|Year : 2018 | Volume
| Issue : 4 | Page : 186-190
Importance of cone-beam computed tomography in dentistry: An update
Shruthi Hegde1, Vidya Ajila1, Jasmine Shanti Kamath1, Subhas Babu1, Devika S Pillai1, S Mithula Nair2
1 Department of Oral Medicine and Radiology, A B Shetty Memorial Institute of Dental Sciences, Nitte (Deemed to be University), Mangalore, Karnataka, India
2 Oral Physician and Radiologist, Valluvand Hospital Complex, Palakkad, Kerala, India
|Date of Web Publication||18-Dec-2018|
Department of Oral Medicine and Radiology, A B Shetty Memorial Institute of Dental Sciences, Nitte (Deemed to be University), Mangalore, Karnataka
In this era of advanced technology, cone-beam computed tomography (CBCT) has gained popularity in the field of oral radiology due to its advantages over conventional radiography. The use of CBCT is profoundly increasing for diagnosis and treatment planning in different specialties of dentistry. The incorporation of cone-beam technology into clinical practice is taking place because of the progress in image acquisition and three-dimensional (3D) imaging. The equipment design is easier to use, image distortion is minimal, and the images are compatible with other planning and simulation software. The 3D imaging has made the complex craniofacial structures more accessible for examination. Early and accurate diagnosis of deep-seated lesions is possible. CBCT provides a high-spatial resolution of bone and teeth which allows accurate understanding of the relationship of the adjacent structures. CBCT has helped in detecting a variety of cysts, tumors, infections, developmental anomalies, and traumatic injuries involving the maxillofacial structures. It has been used extensively for evaluating dental and osseous disease in the jaws. This paper reviews current advances in CBCT and their uses in dentistry.
Keywords: Cone-beam computed tomography, dentistry, diagnostic imaging
|How to cite this article:|
Hegde S, Ajila V, Kamath JS, Babu S, Pillai DS, Nair S M. Importance of cone-beam computed tomography in dentistry: An update. SRM J Res Dent Sci 2018;9:186-90
|How to cite this URL:|
Hegde S, Ajila V, Kamath JS, Babu S, Pillai DS, Nair S M. Importance of cone-beam computed tomography in dentistry: An update. SRM J Res Dent Sci [serial online] 2018 [cited 2019 Jan 20];9:186-90. Available from: http://www.srmjrds.in/text.asp?2018/9/4/186/247840
| Introduction|| |
Cone-beam computed tomography (CBCT) introduction in maxillofacial imaging heralds a true paradigm shift from two-dimensional (2D) imaging to 3D imaging in dentistry. CBCT has emerged as an alternative to medical CT for diagnosing and treatment planning of oral and maxillofacial lesions. This imaging modality is a boon to dentistry due to its advantages over conventional 2D techniques and medical CT.,
First commercial CBCT unit marketed to the dental use was introduced in Europe in 1999. Use of CBCT in oral and maxillofacial imaging was initiated in the past decade in several countries; however, in India, its use was limited due to the cost of procuring the machine. Currently, the availability of this technology is increasing in many dental institutions and diagnostic centers across the country. Thus, CBCT is providing the dental clinician a modality for 3D representation of the maxillofacial structures, which in turn has reduced the dependence on the CT and super specialty setups for 3D imaging of oral and maxillofacial region.,
Initially, in the field of dental implantology, CBCT gained popularity for its crucial role. Currently, the utility of CBCT encompasses field orthodontics, oral and maxillofacial surgery, endodontics, temporomandibular joint (TMJ) disorders, periodontics, sleep disorders, airway analysis along with dental implantology.,,,,,
| Two-Dimensional Imaging to Three-Dimensional Imaging in Dental Practice|| |
Imaging is a very important aspect in the diagnosis and management of a patient. Although new imaging techniques have been introduced, conventional 2D radiographs such as periapical radiographs, panoramic, and occlusal remains as a commonly used modality for the primary diagnosis and treatment planning in dentistry. However, 2D imaging techniques have got limitations such as magnification, distortion, and superimposition.
Multiplanar imaging has provided the best diagnostic approach for dental practitioners. The volume of data that is acquired during a CBCT scan is stored, reformatted, and realigned. Several different types of images can be synthesized according to the requirements of the diagnostician. Elimination of superimposition of the area under investigation with other neighboring structures is the major advantage of CBCT imaging compared to the 2D imaging. With multiplanar imaging, images can be recreated in different planes (flat or curved). Images can be displayed in axial, sagittal, coronal views, panoramic reconstruction, cross-sectional views, and 3D reconstructions. They can also be visualized in corrected views for diagnosis of specific areas like the TMJ all of which increases the diagnostic efficiency in an unparalleled way.,
| Conventional Computed Tomography to Cone-Beam Computed Tomography|| |
CBCT is a preferred substitute for conventional CT for diagnosis and treatment planning of most of the oral and maxillofacial lesions. It have several advantages over the conventional CT such as it reduces the dependability on medical setup for imaging, generates a very low amount of radiation, cost factor, rapid scan time, display modes unique to maxillofacial imaging, it allows modification of the visual field, provides a high resolution with voxel size range of 0.076–0.4 mm, reduces artifacts caused by metals in conventional CT. The equipment design is more ergonomic, easier to use, image distortion is minimal, and the images are compatible with other planning and simulation software due to their DICOM format., However, in certain conditions where contrast is required, contrast-enhanced computed tomography is indicated. CT is also preferred for accurate estimation of the Hounsfield units and imaging of larger area.
