The first cone beam computed tomography or CBCT devices hit the dental world in the late nineties. The overall advantage of using a CBCT was the ability to get detailed information of the maxillofacial region including the maxilla, mandible, base of skull, and temporomandibular joints for not only presurgical planning purposes but also its diagnostic abilities.

Since the inception the market has grown to over 85 distinct CBCT models available. CBCT machines include some models called hybrid that incorporate panoramic and/or cephalometric images. The drive of success for CBCT machines can be related to the accessibility. The low cost, small size, and ease of use all contribute to the equation. High resolution images at one-tenth the cost and a fraction of the radiation compared to a CT scanner makes CBCT machines a leading method in the evaluation and planning for dental implants.

Hundreds of “slices” of information are gathered and assembled by software into three-dimensional views of any aspect in a given study. Data can be assimilated for the purpose of comprehensive diagnostic analysis and presurgical treatment planning, as well as for the production of stereolithographic bio-models.

There can be cause for concern with clinicians who are unfamiliar and/or poorly trained with CBCT’s. The value of getting education beyond what the vendor teaches is beneficial. CBCT’s reveals more information about the maxillofacial region in comparison to the narrow zone of osseous and dental-mostly-structures seen in panoramic and intraoral imaging. The incidental findings on a scan can range from thickening of the mucosal lining of the maxillary sinuses to a deviated septum and even tonsilloliths. 

There are three findings that may require action to be taken for the long-term health of the patient and the success of the implants.

Narrowing of the Airway

This is the most common incidental finding and is most frequently associated with a retruded tongue, soft palate, or even tonsillar hypertrophy, and may be one of the causes of sleep apnea. A referral to an ENT physician or sleep specialist may be the proper management or if in your dental practice you treat sleep disordered breathing your evaluation doesn’t need to be referred. The pattern of implant complications related to sleep apnea is bruxism as related to sleep apnea. The jaw is one of the main supports of your airway, which is all soft tissue. When the throat muscles relax, the airway basically hangs on the jaw. When the airway collapses, cutting off air, the body has to put the jaw into a position where it helps hold the airway open better. That’s what causes the jaw to clench together, and this clenching behavior can last for a moderate amount of time   after each apnea. With potentially hundreds of apneas each night, it can drive a clenching behavior that is very destructive for teeth and for restorations like dental crowns, whether they’re on dental implants or natural teeth.

Sinus Inflammation

The maxillary and other paranasal sinuses may show different degrees of concentration of inflammatory tissues in CBCT scans that could be asymptomatic or the symptoms are low grade. The symptoms could be sinus congestion, coughing and pressure headaches. Most sinus infections are caused by bacteria and are successfully treated with antibiotics. People who suffer from chronic sinusitis are at a higher risk of developing dangerous complications including, osteomyelitis, eye socket infection and meningitis. There is an increased risk in implant placement of developing a sinus infection or sinusitis. Using a CBCT may help prevent more problems in the sinus area which is easier than fixing them later.  

Carotid Calcifications

The ability to see carotid calcifications on panoramic radiographs have been known for years. A CBCT can show them as well but it is not necessarily a diagnostic tool. The most common location is the carotid bifurcation, where the carotid artery splits into the external and internal carotid arteries. It occurs at the level of C3 and C4 vertebra, posterior-laterally to the airway. Carotid atheromatosis is a silent disease that is associated with a high risk of stroke in older individuals.  Clinicians using the opportunity to impact a patient’s overall health by being familiar with the appearance of disease and anatomical variation is just another way the profession is a value to healthcare.

Cost

A CBCT scanner is just about the most expensive piece of equipment a dental practice could purchase aside from in-office milling systems. Speculation is that it takes three years for dentists to recoup their investment. There are however opportunities to send a patient to another practice who takes the scan and sends the CD back to your office. There are also imaging businesses in many cities that are set up outside dental practices that do the same thing. There are some concerns with dentists about having more data will put them at risk for liability. An option to help with that concern, radiologists will read the scans for $50-70 each and they will spend the time analyzing for pathologies and such.  If you can afford one inside your office it helps with efficiency and broadens your scope of practice. A CBCT is probably standard of care for placing implants but it can help to incorporate sleep disordered breathing into your practice. It can be used in orthodontics, endodontics and seeing pathologies more clearly than on a 2-D image.

Radiation

Radiographs are one of the best diagnostic tools we have in not only dentistry but in medicine. Taking radiation safety seriously is of great importance. Effective radiation doses for CBCT should be far below the levels of a CT and be an equivalent of 2-10 panoramic radiographs. However, the reality is the variance is equivalent of 2-200 panoramic images. As hard as it may be patients should be informed of the potential risks, benefits, and alternatives. We should subscribe to the ALARA Principle, "As Low as Reasonably Achievable," which mandates that every precaution should be taken to minimize radiation exposure to patients.

Repeated patient exposure to radiation over long periods of time is associated with irreversible eye damage, genetic defects, and the development of malignancies in the lens of the eye, thyroid, salivary glands, bone marrow, and skin.

We as health-care professions must be careful and ionizing radiation should be used with care. The unfortunate part of CBCT scans are when dosage levels go too low the images may be unusable. Concerns about radiation exposure are greater for younger patients because they are more sensitive to radiation (i.e., estimates of their lifetime risk for cancer incidence and mortality per unit dose of ionizing radiation are higher) and they have a longer lifetime for ill effects to develop.

The FDA has launched a pediatric X-ray imaging website that provide specific recommendations for parents and healthcare providers. There is also a website from the FDA that addresses guidelines for dental providers using CBCT’s in their practices.

https://www.fda.gov/radiation-emitting-products/medical-x-ray-imaging/dental-cone-beam-computed-tomography

Many dentists have placed implants successfully using only 2-D images, but having the enhanced predictability in implant placement due to thorough analysis and preplanning with a CBCT is a wonderful benefit for the success of your implant practice.