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* From the Department of Medicine, Respiratory Division, St. Michaels Hospital, University of Toronto, Ontario, Canada.
Correspondence to: Victor Hoffstein, PhD, MD, FCCP, St. Michaels Hospital, 30 Bond St, Toronto, Ontario, Canada M5B 1W8; e-mail: victor.hoffstein{at}utoronto.ca
| Abstract |
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Methods: One hundred thirty-four patients with baseline apnea/hypopnea index (AHI) of 37 ± 28 events/h (mean ± SD) received the appliance. The efficacy of the appliance was assessed by the following investigations, performed at baseline and with the appliance: polysomnography, Epworth sleepiness scale, bedpartners assessment of snoring severity, patients assessment of side effects, and overall satisfaction.
Results: Thirteen patients were lost to follow-up. An additional 46 patients had no follow-up polysomnography, but answered the questionnaires. A total of 75 patients had polysomnography at baseline and with the appliance. We found a significant reduction in AHI from 44 ± 28 events/h to 12 ± 15 events/h (p < 0.0005) and a reduction in the arousal index from 37 ± 27 events/h to 16 ± 13 events/h (p < 0.05). Epworth scores fell from 11 ± 5 to 7 ± 3 (p < 0.0005). Bedpartners assessment revealed marked improvement in snoring. For example, at baseline 96% of patients were judged to snore loudly "often" or "always" by their bedpartners, whereas only 2% were judged so while using dental appliance. The most frequent side effect was teeth discomfort, present "sometimes" or "often" in up to 32% of patients. Follow-up clinical assessment in 121 patients conducted on the average 350 days after the insertion of the appliance revealed that 86% of patients continued to use the appliance nightly; 60% were very satisfied with the appliance, 27% were moderately satisfied, 11% were moderately dissatisfied, and 2% were very dissatisfied.
Conclusion: We conclude that the adjustable mandibular positioning appliance is an effective treatment alternative for some patients with snoring and sleep apnea.
Key Words: oral appliance sleep apnea snoring
| Introduction |
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A very important aspect of a successful appliance is the patients comfort. To achieve this goal the appliance must be custom fit for the patient to minimize the discomfort. This is best accomplished with mandibular advancement appliances (MAAs). There are several such appliances in use today. Most of them are relatively bulky and cannot be adjusted in situ, and many have not been tested objectively by comparing respiration and sleep architecture in a large group of patients. In this study, we present the results of nocturnal polysomnography and subjective assessment in patients fitted with a new adjustable mandibular positioning appliance, described by Thornton and Roberts1 the Thornton anterior positioner (TAP) appliance (Oral Appliance Technologies; Dallas, TX).
| Materials and Methods |
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8 to 10 teeth per arch that were
structurally sound and in good periodontal health. The above process, performed during a period of 18 months, resulted in selection of 134 consecutive patients. They were generally healthy outpatients without any significant chronic disease.
Oral Appliance
The TAP appliance is a mandibular advancement device (Fig 1
) composed of two separate archesupper (maxillary) and lower
mandibular) containing the advancing mechanism, which permits a maximum
of 16 mm advancement of the lower jaw. These arches are made of shells
containing thermoplastic material that becomes soft when placed in
boiling water. The dentist inserts the warm arches into the patients
mouth to obtain an impression. The arches are then removed and allowed
to cool, thereby maintaining the shape of the teeth indefinitely. After
this, they are reinserted and the advancing mechanism is engaged. The
screw mechanism in the upper jaw is then turned to advance the mandible
until the patient begins to feel any discomfort in the
temporomandibular joint or in the facial muscles. The advancing screw
was then turned back two turns to ascertain patient comfort. This
became the initial position for home use.
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The final protrusion of the jaw was not recorded because the patients were instructed how to change the amount of protrusion depending on symptoms and did so regularly at home.
Investigations
Objective investigations included in-hospital nocturnal
polysomnography with measurements of respiration (inductance
plethysmography using Respitrace (Ambulatory Monitoring, Inc.; Ardsley,
NY), temperature of exhaled air using thermistors), oxygen saturation
(using a pulse oximeter), sleep architecture (EEG, chin electromyogram,
and electrooculogram), ECG, and leg electromyogram. Apneas were defined
as complete episodes of cessation of breathing lasting
10 s.
Hypopneas were defined as episodes with > 50% reduction in
respiratory flow accompanied by oxygen desaturation of > 4%.
Arousals were defined as 3 to 15 s of alpha and fast theta EEG
frequency.
Subjective assessments included Epworth sleepiness scale (ESS) and a questionnaire dealing with snoring answered by the bedpartner (Table 1 ).
