For more on this topic, go to www.dentaleconomics.com and search using the following key words: cone beam, CBCT, digital imaging, endodontics, curvature, patency.
by Emanuele Ambu, DDS; Carlos Estrela, DDS, MSc, PhD; and José Antonio Poli de Figueiredo, BDS, MSc, PhD
Cone beam computed tomography (CBCT) has proven to be an essential tool for successful diagnosis, treatment planning, and postprocedure monitoring for endodontic applications. With its accurate and high-quality 3-D representations of maxillofacial structures, CBCT technology offers tremendous improvements in diagnostic capabilities, eliminating surprises and minimizing the need for exploratory surgery. The result: more effective care and improved patient outcomes.
A brief history of imaging in endodontics
Throughout the decades, imaging services have served a fundamental role in all stages of the endodontic treatment process. Endodontic treatments today rely on effective imaging techniques to assess tooth anatomy as well as surrounding structures and tissues during treatment planning. Digital dental radiography was introduced in the 1980s by French dentist Francis Mouyen. Technology continued to evolve and become increasingly easier to use and more cost-effective, such that by the turn of the century, digital technology superseded conventional film imaging in endodontics. Today, digital images provide information about the tooth, pulp chamber and contents, number, patency, curvature, and length of the canals. They may also help identify canal perforations, broken implants, failure to adequately obturate, ineffective surgical results, and a number of other pathological conditions.
Unlike traditional X-ray films, 2-D digital images can be manipulated — enlarged or colorized — to clearly show decay, fractures, or bone loss. Furthermore, digital radiography streamlines data storage, eliminating the need to file and retrieve images by hand. Digital images can also be easily shared with other practitioners, facilitating communication. However, these two-dimensional technologies (intraoral radiography, panoramic radiography, and traditional tomography) often require multiple exposures, and sometimes fail to provide complete and fully accurate information. For example, a single radiograph may indicate an apparently successful treatment, yet a second or third viewpoint may demonstrate an important discrepancy.
Advances in digital imaging — especially 3-D imaging — provide a critical and highly accurate diagnostic and treatment-planning tool that allows today’s practitioners to more accurately visualize internal anatomy, assess risk, and plan treatment. In short, cone beam computed tomography has provided the greatest advancement in digital imaging over the past decade.
A comparison of 2-D and 3-D imaging
Developed in the late 1990s, CBCT uses a cone-shaped beam and digital processing to reconstruct a virtually distortion-free 3-D image of the patient’s craniofacial hard tissue anatomy in a single pass. CBCT scanners employ a 2-D detector and X-ray generator that acquires up to 580 individual basis images or projections during a single rotation of the gantry to generate a scan of the entire region of interest. Because it requires only a single scan to capture the entire region, an eight- to 20-second scan is all that is required to acquire a single cone-beam scan.
3-D CBCT imaging offers a tremendous advantage compared to earlier 2-D scans. Unlike regular X-rays, CBCT scans are able to differentiate between many types of structures and airspaces — including bone, teeth, airway, paranasal sinuses, and sometimes soft tissue — while avoiding diagnostic limitations inherent in 2-D images, including superimposition of structures, nonuniform magnification and distortion and no depth information. Other advantages of CBCT scanning over 2-D technology include the ability to visualize the patient as he or she truly exists and the ability to view the anatomy from a variety of slice thicknesses and viewing angles, including curved and planar reformations.
Because they collimate to capture only a smaller region of interest as needed for endodontic examinations, focused field of view (FOV) CBCT systems, such as the KODAK 9000 3-D Extraoral Imaging System, provide high resolution 3-D images at a low effective dose. In fact, such systems emit doses comparable to that of conventional panoramic images, significantly less than a day of effective annual background radiation. Often conventional 2-D images provide less adequate data for making scientific decisions regarding diagnosis and treatment planning, requiring guesswork on the part of the practitioner. Because success in endodontics is often assessed via the healing of the periapical bone and related structures, accurate imaging can make the difference between confirmed success in a single procedure and expensive, time-intensive repeat recall visits.
Endodontic advantages of CBCT imaging
Using 3-D imaging makes it easier for practitioners to detect, diagnose, and develop highly effective treatment plans. Endodontic radiographic diagnosis is based on many factors, including anatomical limitations such as thickness of the cortical bone; positioning of the apical abscess to the cortical bone; and is complicated by proximity to other anatomical structures including the zygomatic bone, sinus, and proximity of neighboring teeth. With 2-D images, these structures are often superimposed on a planar image.
