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REVIEW ARTICLE
Year : 2015  |  Volume : 6  |  Issue : 1  |  Page : 48-52

CBCT: A guide to a periodontologist


Department of Oral Medicine and Radiology, Swami Devi Dyal Hospital and Dental College, Haryana, India

Date of Web Publication19-Jan-2015

Correspondence Address:
Tarun Kumar
Department of Oral Medicine and Radiology, Swami Devi Dyal Hospital and Dental College, Barwala, Panchkulla, Haryana
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/0976-433X.149594

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  Abstract 

Radiographs are the essential tools in the field of dentistry. Plain film radiography provides a two-dimensional view of the structures. In the field of periodontology, assessment of the condition of teeth and surrounding alveolar bone depends largely on these two-dimensional imaging modalities such as periapical radiographs and bitewing radiographs. Although these modalities are very useful and have less radiation exposure, they still cannot determine a three-dimensional (3D) architecture of the bony defects. Hence, an imaging modality which would give an undistorted 3D vision of a tooth and surrounding structures is required to improve the diagnostic potential of the clinician. Cone-beam computed tomography (CBCT) provides 3D images that facilitate the transition of dental imaging from initial diagnosis to image guidance throughout the treatment procedures. This technology offers increased precision, lower doses, and lower costs when compared with conventional computed tomography. This review discusses how CBCT can be a guide to the periodontologist.

Keywords: Bone, cone-beam computed tomography, loss


How to cite this article:
Kumar T, Puri G, Aravinda K, Laller S, Malik M, Bansal T. CBCT: A guide to a periodontologist. SRM J Res Dent Sci 2015;6:48-52

How to cite this URL:
Kumar T, Puri G, Aravinda K, Laller S, Malik M, Bansal T. CBCT: A guide to a periodontologist. SRM J Res Dent Sci [serial online] 2015 [cited 2022 Dec 8];6:48-52. Available from: https://www.srmjrds.in/text.asp?2015/6/1/48/149594


  Introduction Top


Dental radiology has long played an exciting and critical diagnostic role in dentistry, with the rapidly expanding array of imaging modalities. Intraoral radiography was first used within weeks of the discovery of X-rays by Roentgen in 1895. Extraoral imaging, including cephalometric radiography, followed soon thereafter. The introduction of panoramic radiography in the 1960s and its widespread adoption throughout the 1970s and 1980s heralded major progress in dental radiology, providing clinicians with a single comprehensive image of jaws and maxillofacial structures. However, intraoral and extraoral procedures, used individually or in combination, suffer from the same inherent limitations of all planar two-dimensional (2D) projections: Magnification, distortion, superimposition, and misrepresentation of structures. [1]

Numerous efforts have been made toward three-dimensional (3D) radiographic imaging (e.g., stereoscopy, tuned aperture computed tomography [TACT]) and although computed tomography (CT) has been available, its application in dentistry has been limited because of cost, access, and dose considerations. The introduction of cone-beam computed tomography (CBCT) specifically dedicated to imaging the maxillofacial region heralds a true paradigm shift from 2D to 3D approach to data acquisition and image reconstruction. Interest in CBCT from all fields of dentistry is unprecedented because it has created a revolution in maxillofacial imaging, facilitating the transition of dental diagnosis from 2D to 3D images and expanding the role of imaging from diagnosis to image guidance of operative and surgical procedures by way of third-party applications software. [1]

The most common indications for cone-beam imaging in dentistry are assessment of the jaws for placement of dental implants, examination of teeth and facial structures for orthodontic treatment planning, evaluation of the temporomandibular joints (TMJs) for osseous degenerative changes, localization of inferior alveolar nerve canal before extraction of mandibular third molar, assessment of teeth for root fracture or periapical disease, and evaluation of bone for signs of infections, cysts, or tumors. Cone-beam imaging is rapidly replacing conventional tomography for these tasks. All these applications, and many others, benefit from viewing thin slices through the region of interest without superposition of local complex anatomy onto the image. [2]

In the field of periodontology, assessment of the condition of teeth and surrounding alveolar bone depends largely on traditional two-dimensional imaging modalities such as conventional radiography and digital radiography. Although these modalities are very useful and have less radiation exposure, they still cannot determine a 3D architecture of osseous defects. Hence, an imaging modality which would give an undistorted 3D vision of a tooth and surrounding structures is essential to improve the diagnostic potential. A well-diagnosed periodontal lesion warrants an appropriate treatment.

