Treatment With Oral Appliance

THE PM POSITIONER AND OTHER ORAL APPLIANCES USED

FOR TREATMENT OF SNORING AND OBSTRUCTIVE SLEEP

APNEA

by Jonathan A. Parker, D.D.S.

INTRODUCTION

Snoring and obstructive sleep apnea (OSA) are respiratory obstructive sleep disorders which are gaining increased public awareness. Health care providers have been more involved in evaluation and treatment of all sleep disorders which is evidenced by the dramatic increase in the number of sleep centers over the past eight years. Snoring is a problem which may effect as much as 37% of the adult population12 and 60% of males over sixty years of age.13 Whereas snoring tends to be a social problem, obstructive sleep apnea can be a serious health problem.

Obstructive sleep apnea is a failure of breathing during sleep brought about by obstruction of the upper airway in the presence of continued diaphragmatic effort. Obstructive sleep apnea is defined as a cessation of ventilation for a period of ten seconds or more. The most frequent symptoms associated with obstructive sleep apnea include loud snoring, excessive daytime sleepiness, restless and non-refreshing sleep, morning headaches, and awakenings in which the individual will feel like they are choking or gasping. Some of the clinical signs of obstructive sleep apnea are systemic hypertension, nocturnal cardiac arrhythmias, pulmonary hypertension, increased motor activity during sleep, and polycythemia. These signs can be an indication of a significant health problem.

The pathophysiology of obstructive sleep apnea has been studied extensively over the past twenty-five years. Studies have revealed that patients with obstructive sleep apnea tend to have a narrower pharyngeal lumen and altered activity of the muscles in the upper airway.14 A retrognathic mandible, antero-posterior discrepancy between the maxilla and mandible, large tongue and soft palate volume, obesity, and an anterior open bite tendency are associated with a higher apnea index.15 The patency of the pharyngeal airway is effected by the balance between the pharyngeal muscles and the negative intrapharyngeal pressure during inspiration. Activity of the genioglossus (GG) muscle during respiration is also extremely important in maintaining a patent airway. Research information indicates that one of the primary causes of airway obstruction and apneas is loss of tonicity of the genioglossus muscle.16 As the velocity of the airflow increases in combination with reduced tone of the genioglossus, the tongue (at the level of the base of the tongue) is "sucked back" into the airway causing the obstruction.

MEDICAL TREATMENT

Treatment for obstructive sleep apnea can vary from a less invasive non-surgical approach to more extensive surgical procedures depending on the severity of the condition. The most conservative methods of treatment include weight loss, education and training regarding appropriate sleep posture, and use of medications. These treatment measures have been found to be effective in certain populations of patients (very mild OSA and primary snoring).17,18 However, the long term effectiveness of these treatment measures is somewhat guarded.

Use of nasal continuous positive air pressure has been the most popular treatment among sleep specialists because of its high prognosis for success. The positive air pressure is administered through a nasal face mask and works as a pneumatic splint to maintain the patency of the airway. Although this treatment is very effective, patient compliance with the nasal CPAP has been relatively poor because of the side effects. These side effects may include rhinitis, drying of the airway, nasal irritation, and discomfort from the pressure applied by the mask. Surgical procedures to alter the anatomical structures, which may narrow the airway and restrict air flow, is another alternative to managing obstructive sleep apnea. Tracheostomy is the most effective surgical measure. However, it is poorly accepted by patients. The uvulopalatopharyngoplasty was introduced by Dr. Fujita in 1981 as a surgical procedure to enlarge the oropharyngeal area of patients with obstructive sleep apnea.1 This is accomplished by removal of redundant tissues of the soft palate, uvula, tonsils, lateral and posterior pharyngeal walls. Research studies indicate a 50% rate of success in management of obstructive sleep apnea using the UPPP.11 The main concern regarding UPPP is the difficulty in predicting which patients will benefit from the procedure. In many cases this treatment is used on patients who have not responded well to other forms of non-surgical management. A newer surgical procedure is now being utilized which involves advancement of the maxilla and mandible and suspension of the hyoid bone. The extensive nature of this procedure and the cost to complete the procedure have made it less appealing to patients; although, in a situation in which severe obstructive sleep apnea is significantly effecting a patient's health this type of surgical intervention may be beneficial.

ORAL APPLIANCE THERAPY

The interest in using oral appliances to manage patients with obstructive sleep apnea has grown over the past ten years. The first article pertaining to oral appliances used for this purpose was published by Pierre Robin in 1934.19 He described infants with retrognathic mandibles and obstructive sleep apnea whose condition was managed with a mandibular repositioning device. Today there are numerous appliances which are being used for management of snoring and obstructive sleep apnea. The three main categories of oral appliances include:

1. mandibular repositioning appliances

2. tongue retaining devices

3. palatal lifting devices

At this time, the palatal lifting devices have very little scientific evidence to support their effectiveness. The two most commonly used oral prosthetic devices are the mandibular repositioning appliances and the tongue retaining devices.