3-D output, with its associated geometric accuracy in all three planes, offers tremendous advantages in these situations. 3-D images deliver accurate visualizations of the complex relationships and boundaries between teeth, related anatomical features, and their associated pathology. Other key benefits include assessment of internal tooth morphology, periodontal ligament space, the presence or absence of periapical lesions in association with critical anatomical structures, and maxillary sinus involvement.
CBCT also offers speed and versatility to the practitioner and patient alike. Within a few minutes of acquiring the scan, the dentist may fully explore the patient’s 3-D image. The image can then be rotated, color-contrasted, and slices can be isolated and further analyzed — even down to a single voxel size of 76 microns in thickness. Anatomic structures including nerve canals can be traced and highlighted for easy recognition. Moreover, each root and its surrounding structures can be evaluated, eliminating the need for exploratory surgery.
CBCT imaging provides significant advantages in the detection of apical periodontitis, diagnosis of endodontic failures and complications, perio-endo lesions, and as part of pre- and postsurgical assessment. CBCT also allows for detection of more periapical lesions than conventional radiographs — particularly in the second maxillary posterior teeth where CBCT has been found to be far more effective than conventional radiography. High resolution focused field CBCT has also been shown to provide 100% sensitivity and specificity in the detection of artificially created periapical lesions in dry human mandibles.
When assessing dental trauma, CBCT of adequate resolution can be used to detect horizontal root fractures and cortical bone fractures, which may otherwise have required multiple periapical radiographs for detection. In treating teeth with unusual anatomy, CBCT can help reveal the actual number of canals present in teeth, as well as the true nature and exact locations of lesions, the “portal of entry” of a resorptive lesion, and previously undetected lesions.
CBCT makes it easy to analyze specific areas of interest and provides the highly detailed anatomical information necessary for making confident treatment decisions. It also facilitates earlier and more accurate diagnosis, resulting in more predictable management and significantly higher treatment success rates.
CBCT as a treatment tool
When used for preoperative assessment, CBCT imaging provides highly detailed information on the entire tooth structure, including the location and number of canals, pulp chamber size and degree of calcification, direction and curvature of root morphology, tooth and root fractures, inflammatory lesions and defects. Further, it can provide insight into root resorption, the effects of periradicular and periapical disease, as well as predict the potential for complications.
CBCT is an invaluable endodontic tool for use before, during, and after treatment. Once a treatment plan has been determined, CBCT can be used to ensure that metallic files placed into the root canal are the appropriate size and shape. Following a treatment, CBCT can then provide immediate analysis, ensuring that the obturation material is adequately and appropriately situated within the root canal system. It also offers a baseline for healing in the short and long term, which is of the utmost importance in monitoring treatment results, delays in healing, re-treatment, and surgical options.
3-D scans also may be easily shared among practitioners to provide comprehensive patient care. Not only does this ensure robust collaboration and that everyone is working from the same data, it elevates the standard of care and patient satisfaction by reducing the need for the patient to undergo multiple scans for each practitioner. AAE AAOMR joint guidelines for the use of CBCT ion endodontics can be found at http://www.aaomr.org/resource/resmgr/Docs/AAOMR-AAE_postition_paper_CB.pdf.
Conclusion
CBCT scanning drives diagnostic accuracy, which directly and positively impacts clinical decisions, increases speed of treatment, and improves productivity and patient outcomes. With CBCT technology, the practice is empowered with immediate access to accurate 3-D images of anatomical structures, critical to precise diagnoses, more effective treatment planning, increased case acceptance, and better care for the patient.
References for this article are available on the DentistryIQ website at www.DentistryIQ.com.
Emanuele Ambu, DDS, master of endodontics, is a professor of endodontics at the University of Modena, Regiio Emila Dental School. He is a member officer of the Italian Endodontic Society and a certified member of the European Society of Endodontology. Contact Dr. Ambu by email at [email protected].
Carlos Estrela, DDS, MSc, PhD in endodontics is the professor of the Dental School, Federal University of Goiás, Health Sciences Post-Graduate Program, Brazil. Contact Dr. Estrela by email at [email protected].
José Antonio Poli de Figueiredo, BDS, MSc, PhD, coordinates the PUCRS Post-Graduate Program in Dentistry, Brazil. He is associate editor of Dental Press Endodontics and Journal of Dental Sciences. Contact Dr. de Figueiredo at [email protected].