| Analysis of Cone-Beam Computed Tomography Images|| |
Practitioners deciding to use CBCT for their patients need to take responsibility for the interpretation of the entire volume encompassed in the scan. Methodical, diagnostic approach is required. Formal reporting done by the oral and maxillofacial radiologist helps referring dentist to review the CBCT volumes. The most important in reviewing a CBCT scan is to apply a systematic approach to ensure that no available diagnostic feature is missed. An example of such an approach might be dividing the imaging volume into several smaller sections based on anatomical locations such as maxilla and maxillary teeth, mandible and mandibular teeth, nose and paranasal sinuses, TMJs, neck, cervical spine, and skull base, other findings. In reviewing each of the anatomical regions, special attention is paid to the reason for the scan acquisition. The review of a CBCT scan is a step-by-step analysis of all abnormal radiographic findings in the various image reconstructions. The diagnostician should check for any irregularities in the appearance of the region of interest along with changes in the shape, size, and density. Protocol can be adapted by the diagnostician for reviewing the CBCT volume. In the axial section, viewing from the most inferior slice to the most superior and identifying structures and comparing right and left can be done. Further, determine the nature of the structure as anatomic or pathologic. In coronal sections, viewing from the most anterior to the posterior section can be followed, similarly, for sagittal sections, view from one side to the other. Evaluation of reconstructed panoramic section and cross sections can be carried out. Due to the oblique angle of the mandibular condyles with midsagittal plane, the standard MPR images are not ideal for evaluating the TMJs. TMJ view is used to evaluate TMJs. Finally, 3D volumetric renderings can be reviewed. If abnormality is detected in the scan volume, determining whether normal variant or pathology is necessary. Lesions detected on CBCT should be evaluated for the following features: location, periphery, shape, internal structure, and effects of lesion on adjacent structures. After a thorough evaluation of the above features, clinician need to provide radiographic diagnosis/differential diagnosis and decide regarding further investigations, biopsy, observation for some period, other specialty referral or treatment.
| Applications|| |
The clinical applications of CBCT imaging in the oral and maxillofacial region are vast. Multiplanar imaging in CBCT has provided a highly useful technique for oral and maxillofacial radiologist for the diagnosis of any bone pathology and developmental anomaly in the orofacial region. This technique is a boon for diagnosis and the evaluation of fractures in oral and maxillofacial region, to determine size, extent, and location and to assess their relation to vital structures in cases of cysts and tumors in the orofacial region, CBCT is preferred for object localization, impacted teeth, supernumerary teeth and to assess their relation to vital structures, osteomyelitis, soft-tissue calcifications, cleft palate, developmental anomalies, presurgical planning, and postoperative evaluation.
| Implantology|| |
CBCT is very useful in implant dentistry. Preoperative imaging is done to evaluate the height, width, and quality of alveolar bone available for implant placement and also to assess the proximity to any of the vital structures in the maxilla and mandible so that these structures are not affected by the implant fixture [Figure 1]a, [Figure 1]b, [Figure 1]c. In the maxillary posterior region, it is used to assess the inferior extent of the maxillary sinus and in the maxillary anterior region, the proximity of the implant site to the incisive foramen. In the mandibular posterior region, it is used to assess the position of the mental foramen and mandibular canal for the premolar and molar implants. Whereas, in the mandibular anterior region, it is used to assess the proximity of the lingual foramen to the proposed implant site, which is often overlooked.
|Figure 1: (a) Panoramic reconstruction with virtual implant placed from the software library. (b) Inferior alveolar nerve tracing done in cross sections. (c) Three-dimensional reformated image|
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Greater accuracy of measurements with low radiation dose has made CBCT a preferred option in implant dentistry. Further incorporation of new software to construct surgical guides has reduced the possibility of structural damage. Information obtained from CBCT has helped in case selection, assessment of the success of bone grafts, other posttreatment evaluations and has reduced the possibility of implant failure. Virtual implant planning allows the clinicians to predict and visualize the outcome.
| Endodontics|| |
CBCT in endodontics can be used for identification and measurement of the extent of periapical lesions [[Figure 2]a and [Figure 2]b dotted arrows] and to differentiate solid from fluid-filled lesions. CBCT helps in successful endodontic therapy by identification of all root canals, especially in the identification of second mesiobuccal canal (MB2) in maxillary first molars [Figure 2]c and [Figure 2]d, multiple and accessory canals. CBCT plays an important role in the diagnosis and management of cases with varied pulpal anatomy, root fractures [Figure 2]a, dens invaginatus [Figure 2]b, luxation, displacement, alveolar fracture, root resorption and for the better visualization of the fractured instrument, and root perforation.,,,
|Figure 2: (a) Fracture line evident in an endodontically treated tooth (solid arrow), periapical cyst (dotted arrow). (b) Dens invaginatus (solid arrow), periapical cyst (dotted arrow). (c) MB2 as seen in the axial section. (d) MB2 seen in the corrected coronal section|
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| Periodontics|| |
Previous studies have shown that CBCT is highly accurate for detecting morphology of intrabony defect when compared with intraoral periapical radiographs. Morphology of periodontal tissues can be better visualized with CBCT images. CBCT also provides high accuracy for detecting the furcation involvement. This technique has demonstrated advantages when more invasive treatment is required.
