Comparison of two dental devices for treatment obstructive sleep apnea syndrome (OSAS)

of

Mark G. Hans, DDS, MSD, a Suchitra Nelson, PhD, b Virginia G. Luks, DDS, c Paul Lorkovich, d and Seung-Jin Baek, DDS, PhD e Cleveland, Ohio

Previous case reports have indicated dental devices can be an effective nonsurgical treatment for snoring and obstructive sleep apnea. This pilot study evaluated the effectiveness of two intraoral devices in reducing the Respiratory Disturbance Index (RDI) and Epworth Sleepiness Scale (ESS) scores in a group of 24 adult volunteers with a history of loud snoring. Subjects were randomly assigned to two groups. Twelve subjects were fitted with a dental device designed to increase vertical dimension and protrude the mandible (device A). The other 12 subjects received a different device designed to minimally increase vertical opening without protruding the mandible (device B). Unattended home sleep monitoring (Edentrace II Digital Recorder, Edentech Corp.) was used to compute RDI at two time periods: (TO) before using any dental device and (T1) while using a dental device 2 weeks after the initial delivery date. The mean RDI and ESS scores at TO for subjects in the device A group were 35.6 _+ 28.4 and 12.0 + 3.9, respectively. Means for the same measures at T1 were 21.1 _+ 21.4 and 8.2 _+ 4.0. For subjects in the device B group, means for RDI and ESS scores at TO were 36.5 _+ 43.7 and 13.0 _+ 4.5, the means at T1 were 46.8 _+ 47.0 and 12.5 + 5.7. The effectiveness of the two devices was estimated by comparing the difference in RDI scores from TO to T1 for the 10 subjects who were using device A and completed the study and the 8 subjects who were using device B and completed the study. Six subjects withdrew for various reasons. From TO to T1, device A reduced RDI scores in 9 of 10 subjects, with a mean reduction in RDI of 14.5 (p - 0.05) and in ESS score of 3.8 (p -< 0.005). Device B showed no change or an increased RDI score in 8 of 8 subjects. Seven of the eight subjects who showed no improvement in RDI with device B were then fitted with device A. Four of these seven subjects showed a reduction in RDI and five showed a reduction in ESS after using device A for 2 weeks. The mean reduction in RDI and ESS was 2.4 _+ 19.8 and 2.4 _+ 3.0, respectively. Hence, we conclude that a dental device that advances the mandible and increases the vertical dimension to open the upper airway is more effective in reducing the number of apneic and snoring events during sleep than one which does not. (Am J Orthod Dentofac Orthop 1997;111:562-70.)

A n increasing number of orthodontists are participating in the multidisciplinary manage- ment of patients with obstructive sleep apnea syn- drome (OSAS) or socially disruptive snoring. The OSAS is characterized by a constellation of signs and symptoms related to arterial oxygen desatura-

From the Department of Orthodontics, Case Western Reserve University, School of Dentistry. Research supported in part by NIDR grant DE10672, a SCOR grant in Cardiopulmonary Disorders of Sleep #HIA2215, NIH grant #HL46380, and a grant from the American Association of Orthodontists Foundation. aAssociate professor and chairman. bVisiting assistant professor. °Lesley Newton Fellow. dResearch coordinator. eVisiting scholar. Reprint requests to: Dr. Mark G. Hans, Department of Orthodontics, Case Western Reserve University, School of Dentistry, 10900 Euclid Ave., Cleveland, OH 44106-4905. E-mail: mgh4@po.cwru.edu Copyright © 1997 by the American Association of Orthodontists. 0889-5406/97/$5.00 + 0 8/1/71635

562

tion and sleep fragmentation, caused by pharyngeal obstruction during sleep. 1'2 A recent epidemiologic study suggested that the prevalence of OSAS is at least 9% of the adult male and 4% of the adult female population? In addition, a much larger num- ber of adults exhibit socially disruptive snoring behavior.

