Cone Beam Computed Tomography in General Dental Practice

Paul Feuerstein, DMD, discusses applications for three-dimensional cone beam imaging in general dentistry
The increasing availability of cone beam computed tomography (CBCT) has raised questions in some clinicians’ minds regarding its true utility in general dental practice. The range of features available with this technology, combined with the ability to limit the field of view (and, thus, radiation exposure), increases a practitioner’s diagnostic and treatment planning capabilities. In addition, the integration of three-dimensional (3D) dental imaging opens the door to expanding your practice offerings to include endodontic, periodontal and implant treatment, among others.

To help explore applications in general dentistry, we asked noted technology expert Paul Feuerstein, DMD, a Boston-based general practitioner, lecturer, author, and adjunct assistant professor at Tufts University School of Dental Medicine, to share insights into how CBCT can be integrated into daily practice.

Editor’s Note: The views expressed in this interview are the author’s.

While highly regarded for its applications in endodontic treatment and implant therapy, are there also advantages to using CBCT imaging in general dental practice?

This imaging modality is a great diagnostic tool in general practice. For example, we often see radiolucencies or radiopacities on the corner of a periapical X-ray or even on a panoramic image. Are these superimposed buccal or lingual? How large are they? And how wide? Are we looking at the mental foramen? The use of 3D cone beam imaging solves these issues. Tooth fractures are also easier to see, whether in the crown, root or furcation.

Speaking of furcations, this technology’s utility in treating periodontal disease opens new vistas. If the cone beam unit has the option of 3D reconstruction, the true meaning of bone loss is quite clear to a patient viewing the image. In addition to furcations, bony defects and similar structures are more easily detected. With cone beam imaging, extractions are also more predictable, especially near the mandibular canal or in areas near the sinuses. You see the precise location of the tooth in relation to these structures, adjacent teeth and other anatomy. Looking at apicoectomies or uncovering impacted cuspids with CBCT technology, for example, leaves no question where to enter the bone.

Cone beam imaging emits greater radiation than conventional radiography. When its benefits outweigh potential risks of use, how can clinicians minimize CBCT exposure levels?

The newer machines use less radiation in general than earlier devices and are being marketed as “green” units. Many allow the radiation to be collimated to a much smaller field of view, highlighting only the area of interest and thus limiting exposure. You can also do a full “quick scan” with many of today’s units. It might provide less resolution, but it yields basic diagnostic information and allows the practitioner to identify the area of interest and zoom in for greater detail.

For general dentists who perform root canal treatment, what are the benefits of CBCT technology? Does it have any role in referral decisions?

There has never been a diagnostic tool like this to evaluate extra and accessory root canals. A dentist will see accessory canals, calcified canals, actual curvatures and other anatomic situations, which, in turn, helps in deciding if the practitioner is comfortable treating the patient, or whether the individual should be referred to an endodontist. In the same vein, in retreatment cases, cone beam imaging provides key information for assessing the difficulty of a given case.

From a general practitioner’s perspective, how is this imaging modality helpful for implant therapy or periodontal treatment?

In terms of dental implants, I believe the standard of care will soon require a cone beam diagnosis for at least the location and bone density of the area where the implant will be placed. In the past, the use of surgical guides might have been over the top for some clinicians due to laboratory time and fabrication costs, but with new chairside design software and the ability to 3D-print a guide for less than $10, it makes implant therapy more predictable.

As far as periodontal diagnosis and treatment, as previously noted, the areas of bone loss are seen three-dimensionally, which lends greater predictability to procedures such as osseous surgery, bone grafting and more. This imaging modality helps eliminate surprises that might otherwise be found in the middle of surgery. In addition, clinicians can follow the progress of bone healing or deterioration via cone beam scans.

If a general dentist only treats straightforward endodontic and/or implant cases, would the office still benefit from 3D imaging?

Every dentist knows the term “straightforward” is full of surprises, even in the smallest of operative procedures. Any endodontic or implant case should be looked at with 3D imaging to perhaps prove it will be relatively straightforward and within the provider’s comfort zone. Two-dimensional radiography is full of superimpositions and can’t compare to the information provided by CBCT technology. Given the options for having cone beam images taken, if they are indicated, there is no excuse not to have a CBCT scan. Even if the office doesn’t have an in-house unit, it can partner with other offices or clinics to obtain 3D imaging.

Cone beam units are available with limited or full fields of view. Please briefly explain what this means, its ramifications for exposure levels, and how dentists can decide which field of view best fits their practice.

This is the toughest decision. Some companies offer multiple CBCT units in many configurations and with different maximum fields of view. This means the sensor in the machine could be smaller and the mechanics simpler, thus bringing down costs. If the practitioner is absolutely sure that he or she will only be doing single-tooth endodontics, or single (or perhaps two adjacent) implants, the smallest field of view is acceptable. But once the doctor sees the value, he or she might find other areas and procedures for which the unit would be helpful, and regret not having a larger field of view.

Some units allow you to take multiple scans and stitch them together, but this requires additional radiation exposure. Certainly, the full field-of-view units will show the upper and lower arches, including the temporomandibular joints and parts of the sinus. I believe these are best suited for oral surgeons, although there is no harm in using them in general practice. Most of the full field-of-view units allow you to select smaller focused fields, down to one or two teeth, which limits exposure.

Another consideration is that larger fields of view will show non-dental structures. Because practitioners have a medical responsibility for everything in the scan, this usually requires a radiologist to issue a medical report on what is found in the scan, including any pathosis. There are many resources available for this purpose, including dental schools, independent dental radiologists and online services. There is a fee for this report, so this must be factored in — but you might actually save someone’s life in the process.

Before purchasing a CBCT unit, general dentists can utilize 3D radiography via imaging centers or by partnering with offices that have the equipment. What are the advantages of this approach?

As previously stated, there is no excuse if you want to get a scan. Besides partnering with practices that have CBCT capability, dentists can utilize imaging centers that offer cone beam scans. There are also mobile imaging units that come right to the office and meet the patient. Some provide an analysis, while other just take the scan and give you a disc. They often bill the patient directly.

Of course, a key selling point is that if you own the unit, you have a billable service. Having said that, many endodontists take the image as a routine part of the treatment fee. Depending on the general practitioner’s relationship with the specialist, some will take the image for you (with them billing the patient for the service) and send the images to you on a disc or USB drive, or via an online portal. In a nonemergency situation, this is certainly workable and will allow dentists to evaluate the utility of cone beam imaging in their practice.

Any final thoughts?

Cost and the size of certain units is a deterrent to some practitioners. From a purely economic sense, the return on investment is hard to calculate, but the diagnostic capabilities and patient care it allows overshadow this. Planning for the future, 3D radiographic imaging will eventually be the standard of care. As with any technology, we can wait for improvements and prices to drop, but the trade-off is not utilizing this technology in the meantime.

Dental imaging is a very competitive industry and each company has unique CBCT models and software setups, and all are improving. Some have fees for maintenance and upgrades, and all of these considerations should be factored into a purchase decision. My advice is to learn how to read the scans and familiarize yourself with the various features and software that are available. With this foundation, you will understand the presentations of the various systems so you can choose the best imaging unit for your practice.

The author has no commercial conflicts of interest to disclose.

Featured image by  ISTOCK_OLES/ISTOCK/GETTY IMAGES PLUS

From Decisions in Dentistry. January 2019;5(1):24–26.

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