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CASE SERIES
Year : 2020  |  Volume : 11  |  Issue : 1  |  Page : 54-59

Conventional radiograph and cone-beam computed tomography in the evaluation of odontogenic cysts and tumors - An analysis of seven cases


Department of Oral Medicine and Radiology, Mahatma Gandhi Postgraduate Institute of Dental Sciences, Puducherry (UT), India

Date of Submission18-Dec-2019
Date of Acceptance23-Jan-2020
Date of Web Publication11-Mar-2020

Correspondence Address:
Dr. Durgadevi Boopathi
Department of Oral Medicine and Radiology, Mahatma Gandhi Postgraduate Institute of Dental Sciences, Puducherry (UT)
India
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DOI: 10.4103/srmjrds.srmjrds_90_19

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  Abstract 

Introduction: Odontogenic cysts and tumors are the most common pathologies affecting the jaws. Radiographic evaluation of cysts and tumors is an important aspect of diagnosis and surgical treatment planning. Cone-beam computed tomography (CBCT) provides three-dimensional views of cysts and tumors regarding accuracy and quality of interpretation. Aim and Objective: The aim of the study is to determine the radiographic features of odontogenic cysts and tumors in conventional radiograph and in CBCT and to assess the advantages of CBCT over conventional radiography in the evaluation of cysts and tumors. Materials and Methods: All types of odontogenic cysts and tumors in both males and females were included. Nonodontogenic cysts and tumors were excluded. Conventional radiograph and cone-beam computed tomographic images of seven patients who had histopathologically confirmed odontogenic cysts and tumors were retrospectively reviewed from the archives of the department of oral medicine and radiology in the institution. Conclusion: In this radiographic study, the advantages of CBCT in the assessment of extent, effect on surrounding structures and internal structure of odontogenic cysts and tumors were determined, and specific advantages of CBCT were ascertained.

Keywords: Cone-beam computed tomography, odontogenic cysts, odontogenic tumors


How to cite this article:
Boopathi D, Kumaran JV, Vasudevan SS, Mariappan JD. Conventional radiograph and cone-beam computed tomography in the evaluation of odontogenic cysts and tumors - An analysis of seven cases. SRM J Res Dent Sci 2020;11:54-9

How to cite this URL:
Boopathi D, Kumaran JV, Vasudevan SS, Mariappan JD. Conventional radiograph and cone-beam computed tomography in the evaluation of odontogenic cysts and tumors - An analysis of seven cases. SRM J Res Dent Sci [serial online] 2020 [cited 2020 Jun 3];11:54-9. Available from: http://www.srmjrds.in/text.asp?2020/11/1/54/280380


  Introduction Top


Odontogenic cysts and tumors are common pathologies affecting the jaws. It has been found that the distribution of the cysts affecting the jaws were radicular cysts 56%, dentigerous cysts 17%, nasopalatine duct cysts 13%, odontogenic keratocysts 11%, globulomaxillary cysts 2.3%, traumatic bone cysts 1.0%, and eruption cysts 0.7%.[1] The conventional radiography is being used in the assessment of odontogenic cysts and tumors for decades till now. Cone-beam computed tomography (CBCT) provides three-dimensional (3D) views of cysts and tumors, which provides furthermore accuracy and finer quality of interpretation. The most significant advantage is the acquisition of images with higher diagnostic quality using submillimeter resolution with lower doses of radiation.[2] Many studies proved that the accuracy of CBCT in diagnosis was compared or higher than multislice computed tomography because it has high resolution and small voxel size <0.3 mm, and it could produce 160–360 slices with high resolution compared with multidetector computed tomography. CBCT yields greater accuracy with <1% error when compared to the gold standard method in measuring osseous components.[3] In this study, the distinct cone-beam computed tomographic features of odontogenic cysts and tumors that are distinguished from conventional radiographs were studied and are matched with the histopathologic diagnosis.

Inclusion criteria

  • All types of odontogenic cysts and tumors in both males and females.


Exclusion criteria

  • Nonodontogenic tumors.



  Materials and Methods Top


  • Conventional radiograph and CBCT images of seven patients who had histopathologically confirmed odontogenic cysts and tumors, after obtaining informed consent, were retrospectively reviewed from the archives of the department of oral medicine and radiology in the institution
  • The 3D images were recorded using (PAX-i3D, vatech-Korea), a flat panel-based CBCT machine. The device was operated at 10 mA and 90 kV, 0.5 mm focal spot, 0.12 mm voxel size, and a typical exposure time of 15 s. On completion, the image was processed using application software
  • Orthopantomogram were recorded with PM 2002, EC Proline Panoramic X-ray unit. The device was operated at 8 mA, Kvp 72, exposure time 18 s. On completion, the image was manually processed.


