Oral Appliances
Snoring and obstructive sleep apnea (OSA) are common in the adult population, and oral appliances represent a noninvasive and easy and treatment option for many of these individuals. Mandibular re-positioning appliances (MRAs) move the mandible downward and forward to improve the upper airway patency. The primary mechanism of action of an MRA is generally considered to relate to the anterior movement of the tongue and consequent increase in the anteroposterior dimensions of the oropharynx. The use of the tongue-retaining device (TRD) that produces suction of the tongue into an anterior bulb is less common. There is very little good evidence of any beneficial clinical effects from TRDs.
Clinical Outcomes
The majority of patients treated with MRAs describe reduced daytime sleepiness, and snoring. Sleep apnea measurements confirm fewer apneic and hypopneic events. Complete treatment success, defined as an apnea-hypopnea index (AHI) of fewer than 5 events per hour and resolution of symptoms, has been reported to occur in 19% to 75% of patients with mild-to-moderate OSA. The use of a more liberal definition of success, namely an AHI of fewer than 10 events per hour, has demonstrated higher success rates. 5-8 Continual snoring and daytime sleepiness during MRA treatment indicate a subtherapeutic effect.
Continuous positive airway pressure (CPAP) more effectively reduces sleep-related breathing disturbances than do oral appliances, particularly in patients with more severe disease. Yet, patients usually prefer MRAs over CPAP when both treatments are effective.
The adjustment of the health risks associated with OSA is a key goal of treatment. Studies demonstrate MRAs to have a blood pressure-lowering effect of a similar magnitude to that achieved with CPAP. Furthermore, some studies reveal improvements in quality of life and aspects of neurocognitive performance, such as psychomotor speed, when MRAs are used.
Side Effects
Initial common side effects from MRAs:
- Excessive salivation
- Dryness in the mouth
- Jaw soreness
- Tenderness in the teeth
- Perception of an abnormal occlusion in the morning
Longer term potential risks of MRAs:
- Occlusal changes become more prominent
- Overjet and the overbite diminish
- Occlusion may open laterally.
Patients with distal occlusion may benefit from the treatment. Whereas, patients with normal or mesial occlusion will risk unfavorable occlusal changes. The smallest occlusal changes may be expected in patients with initially deep bites and from devices that reduce the forces on the anterior teeth. Nevertheless, the adverse effects of MRAs are generally considered to be negligible among most patients.
Clinical Protocol
Multidisciplinary approach
MRA treatment requires a multidisciplinary collaboration among doctors who have the therapeutic, diagnostic, and overall medical responsibility for the patient. Dentist who treat sleep apnea have the main responsibility of selecting the best oral appliance for the given conditions. This includes evaluating the teeth and periodontal tissue. The patient can be fully or partially edentulous and the dentist must select the appropriate MRA treatment. Dentists must monitor the effectiveness of the chosen oral appliance and validate the effectiveness with a sleep study.
Clinical and Cephalometric Predictors of successful treatment with an MRA
Clinical Predictors:
- Lower body mass index
- Younger age
- Supine dependent OSA
- Smaller overjet
- Smaller oropharynx
- Shorter soft palate
- Smaller neck circumference
- Lower AHI
Cephalometric Predictors
- Shorter soft palate
- Longer Maxilla
- Decreased distance between mandibular plane and hyoid bone
Indications and conditions
The decision to prescribe an oral appliance involves an understanding of all therapeutic options in the context of the individual patient’s circumstances.
According to published practice guidelines:
Oral appliances are indicated for patients with mild-to moderate OSA who prefer this form of treatment over CPAP or who do not respond to or are unable to tolerate CPAP.
The guidelines also recommend that, whenever possible:
CPAP be considered for patients with severe OSA in preference to oral appliances, given its greater efficacy.
Initial dental assessment
Dr. Nugent will perform a complete dental examination. This includes:
- Written dental and medical history
- Taking and interpreting dental x-rays
- Periodontal tissue examination
- Check for tooth decay
- Evaluate current dental restorations
- Oral Cancer screening
- TMJ evaluation
Before an oral appliance for sleep apnea can be made the patient must be in good dental health. If needed Dr. Nugent can perform the dental care needed so that the patient become eligible for a MRA treatment. The presence of 8 to 10 teeth in each arch and a minimum of 5mm protrusive ability of the mandible is usually required for optimal results from MRA treatment.
After the dental assessment is completed, the Dr. Nugent will give the patient a personal assessment about the chances of treatment success in relation to the risk for side effects. Written consent is signed by the patient to document that the treatment and associated risks were given.
Appliance selection
Dr. Nugent uses several types of MRAs. He examines each patient and identifies which MRA would be most appropriate oral appliance for each patient.
Appliance adjustments
Dr. Nugent takes impressions of the teeth and a bite registration in a comfortable and effective jaw position. Generally, initial mandibular advancement of about 5.0mm or 50% to 60% of maximal protrusion is recommended. Then titration can be accomplished over the coming weeks while monitoring patient for any negative symptoms such as jaw pain. The final extent of jaw repositioning depends on the patient’s severity of OSA, ability to protrude, occlusal diagnosis, the type of appliance, and the patient’s ability to breathe through the nose.
During the initial stages (weeks to months), the patient and, if possible the sleep partner evaluates the improvement in well-being and decline of OSA symptoms. Patients who have achieved the desired subjective therapeutic response are referred for a follow-up sleep test to verify the MRA is working.
Follow-up
Once titration is complete and the best subjective therapeutic response has been achieved, the patient undergoes another sleep test while wearing the appliance. Patients will be seen for at a one month, six month and then yearly follow ups. The appliance is changed every five years.
Dr. Nugent will monitor the usage, symptoms, side effects, dental and oral health, degree of jaw repositioning, and condition of the appliance. Ongoing communication with the sleep clinician is important because the treatment effects on OSA may vary over time. This will necessitate another sleep study or consideration of an alternative treatment modality because of side effects or medical concerns.
Final Thoughts
MRAs are indicated as the first of treatment for snoring and for patients with mild-to-moderate OSA who are otherwise generally healthy. Patients who cannot tolerate CPAP therapy or who prefer MRA therapy can use this device provided that a sleep study has confirmed an adequate therapeutic response. Side effects are usually mild and transient but may influence the length of acclimatization required to complete the treatment. Minor occlusal changes are common, but these are acceptable for most patients. A multidisciplinary approach is required to achieve accurate diagnosis and optimal treatment with oral appliances.