Today, CBCT scanning has become a valuable imaging modality in periodontology as well as implantology. For the detection of smallest osseous defects, CBCT can display the image in all its three dimensions by removing the disturbing anatomical structures and making it possible to evaluate each root and surrounding bone. In implant treatment, appropriate site or size can be chosen before placement, and osseointegration can be studied over a period of time. This review discusses how CBCT can be a guide to the periodontologist.


  Applications of cbct in periodontics Top


The first reported applications of CBCT in periodontology were for diagnostic- and treatment-outcome evaluations of periodontitis. [3],[4] The impact of radiographic imaging on the diagnosis and treatment of periodontal disease has essentially remained unchanged for decades. Periodontal diagnosis relies primarily on traditional two-dimensional representation of the alveolar bone. Usefulness of CBCT for periodontal applications is still in progress. Field of interest for the use in periodontology would be the diagnostic and quantitative measurements of soft tissue and alveolar bone levels in three dimensions, imaging of periodontal intrabony defects, dehiscence and fenestration defects, diagnosis of furcation-involved molars, and implant site imaging. [3],[4],[5],[6]

CBCT in assessment of PDL space

The earliest signs of periodontal disease in radiographs are fuzziness, break in the continuity of lamina dura, and a wedge-shaped radiolucent area at the mesial and distal aspect of the PDL space. In addition to this, the proper observation of PDL space may offer some potential regarding detection of occlusal trauma and the effects of systemic diseases on the periodontium.

CBCT ex vivo visualization of the periodontal ligament and periodontal ligament space has been evaluated in comparison with radiography with mixed results. [7]

CBCT for periodontal defect measurements

The extent of periodontal marginal bone loss is not always easy to determine and certainly not the extent with which furcation areas are involved. CBCT images provide better diagnostic and quantitative information on periodontal bone levels in three dimensions than conventional radiography. CBCT is found to be as accurate as direct measurements using a periodontal probe and as reliable as radiographs for interproximal areas. Although two-dimensional radiography is of use for interproximal lesions, its limitation was anticipated during early investigations, determining its diagnostic value for periapical and periodontal disease. So, when buccal and lingual defects cannot be diagnosed with radiography, CBCT is a superior technique. [8],[9],[10],[11],[12] A study on the use of CBCT to examine the geometric relationship between the roots and furcation areas of the mandibular first molars has verified that the X-ray beam projection angle affects the accuracy and diagnosis of a furcation defect. Changes in horizontal angulation cause geometric distortion in intraoral radiography. [13]

Soft tissue CBCT for the measurement of gingival tissue and the dimensions of the dentogingival unit

This novel method is based on CBCT technology called soft tissue CBCT (ST-CBCT), to visualize and precisely measure distances corresponding to the hard and soft tissues of the periodontium and dentogingival attachment apparatus. With this simple and noninvasive technique, clinicians are able to determine the relationships between gingival margin and the facial bone crest, gingival margin and the cemento - enamel junction (CEJ), and CEJ and facial bone crest. The width of the facial and palatal/lingual alveolar bone and the width of the facial and palatal/lingual gingival also could be measured. [14] Tissue biotypes have been linked to the outcomes of periodontal and implant therapy. When tissue biotypes of 22 fresh cadaver heads were assessed clinically and radiographically with CBCT scans, the labial gingival thickness was moderately associated with the underlying bone thickness measured with CBCT. These measurements were accurate representation of the clinical thickness of both labial gingiva and alveolar bone. [15] ST-CBCT will certainly aid clinicians in the planning and execution of a number of procedures in dentistry with increased predictability.

CBCT precision in alveolar bone density measurement

Radiographic follow-up of bone healing after grafting is challenging because of the overlapping of gaining and losing areas within the graft. The new volumetric imaging method, CBCT, offers an opportunity to see inside the bone and pinpoint and measure densities in small localized areas such as a vertical periodontal defect or an alveolar bone graft. This precision would make it possible to reproducibly quantify the bone remodeling after bone grafting. [4]