Case 1

A 32-year-old male patient visited our institution with the complaint of pain and swelling in the left lower back teeth area for the past 1 month, associated with a restricted mouth opening of about 11 mm and restricted lateral and protrusive movements of the jaw. No relevant medical history was reported by the patient. Clinically missing 38 was observed. On the basis of history and clinical examination, a provisional diagnosis of infected dentigerous cyst in relation to 38 was arrived.

The patient was subjected to radiographic examination, panoramic radiograph revealed unilocular radiolucency involving the entire left ramus and angle of mandible, involving whole anterior border of the ramus of mandible, coronoid, and condylar process with horizontally impacted single-rooted 38, crown facing distally and root facing mesially. The inferior alveolar nerve canal could not be traced [Figure 1]a.
Figure 1: (a) Orthopantomogram. (b) Cone-beam computed tomography axial section. (c) Cone-beam computed tomography three-dimensional reconstruction

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Whereas CBCT axial section revealed bicortical expansion with perforation in multiple sites. Coronal and sagittal section revealed thin septa in internal structure and destruction of the coronoid and condylar process. The localization of the impacted teeth and anteroposterior angulation was evident, which correlated with 3D reconstruction [Figure 1]b and [Figure 1]c. The radiographic diagnosis arrived was ameloblastoma and its variants, and the final histopathological diagnosis was ameloblastic carcinoma.

Case 2

A 33-year-old male patient came to our institution with a complaint of swelling in lower jaw for the past 9 months. He also presented with a history of trauma 20 years back. The swelling was not associated with pain, numbness, or paresthesia. There was no associated medical history.

On clinical examination, distal tipping of 32 on mesial tipping of 33 was evident. On vitality testing, 42, 41, 31, and 32 were found non vital.

On the basis of history and clinical examination, we arrived at a provisional diagnosis of inflammatory odontogenic cyst most probably radicular cyst in relation to 42, 41, 31, and 32.

Mandibular anterior occlusal radiograph revealed well-defined radiolucency in anterior mandible, extending periapical aspect of teeth 31, 32, 33, and displacement of teeth 32, 33 was evident.

Panoramic radiograph [Figure 2]a revealed unilocular radiolucency in anterior mandible with distinct sclerotic borders. The displacement of teeth 32, 33 was present. Root resorption was evident in teeth 42, 41, 31, 32, 33, 34, 35.
Figure 2: (a) Orthopantomogram. (b) Cone-beam computed tomography axial section

Click here to view


CBCT axial section [Figure 2]b revealed bicortical expansion with thinning of cortex and perforation. Varying sections revealed multiple thin septa in the internal structure.

The radiographic diagnosis arrived was odontogenic tumor, based on these findings and the histopathological diagnosis was plexiform ameloblastoma.

Case 3

A 35-year-old male patient came to our institution with a chief complaint of swelling in the right lower posterior teeth area for the past 15 days. The patient also gave the previous history of extraction and surgical procedure in the same region 10 years before. No relevant medical history. Clinically, missing teeth 48 with swelling in relation to edentulous area of 48 was present, which extends to retromolar area posteriorly.

On the basis of history and clinical examination, a provisional diagnosis of recurrent odontogenic keratocyst was arrived.

Mandibular right lateral occlusal radiograph [Figure 3]b revealed multilocular radiolucency extending in buccal aspect in relation to 46 and posteriorly to retromolar area. The full extent of the radiolucency was not covered. The mild buccal cortical expansion was evident.
Figure 3: (a) Orthopantomogram. (b) Mandibular cross-sectional occlusal radiograph. (c) Cone-beam computed tomography axial section

Click here to view


Orthopantomogram [Figure 3]a revealed well-defined unilocular radiolucency in the right body of the mandible extending anteriorly from distal aspect of 34, posteriorly up to junction of body and angle of the mandible, superiorly extending into periapical aspect of 35, 36, 37 and retromolar area. Inferiorly toward lower border of mandible, but cortex seemed unaffected. Missing teeth 48 and apical root resorption of teeth 45, 46, 47 were evident.

CBCT axial section [Figure 3]c revealed full extent of lesion with septa and multilocularity. Mild bicortical expansion with distinct feature showed even small locules.

