Associate Professor Michael Stubbs - Specialist Oral Medicine BDS MDS MDSc FRACDS
Sleep disordered breathing includes obstructive sleep apnoea and upper airway resistance syndrome. The treatments currently used in the management of patients involve Continuous Positive Air Pressure (CPAP); Surgery and Mandibular Advancement Splints (MAS). In the general population it is estimated that 4% of males and 2% of females suffer obstructive sleep apnoea (1). An estimated 10% of patients who snore have sleep apnoea.
The primary management protocol involves the objective assessment of patients via a polysomnography which permits a measure of the sleep apnoea severity. This can be reported as a RDI (Respiratory Distress Index) and AHI (Apnoea and hypopnea index ratio). Other relevant clinical variables such as cardiac arrhythmia; hypertension; oxygen saturation; brain activity; airflow; recording of chest wall movements; restless leg or periodic limb movements.
The use of MAS is recommended primarily for the treatment of snoring and mild to moderate sleep apnoea. Generally this patient group are those with an AHI less than 25 events per hour without significant reductions in oxygen nadir. These devices are also used as second line therapy for patients intolerant of CPAP.
The dental profession has a role in the recognition and treatment of patients with a sleeping disorder provided these patients have been properly assessed via a polysomnography test and/or are referred for treatment by sleep physician or medical specialist such as cardiologist or otolaryngologist. Dental colleagues who undertake these treatments for patients should be trained both in the use of devices appropriate to the patient case and how to manage the complications that can occur in this patient treatment group.
Types of oral devices
Tongue retaining devices
These devices retain the tongue in a forward position thereby attempting to prevent the tongue from distalizing during sleep and obstructing the airway or vibrating against the soft palate.
Some of these devices include the Aveo –TSD (tongue stabilizing device) which can be purchased over the counter and essentially is placed in the front of the mouth with the patient protruding their tongue into the cavity of the device thus retaining the tongue tip (figure 1). Another type of tongue retaining device (figure 2) involves the placement of an upper and lower rim into the mouth with an anterior space to capture the tongue tip.
Some of the clinical problems a patient may encounter include difficulty in tolerating the device if they have a compromised nasal passage; loss of suction and thereby the tongue recoils into the mouth and discomfort from wearing (2). Interestingly however the clinical advantage in this form of treatment is patients can use irrespective of number of teeth present, especially in an edentulous patient (2)
One piece mandibular advancement devices
Therasnore™ is a laboratory produced device that following an impression of the patient’s teeth, it has an upper rim that retains the device onto the teeth. The lower plate in which a lug of acrylic is positioned is designed to engage the lingual surfaces of the lower incisor teeth only. The lower plate has several acrylic attachments which permit advancement of the lug in a forward direction to further hold the mandible protrusively when being worn (figure 3)
Overall, titratable oral appliances were better than non-titratable devices in the improvement of AHI, daytime sleepiness, snoring, and quality of life (17)
Two piece mandibular advancement devices
These types of dental devices allow a range of vertical, anterior and lateral movements which may help reduce pain within the temporomandibular joint-muscle complex and increase compliance (4). These splints are titratable, which enables gradual mandibular advancement. The advantage of this feature is the reduced jaw pain and discomfort and allows for the variation of mandibular protrusive ranges between patients.
Some examples of these devices include:
- Somnomed splint (figure 4)
- MDSA Medical Dental Sleep Appliance (figure 5)
- Guardian Angel titratable (figure 6)
Efficacy of mandibular advancement splints
Subjective reporting demonstrates improvement in snoring; sleep quality and day-time sleepiness in a high proportion of mandibular advancement splint users (5, 6, 7, 8)
Increases in slow wave and REM sleep (9, 10)
Long term usage and maintenance of improvement in symptoms have been demonstrated in 4 and 5 year studies respectively (11, 12) however an increased AHI has also been reported in 13% of MAS users (5). This underlines the importance of follow-up polysomnography testing long-term in monitoring effectiveness of the current patient treatment.
Lim et al (13) identified 17 random controlled trials that met their inclusion criteria and concluded that oral appliances improved subjective measures of sleepiness and sleep disordered breathing compared to no treatment or placebo. When oral appliances were compared with CPAP they concluded that CPAP was more effective at improving sleep disordered breathing, but it was unclear if CPAP improved quality of life compared to oral appliances.
Mandibular Advancement Splint Side-effects
These are usually mild symptoms in nature and for a short duration. The most common dental side-effect is occlusal (bite related) changes that usually develop between 18 months to 36 months of wearing the MAS. A decrease in over-jet, over-bite, number of occlusal contact points, and a different anterior–posterior relationship are dental changes most likely to occur (14). There is an association between the decrease in overbite and the amount of mandibular protrusion associated with wearing an oral appliance. This is a common international experience and for most patients may result in difficulties in biting their finger nails or tearing food between the anterior teeth.
Frequently on awakening, the patient will report a temporary change in their occlusion (bite) which will correct itself over several hours in most cases. The cause for this is either due to partial contraction of the lateral pterygoid muscle or pooling of blood within the posterior retro-discal tissues overnight due to the protrusion of the mandible. In my experience, the management of this can involve either jaw exercises in the morning or the chewing of a small piece of gum for 10-15 minutes after removing the device from the oral cavity.
Pain within the temporomandibular joint- masticatory muscle complex (TMD) can also occur but is usually of a short duration. This particular side-effect can often be managed where appropriate with either simple analgesia and jaw exercises. No reported increase in prevalence of TMD after 5 year follow-up has been reported (16). Follow-up with the treating dentist however is important and patients wearing MAS should be reviewed once every 6 months in the first year and then annually thereafter. This enables effective monitoring of any clinical side-effects as described above and to evaluate the retention and condition of the oral appliance in order to maintain effective patient compliance (15)
Website: www.michaelstubbs.com.au
References
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