Clinically, the designation of OSAS should be applied to those persons who experience frequent apnea and hypopnea during sleep with pathophysi- ologic consequences. Anatomic risk factors that have been implicated in OSAS include a number of abnormalities in craniofacial structure. 4-14 Obstruc- tion of the airway is thought to be caused by occlusion of the lower pharynx, as the tongue settles back posteriorly against the pharyngeal wall. Nasal continuous positive air pressure (nasal CPAP), which acts as a pneumatic splint to passively open the upper airway and prevent obstructive apnea, is

American Journal of Orthodontics and Dentofacial Orthopedics Hans et al. 563 Volume 111, No. 5

currently the gold standard for conservative man- agement of mild to moderate OSAS. Although this is a logical first step, some patients cannot tolerate nasal CPAP, creating a demand for alternative nonsurgical treatment modalities. Differences in craniofacial structure have been observed between OSAS subjects and normal controls. These findings have resulted in dental devices being promoted as an alternative conservative, noninvasive modality for management of some patients with mild OSAS symptoms and those subjects who have a history of disruptive snoring. Orthodontists have experience with removable orthopedic appliances and therefore may be asked to place intraoral mechanical devices for OSAS treatment. These devices are usually designed to increase the pharyngeal airway by pro- truding the mandible and increasing the vertical dimension of occlusion. While this approach seems empirically correct, it has not been scientifically tested.

The rationales for using dental appliances can be divided into three categories. One type of appliance is designed to reposition the tongue in a more forward position (tongue retaining device). 15,16 This type of appliance increases posterior airway space by holding the tongue away from the posterior pharyn- geal wall. A second type of device positions the mandible forward, nocturnal airway-patency appli- ance (NAPA), 17 SnoreGuard (Dental Sleep Disor- der Prevention, Inc.), z8 Herbst, ~9'2° mandibular re- positionerY -23 The rationale for this movement is that the tongue is attached to the genial tubercles of the mandible and positioning the mandible forward moves the tongue forward. These mandibular repo- sitioning appliances also change hyoid bone position and modify the lower airway space below the level of the base of the tongue. The third type of intraoral device is designed to lift the soft palate or reposition the uvula (equailizer). 24 The rationale for the use of palate-lifting devices is to reduce the vibration of the soft palate that causes the snoring sound. Although there are logical clinical reasons for using different appliances, there is not enough scientific evidence for the clinician to determine which appliance is most likely to improve symptoms for a given patient.

Initial results with dental appliances ha~)e been encouraging. Knudson and M e y e r 21,22 have reported on the use of a modified activator-type appliance to treat two patients with variable OSAS histories. One subject was edentulous and the other one was dentate. Both had failed to show improvement after uvulopalatopharyngoplasty (UPPP) and could not tolerate nasal CPAP. After being fitted with a modified activator, both patients had significant improvement in their sleepiness, snoring by report, and apneic events per hour as recorded by overnight polysomnography. Rider 24 has reported similar an-

ecdotal results by using a Herbst-type appliance to change mandibular posture in 16 subjects. Rider's improvement was documented only by patient self- report of symptoms and no polysomnography was used.

Taking a different approach to conservative treatment, Cartwright et al. 15,16 have used a tongue retaining device (TRD) to increase the posterior airway space by holding the tongue forward, with a suction-type bulb that captures the tip of the tongue by using negative pressure and holds the tongue in a forward position. This group reported on 24 male subjects, 12 of whom received the TRD as the only treatment, the remaining 12 subjects had submucous resection of the septum (SMR) or UPPP surgical procedures. Interestingly, this group reported that the TRD was useful both alone and in combination with surgical intervention. The Cartwright group also attempted to use multivariate discriminant analysis to predict successful outcomes of TRD treatment. They concluded that successful treatment with the TRD is more likely in subjects where postural sleeping habits influence apneic events and when the subjects are "no more than 50% above the ideal weight for their computed height."

Bonham et al. 23 have reported on the use of a removable activator-type appliance that was de- signed to hold the mandible downward and forward 8 mm and 2 mm, respectively. They used lateral cephalometric films to confirm that the appliance produced an increase in posterior pharyngeal space as viewed on the cephalometric film. They reported a decrease in apneic events from 29 to 19 per hour and a reduction in the RDI (apneic events + hypopneic events) from 54 to 36 per hour. This group also suggested that cephalometric variables may be used to predict treatment outcomes.