CBCT for diagnostic imaging for the implant patient

For the evaluation of implant placement, many radiographic projections are available, each with advantages and disadvantages. Radiography is an essential diagnostic tool for implant design and successful treatment of the implant patient. Selection of appropriate radiographic modality will provide the maximum diagnostic information, help avoid unwanted complications, and maximize treatment outcomes while delivering "as low as reasonably achievable" radiation dose to the patient. [6] Clinicians have been diagnosing, treatment planning, placing, and restoring modern dental implants using periapical and panoramic imaging films to assess bone anatomy for several decades. Two-dimensional film images have been found to have limitations because of inherent distortion factors, and the noninteractive nature of film itself provides little information regarding bone density, bone width, or spatial proximity of vital structures. Diagnostic imaging techniques must always be interpreted in conjunction with good clinical examination. Many factors influence the selection of radiographic techniques for a particular case, including cost, availability, radiation exposure, and case type. The decision is a balance between these factors and the desire to minimize risk of complications to the patient. Cross-sectional imaging modalities that include conventional x-ray tomography, computer tomography, and CBCT are valuable imaging modalities. Of all the three, CBCT scanning is the most successful, useful, and valuable imaging modality for 3D and cross-sectional evaluation of the implant patient. It has similar advantages and disadvantages as CT scanning. The most significant difference is that CBCT imaging requires much less radiation exposure.

Location is the most important factor while placing an implant. From 3D planning to CT-directed placement, to take the advantage of available bone, and avoid anatomic structures, the science of implantology has been revolutionized by 3D imaging. Not only has it added safety and accuracy, it has also minimized or eliminated the need for supportive procedures like bone and tissue grafting in many situations.

Software and technology development trends suggest that in the near future, CBCT scans will be used to develop a patient-specific 3D model that will be used for implant diagnosis, treatment planning, treatment simulation, implant placement (surgery), and tooth replacement (restoration of implant).


  Discussion Top


In his summary of periodontal imaging methods in Periodontology, Mol stated, "Relatively few technologies have emerged to address the critical needs in periodontal diagnosis." [16] He pointed out that although digital imaging has added value to intraoral imaging, an increase in diagnostic capabilities has not been one of the benefits. Mol not only discussed the limitations of extraoral imaging (panoramic) with its associated drawbacks but also pointed out its usefulness in association with bitewings and selected periapicals. Mol also reviewed the more advanced digital technologies, such as TACT, digital subtraction, and conventional CT scanning, and stated their potential for an increase in diagnostic efficacy and characterization of the periodontal bone status. He concluded by outlining the practical limits of these technologies and explained why they are not going to be particularly useful in the practice of dentistry. [5] Previous studies have shown that CT assessment of alveolar bone height and bony pockets is reasonable, accurate, and precise. [17],[18],[19],[20] Mol stated that CBCT studies applied to periodontal imaging were in progress and not available at the time of publication of his review. Several of these studies are now available. Most studies investigating the application of CBCT imaging to periodontal bone status are in vitro, although a few are in vivo, with either full-volume CBCT or limited-volume units used.

Vandenberghe and coworkers investigated periodontal bone architecture using 2D CCD and 3D full-volume CBCT-based imaging modalities. [21] Periodontal bone levels and defects were assessed and evaluated against two human skulls' gold standard. Visualization of lamina dura, crater defects, furcation involvements, contrast, and bone quality were also evaluated. They concluded that CBCT image measurements of periodontal bone levels and defects were comparable to intraoral radiography. It was found that CBCT images demonstrated more potential in the morphologic description of periodontal bone defects and conversely, the CCD images provided more bone details. Using a dry skull with artificial defects and full-volume CBCT, Misch and colleagues found similar results. [22] Their investigation demonstrated that CBCT was as accurate as direct measurements using a periodontal probe and as reliable as radiographs for interproximal areas. In measurements of buccal and lingual defects, CBCT proved superior to conventional radiography. Because of this finding, the investigators concluded that CBCT offered a significant advantage over conventional radiography.

In a 2005 study using human and pig material, Mengel and coworkers investigated the use of CBCT in the diagnosis of periodontal defects using intraoral radiography, panoramic radiography, CT, and LCBCT in comparison with histologic specimens. [23] It was demonstrated that all intrabony defects could be measured in three planes in the CT and LCBCT scans with great accuracy true to scale, whereas only mesial, distal, and cranio-caudal plane defects could be detected by intraoral and panoramic imaging. It was also concluded that the LCBCT system produced higher quality images. Noujeim and coworkers found similar results when using the LCBCT system to detect simulated inter-radicular lesions of varying depth in comparison with intraoral radiography. [24] Loubele and coworkers designed a study to compare the accuracy of LCBCT with multislice CT for linear measurements with caliper-determined measurements using cadaveric materials. [25] They concluded that both systems were accurate with submillimeter measures. In a study directed more to periodontal defects, Mol, using an older form of CBCT using a full field of view, found that CBCT images provided better diagnostic and quantitative information on periodontal bone levels in three dimensions than conventional radiography. [26] The study also demonstrated a limitation in that the accuracy in the anterior aspect of the jaws was limited. The system used a NewTom 9000 unit (APF Imaging, Elmsford, New York), generating images that were inferior in quality to what more up-to-date systems can generate.