The radiographic diagnosis arrived was odontogenic keratocyst, and histopathological diagnosis supported the same.

Case 4

A 21-year-old female patient came with the chief complaint of pain and swelling in relation to the left upper posterior teeth for the past 3 years. She was diagnosed with a cystic lesion, and surgical excision of the cystic lesion and extraction of the associated tooth was done 6 years before. Based on history and clinical examination, we arrived at a provisional diagnosis of residual cyst.

OPG [Figure 4]a revealed ill-defined radiolucency in relation to the edentulous region of teeth 24, 25, 26 and with mild elevation of sinus floor and all other walls of sinus were intact.
Figure 4: (a) Orthopantomogram. (b) Cone-beam computed tomography axial section. (c) Cone-beam computed tomography coronal section

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CBCT axial section [Figure 4]b revealed the lesion extension into posteromedial wall of maxillary antrum and involving the content of the antrum, no distinct cortical border was evident.

CBCT coronal and sagittal [Figure 4]c view revealed ill-defined hypodense area extending in the left maxilla, eroding the floor of the maxillary sinus.

The radiographic diagnosis of residual odontogenic cyst was arrived, and the final diagnosis was residual dentigerous cyst.

Case 5

A 28-year-old female patient came to our institute with a chief complaint of swelling and pus discharge in the right upper back tooth area for the past 3 months. Associated dull aching, intermittent moderate type of pain was present. Clinical findings included missing 18. No relevant medical history was given by the patient.

On the basis of history and clinical examination, provisional diagnosis of odontogenic cyst, most probably infected dentigerous cyst in relation to 18 was arrived.

OPG revealed impacted 18 at the level of the superior aspect of the right maxillary sinus approximately 1 cm above the hard palate. The crown of 18 was facing toward hard palate and root toward the floor of the orbit. Ill-defined radiolucency involving right posterior maxilla was present extending inferiorly in periapical area of teeth 24, 25, 26, 27 with superior extent not traceable with apical root resorption evident in apical one-third of 25, 26 [Figure 5]a.
Figure 5: (a) Orthopantomogram. (b) Paranasal sinus view. (c) Cone-beam computed tomography axial section

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Paranasal sinus view (PNS) [Figure 5]b revealed impacted 18 in relation to the right lateral wall of nose at the level of the middle meatus with crown toward the hard palate and not toward the orbital floor.

CBCT axial section [Figure 5]c reveals hypodense area in the right maxillary sinus with distinct corticated border. All borders of the maxillary antrum were traceable. The internal structure revealed impacted teeth aligned toward the lateral wall of nose at the level of middle meatus.

The radiographic differentials arrived was dentigerous cyst, odontogenic keratocyst, and calcifying epithelial odontogenic tumor. The histological diagnosis was infected odontogenic keratocyst.

Case 6

A 38-year-old female patient comes with a complaint of pain and swelling in the left lower back teeth area for the past 4 months. No relevant medical history was recorded. Clinical findings included the presence of retained deciduous 75. A provisional diagnosis of dentigerous cyst in relation to clinically missing was arrived.

Mandibular anterior occlusal radiograph revealed well-defined unilocular radiolucency extending from mesial aspect of 43 till distal aspect of 37. Distinct buccal cortical bone expansion and thinning were evident in relation to distal aspect of 34 till distal aspect of 36. The internal structure showed localized radiopacity in proximity to 75, suggesting impacted 35.

A panoramic radiograph [Figure 6]a revealed well-defined unilocular radiolucency in the anterior mandible with apical root resorption of teeth 42, 41, 31, 32, and 33. The internal structure revealed impacted 34 in periapical aspect of 75.
Figure 6: (a) Orthopantomogram. (b) Cone-beam computed tomography axial section

Click here to view


CBCT axial section [Figure 6]b revealed a well-defined hypodense area extending from mesial aspect of 43 till distal aspect of 36. Bicortical expansion, thinning, and perforation of cortical plate were evident.

Radiographic differentials were dentigerous cyst, odontogenic keratocyst, and histopathological diagnosis was odontogenic keratocyst cyst.

Case 7

A 16-year-old young male patient reported to the institute with a chief complaint of slowly increasing large painless swelling over the left side of the lower jaw for the past 6 months. There were no signs of difficulty in deglutition or breathing. No underlying significant medical history was recorded.