In 1991, Schmidt-Nowara et al. 18 reported on the use of a simple thermoplastic device that was de- signed to hold the mandible in a forward and downward position. This group examined a conve- nient sample of 71 patients who were referred by their physician for treatment of socially disruptive snoring or subjects with mild OSAS symptoms or subjects who had failed another conservative treat- ment for OSAS. Lateral cephalometric radiographs were used to confirm the increase in posterior airway space as measured on radiographic film. The results of 68 patients are reported. Interestingly, the group reported an improvement in their snoring complaints ranging from 27 patients in whom snor- ing was eliminated, 37 in whom the snoring was reduced, one patient reported no change, and 3 patients could not use the appliance. Twenty of their subjects had sleep studies before and with the use of the appliance. In this group, improvement in the RDI was shown from 47.4 before treatment to 19.7

564 Hans et aL American Journal of Orthodontics and Dentofacial Orthopedics May 1997

after treatment. This change in R D I was accompa- nied by a marked decrease in nonrapid eye move- ment (REM) sleep from 44% before t reatment to 10% with the appliance in place. Unfortunately, this study, like all the others, did not use a randomized design to assign subjects to t reatment and control groups and not all subjects had sleep studies to confirm the questionnaire data. Nonetheless, it ap- pears that a simple appliance designed to hold the mandible forward and downward may be of value in the t reatment of mild cases of OSAS and in cases where the primary complaint is loud, socially disrup- tive snoring without evidence of OSAS. One factor that must be kept in mind is that 25% of the subjects did not tolerate the appliance and discontinued its use. Also, a third of the subjects with postappliance sleep studies had R D I values greater than 20, indi- cating that the disease was not adequately con- trolled with the use of the appliance.

In conclusion, it would appear from the litera- ture that dental appliances may have a place in the t reatment of mild cases of OSAS and for patients with socially disruptive snoring behavior. However, all of these previous studies were case series and appropriate control groups were not used. The current study used random assignment of subjects to t reatment and control groups to determine the short-term clinical effectiveness of two dental de- vices in treating patients with a history of loud snoring with or without apnea.

MATERIALS AND METHODS Study Population

Twenty-four otherwise healthy adult volunteers, be- tween the age of 25 and 69 years, with a self-reported history of loud snoring were recruited by poster advertis- ing in prominent locations throughout the university community, referral from local dentists and physicians, or by referral from the Veterans Administration or Univer- sity Hospitals Sleep Disorders Center. To be included in the study, subjects had to have an RDI below 30 (or a referral from a managing physician) and have no systemic diseases other than OSAS. Excluded from the study were pregnant women, prisoners, minors, and persons with chronic illness (other than OSAS), persons who were mentally disabled or with an RDI above 30 with patho- physiologic symptoms, edentulous subjects, and persons who had surgical attempts to correct their snoring or apnea. Other subjects excluded were those with significant nonOSAS sleep disorders: periodic leg movements (PLM- Arousal Index > 10), chronic insufficient sleep efficiency >90% on polysomnography (PSG) and supportive clinical history, narcolepsy; pathologic sleepiness (MSLT < 5 minutes), diagnosed central nervous system diseases; ma- jor psychiatric diseases; alcoholism; severe obstructive or restrictive lung diseases (FEV 1 -< 1.0 L. daytime pO2 < 65 or CO2 > 47); unstable ischemic heart disease (myocar-

dial infarction in the last 3 months, angina occurring > 1 per week); hospitalization for pulmonary edema in the last 3 months, or poorly controlled hypertension (systolic BP > 195, diastolic BP > 105) recorded within the 2 months preceding study enrollment, as were subjects using sedative or hypnotic medication regularly and those on rotating or night shifts.

Treatment Device

Half of the subjects (n = 12) received a thermoplastic intraoral appliance (SnoreGuard, Dental Sleep Disorder Prevention, Inc.) that was fitted to the upper dentition by molding the softened plastic around the upper teeth (device A). An anterior jig of thermoplastic material was then softened and the mandible positioned forward to an edge-to-edge incisor position (approximately 6 to 8 mm). The anterior jig also increased the vertical dimension of occlusion about 8 mm. (See Fig. 1.) This removable device was designed to enlarge the pharyngeal airway and is FDA approved for intraoral use.

Twelve subjects were fitted with a similar device designed to minimally increase vertical opening (about 1 mm) without protruding the mandible (device B). Device B was constructed by modifying device A. The anterior portion of the SnoreGuard appliance was removed and the resulting device resembles a soft athletic mouth guard that covers the upper teeth. (See Fig. 2.) This device is removable and is FDA approved for intraoral use.