| Oral and Maxillofacial Surgery|| |
CBCT plays an important role in the analysis of benign and malignant lesions of the oral and maxillofacial region. CBCT is the technology of choice for fracture assessment and treatment planning in the oral and maxillofacial region [Figure 3]a, [Figure 3]b, [Figure 3]c, [Figure 3]d. It, thus, eliminates usage of multiple 2D radiographs to do the same. Benign lesions of the jaws have varied radiographic appearances. Plain radiographs along with advanced imaging help the practitioners in arriving at a diagnosis and planning treatment for the lesion. CBCT imaging is highly beneficial for the evaluation of the location, size, extent, expansion, and involvement of any surrounding vital structures due to the disease process [Figure 4]a and [Figure 4]b.
|Figure 3: (a) Panoramic reconstruction showing fractured right condyle that appears displaced anteriorly. (b) Axial section showing medially displaced fractured condylar head. (c) Coronal section showing medially displaced fractured condylar head. (d) Three-dimensional reformatted image|
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|Figure 4: (a) Axial section of the mandible showing bicortical plate expansion, with perforation of both the lingual and buccal cortex. (b) Multilocular appearance appreciated in the coronal section|
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In oral cancer cases, CBCT is useful in detecting osteolysis with sensitivity 89%–93% and specificity 60%–96.5%. The accuracy of CBCT is comparable to magnetic resonance imaging (MRI), CT and bone scintigraphy and is more accurate than panoramic radiography. Increasing use of CBCT in day-to-day practice results in improved detection of bone involvement in cases of oral cancers. However, poor soft-tissue assessment is the limitation in oral cancer cases. Czerwonka et al. conducted a CBCT study to assess the bone invasion in oral cancer cases and compared it with conventional computed tomography and concluded that CBCT offers marginally improved sensitivity at the cost of reduced specificity for assessment of bone invasion compared to CT.
For object localization CBCT is the preferred technique. Recent studies have shown that CBCT is a more accurate and precise examination method for the localization of impacted teeth and impacted supernumerary teeth. It also aids in the assessment of the effect of these impacted teeth on the adjacent teeth and other vital structures. CBCT evaluation is, therefore, recommended for accurate treatment planning in these cases.,,
Retained foreign body in the maxillofacial region following trauma may pose a diagnostic difficulty for dental practitioners. CBCT helps in foreign-body localization [Figure 5]a, [Figure 5]b, [Figure 5]c, [Figure 5]d. As an incidental finding radiopacity was noticed in the mandibular anterior region in a panoramic radiograph. Patient revealed that he had sustained a road traffic accident 10 years back and was unaware of any foreign body. CBCT confirmed the presence of foreign body in the soft tissues below the lower lip. Foreign bodies in the maxillofacial region may cause functional, allergic, and infective complications. However, our patient did not report of any complications.
|Figure 5: (a) Panoramic radiograph showing radiopacity in the mandibular anterior region. (b) Axial section of the mandible showing multiple radiopaque structures anterior to the mandible suggestive of presence of foreign body in the soft tissue region. (c) Cross section showing presence of radiopaque structure labially. (d) Three-dimensional reconstruction of the same region|
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| Orthodontics|| |
CBCT primarily recommended in cases in which the diagnostic information provided by the conventional radiography is not satisfactory. CBCT imaging is very useful in patients with cleft palate, craniofacial anomalies, facial asymmetry, large anterior open bite, unerupted tooth, supernumerary teeth, root resorption, and for the planning of orthognathic surgery. Valuable information is provided by CBCT imaging for the placement of endosseous dental implants and temporary anchorage devices. A study by da Silva Santos et al. described the relationship of impacted upper canines with adjacent structures through CBCT imaging. They reported that most of their cases showed the presence of root resorption of the adjacent teeth.
| Forensic Odontology|| |
Dental age estimation of living or deceased individuals is considered an important aspect in the field of forensic science. CBCT serve as noninvasive method for dental age assessment. Various dental age estimation methods were reported in the literature.,,, A previous study showed that CBCT images of the face could be used for measuring soft-tissue thickness in the facial region.
| Conclusion|| |
The use of CBCT technology is profoundly increasing for diagnosis and treatment planning in dentistry. The 3D imaging has made the complex craniofacial structures more accessible for examination and also helped in early and accurate diagnosis of lesions. CBCT has reduced the dependence of dental clinician on the CT and super specialty setups for 3D imaging of oral and maxillofacial region.
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Conflicts of interest
There are no conflicts of interest.
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