back to the OPJ. The former have been shown to improve primarily by mandibular advancement 3, however for the latter, this author has observed through acoustic reflection and post-OAT therapy home sleep testing (HST), that objectively increasing vertical dimension can be of significant benefit.
So just how does one determine where the problem exists within a given airway? As of today, there are only four ways to visualize the active airway threedimensionally and map the etiology for an individual patient. C-T ( or cone beam C-T) imaging 5, MRI 6, Sleep Endoscopy 7, and Acoustic Reflection 8,9. MRI is well documented to see contributing soft tissue location and enlargement however the test may be cost-prohibitive and differentiation between the airway and dense cortical bone may be difficult. C-T is a static image that could require multiple images to compare the patency of the airway, and in the case of a cone beam, variations in positioning, head posture, and timing of the image capture may necessitate retakes that expose the patient to un-necessary radiation. Both MRI and C-T are sufficient for assessing risk for the disease, but may not define it in the active airway. Drug Induced Sleep Endoscopy (DISE) is perhaps the most accurate way of determining the site or sites of greatest constriction in the active airway during sleep 7, however as the name suggests, this procedure requires sedatives or general anesthetic, which may be of risk to the many health-compromised patients we treat for OSA. Acoustic Rhinometry/ Pharyngometry is an accurate, time and cost-efficient test that utilizes sound waves to safely map the cross-sectional area of both the nasal and oro/hypopharyngeal
airway to the level of the glottis. 8, 9 The test is performed on the awake patient using the Muller maneuver to simulate airway collapse. The Muller maneuver has been proven to be comparable to DISE in its’ accuracy at determining the offending structures in OSA. 10
As a practitioner, the author has used acoustic reflection to map the airway and simulated collapse of each and every OAT patient he has treated in the past three years. Over this time, a common theme has emerged. Patients who show greater collapse with Pharyngometry at the pre-OPJ and OPJ space tend to benefit from vertical opening to allow air past the space between the dorsal surface of the tongue and the hard and soft palate. (FIG 1) As a trend, this tends to benefit those with deep bite or low mandibular plane angle (MPA) tendencies and can be seen on lateral cephalogram or cone beam image as a lack of “tongue bubble” space.(FIG 3,4) With the addition of vertical in these patients, an immediate improvement in the anterior part of the airway can be seen with pharyngometry (FIG 2) For those with a higher MPA, vertical must be applied with discretion as these patients may worsen due to distal rotation of the mandible. With acoustic reflection, this will be seen as a decrease in the cross sectional area of the airway. 8, 9 The advantage of acoustic reflection is that the practitioner can determine the location of the compromised airway and apply vertical dimension enhancement as necessary with objective measurement. The most anterior problems can be immediately improved prior to A-P repositioning which may have more
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About the Author: Dr Horowitz is a 1991 Graduate of the Medical University of South Carolina College of Dental Medicine in Charleston, S.C. He is the owner and director of the Carolina Center for Advanced Dentistry and Advanced Sleep and Breathing Centers in Conway, S.C. Dr Horowitz is a fellow and delegate of the Academy of General Dentistry and an active member of the American Academy of Dental Sleep Medicine, the American Academy of Craniofacial Pain, the American Equilibration Society, the American Academy of Cosmetic Dentistry and the Dental Organization for Conscious Sedation. He also serves as a mentor at the prestigious Kois Center in Seattle, WA., Dr. Horowitz lectures to dentists world-wide for Sleep Group Solutions and the Catapult Group, where he also serves as a Key Opinion Leader for several dental manufacturers..
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