Data Collection

Baseline and outcome measures included subjective and objective measures of sleep quality. The Epworth Sleepiness Scale (ESS) was developed to measure daytime sleepiness in persons suspected of having any one of a number of underlying sleep disorders. The ESS scores range between 0 and 24, with the lower scores indicating decreased daytime sleepiness and higher scores indicating increased daytime sleepiness. The mean score for subjects with a history of normal sleep habits without apnea is 6, whereas those with mild to severe sleep apnea score between 10 and 16. 25 This scale was administered by a single investigator (P.L.) to provide subjective data on sleepiness and snoringl Unattended in-home 6-channel sleep studies were performed in all subjects. The Respi- ratory Disturbance Index (RDI) was computed by count- ing the number of apneas and hypopneas that occurred while the subject was sleeping and dividing this total by the number of hours of sleep. This portable monitor (Edentrace II Digital Recorder, Edentech Corp.) allowed accurate measurement of oxygenation, airflow, snoring, body position, chest wall movement, and heart rate during sleep. This monitor has been used extensively by our group and has proven to be a cost-effective and accurate means of quantitating the RDI and characterizing the oxy- gen saturation profile. Previous studies have shown a high correlation with overnight polysomnography (r = 0.96). 26

Data were collected for groups A and B before using

American Journal of Orthodontics and Dentofacial Orthopedics Hans et aL 565 Volume 111, No. 5

Fig. 1. A, Frontal intraoral view of subject without any dental device in place. B, Frontal intraoral view of subject with dental device A in place. C, Lateral intraoral view of subject without any dental device in place. D, Lateral intraoral view of subject with dental device A in place. E, Frontal intraoral view of subject with dental device A in place while opening mouth.

any dental device (TO) and at the end of a 2-week period of intervention (T1). In addition, seven subjects in group B were also fitted with device A after they had completed data collection with device B. Additional outcome data were collected on this subset of group B subjects 2 weeks after they were fitted with device A (TIX). The short-term effectiveness of the two devices was measured by compar- ing the difference in the outcome variables at TO to T1 or TO to T1X. Statistical analyses were performed using the SPSS for Windows (SPSS Inc.). One technician scored all sleep studies (P.L.) and one investigator (S.B.) traced all cephalometric radiographs.

Statistical Analysis

The device groups were comparable at baseline as shown in Table I. The RDI and Epworth Sleepiness Scale

scores were treated as continuous variables, and means and standard deviations were calculated for each treat- ment group. Because of the small sample size, nonpara- metric tests were used for statistical analysis. Wilcoxon- matched pairs tests were used to examine within group differences (T0 to T1) and Mann-Whitney tests were used for between group differences. A p value of -< 0.05 was used to assign statistical significance for all tests.

RESULTS

A to ta l of 24 subjects ( m e a n age: 51.875 years , SD + 12.27, 83% male) were el igible for the study. R a n d o m i z a t i o n of subjects to t r e a t m e n t resu l ted in two groups that were s imilar in base l ine charac te r - istics (RDI , BMI, and ESS) as shown in Tab le I. Of

566 Hans et aL American Journal of Orthodontics and Dentofacial Orthopedics May 1997

Fig. 2. ,6,, Frontal intraoral view of subject without any dental device in place. B, Frontal intraoral view of subject with dental device B in place. C, Lateral intraoral view of subject without any dental device in place. 13, Lateral intraoral view of subject with dental device B in place.

the 12 subjects enrolled in group A, 10 subjects completed the 2-week trial period and 2 subjects withdrew for various reasons. Nine of those 10 (90%) showed an improvement in RDI scores from TO to T1 and 7 of 10 (70%) showed improvement in ESS scores. The effects of device A on RDI ranged from a minimal reduction of 4 to a maximum reduction of 57. The within-group difference in RDI from T0 to T1 was statistically significant (p -< 0.0218). Only one subject (C-176) showed an in- crease in RDI score. The within-group difference in ESS was also statistically significant (p -< 0.033).