The tongue retaining device (TRD) developed by Dr. Charles Samelson, is an appliance made of a soft polyvinyl material which holds the tongue forward during sleep to increase the pharyngeal airway and improve airflow. The tongue is placed in a compartment (bubble) which projects outward between the upper and lower lips. The tongue is held in the compartment by increased surface tension (suction). Studies testing the effectiveness of the tongue retaining device revealed a 75% success rate (50% reduction of the apnea index).20, 21, 22 Although long-term follow-up needs to be completed, the TRD appears to be an effective treatment alternative. A drawback of the TRD is that some patients find the device cumbersome, and have a feeling of claustrophobia due to the size of the appliance in the mouth and the reduced freedom of tongue movement. Breathing tubes can be placed on the appliance to facilitate oral breathing.

The mandibular repositioning appliances are the dental prosthetic devices most widely used for treatment of snoring and obstructive sleep apnea. These appliances hold the mandible in an anterior and inferior position during sleep. The nocturnal airway patency appliance (NAPA) was developed by Dr. Peter George. His study evaluated the effectiveness of the appliance and revealed five out of five patients had a reduction in the apnea index of at least 50%.23 All patients had apnea indexes below 20, and three out of five patients had an apnea index below 10 with treatment. The snore-guard was evaluated for 20 patients with sleep studies completed before treatment and while using the device.24 A 50% reduction in RDI was seen in 75% of the patients. Bonham, et al. evaluated 12 patients to determine the effect of a modified functional appliance on apnea index. Seven out of the twelve patients had successful objective findings.25 Subjectively, 75% had reduced daytime somnolence and 67% had significantly reduced snoring. Similar results were reported by Bixler, et al. using the SNOAR appliance.26 In addition, the study indicated the patients had 100% compliance with the device over an eighteen month period. Other studies using the Herbst appliance,27or an elastomeric appliance,28 have reported similar findings when evaluating the effect of these mandibular repositioning devices on snoring and obstructive sleep apnea.

The mechanism of action of mandibular repositioning devices is still under investigation. However, it appears that the mandibular position has a significant effect on genioglossus muscle activity. It has been documented that contraction of the genioglossus muscle will advance the base of the tongue, thus increasing the volume of the upper airway. As the mandible is advanced and rotated downward with the mandibular repositioning appliance, there is an increase in baseline genioglossus activity, and the base of the tongue advances to open the airway.29,30

PM POSITIONER

In order for a mandibular repositioning device to be effective in consistently increasing the genioglossus muscle activity and maintaining patency of the airway, the mandible must be held firmly in its anterior inferior position during sleep. The PM Positioner is a one-piece mandibular repositioning device. This appliance fits over the maxillary and mandibular teeth and is connected in the right and left posterior quadrants leaving a large rectangular opening between the anterior teeth for sufficient airflow for oral breathing during sleep. The appliance is made of an acrylic material called Bruxeze.

Bruxeze is a heat-cured resin which is used by the dental laboratory to fabricate dental appliances. This acrylic material has a unique feature in that it will soften slightly at body temperature. The PM Positioner is fabricated with projections of the acrylic which are placed just below the height of contour of a molar and a bicuspid tooth in each quadrant.

These projections of acrylic are an integral part of the appliance and supply sufficient retention for the appliance to maintain the mandible in the appropriate jaw position throughout the night. The ability of the appliance to soften at body temperature allows for secure retention without causing any pain or discomfort to the teeth or intraoral tissues. This property enhances retention of the appliance while maintaining patient comfort and improving compliance with the device. The appliance is fabricated to position the mandible approximately 60-75% of maximum protrusive movement. If the appliance should cause any discomfort to the teeth, it is easily adjusted with a dental handpiece and bur. If the jaw position is uncomfortable for the patient, or it is not providing the necessary relief of symptoms, the upper and lower portions of the appliance can be separated and rebonded in the appropriate jaw position. The PM Positioner is easy to construct, easy to clean, can be readily adjusted to obtain a comfortable fit, and is strong and long-lasting. This appliance is substantially equivalent to existing appliances which have received FDA approval.

Preliminary data was gathered to evaluate the effectiveness of the PM Positioner in 8 patients with mild to moderate obstructive sleep apnea. These patients had a sleep study (polysomnogram) before and after use of the PM Positioner. The pre-treatment apnea indexes (AI) ranged from 5 to 57. 75% (6 out of 8) of the patients were treated successfully with the PM Positioner. These patients had either a 50% reduction in the AI or an index level below 10. (Note: One patient had the AI reduced from 7 to 6). All six patients with significant reduction in the AI also reported a significant reduction or complete resolution of the snoring and daytime drowsiness. Based on this preliminary data, the PM Positioner can be an effective treatment for patients with heavy snoring and mild to moderate obstructive sleep apnea.

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