While there’s an array of treatments on the market to control obstructive sleep apnoea, a dentist has produced a pioneering device that’s become a real game changer. By James Gallaway
Understanding the mechanisms of sleep apnoea for dentists—its relationship to breathing and sleep and other aspects of posture and symptomology—is now a vital part of dental practice in Australia, in terms of revenue and patient health outcomes.
Dr Chris Hart is an Australian dentist who’s going beyond positive airway pressure devices to produce his own mandibular advancement device for treatment in mild to moderate obstructive sleep apnoea where there is an intolerance to positive airways pressure devices.
Personal circumstances inspired action in Dr Hart—in fact, the affliction was his own. “I had all the symptomology—excessive somnolence, headaches and drowsiness.”
Dr Hart worked from the mid-2000s on aesthetic work and implants where he found himself increasingly frustrated at the damage bruxism wrought on his patient’s teeth. Marshalling his experience to work on this problem and, more broadly, the effects on posture and temporomandibular joint disorders (TMD) he moved on to the source of some of that symptomology: obstructive sleep apnoea (OSA).
“With all of these issues, you need to get in there and short-circuit it somehow,” he says. “People develop coping mechanisms that help them adapt to grinding or problems with posture. And they learn to cope but, sometimes, life experience will intrude and break down the adaptive processes.”
At the time, Dr Hart sold his dental practice and training centre to become a full-time director at Oventus Medical Ltd. The company took the prototype, Oventus O2Vent, to the CSIRO where it was printed in titanium. A development that provided strength and durability in a lighter structure with a wall thickness of only 300 microns.
“Because titanium is a class three implantable material,” he says, “it was able to be used in the mouth allowing air to flow through unutilised dead space that would normally be filled by acrylic in standard mouth guards.”
With a device that provided the same volume of air formerly supplied by the nose now able to enter the lungs, Dr Hart moved on to registration with the TGA in 2012.
Distribution began in Brisbane and moved on to the rest of Australia, with a launch in the United States in February of this year. All up, Dr Hart says 2500 devices, most of which are in Australia, have been provided to patients suffering from OSA.
Past and present
When the first continuous positive airway pressure (CPAP) devices to treat the condition were developed by Professor Colin Sullivan in the 1970s, surgery, including tracheotomies, was the dominant treatment in life-threatening forms of the condition.
Professor Sullivan, who worked on upper respiratory airways as a researcher at the University of Sydney and clinician at Royal Prince Alfred Hospital, developed the machine, experimentally, because a patient, whose blood oxygen levels were dropping to almost half each night, refused surgery.
“People develop coping mechanisms that help them adapt to grinding or problems with posture. And they learn to cope but, sometimes, life experience will intrude and break down the adaptive processes.”—Dr Chris Hart, director, Oventus Medical Ltd
The results were dramatic and the CPAP machine moved to centre stage as a form of treatment.
For Dr Derek Mahony, world-renowned orthodontist based in Sydney, sleep disordered breathing has formed a major part of his work for over two decades.
He views the work as continuing a focus on the oral cavity for better health, though he is also motivated because his father suffered from obstructive sleep apnoea and struggled with a CPAP machine.
“My father couldn’t tolerate the CPAP machine, which was very primitive back then,” he says. “It was a time when oral devices were no more complex than boil-and-bite mouthguards.”
Dr Mahony champions the effectiveness of CPAP treatment but is wary of its drop-off rate which, he says, “involves most patients giving it away, in the first year”.
Waking up tired
Sleep disordered breathing is a set of conditions that may begin with snoring and develop into UARS (upper airways resistance syndrome) or OSA, which is characterised by excessive sleepiness during the day and increased breathing effort. Patients in this category usually present with issues as broad ranging as irritable bowel syndrome, headaches, bruxism and depression.
The upper airways resistance is caused by airway interference. In children, the sleep disordered breathing condition relates to anatomical irregularities while adult conditions are more usually related to obesity and placement of the tongue and soft palate.
The deprivation of breathing that UARS produces precipitates micro-arousals in patients that naturally result from a triggering function in the sympathetic nervous system. When this continues throughout the night, it contributes to a fragmented sleep that occurs without apnoea or oxygen desaturation. However, the more serious occurrence of OSA can then develop, which will require an overnight sleep study (polysommnogram) for diagnosis.