Compliance was poorer in group B. Four sub- jects fitted with device B did not complete the 2-week trial period for various reasons. The primary complaint was poor tolerance of the device. The effect of device B on RDI was reversed in this group, with six of eight (75%) showing increases in RDI from TO to T1. The mean within-group difference in RDI was not significant (p -< 0.1235). Only two subjects (C-173 and C-208) demonstrated modest reductions in RDI score from TO to T1. One of these

subjects also had a significant decrease in ESS score from 11 to 8. All the other subjects had almost none, or marginally higher or lower ESS score from T0 to T1.

All the subjects enrolled in group B were crossed over to device A after the 2-week trial period. Seven subjects agreed to continue participation in the trial. Of the seven who elected to try device A, three showed a reduction in RDI from TO to T1X and five showed a reduction in ESS score from T0 to TIX. Interestingly, the same person (C-173) who had a reduction in ESS at T1 also had an additional reduction in ESS of 4 points when crossed over to device A (T1X).

The data for all the subjects on device A were pooled together (Table II) at the end of the trial. Statistical analysis of this pooled sample (n = 17) revealed a significant reduction in both RDI (p -< 0.03) and ESS (p -< 0.005) from TO to T1 or T1X.

Comparison of between group (device A to device B) means showed a statistically significant difference in RDI at T1 (/9 --< 0.0045). However, the

American Journal of Orthodontics and Dentofacial Orthopedics Hans et al. 567 Volume 111, No. 5

Table I. R a w da ta , m e a n s a n d s t a n d a r d dev ia t i ons for all sub jec ts in g r o u p A a n d g r o u p B

Group BMI RDI Epworth identification

number TO TO T1 T1X TO T1 TIX

A C-147 25.8 9.7 N/A N/A N/A N/A N/A C-174 27.4 8.0 N/A N/A 11.0 N/A N/A C-139 24.9 23.0 14.2 N/A 12.0 12.0 N/A C-150 33.6 20.0 15.8 N/A 17.0 8.0 N/A C-155 27.4 65.6 8.5 N/A 12.0, 2.0 N/A C-163 26.5 12.5 8.7 N/A 11.0 12.0 N/A C-166 30.7 38.4 5.9 N/A 13.0 4.0 N/A C-170 33.9 66.7 12.4 N/A 11.0 6.0 N/A C-175 36.0 76.1 50.0 N/A 16.0 11.0 N/A C-176 29.8 2.8 14.9 N/A 12.0 8.0 N/A C-177 23.8 26.6 10.6 N/A 2.0 5.0 N/A C-186 34.6 78.4 70.5 N/A 15.0 14.0 N/A

Mean 29.5 *35.6 "21.1 "12.0 *8.2 SD 4.2 28.4 21.4 3.9 4.0

B C-162 32.5 18.5 N/A N/A 10.0 N/A N/A C-161 33.0 85.8 N/A N/A 16.0 N/A N/A C-204 23.2 11.5 N/A N/A 20.0 N/A N/A C-172 29.2 9.1 N/A N/A 10.0 N/A N/A C-191 25.1 3.0 3.7 N/A 6.0 4.0 3.0 C-171 23.9 2.4 28.6 9.3 11.0 11.0 8.0 C-168 26.6 12.8 15.1 5.1 11.0 10.0 8.0 C-173 24.3 5.6 3.4 2.3 11.0 8.0 4.0 C-185 41.8 127.7 137.1 151.3 18.0 20.0 14.0 C-188 25.8 55.7 60.3 17.7 11.0 11.0 8.0 C-213 28.4 9.7 36.0 22.1 19.0 20.0 21.0 C-208 38.8 96.7 90.2 85.9 17.0 16.0 19.0

Mean 29.4 36.5 46.8 41.9 13.0 12.5 10.6 SD 6.0 43.7 46.9 56.1 4.5 5.7 6.7

Statistically significant differences: *p < 0.05.

reduction in mean ESS scores between groups was not significant (see Fig. 3).