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Data Analysis
The results were analyzed using t tests and
2 tests to compare the differences in sleep
variables before and with oral appliance and changes in snoring. In an
attempt to determine whether response to oral appliance can be
predicted from the initial patient data, we used linear regression
analysis to determine the relationship between percent improvement in
apnea/hypopnea index (AHI) and age, initial body mass index (BMI), and
initial AHI. Statistical significance was defined as p < 0.05. All
data analysis was performed using SAS software, version 6.12 (SAS
Institute; Cary, NC).
| Results |
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Table 3 shows age, sex, initial BMI, initial AHI, and initial ESS in four groups of patients: the initial set, those who were contacted in follow-up, those lost to follow-up, and those who had sleep studies with the TAP appliance.
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Effect of Dental Appliance on Polysomnographic Variables
Sleep studies with the appliance were conducted in 75 patients68
males and 7 females. The average age was 50 years, ranging from 28 to
74 years. Patients wore the appliance for an average of 85 days before
polysomnography. There was no significant difference in BMI between the
diagnostic and follow-up studies (29.3 ± 5.3
kg/m2 vs 28.9 ± 5.8
kg/m2, respectively).
The individual AHIs for all patients are shown in Table 4 . The patients are grouped into respon-ders (AHIappliance < 10 events/h), nonresponders (AHIappliance > 10 events/h), nonapneic snorers, and those who got worse (AHIappliance >AHIbaseline).
In 38 of 75 patients, sleep apnea was abolished (baseline AHI, 39 ± 21 events/h; appliance AHI, 5± 3 events/h). In an additional 31 of 75 patients with sleep apnea, there was a significant reduction in AHI (baseline AHI, 54 ± 31 events/h; appliance AHI, 20 ± 12 events/h). There were three nonapneic snorers whose AHI remained unchanged (baseline AHI, 5 ± 1 events/h; appliance AHI, 4 ± 1 events/h), and three additional patients (two nonapneic snorers and one with severe sleep apnea) whose AHI was higher on the night with the appliance than at baseline.
If we define the response to the appliance as a reduction in AHI to
< 10 events/h, we find that 51% were responders. Alternatively, if
we define the response as reduction in AHI by
50%, we find that 61
of 75 patients (81%) were responders (baseline AHI, 47 ± 27
events/h; appliance AHI, 10 ± 9 events/h). Even these 61 patients
responded on the average with a > 50% reduction in AHI. In all
subsequent descriptions we shall use the term responders in its most
strict senseappliance AHI < 10 events/h.
The mean results for the entire group, as well as for responders (defined as appliance AHI > 10 events/h) and nonresponders, are summarized in Table 5 .
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Univariate linear regression analysis between percent improvement in AHI, defined as 100 x (AHIbaseline - AHIappliance) / AHIbaseline, and age, initial BMI, and baseline AHI revealed no correlation with age, but there was a significant inverse correlation with BMI (r = -0.33, p = 0.008) and AHI (r = 0.27, p = 0.18).
Questionnaire Results
Side Effects of Oral Appliance:
These are summarized in Table 6
. The entries in this table represent the percentage of patients with a
particular side effect. Teeth discomfort, excessive salivation, and jaw
discomfort were the most common side effects.
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Final clinical follow-up was performed, on average, 350 days after insertion of the appliance. At the time of follow-up, 86% of patients continued to use the appliance nightly; 60% were very satisfied with the appliance, 27% were moderately satisfied, 11% were moderately dissatisfied, and 2% were very dissatisfied.
| Discussion |
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One of the earliest mandibular positioning appliances was a nocturnal airway patency appliance described in a case report in 19852 and 2 years later in a series of five patients with sleep apnea.3 The initial success of this treatment (reduction in AHI from 48 to 9 and disappearance of snoring) contributed much to the subsequent interest in MAAs. By 1995, there was sufficient evidence for the efficacy of oral appliances, such that Schmidt-Nowarra et al,4 in a review written on behalf of the American Sleep Disorders Association, concluded that " ... oral appliances present a useful alternative, especially for patients with simple snoring and others with moderate [obstructive sleep apnea] who cannot tolerate nasal CPAP". This further increased interest in oral appliances and resulted in additional evaluation of this treatment modality.
Depending on the particular device and the particular study, > 50% reduction in the AHI, on average, was achieved using MAAs (Table 7 ); the mean response rate (percentage of patients whose AHI was reduced to < 10 events/h) was 53%.7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 Large variability between different studies is undoubtedly caused by differences in apnea severity, facial morphology of patients, type of appliances used and whether it was at the optimum setting at the time of sleep study, methods of end point assessment, and so forth.