Panoramic radiograph [Figure 7]a revealed well-defined multilocular radiolucency in the left body of mandible extending from mesial aspect of 35, posteriorly involving horizontally impacted 37, 38 and inferiorly causing ballooning of lower border of mandible. The internal structure revealed distinct thin radiopaque septa.
Figure 7: (a) Orthopantomogram. (b) Cone-beam computed tomography axial section

Click here to view


CBCT axial section [Figure 7]b revealed distinct bicortical expansion with perforation at multiple sites and horizontaly impacted 37 and 38 in the internal structure.

The radiographic diagnosis arrived was ameloblastoma, and its variants and the histopathological diagnosis was follicular ameloblastoma.


  Discussion Top


Among the various pathologies, odontogenic cysts and tumors are the most common which affects the jaws. Even though, they generally have a nonaggressive nature, keratocystic odontogenic tumor (KCOT), and malignant variants of ameloblastoma can be more aggressive and cause loss of function. The odontogenic cysts and tumors such as ameloblastoma, dentigerous cyst, and odontogenic keratocyst can appear as well-defined, unilocular or multilocular, well-corticated radiolucent lesion, due to the absence of mineralization and are often associated with crown of an impacted or unerupted tooth. Previously, Simon et al.[4] in his study, carried on 17 large periapical lesions concluded that CBCT scan gray value can measure and differentially diagnose a solid from a fluid-filled lesion or cavity, which paved way in differentiating cyst and tumor. This study was also supported by a study done by Nasim et al.[5]

Conventional radiographs are diagnostic and have profound value in the evaluation of cysts in mandible, but less value in maxilla. In case 4 of our study, conventional radiograph did not provide detail on the extent of the lesion in regard to the antrum. CBCT distinctly revealed borders, extent, and effect on adjacent structures. Clinical and radiological diagnosis was in agreement with the actual diagnosis of recurrent dentigerous cyst.

In the available literature on odontogenic keratocyst evaluation, Koçak-Berberoǧlu et al.,[6] in a case series of CBCT evaluation of KCOTs; observed that the panoramic radiograph gives more detailed information in the mandible when compared to maxilla. Especially in the maxillary sinus, the panoramic radiograph was very weak to describe the lesion. They concluded that the CBCT evaluation looms large in clinical practice, especially for the odontogenic keratocyst located in the maxillary sinus, to maintain a good preoperative planning. The radiographic findings often help in the diagnosis of odontogenic keratocyst. In conventional radiographs, distinct scalloping borders were evident in some cases with apical root resorption. Whereas, CBCT distinctly revealed the multilocularity and septa that was not prominent in the conventional radiographs. In case 3 of our study, the provisional diagnosis and radiological diagnosis matched with the histopathological diagnosis of odontogenic keratocyst and 3D imaging showed more of the distinct scalloping and extent of the lesion, which was not well pronounced in two-dimensional (2D) imaging.

In case 5, even though localization of the impacted teeth was achievable with the help of orthopantamogram and PNS view, the morphology of impacted teeth and localization in regard to the lateral wall of the nose were more feasible in 3D imaging. CBCT also revealed the distinct cortical borders suggesting that the cystic lesion extended into the sinus. Scalloping was evident in the sagittal section giving more insight, suggesting a radiographic diagnosis of odontogenic keratocyst. Histopathological diagnosis confirmed the lesion as an infected odontogenic keratocyst. In case 6, lingual cortical expansion was not evident in conventional radiograph and was appreciable in CBCT. The localization of impacted 35 was more appreciable. The histopathological diagnosis was odontogenic keratocyst.

The KCOT has a thin lining of parakeratinized epithelium and can have thick cheesy contents due to desquamated keratinizing squamous cells. These contents increase the radiographic attenuation of the lesion at computerized tomography. These features cannot be readily visualized by means of conventional 2D imaging.

Among the odontogenic tumors, ameloblastoma is the second-most common odontogenic neoplasm occurring in the oral cavity next to odontoma. Ameloblastoma appears most commonly in the third to fifth decades of life, but it has been reported in patients with age ranging from 10 to 90 years.[7] In CBCT studies of ameloblastoma, a study done by Luo et al.,[8] in 2014, concluded that typical intralesional structure with honeycomb appearance and the dominant buccal cortical expansion with perforation could be proposed as the characteristic features of desmoplastic ameloblastoma on CBCT images. In case 1 of our study, though 2D imaging revealed a unilocular radiolucency with an extension not so evident, CBCT gave more light on multilocularity and typical thin septa extending midway in the internal structure which led to the radiodiagnosis of ameloblastoma. Further, the extent of the lesion suggested that to be an aggressive variant. The histopathological diagnosis confirmed to be ameloblastic carcinoma. Whereas in case 2, the history and clinical examination suggested a cystic lesion and 2D imaging did not differ. Whereas, 3D imaging showed distinct feature of a tumor, which was as seen in plexiform ameloblastoma.