DISCUSSION

There is considerable controversy in the litera- ture regarding the use of dental devices in the treatment of snoring and OSAS. During the past decade, there have been several devices introduced into the market with claims of reducing snoring and apnea, but none to date have been tested for etficacy or effectiveness in the proper clinical trial setting. Many have been case series or individual case reports of the devices, raising questions on validity. Thus this study was undertaken to examine the effect of a simple thermoplastic device that pro- truded the mandible and opened the pharyngeal airway compared with a placebo device that effec- tively acted like an athletic mouth guard. The results of this study indicate that alterations in mandibular posture may be effective in reducing RDI and subjective daytime sleepiness. Further, the superior- ity of device A in reducing RDI warranted the

termination of the use of device B for ethical reasons. Therefore we conclude that simple mouth guard devices that do not alter mandibular position are of no benefit for subjects suffering from loud snoring or sleep disordered breathing. In fact, the data strongly suggest that future random clinical trials of dental devices for treatment of OSAS and snoring should not use a placebo device as one of the treatment groups.

Currently, nasal CPAP is the standard of care in conservative management of mild to moderate OSAS. Because CPAP provides a pneumatic splint to open the airway, it is 100% successful in keeping the airway open at night, as long as the device is used regularly by the patient. However, there is a compliance failure rate of approximately 35% in subjects who use CPAP. In this group of CPAP failures, as well as for persons suffering from socially disruptive snoring, dental appliances may have a role in the management of the problem. Of the 17 subjects who tried device A, 14 showed a decrease in RDI and 12 showed a decrease in ESS score. Of

568 H a n s e t al. American Journal of Orthodontics and Dentofacial Orthopedics May 1997

20

15

10

-5

I

-10 ~-

19.9 +-22.6

-7.6 +-12.4

• Device A

[ ] Device B

3.9+-4.6

0.5+-1 .6

RDI ESS

Fig. 3. Mean change in RDI and ESS scores between TO and T1. Difference between devices A and B significant at p < 0.05 level.

Table II. R a w da ta , m e a n s , a n d s t a n d a r d dev ia t ions fo r all sub jec ts us ing device A (n = 17)

Device A identification number BMI

RDI

TO 7"1 TIX

C-139 24.9 23.0 14.2 C-150 33.6 20.0 15.8 C-155 27.4 65.6 8.5 C-163 26.5 12.5 8.7 C-166 30.7 38.4 5.9 C-170 33.9 66.7 12.4 C-175 36.0 76.1 50.0 C-176 29.8 2.8 14.9 C-177 23.8 26.6 10.6 C-186 34.6 78.4 70.5 C-171 23.9 2.4 C-168 26.6 12.8 C-173 24.3 5.6 C-185 41.8 127.7 C-188 25.8 55.7 C-213 28.4 9.7 C-208 38.8 96.7

Mean 30.0 42.4* 29.7* SD 5.5 37.5 21.4

9.3 5.1 2.3

151.3 17.7 22.1 85.9

ESS

TO T1 TIX

12.0 12.0 8.0 17.0 8.0 12.0 2.0 11.0 12.0 13.0 4.0 11.0 6.0 16.0 11.0 12.0 8.0 2.0 5.0

15.0 14.0 11.0 8.0 11.0 8.0 11.0 4.0 18.0 14.0 11.0 8.0 19.0 21.0 17.0 19.0

12.9"* 9.6** 4.0 4.0

Statistically significant differences: *p -< 0.05; **p -< 0.005.

these 14 subjects, 7 demonstrated a clinically signif- icant reduction in RDI (i.e., below 20) after 2 weeks of device wear. It is probably this subset of subjects who could benefit from the use of dental appliances as a treatment alternative. Interestingly, it was also found that many in this subset of subjects were also nonobese (BMI < 30), supporting the contention

that craniofacial risk factors may actually have a larger role to play in nonobese persons. However, the sample sizes in this study were too small to test this hypothesis. Cartwright et al. ls,16 have suggested that the tongue-retaining device is more effective in patients who sleep in the supine position, and are greater than 50% over their ideal body weight. It

American Journal of Orthodontics and Dentofacial Orthopedics Hans et al. 569 Volume 111, No. 5

may be that mandibular repositioning is most effec- tive in a subset of patients with predictable and identifiable craniofacial characteristics. Pretreat- ment cephalometric radiographs could be used to predict treatment response based on cephalometric values. Hence, the use of cephalometrics may help in the decision-making process of treatment alter- natives such as dental devices, weight reduction, or nasal CPAP.

