What are oral appliances (OA) for obstructive sleep apnea?

What are oral appliances (OA) for obstructive sleep apnea?

Sleep apnea oral appliances are primarily intended for the treatment of patients with mild to moderate obstructive sleep apnea. In some cases, oral appliance therapy of a patient with severe sleep apnea may also be considered in cases where, for some reason, CPAP therapy is not appropriate. Untreated sleep apnea increases the patient’s risk of traffic accidents and cardiovascular disease and metabolic syndromes. This will also increase the costs to society through increased use of health services. The role of the basic trained dentist in identifying patients at risk should be emphasized. Informing the patient about the different treatment options is important, but the choice of treatment line is made by the doctor and the dentist in collaboration with the patient. The use of the oral appliance therapy should be monitored annually. At the same time, side effects related to oral appliance therapy, such as possible changes in the bite, are monitored.

Different types of oral appliances

There are numerous different types of oral appliances for the treatment of sleep apnea, and the purpose of this article is to compare mandibular advancement devices (MADs). They are one-piece or two-piece devices and have adjustment options for both jaw forward and lateral movements. The height of the rails also varies depending on the manufacturer. The instruments are usually individually made based on replicas, but home-fit thermoplastic sleep apnea oral appliances are also available on the market. Very little research has been done on the relationship between the sleep apnea oral appliance model and the follow-up of treatment outcomes or the number of side effects. According to current knowledge, sleep apnea devices that allow vertical movement and opening of the mouth are less effective than appliances that allow lateral movement alone. No studies have been performed on the effect of sleep apnea oral appliance material on the treatment of sleep apnea. Generally, sleep apnea devices are made of acrylic material and their hardness varies depending on the type and manufacturer.

Monobloc oral appliance (OA)
Monobloc - Single piece oral appliance

Single piece oral appliance – Monobloc

One-piece “monobloc” sleep apnea oral appliances are usually instruments made of acrylic plastic that do not have the ability to adjust the lower jaw forward or rail height. They are cheap and easy to manufacture compared to two-piece sleep apnea oral appliances.

When comparing different devices for treating sleep apnea, the advantages of a one-piece monobloc device were found to be low cost, fit and quick start of treatment. However, the Monobloc oral appliance can’t be adjusted after it has been manufactured. This can lead to poor treatment outcome due to insufficient protruusion and the consequent residual AHI. The monobloc rail has been shown to reduce the number of breathing breaks, but has not been shown to normalize AHI or provide adequate therapeutic efficacy in the treatment of obstructive sleep apnea.

Bibloc oral appliance – separate constructions for the upper and lower jaws

Bibloc oral appliance has separate constructions for the upper and lower jaws and is equipped with connectors or attachments that advance the mandible. The most common and effective sleep apnea oral appliance model is a custom-made, two-part device with an adjustment mechanism to determine the correct position of the lower jaw. Two-piece mouthpiece also allows lateral and / or vertical movements of the lower jaw when the one-piece rail does not allow movement of the jaw at all. The two-piece sleep apnea rails vary in terms of upper and lower fixation mechanism, jaw range of motion, vertical height, material, and dentition coverage.

SomnoMed oral appliance (OA)
SomnoMed oral appliance (OA)

SomnoMed oral appliance

SomnoMed sleep apnea oral appliances are bibloc ,two part devices and come in several different models. The traditional SomnoMed sleep apnea device has fixed wing-like brackets (Figure 5) that do not allow lateral movements of the lower jaw, but allow full opening of the mouth. The amount of forward import of the lower jaw can be adjusted from the side of the device. The extent of the protrusion movement is practically limitless when using the device.

TAP oral appliance (OA)
TAP oral appliance (OA)

M.D.S.A. and TAP oral appliances

M.D.S.A. (Medical Dental Sleep Appliance) and TAP (Thornton Adjustable Positioner) sleep apnea devices are two-piece instruments covering both dental arches. The upper incisors have a hook-like bracket (Figure 4) that secures the upper and lower jaw parts together. At the same time, the lower jaw can be held in the protrusion position when the hook in the lock pulls the lower jaw forward. M.D.S.A. and TAP ddevices allow for extensive lateral movement, but vertical mouth opening is more limited.