In conditions involving obstructive and central sleep apnoea—which involves dysfunction of brain function stimulating breathing—air flow stops completely and the severity is measured in the duration and number of apnoeas that occur each hour.
The condition has always been regarded as life-threatening. Withholding breath is never healthy and, when this happens for more than 10 seconds at a time, it can cause desaturation of oxygen levels in blood of around four per cent.
As this continues throughout the night, a patient may be sleeping in conditions that are equivalent to the atmosphere they might encounter climbing Everest without oxygen.
In children, OSA peaks in prevalence from ages two to eight years of age when tonsils and adenoids are largest in relation to the rest of the airways. Causes in children can relate to craniofacial anomalies and obesity while, for adults, they may include hay fever, obesity, cigarette and alcohol consumption, menopause and craniofacial abnormalities.
“My father couldn’t tolerate the CPAP machine, which was very primitive back then. It was a time when oral devices were no more complex than boil-and-bite mouthguards.”—Dr Derek Mahony, orthodontist, Full Face Orthodontics
OSA has a serious relationship with morbidity in complications that relate to SIDS (sudden infant death syndrome) and ADHD (attention deficit hyperactivity disorder), are related to a decline in intellectual function, serious accidents involving a lack of coordination while manoeuvring machinery and motor vehicles, and are associated with hypertension, cardiovascular disease and stroke. It almost goes without saying, these conditions are increasingly comorbid with obesity epidemics currently plaguing the developed world.
Home study performed
“A diagnosis in a sleep study is required by law,” Dr Mahony says, “which used to be an expensive process, involving an overnight stay in a hospital, but the procedure is now available on Medicare. Patients can have a study performed at home with a unit that collects data overnight installed in their bedrooms.”
Data collected during sleep studies is detailed, including volumes of nasal airflow, blood levels of oxygen, along with electrical impulses related to heart, brain, muscle and eye activity. The last of these, which involves REM sleep, is particularly important as it relates to the measurement of other symptomology, including bruxism.
Recognising airway issues extra-orally is difficult in adults with yawning, mouth breathing and forward head posture as reliable indicators. Intra-orally, Dr Mahony says, there are a number of indicators in the oral cavity that a dentist can look for in their patients that may point to obstructive sleep apnoea.
“We work in threes,” he says. “First, the dentist looks in the mouth, then they have a STOP BANG conversation with adults [or BEARS for their children] and then you follow this with a sleep study.”
Dr Mahony is particularly concerned that dentists might mistake bruxism as an indicator of stress and anxiety, rather than sleep disordered breathing. He points out that the work by Dr Giles Lavigne from the University of Montreal found a high correlation with bruxism as it relates to sleep disorders. “Night grinders release cortisol, which affects the parasympathetic and sympathetic nervous systems,” he says.
Dr Lavigne’s work charts the evolution of definitions, classifications and causal theories as they relate to bruxism, which have changed considerably and it is no longer considered a parasomnia with aetiology that relies on mechanical factors or psychological issues.
Dr Mahony wants dentists to see bruxism as a sleep-related movement disorder that involves, as yet, an undetermined complex multisystem physiological processes.
As it relates to OSA, bruxism is more properly connected to the central and autonomic nervous systems, which work on sleep-related mechanisms that are influenced by neurochemicals in the maintenance of airflow during sleep. The relationship may involve increased motor activity underlying the genesis of sleep bruxism and rhythmic masticatory muscle activity preceding teeth grinding, in sleep.
Dr Chris Hart, the inventor of O2Vent, recommends dentists look for symptomology in their patients and test this with surveys and questionnaires. “It’s a great area to work in,” he says, “because you don’t need much kit.
“It also improves patient outcomes in a manner that is life changing so patients will refer others on and the revenues generated are in the thousands for each patient. We are in a situation now where around 34 per cent of males and 17 per cent of females suffer from the condition.”
Dr Hart believes dentists are best placed to work with patients who suffer this condition because they review patients at least annually and are already looking at patients’ airways regularly. “This year,” he says, “Southern Cross Dental is bringing out Leopoldo Correa, associate professor and director of the Dental Sleep Medicine Fellowship Program, Tufts University School of Dental Medicine in Boston.” The seminars delivered will help dentists take the first steps toward learning about incorporating dental sleep medicine into their practice.