The importance of using both objective and subjective methods to assess outcome i s clearly evident in our results. All subjects who showed a decrease in RDI did not report a decrease in subjective symptoms. This type of error may lead to a subject discontinuing the appliance when in fact the device was reducing the level of sleep distur- bance. Likewise, all subjects with a subjective im- provement did not show a reduction in RDI. This problem is potentially more critical. Consider sub- ject C-185, who used device A. This person showed a subjective improvement of 4 on the Epworth scale while recording an increase in RDI from 127 to 150. This subject had increased apneas, but was not as sleepy during the day. Therefore postappliance test- ing to insure adequate control of apneic activity is critical to the safe and meaningful testing of these devices. At this point in time, the only way to accurately assess treatment efficacy is with in-home or overnight hospital sleep monitoring.

There have been method limitations to this study. The sample sizes are small, and extrapolation of the results to a larger population may be ques- tionable for several reasons. First, we had no objec- tive data to support our contention that the pharyn- geal airway was increased with device A in position. In future studies, the use of cephalometric radio- graphs could provide objective data to support this claim. At this time, it is not clear whether the device that increases pharyngeal dimensions works because of increases in vertical dimension or anteroposterior changes in mandibular posture or a combination of both. Second, the sustained reduction in RDI over a longer time period without undue side effects was not investigated in this study. The effects of long- term alteration in mandibular posture on the tem- poromandibular joint and the oral tissues needs to be investigated. The morbidity associated with OSAS is of a chronic nature. Persons suffer from pulmonary hypertension and daytime sleepiness. Successful management of chronic disease requires therapy that is effective over a period of years rather than weeks. This study also did not quantify the reduction in the intensity of snoring in these sub-

jects. In fact, we do not have data on the level of reduction in snoring in these subjects. A subjective bed partner questionnaire would be helpful in fu- ture studies. The ESS was useful in evaluating subjective daytime sleepiness most often associated with repeated nocturnal arousals. Perhaps an im- provement in daytime sleepiness is best reflected long-term rather than in a span of 2 weeks. Subjec- tive recall of information has its potential biases. Finally, the subjects used in this study have all been care-seeking volunteers with the likelihood of intro- ducing selection bias. But, the failure of device B clearly indicated that the motivation of the subjects is not linked to the positive outcome of the treat- ments.

CONCLUSION

In conclusion, the use of dental appliances to treat obstruction of the upper airway is not new. In 1934, Pierre Robin advocated the use of a modified monobloc to move the mandible forward to open the airway in children with micrognathia. 27 For approximately the next 50 years, the use of dental devices for apnea was reserved for the rare cases of severe retrognathia that were not amenable to surgical correction by mandibular advancement osteot- omy. Paradoxically, at a time when refinement in surgical techniques has virtually eliminated the use of dental appliances in this younger age group, the use of dental devices has become popular for middle-aged snorers with or without apnea. However, if orthodontists are to play in increasing role in the management of sleep disorders in the future, we must insist that comparative data, such as those from this study, be provided to support all claims of treatment efficacy.

We thank Ms. LaVerne Vogel for her help in the preparation of the manuscript.

REFERENCES

1. Phillipson E. Sleep apnea-a major public health problem. N Engl J Med 1993;328: 1271-3.

2. Strohl KP, Cherniak N, Gothe B. Physiologic basis of therapy for sleep apnea. Am Rev Resp Dis 1986;134:791-802.

3. Young T, Palta M, Dempsey J, Skatrud J, Weber S, Badr S. The occurrence of sleep-disordered breathing among middle aged adults, N Engl J Med 1993,328:1230-5.

4. Pracharktam N, Hans MG, Strohl KP, Redline S. Upright and supine cephalomet- ric evaluation of obstructive sleep apnca syndrome and snoring subjects. Angle Orthod 1994;64:1-10.

5. Pracharktam N, Nelson S, Hans MG, Broadbent BH, Redline S, Rosenberg K, et al. Cephalometric assessment in obstructive sleep apnea. Am J Orthod Dentofac Orthop 1996;109:410-9.

6. deBerry-Borowiecki B, Kukwa A, Blanks RH. Cephalometric analysis for diagnosis and treatment of obstructive sleep apnea. Laryngoscope 1988;98:226-34.

7. Anonsen C. Laryngeal obstruction and obstructive sleep apuea syndrome. Laryn- goscope 1990;100:775-8.

8. Strelzow VV, Blanks RHI, Basle A, Strelzow AE. Cephalometric airway analysis in obstructive sleep apnea syndrome. Laryngoscope 1988;98:1149-58.

