The ability of orthodontists to understand, visualize and measure the upper airways on our patients is becoming increasingly relevant due to the accumulating scientific research strongly correlating facial shapes with airway character. The human upper airway is readily viewable and measurable through CBCT (Figure 1a, 1b). This article will explore the ability to analyze the human airway through the use of low dose CBCT.
Cone beam computed tomography (CBCT) was developed in the 1990’s and is increasingly becoming the imaging modality of choice in just about every specialty in dentistry. With the introduction of newer CBCT machines (such as the i-CAT FLXTM) which are actually less radiation than a traditional 2D panorex13, CBCT is quickly becoming THE standard of care in clinical Orthodontics14. It now becomes the obligation for, and the responsibility of, every orthodontist to not only consider upper airway measurement and risk for OSA in every orthodontic case, but to actually treatment plan the case for the best supportive airways (Figure 2).
CBCT is already the imaging technique of choice in orthodontic academia and orthodontic research. This is mainly due to significantly lower effective dose, reduced costs, reduced acquisition time, and greater market availability compared to conventional medical grade CT scanners known as multidetector or multislice CT (MDCT or MSCT)8.
In the next article posted on this blog, we will be reviewing the scientific research linking facial types, to upper airway measurements, to obstructive sleep apnea (OSA). This relationship has driven an increased interest in the ability to use craniofacial imaging techniques such as CBCT to screen for patients at risk for OSA and treatment plan orthodontic treatments relative to airways. It has also fueled a slew of recent studies providing insight into the effects of various treatments and their effects on airways, and thus OSA.
According to the medical literature, we now know that airway evaluation can be performed accurately with magnetic resonance imaging (MRI)1,2,3. Although medical grade CT scans are superior to CBCT in discerning between different soft-tissue structures of the craniofacial region, they do so at the expense of greater biological and financial costs (i.e. money and radiation). Evaluation of the upper airway, using CBCT imaging has been scientifically studied, validated and documented to be as accurate as medical grade CT.4, 5, 6, 7, 8, 9, 10, 11, 12.
Because of its easy access, reduced cost and lower radiation compared with medical CT’s and especially its ability to distinguish the boundaries between soft tissue and airspace such as the sinuses and the pharyngeal airway accurately, “CBCT has become an unprecedented diagnostic method to analyze the airway three dimensionally”, according to researcher Dr. R. Guijarro-Martinez8 (Figure 3).
As a result, the number of publications related to upper airway evaluation with CBCT has increased significantly during the last few years8. CBCT technology has emerged as the standard of care for obtaining a thorough 3D assessment of the upper airway in orthodontics14. Other major benefits of CBCT include the ability to see the 3rd dimension, the width of gum’s & bone, the TMJ’s, the sinuses, forecasting the eruption of future teeth in children, assessment of third molars, screening for potential pathology and many more (Figure 4).
Of course from an orthodontic treatment planning perspective the sky is the limit with advanced virtual treatment planning allowing the orthodontist to simulate various treatment plans and their potential effect on airways (Figure 5).
This airway screening approach, and this airway-based orthodontic treatment, could very well be the key to preventing OSA in children and in their future adulthood as in Dr. Quintero’s own son (Figure 6, 7)15.
The following training video demonstrates the ease of identifying, segmenting, and measuring the upper airway using software called Invivodental from Anatomage Corporation (www.anatomage.com):
- Abbott MB, Donnelly LF, Dardzinski BJ, Poe SA, Chini BA, Amin RS. Obstructive sleep apnea:MR imaging volume segmentation analysis. Radiology 2004: 232: 889–895.
- Arens R, McDonough JM, Corbin AM, Rubin NK, Carroll ME, Pack AI, Liu J, Udupa JK. Upper airway size analysis by magnetic resonance imaging of children with obstructive sleep apnea syndrome. Am J Respir Crit Care Med 2003: 167: 65–70.
- Arens R, McDonough JM, Costarino AT, Mahboubi S, Tayag-Kier CE, Maislin G, Schwab RJ, Pack AI. Magnetic resonance imaging of the upper airway structure of children with obstructive sleep apnea syndrome. Am J Respir Crit Care Med 2001: 164: 698–703.
- Ghoneima A, Kula K. Accuracy and reliability of cone-beam computed tomography for airway volume analysis. Eur J Orthod. 2011 Aug 10.
- McCrillis JM, Haskell J, Haskell BS, Brammer M, Chenin D, Scarfe WC, Farman AG. Obstructive sleep apnea and the use of cone beam computed tomography in airway imaging: a review. Semin Orthod. 2009;15:63–69.
- Ogawa T, Enciso R, Memon A, Mah JK, Clark GT. Evaluation of 3D airway imaging of obstructive sleep apnea with cone-beam computed tomography. Stud Health Technol Inform. 2005;111:365–368.
- Ogawa T, Enciso R, Shintaku WH, Clark GT. Evaluation of cross-section airway configuration of obstructive sleep apnea. Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2007;103:102–108.
- Guijarro-Martinez R, Swennen GR. Cone-beam computerized tomography imaging and analysis of the upper airway: a systematic review of the literature. Int J Oral Maxillofac Surg. 2011;40:1227–1237.
- Lohse AK, ScarfeWC, Shaib F, Farman AG. Obstructive sleep apnea-hypopnea syndrome: clinical applications of cone beam CT. Australasian Dental Practice. 2009;20:122–132.
- Abramson Z, Susarla S, August M, Troulis M, Kaban L. Three-dimensional computed tomographic analysis of airway anatomy in patients with obstructive sleep apnea. J Oral Maxillofac Surg. 2010;68:354–362.
- Cameron Aboudara, Ib Nielsen, John C. Huang, Koutaro Maki, Arthur J. Miller, and David Hatcher. Comparison of airway space with conventional lateral headfilms and 3-dimensional reconstruction from cone-beam computed tomography. Am J Orthod Dentofacial Orthop 2009;135:468-79)
- Lenza MG, Lenza MM, Dalstra M, Melsen B, Cattaneo PM. An analysis of different approaches to the assessment of upper airway morphology: a CBCT study. Orthod Craniofac Res 2010: 13: 96–105.
- John B. Ludlow and Cameron Walker Assessment of phantom dosimetry and image quality of i-CAT FLX cone-beam computed tomography Am J Orthod Dentofacial Orthop 2013;144:802-17
- Quintero, JC. New Study May Change the Face of Orthodonitcs. Orthodontic Practice US. January/February 2014- Volume 5, N0 1. Page 41-43
- Quintero, JC. (Case Report) Unlocking King Airway, TMJ and Growth with CBCT as the key. OrthoTown, September 2011, Page 70.