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The current study examined the largest group of patients to date. The
results show highly significant reduction in AHI (from 44 to 12
events/h) and high response rate of 81% as defined by
50%
reduction in AHI. This high success rate is most likely a result of the
particular type of appliance used in this study. It has several unique
features not present in other adjustable mandibular appliances. The
main ones are (1) a wide range (1 to 16 mm) of adjustable anterior
displacements and lateral and vertical movements, and (2) the anterior
location of the adjustment screw. The latter feature is important
because it allows for an easy adjustment of the device. The patients
themselves were able to easily adjust the appliance in response to
their bedpartners comments about snoring. Similarly, a sleep
technologist may be capable of adjusting the appliance during nocturnal
polysomnography, thus titrating the degree of anterior mandibular
protrusion in the laboratory to eliminate snoring or apnea. The
appliance is durable but can be easily repaired by the dentist in the
office without sending it to an outside laboratory. The cost of the
appliance, including manufacturing and all of the necessary follow-up
visits for 1 year, is comparable to the cost of nasal CPAP equipment in
Ontario.
Probably the most important drawback of the current study is the fact that 59 of 134 patients (44%) did have follow-up polysomnography with the oral appliance. Clearly, if we speculate that all of them are nonresponders, our conclusion regarding the success rate of the appliance may not be valid. However, from the initial characteristics of these 59 patients (Table 3) there is no a priori reason why they should all be nonresponders; the most likely scenario is that the response rate among them is similar to that seen in the 75 patients who had follow-up polysomnography. In fact, when we assumed the worse case scenario by setting AHIappliance = AHIbaseline for all patients without a follow-up polysomnography, we still achieved a significant reduction in AHI from 38 ± 28 events/h to 20 ± 22 events/h (p = 0.0001). Finally, subjective information about snoring was available in 121 of 134 patients (90%), which is a very acceptable follow-up rate.
There is generally some hesitancy in recommending an oral appliance for fear that it will interfere with sleep. This fear is unfounded. Studies in which sleep architecture was monitored uniformly show either no change19 22 23 or improvement17 18 20 25 in sleep quality; our results also demonstrate a significant decrease in sleep fragmentation with the dental appliance.
Side effects occur on the average in 30% of patients as
reported by various investigators9
12
13
14
15
16
18
19
20
21
22
24
; they
range from 0 to 67% and include generally nonspecific discomfort
or temporomandibular joint pain. However, many patients consider these
side effects as being minor and not influencing their compliance. In
the studies in which side effects were compared between wearers and
nonwearers of the appliance, no significant differences in the
incidence of side effects was found. We found similar results in that
45% of patients complained of some side effects. The most frequent
ones are excessive salivation, teeth discomfort, and jaw
discomfort, occurring often in
26% of patients. The frequency and
the severity of side effects are undoubtedly affected by the type of
appliance, wear time, degree of protrusion, and care taken by the
dentist in fitting the appliance.
As with any treatment, the ability to select patients who are
most likely to respond to it is important in improving compliance with
therapy. Our study does not allow us to make such predictions. We did
not perform any objective measurements of facial morphology, but on the
basis of previous studies, such measurements are unlikely to be of
clinical value over and above simple clinical examination by a
qualified and experienced dentist. Although we did find inverse
correlation between BMI and degree of improvement, this association
does not imply cause and effect relationship and cannot be used to
predict success. On the other hand, our results allow us to argue with
the existing belief that oral appliances should not be used for
treatment of severe sleep apnea. Of the 21 patients with severe sleep
apnea (AHI ranging between 50 and 115 events/h), the use of the
appliance brought AHI to
10 events/h in 6 patients, resulted in
> 50% reduction in AHI in an additional 13, and had no beneficial
change in AHI in only 2 patients.
Finally, we must comment on the fact that even in the nonresponders, there was a significant improvement in snoring as perceived by the bedpartner. Undoubtedly, an oral appliance modifies pharyngeal cross-sectional area and compliance of pharyngeal walls. This alters the properties of sound (frequency and amplitude) and its perception by a listener. We found the same result in our earlier investigation28 of the effect of uvulopalatopharyngoplasty on snoring and apnea.
We conclude that adjustable oral appliances appear to be an effective treatment alternative for selected patients with snoring and varying degrees of sleep apnea, including those with severe obstructive sleep apnea. However, predictors for response have yet to be determined.
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| Footnotes |
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Received for publication April 8, 1999. Accepted for publication August 7, 1999.
| References |
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