9. Wilms D, Popovich J, Conway W, Fujita S, Zorick F. Anatomic abnormalities in obstructive sleep apnea. Ann Otol Rhinol Laryngol 1982;91:595-6.

10. Riley R, Guilleminault C, Herran J, Powell N. Cephalometric analysis and flow-volume loops in obstructive sleep apnea patients. Sleep 1983;6:305-11.

11. Adamidis P, Syropoulos MN. The effects of lymphadenoid hypertrophy on the

570 H a n s et al. American Journal of Orthodontics and Dentofacial Orthopedics May 1997

position of the tongue, the mandible, and the hyoid bone. Eur J Orthod 1983;5:287-94.

12. Lowe AA. The tongue and airway. Otolaryngol Clin North Am 1990;23:677- 98.

13. Partinen M, Guilleminault C, Quera-Salva MA, Jamieson A. Obstructive sleep apnea and cephalometric roentgenograms: the role of anatomic upper airway abnormalities in the definition of abnormal breathing during sleep. Chest 1988;93: 1199-205.

14. Pae E-K. A comparative study of the relationship between airway size, tongue activity, and body position. [Master's thesis]. Vancouver: University of British Columbia, 1989.

15. Cartwright RD, Samelson CF. The effects of a nonsurgical treatment for obstruc- tive sleep apnea: the tongue retaining device. JAMA 1982;248:705-9.

16. Cartwright RD, Stefoski D, Caldarelli D, Kravitz H, Knight S, Lloyd S. Toward a treatment logic for sleep apnea: the place of the tongue retaining device. Behav Res Ther 1988;26:121-6.

17. Soil BA, George PT. Treatment of obstructive sleep apnea with a nocturnal airway.patency appliance. N Engl J Med 1985;313:386-7.

18. Schmidt-Nowara WW, Meade TE, Hays MB. Treatment of snoring and obstructive sleep apnea with a dental orthosis. Chest 1991;99:1378-85.

19. Pancherz H. The Herbst appliance-its biologic effects and clinical use. Am J Orthod Dentofae Orthop 1985;87:1-20.

20. Rider EA. Removable Herbst appliance for treatment of obstructive sleep apnea. J Clin Orthod 1988;22:256-7.

21. Knudson RC, Meyer JB, Montalvo R. Sleep apnea prosthesis for dentate patients. J Prosthet Dent 1992;68:I09-11.

22. Knudson RC, Meyer JB. Managing of obstructive sleep apnea. J Am Dent Assoc 1993;I24:75-8.

23. Bonham PE, Currier GF, Orr WC, Othman J, Nanda RS. The effect of a modified functional appliance on obstructive sleep apnea. Am J Orthod Dentofac Orthop 1988;94:384-92.

24. Haze JJ. Treatment of obstructive sleep apnea with the equalizer appliance. J N J Dent Assoc 1987;58:34-6.

25. Johns MW. A new method for measuring daytime sleepiness: the Epworth Sleepiness Scale. Sleep 1991;14:540-5.

26. Redline S, Tosteson T, Boucher TT, Millman RP. Measurement of sleep related breathing disturbances in epidemiologic studies: assessment of the validity and reproducibility of a portable monitoring device. Chest 1991;100:1281-6.

27. Robin P. Glossoptosis due to atresia and hypotrophy of the mandible. Am J Dis Child 1934;48:541-7.

AVAILABILITY OF JOURNAL BACK ISSUES As a service to our subscribers, copies of back issues of the American Journal of Orthodontics and Dentofacial Orthopedics for the preceding 5 years are maintained and are available for purchase from the publisher, Mosby-Year Book, Inc., at a cost of $11.00 per issue. The following quantity discounts are available: 25% off on quantities of 12 to 23, and one third off on quantities of 24 or more. Please write to Mosby-Year Book, Inc., Subscription Services, 11830 Westline Industrial Dr., St. Louis, MO 63146-3318, or call (800)453-4351 or (314)453-4351 for information on availability of particular issues. If unavailable from the publisher, photocopies of complete issues are available from University Microfilms International, 300 N. Zeeb Rd., Ann Arbor, MI 48106 (313)761-4700.