Herbst oral appliance (OA)
Herbst oral appliance (OA)

Herbst-type sleep apnea oral appliances

Hebst-type sleep apnea devices are two-piece and adjustable devices that cover both tooth arches. The tooth-covering parts of the instrument are attached to each other with telescopic metal Hebst brackets. A Herbst-type rail with a hinged side bar allows lateral and vertical movements of the mouth. Thanks to the adjustable rail, it is possible to change the amount of protruusion to increase the efficiency and comfort of the device. In severely grinding patients, the rod may become detached from the acrylic material as a result of the biting forces.

Other sleep apnea oral appliances

Manufacturing an individual sleep apnea oral device requires multiple dental visits, which increases the patient’s time, effort, and cost. Alongside custom-made mouthpieces, there have been inexpensive commercial thermoplastic, so-called “Boil and bite” rails that do not require dental visits. They are a thermoplastic polymeric material and soften under the influence of hot water. The patient bites his teeth into the heated device and the material solidifies, as it cools, according to the patient’s bite. A comparison of an individually manufactured monobloc device and a similar thermoforming device showed that the custom-made device had a treatment success rate of 60 compared to 31% of the thermoplastic model. The majority of study participants (82%) also favored a individually made sleep apnea device at the end of the study. From this, it can be concluded that customizing the mouthpiece according to the patient’s teeth is one of the prerequisites for successful treatment. The problem with thermoformable devices can be poor retention to the teeth. Patients also cannot know the correct position of the lower jaw when fitting the device. It is thus almost impossible for them to get the optimal lower jaw protrusion position on the oral appliance, which is a prerequisite for successful oral appliance treatment.

Another type of mouthpiece brings the tongue forward instead of the lower jaw (tongue-retaining device. TRD). The device has an external holder that pulls the tongue by suction, preventing it from flowing towards the throat. TRDs are poorly stable, which impairs their response to treatment. Tongue-pushing devices are not generally recommended for the treatment of obstructive sleep apnea.

How an individual sleep apnea oral appliance is made?

An individual sleep apnea oral appliance is usually made based on an oral examination done by a dentist and alginate replicas of the dentistry. Prior to this, examinations related to sleep apnea (night polygraphy) and necessary diagnoses (severity of sleep apnea) should be examined by a physician. The suitability of a sleep apnea oral appliance must be determined individually and the patient’s motivation and compliance with the implementation of a oral appliance treatment must be determined.

The examination carried out by the dentist takes into account the condition of the teeth and jaw joints, on the basis of which the type of a device and the amount of jaw forwarding are determined. For example, for people suffering from bruxism (Teeth Grinding) a two-piece device is recommended that allows lower jaw movements. If the teeth are worn, composite plastic shapes can be applied to the premolar and molar areas of the labial surfaces of the teeth that increase rail retention. This is done before taking alginate replicates, if possible. If basic oral treatment and any retention supplements have been made, standard alginate replicas and a bite index can be taken from the dentition. The copy of the upper jaw should show the palate in addition to the dental arch. The bite index is taken with Astynax or beeswax. The dentist guides the patient’s lower jaw to the correct position, about 60% of the maximum protrusion position, and dissects the patient’s teeth against the wax. This is called a construction bite. Copies of alginate and bite index are sent to the dental laboratory, where the sleep apnea oral appliance is prepared according to the dentist’s instructions.

A separate reception is reserved for the mouthpiece fitting, in which case it is checked that the sleep apnea device fits in the patient’s mouth, the degree of protrusion is appropriate and the patient is able to put and remove the mouthpiece in place and ensure proper use and cleaning of the device. The use of the sleep apnea appliance should be reviewed approximately one month after the start of treatment, at which time the function of the device can be assessed.

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