Dentists are playing an active role in helping patients address potentially serious breathing problems that occur during sleep.
The American Dental Association defines obstructive sleep apnea as a disorder in which breathing stops for short periods of time during sleep. In a literature review article published in the May 2009 issue of The Journal of the American Dental Association, researchers say that a periodic lack of oxygen in the blood can have damaging affects throughout the body. The Potentially Harmful Medical Consequences of Untreated Sleep-Disordered Breathing: The Evidence Supporting Brain Damage, is co-authored by Dr. Glenn Clark, director of the Orofacial Pain and Oral Medicine Program at the University of Southern California School of Dentistry, and Dr. Michael Simmons, USC clinical associate professor. "Periodic hypoxia [low oxygen levels] can bring about serious cardiovascular and central nervous system complications," said Dr. Clark.
Episodic hypoxia has been linked to cellular damage in the brain — which may not be reversible — and cognitive changes in laboratory animals and humans. Dr. Clark added that studies have further suggested that sleep-disordered breathing like sleep apnea may have negative affects on learning and memory functions.
What's more, the cardiovascular implications of sleep apnea are worrisome. Dr. Clark said that during periods of hypoxia, hemoglobin, the molecule that normally binds to oxygen in the blood, instead takes oxygen from the cell walls along the interior of blood vessels. This changes the properties of the vessels in such a way that allows plaque to bind more easily, which could potentially lead to atherosclerosis and other serious cardiovascular problems.
"A 40-year-old patient with sleep apnea can have the arteries of a 60-year-old," Dr. Clark said. Dr. Reyes Enciso, assistant professor of clinical dentistry at USC, said the risk of sleep apnea increases greatly according to age and body mass index and is much more common in men.
"As many as 1 out of every six people over 50 has at least mild sleep apnea," Dr. Enciso said. "And it's estimated that almost 75 percent of severe apnea cases are undiagnosed."
The majority of sleep apnea cases involve obstruction of the airway, whether the tongue or soft palate blocks the airway or the surrounding muscles relax and allow the airway to momentarily collapse.
The USC researchers encourage patients to talk about their sleep habits with a dentist or doctor, including instances of daytime sleepiness and snoring. Loud snoring with telltale pauses is an indicator of sleep apnea because it is audible evidence of the tongue or soft palate obstructing the airway, said Dr. Enciso.
Patients at risk are often referred for a polysomnogram, or "sleep study," during which the patient's vital signs and behaviors are closely monitored as they sleep. Treatment for sleep apnea after diagnosis can involve using a continuous positive airway pressure device with a mask that keeps air flowing into the nose during sleep. Dr. Clark said that patients with mild cases of sleep apnea may also find effective relief by using a dental appliance that draws the lower jaw forward and keeps the tongue from blocking the airway.
Drs. Clark and Enciso hope to eventually use cone-beam computerized tomography scans in conjunction with clinical research data in order to better identify patients who may be at risk for sleep apnea in future.
"The airway changes with weight gain and age," said Dr. Clark, explaining how progressively drooping soft tissues can block the airway and how weakened muscles plus the presence of nearby fat deposits can cause the airway to collapse more easily.
Dr. Enciso said the goal is to eventually be able to take a CT scan of a patient and artificially add weight or age to the scan to see how the airway's anatomy could change. Such data could help predict whether a patient might be at risk for sleep apnea in the future and would encourage them to start preventive measures. "We want to be able to find individuals at risk for sleep apnea as early as possible," she said.© American Dental Association. All rights reserved. Reproduction or republication is strictly prohibited without the prior written permission from the American Dental Association.