The fact that these studies used full-volume CBCT and limited-volume systems hints that either system may be more capable than intraoral radiography in the visualization of periodontal bone architecture.

In a recent review on CBCT for periodontology, Kasaj and Willershausen conclude that the low dosage and superior image quality in comparison with conventional CT are promising for periodontal applications, especially in the areas of intrabony defects, dehiscence and fenestration defects, and periodontal cysts, and in the diagnosis of furcation-involved molars. [27]

Another CBCT-based application called soft tissue CBCT (ST-CBCT) helped us to visualize and precisely measure distances corresponding to the hard and soft tissues of the periodontium and dentogingival attachment apparatus. With this simple and noninvasive technique, clinicians are able to determine the relationships between

  1. Gingival margin and the facial bone crest,
  2. Gingival margin and the cemento - enamel junction (CEJ), and
  3. CEJ and facial bone crest.


The width of the facial and palatal/lingual alveolar bone and the width of the facial and palatal/lingual gingival also could be measured. [28] Tissue biotypes have been linked to the outcomes of periodontal and implant therapy. When tissue biotypes of 22 fresh cadaver heads were assessed clinically and radiographically with CBCT scans, the labial gingival thickness was moderately associated with the underlying bone thickness measured with CBCT. These measurements were an accurate representation of the clinical thickness of both labial gingiva and alveolar bone. [29] ST-CBCT will certainly aid clinicians in the planning and execution of a number of procedures in dentistry with increased predictability.

Overall, these studies suggest that CBCT imaging has the potential to replace intraoral imaging for the assessment of periodontal architecture. However, clinical studies would be helpful in supporting this conclusion. CBCT may be a useful and more practical clinical tool than digital subtraction radiography for the assessment of changes in periodontal bone over time.


  Conclusion Top


As CBCT scan is finding more and more applications in oromaxillofacial radiology, it stands as the privileged field of imaging in periodontics. Current methods of detecting alveolar bone level changes over time or determining 3D architecture of osseous defects are inadequate. This issue has been addressed by the recent low-cost CBCT machines, which has resulted in production of an affordable, low-radiation and high-quality 3-D data. CBCT is an essential diagnostic tool also for selection of implant design and its placement. CBCT provides high quality of diagnostic images that have an absorbed dose that is comparable with other dental surveys and less than a conventional CT and thus following the principles of radiation protection to reduce the radiations "as low as reasonably achievable" (ALARA). To conclude, CBCT with its high spatial resolution, affordability, smaller size, lower acquisition and maintenance have made it as a natural fit in periodontal imaging.

 
  References Top

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22.
Misch KA, Yi ES, Sarment DP. Accuracy of cone beam computed tomography for periodontal defect measurements. J Periodontol 2006;77:1261-6.  Back to cited text no. 22
    
23.
Mengel R. Candir M. Shiratori K, Flores-de-Jacoby L. Digital volume tomography in the diagnosis of periodontal defects: An in vitro study on native pig and human mandibles. J Periodontol 2005;76:665-73.  Back to cited text no. 23
    
24.
Noujeim M, Prihoda T, Langlais R, Nummikoski P. Evaluation of high-resolution cone-beam computed tomography in the detection of simulated interradicular bone lesions. Dentomaxillofac Radiol 2009;38:156-62.  Back to cited text no. 24
    
25.
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26.
Mol A, Balasundaram A. In vitro cone beam computed tomography imaging of periodontal bone. Dentomaxillofac Radiol 2008;37: 3l9-24.  Back to cited text no. 26
    
27.
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28.
Januário AL, Barriviera M, Duarte WR. Soft tissue cone-beam computed tomography: A novel method for the measurement of gingival tissue and the dimensions of the dentogingival unit. J Esthet Restor Dent 2008;20:366-73.  Back to cited text no. 28
    
29.
Fu JH, Yeh CY, Chan HL, Tatarakis N, Leong DJ, Wang HL. Tissue biotype and its relation to the underlying bone morphology. J Periodontol 2010;81:569-74.  Back to cited text no. 29
    




 

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