Large FOV CBCT: Bridge the Gap

Jessica Zugai, DMD

It is no secret that the use of Cone Beam Computed Tomography (CBCT) has proven valuable in the specialized fields of Oral Surgery and Endodontics. From diagnosing root fractures to planning precise implant placement and restorations, the CBCT has become an amazing tool in our dental armamentarium. While a specialist may choose a smaller field of view (FOV) for single tooth diagnostics and implant placement, and this type of machine may be a more initially affordable investment, incorporating a larger FOV CBCT into the general dental practice may provide a diagnostic advantage to the general dentist. improved diagnostic and screening abilities of a large FOV CBCT may help bridge the gap with other healthcare professions such as primary care physicians, ENT’s, pediatricians, and chiropractors. This is especially true in the quickly advancing field of Airway Centered Dentistry, which typically requires a team treatment approach.

Image above is an example 23 cm x 23 cm CBCT of a 38 yo male with medical history of moderate sleep apnea, hypertension, and diabetes mellitus type 2. Entire airway is visible from nose to just above the trachea. Narrowest portion is noted posterior to tongue, making oral appliance therapy with a mandibular advancement device a possible therapy option for this patient. This image allows for clear and effective communication with the patient’s sleep physician and entire medical team.

Airway Centered Dentistry refers to dental teams that are trained to recognize and provide treatment and therapy options for patients with sleep disordered breathing. In 2017, the ADA recommended that all dentists screen for obstructive sleep apnea (OSA). Including a sleep and breathing questionnaire into existing medical history and use of the Epworth Sleepiness Scale (ESS) are common ways to incorporate OSA screening. While a CBCT is not necessary to complete the screening process, a large FOV CBCT can help to visualize areas of possible obstruction and many softwares allow the user to measure airway volume. While the CBCT cannot predict airway collapsibility, it is a powerful screening and educational tool for the patient as well as the patient’s medical and dental treatment team.

Clinicians must use judgement when determining which patients may benefit from use of such a tool. A clinician may choose to obtain a large FOV CBCT if a patient has a high score on ESS or other concerns on a sleep and breathing questionnaire. A large FOV CBCT may also be helpful when determining if a patient would benefit from such therapies as oral appliance therapy (OAT) with mandibular advancement devices (MAD). While the radiation exposure is much less than traditional medical CT imaging, it is higher than the dental standard of a panoramic radiograph. These factors should be considered carefully when choosing to use a large FOV CBCT.

The images of 12-year-old male. Medical hx significant for ADHD. Pt has undergone phase 1 ortho with relapse because he was unable to wear his retainer. CBCT obtained and reveals possible airway obstruction of the upper airway as noted with large nasal turbinate structures and adenoidal tissue. CBCT will be used to coordinate successful orthodontic treatment. Referral to his pediatrician to rule out OSA and also to ENT to evaluate nasal breathing ability prior to further orthodontic treatment.

Typical field of view for endodontics and single implant restorations is variable and based on provider preference but may be limited in most cases to keep radiation exposure at a minimum. A FOV of 15 cm x 15 cm or larger can capture many structures vital to understanding and treating the airway. Structures such as Glabella, Nasion, soft tissue landmarks of the tip of nose and bottom of chin, and C1-C5 vertebrae can be captured with a large FOV. By capturing all of these landmarks, the clinician is able to visualize all of the teeth, the maxillary sinuses, the nasal cavity, and the entire maxilla and mandible including the hard tissue structures of the TMJ.

As an added bonus, it allows the clinician to visualize the entire airway from the point of air entry (nose), through the naso and oropharynx, to just above the inferior border of the larynx, where the trachea begins. Visualization of this entire pathway is important because a patient can have more than one area of airway obstruction. Information about an individual’s entire airway space helps to formulate customized treatment plans and allows for better communication with the patient’s medical team.

“Sharing these images and our treatment plans for these patients with their medical teams helps to bridge the gap between professions and allows for more predictable treatment outcomes. It may also serve to educate other medical professionals in all that dentistry has to offer.”

The value of these large FOV images goes beyond the general dentistry practice and airway management. Consider a patient with the chief complaint of TMJ pain. A large FOV CBCT may show an abnormal curvature of the spine and thus the clinician may choose to refer the patient to a chiropractor as part of his or her treatment plan. Another example is a young child that presents with snoring and symptoms of sleep disordered breathing otherwise missed by the pediatrician. A large FOV CBCT may give valuable clues to pharyngeal and palatine tonsillar inflammation that may have been clinically unremarkable.

These images can be shared with the patient’s pediatrician and ENT. Sharing these images and our treatment plans for these patients with their medical teams helps to bridge the gap between professions and allows for more predictable treatment outcomes. It may also serve to educate other medical professionals in all that dentistry has to offer. Furthermore, this type of open communication among local medical professionals serves to promote the best health and wellness options for the patients that we serve in our communities.