In some cases, the diagnosis of ameloblastoma is obvious in conventional radiograph, as in case 7, both conventional and 3D radiography suggested that the lesion could be an odontogenic tumor, most probably ameloblastoma. The histopathological diagnosis was follicular ameloblastoma, in concurrence with radiographic diagnosis.

Newer CBCT units allow slice thickness to be as low as 0.1 mm. These thin slices allow better visualization of the bony margins of cystic lesions and tumors and also about the location and angulation of impacted teeth.

CBCT is also helpful in postsurgical follow-up of lesions that may have high recurrences. Due to superimposition of large tissue volume, an extraoral plain film radiograph often cannot provide reliable information on the internal structure of a lesion. Some of the other benefits of CBCT are accuracy in the measurement and absence of image distortions.[9]


  Conclusion Top


Conventional radiographs seem to be ideal for radiographic diagnosis of odontogenic cysts and tumors of the mandible, but has limitations in the maxilla, due to overlapping of multiple anatomical structures and risk of lesion extending and involving the maxillary sinus and cranial base. In evaluating cysts or tumors, a single, intraoral radiograph may not fully record the superior-inferior and mesiodistal dimensions of the lesion. Multiplanar sections (axial, coronal, and sagittal planes) are required to assess cysts or tumors which are located deep in the tissues. Apart from presurgical evaluation of aggressive benign cysts or tumors, CBCT is helpful in postsurgical follow-up of lesions that may have high recurrences. Although CBCT has these advantages, the increased radiation exposure when compared to conventional radiography and availability may be limitations to use CBCT as a routine investigation.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

 
  References Top

1.
Zainab A, Huda M, Muthanna K, Lateef T. Assessment of cysts and cystic-like lesions of the jaws and their effect on adjacent structures by using cone beam computed tomography (CBCT). J Baghdad Coll Dent 2017;28:77-81.  Back to cited text no. 1
    
2.
Prabhusankar K, Yuvaraj A, Prakash CA, Parthiban J, Praveen B. CBCT cyst leasions diagnosis imaging mandible maxilla. J Clin Diagn Res 2014;8:ZD03-5.  Back to cited text no. 2
    
3.
Ludlow JB, Laster WS, See M, Bailey LJ, Hershey HG. Accuracy of measurements of mandibular anatomy in cone beam computed tomography images. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2007;103:534-42.  Back to cited text no. 3
    
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Simon JH, Enciso R, Malfaz JM, Roges R, Bailey-Perry M, Patel A. Differential diagnosis of large periapical lesions using cone-beam computed tomography measurements and biopsy. J Endod 2006;32:833-7.  Back to cited text no. 4
    
5.
Nasim A, Mohan SR, Nagaraju K, Malik SS, Goel S, Gupta S. Application of cone beam computed tomography gray scale values in the diagnosis of cysts and tumors. J Indian Acad Oral Med Radiol 2018;30:4-9.  Back to cited text no. 5
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6.
Koçak-Berberoǧlu H, Çakarer S, Brkić A, Gürkan-Koseoglu B, Altuǧ-Aydil B, Keskin C. Three-dimensional cone-beam computed tomography for diagnosis of keratocystic odontogenic tumours; evaluation of four cases. Med Oral Patol Oral Cir Bucal 2012;17:e1000-5.  Back to cited text no. 6
    
7.
More C, Tailor M, Patel HJ, Asrani M, Thakkar K, Adalja C. Radiographic analysis of ameloblastoma: A retrospective study. Indian J Dent Res 2012;23:698.  Back to cited text no. 7
[PUBMED]  [Full text]  
8.
Luo J, You M, Zheng G, Xu L. Cone beam computed tomography signs of desmoplastic ameloblastoma: Review of 7 cases. Oral Surg Oral Med Oral Pathol Oral Radiol 2014;118:e126-33.  Back to cited text no. 8
    
9.
Ghaeminia H, Meijer GJ, Soehardi A, Borstlap WA, Mulder J, Bergé SJ. Position of the impacted third molar in relation to the mandibular canal. Diagnostic accuracy of cone beam computed tomography compared with panoramic radiography. Int J Oral Maxillofac Surg 2009;38:964-71.  Back to cited text no. 9
    


    Figures

  [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7]



 

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