which can act as a predisposing factor for other pathologies. Patients presenting with symptoms such as pain and limitation of mandibular function require a complete work-up and comprehensive TMJ analysis.[13] A study reported how an incidental finding affected the treatment plan of a 60-year-old patient who was scanned for implant planning which showed an unilateral (left) mediolateral bifid condyle. As a result, the implant was not indicated in that patient.[13]

Miscellaneous findings in our study comprised 2%. It included broken instrument (Reamer) lying in the soft tissue [Figure 11], spilled out root canal filling material in the periapical region [Figure 12], and enamel pearl [Figure 13]. One interesting incidental finding observed in this category was an osteolytic lesion present on the anterior palatal area [Figure 14]. Cases like palatal resoprtion need a complete evaluation to diagnose any lethal disease. Another case of implant impinging on the nerve was also observed [Figure 15]. These findings may give us a clue to unexplained paresthesia or any other symptoms reported in postimplant recall visits.{Figure 11}{Figure 12}{Figure 13}{Figure 14}{Figure 15}

In our study, we found very few patients with obstruction of airways or hypertrophy of palatine tonsil or adenoids. Airway obstructions can lead to obstructive sleep apnea (OSA).[3] Price et al. have showed incidental finding in airways in 7.86% of the total subjects.[13] Hence, CBCT can serve as a screening tool for patients indicated for sedation during dental procedures. This is important because some sedative agents and narcotics may exacerbate the risk for apnea in patients with airway obstruction.[3]

Other interesting incidental findings observed in our cases were sialolith in the submandibular gland region [Figure 16], pulp stones [Figure 17], and double mental foramen [Figure 18].{Figure 16}{Figure 17}{Figure 18}


As oral radiologists or dentists, these medical conditions are out of our domain and we are not expected to treat them. However, it is our moral responsibility to identify these potential pathologies by carefully interpreting areas of CBCT scan other than the area of interest. These findings can help us in preventing postoperative complications even after dental surgeries. In conclusion, oral radiologists and dentists should be attentive to these incidental findings and comprehensively evaluate the complete image to avoid over or underestimation of the underlying diseases to provide complete health care for patients.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.


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