Mandibular advancement device
Mandibular advancement device
There are several types of efficient mandibular advancement devices for the treatment of sleep apnea.
The Canadian Thoracic Society (CTS) as well as the American Academy of Sleep Medicine (AASM) suggest, as a front-line treatment, the use of dental device in the treatment of simple snoring, in cases of light to moderate obstructive apnea or in patients suffering from several apnea, but who are intolerant or refuse to use CPAP. Advancement devices can be used with a continuous positive airway pressure (CPAP) machine, which increases the therapeutic efficiency of one another.
Dental devices are efficient in reducing the number of apnea-hypopnea episodes (⬇ IAH) and increasing the oxygen saturation level in the blood, in improving sleep architecture and reducing microarousals.
Subjectively and objectively, dental devices reduce daytime sleepiness in the same proportion as CPAP, reduce snoring in most patients, increase cardiovascular health and car driving performance.
Two significant technological breakthroughs enabled the improvement of performances of that kind of appliance:
1- Adjustment of the amplitude of mandibular advancement
2- Improvement of the appliance design to improve retention on teeth
The hard part is to measure the amplitude of advancement suited for a patient. Each case is specific.
In individuals having an apnea-hypopnea index of 5 to 10, 63% of patients see their state become standardized after 4 years.
Mandibular advancement device example
Here is a non-exhaustive presentation of several available appliances:
SomnoDent®: made of upper and lower plates manufactured individually. A mechanism including an inclined plane on the side allows the forward positioning of the lower jaw. Advancement is done by the screw on the sides.
Narval™ CC device: Advancement device in 2 parts with a lateral advancement mechanism located at the plane of upper teeth. The principle is to optimize retention of the mandibular advancement (O.R.M.).
The model shown on the opposite side is older than 2009. Nowadays, the prosthesis is manufactured according to a CAD/CAM technological process and uses a polymer made of white powder, sintered by laser, which makes the prosthesis durable, slim and comfortable.
See ResMed video
TAP® device: (Thornton Adjustable Positioner). Made from thermoplastic sheet and adjusted in the mouth with acrylic padding. This type of prosthesis is very robust.
Klearway™: mandibular advancement device with an expansion screw in the palate. Developed by Dr Alan Lowe, UBC.
Clinical protocol for therapy with mandibular advancement device
- Medical evaluation by a physician, a pulmonologist or an ORL
- Polysomnography and evaluation report from the pulmonologist
- Oral examination by the dentist
- Determination of the type of appliance that meets the patient’s need
- Manufacturing and adjustment of the device in the mouth by the dentist. Instructions on wearing and use of the appliance
- Follow-up with the dentist for the titration of the mandibular advancement, modification of the appliance if required based on the reduction of apnea symptoms
- Re-evaluation by the physician, the pulmonologist or the ORL. Possibility to redo a polysomnography
- If the device is comfortable and efficient, the dentist must re-evaluate the patient, the device and the relationship between the jaws and dentition during the first 2 years
- Annual follow-up with the dentist to evaluate the wearing of the device, the efficiency and the possible undesirable side effects like dental movements
Observance to treatment and side effects
Mandibular advancement devices are efficient…if they are worn.
The main reasons mentioned to avoid wearing this kind of appliance are discomfort or bulking sensation. It can take up to 6 months to get used to the appliance. The observance rate varies from one study to another, but generally, 75% of patients still use the appliance after one year of treatment.
Side effects observed are the following:
A group of researchers from the University of British Columbia studied the long-term sequellae of mandibular advancement devices on a group of 70 individuals having used such an appliance for a period of 7 ± 2 years. The appliance studied was the Klearway™.
Part 1: Cephalometric analysis
• Reduction of overbite (OB)
• Reduction of overjet (OJ)
• Increase in lower facial height (LFH)
• Reduction of the angle between the upper incisors and lower incisors (IIA)
• Retroclination (retrusion) of the upper incisors (reduction of inclination compared with the skull base, U1 to SN)
• Proclination of the lower incisors (forward inclination, L1 to MP)
Part 2: Study models
• 14% of individuals had no changes in their occlusion
• 41% had favorable changes
• 44% had negative changes
• So 85% of the 70 individuals from the study had changes in parameters of their occlusion after using the device for a minimum duration of 5 years.
Changes considered negative occurred in the subgroup of patients having small overjet and overbite (0-4 mm).
Changes considered favorable occurred in the subgroup of patients having accentuated overjet and overbite (> 4 mm).
The group from British Columbia re-actuated data from the 2006 study by using a three-dimensional (3D) analysis method.
Results show a reduction of the maxillary arch width and an increase in mandibular arch width (graph A). Graph D shows a reduction of the overjet. Graph B indicates a reduction of the curve of Spee, which can be correlated with a reduction of the overbite (graph C).
The antero-posterior relationship change (graph E) of the order of -1.8 mm means that the lower jaw tends to move forward by 1 to 2 mm. It is a good thing if an individual has a shift between the 2 jaws at the beginning of treatment. It is not so much a good thing if there is little or no shift between the 2 jaws at the beginning of treatment.
Fernanda Ribeiro de Almeida, Alan A. Lowe, et al, Long-term sequellae of oral appliance therapy in obstructive sleep apnea patients: Part 1. Cephalometric analysis, Am J Orthod Dentofacial Orthop 2006;129:222-9.
Fernanda Ribeiro de Almeida, Alan A. Lowe, et al, Long-term sequellae of oral appliance therapy in obstructive sleep apnea patients: Part 2. Study-model analysis, Am J Orthod Dentofacial Orthop 2006;129:205-13.
Hui Chen, Alan A. Lowe et al, Three-dimensional computer-assisted study model analysis of long-term oral appliance wear. Part 2. Side effects of oral appliances in obstructive sleep apnea patients, Am J Orthod Dentofacial Orthop 2008;134:408-17.
What do these side effects look like concretely?
Here is an intraoral view of a patient who consults because “his teeth do not touch anymore”. He has been wearing a mandibular advancement device for more than 3 years. This device turned out to be very efficient in the treatment of his sleep apnea. We can see that the laryngopharynx is cleared (white arrows).
However, the teeth moved. The upper incisors moved backward and positioned themselves very vertically instead of being inclined forward (red arrows). The lower incisors tilted forward.
The posterior molars do not touch (green bar). There is no positive overjet anymore and it is reversed (negative). There is no overbite anymore, the occlusion is anteriorly open. There is only one contact on each side illustrated by white arrows where the premolars are located.
This patient did not visit the dentist who made the device since he received it. He did not do the exercises that were prescribed to him to avoid or reduce permanent movements.