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ral Appliance Therapy in Sleep Apneayndromes: A Review

tephen P. Warunek

Obstructive sleep apnea (OSA) can present serious health risks and must be

diagnosed by a physician in conjunction with a sleep study. Of nonsurgical

treatment alternatives, nasal continuous positive airway pressure (nCPAP)

has been shown to be more effective than oral appliance therapy in improv-

ing respiratory disturbances. However, many patients initially refuse or

cannot tolerate this treatment and randomized trials report patient prefer-

ence for oral appliances. Since 1980, approximately 150 articles have been

published on oral appliance therapy. This article is a review of case studies

and randomized trials. Terminology, clinical procedures, and patient com-

munication also are discussed as well as contraindications and complica-

tions of this treatment alternative. A 2001 review of 563 patients with

different severities of OSA in 30 case studies since 1985 showed a reduction

in the apnea-hypopnea index to <10 in 61% of the sample. This report and

other studies emphasize that some patients do not improve or become

worse despite improvement of some symptoms, eg, snoring. Therefore,

physicians must continue progress evaluations. Side effects are usually

minor and transient although a small proportion of patients cannot tolerate

this approach. It is not yet possible to predict the most advantageous

appliance type for a particular patient. Recent randomized trials have shown

that devices with a range of vertical openings are effective and adjustability

seems to be a desirable feature. Although oral appliance treatment may last

for many years, patients must be informed that these devices require peri-

odic replacement, which may be a financial consideration should insurance

coverage not be available. (Semin Orthod 2004;10:73-89.) © 2004 Elsevier

Inc. All rights reserved.

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leep apnea is a medical disorder that can bepresent in any age group.1,2 It is estimated to

ffect approximately 2% to 4% of the adult pop-lation and is most commonly observed in mid-le-age overweight males. Strained respiration,ecreased blood oxygen levels, and arousals that

nterrupt a normal sleep pattern characterizehis syndrome. Many cases present a significant

From the Department of Orthodontics, School of Dental Medi-ine, University at Buffalo, Buffalo, NY.

Address correspondence to Stephen P. Warunek, Department ofrthodontics, School of Dental Medicine, Squire Hall, Rm 140,435 Main St, Buffalo, NY 14214-3008.

© 2004 Elsevier Inc. All rights reserved.1073-8746/04/1001-0007$30.00/0

wdoi:10.1053/j.sodo.2003.10.006

Seminars in Orthodontics, Vol 10, N

ealth risk and can result in excessive daytimeleepiness, early morning headaches, impairedoncentration, social impairments, systemic andulmonary hypertension, traffic and work-re-

ated accidents, ischemic heart disease, and ce-ebrovascular disease.3,4 Of the 3 types of sleeppnea, obstructive sleep apnea (OSA) is theost prevalent. Also referred to as obstructive

leep apnea/hypopnea syndrome (OSAHS), thisondition occurs as the base of the tongue peri-dically contacts the posterior pharyngeal wallr partially occludes the upper airway duringleep. Relaxation of the genioglossal musclesnd reduction of tone of surrounding muscula-ure are contributing factors. Whereas almost allatients with OSA exhibit snoring, not all those
ho snore have apneic episodes.
73o 1 (March), 2004: pp 73-89

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74 Stephen P. Warunek

Treatment modalities for OSA and snoring athe present time most typically include nasalontinuous positive airway pressure (nCPAP),ral appliances, and adjunctive measures such aseight loss, medication, avoidance of sedatingedication, and body positioning. Surgery op-

ions include soft palate surgery such as uvulo-alatopharyngoplasty (UPPP) or laser-assistedvulopalatoplasty (LAUP), radiofrequency (RF)

issue ablation, nasal surgery, genioglossusongue advancement, and mandibular advance-

ent surgery. Predominant before 1980, trache-tomy has largely been replaced today. Al-hough several randomized, controlled studiesith placebos have shown that the first line ofonsurgical treatment is nCPAP in terms of ef-

ectiveness,5-7 less than optimal patient compli-nce with respect to tolerating the device, incon-enience, and some side effects lowers theverall treatment efficiency.

A literature search indicates that since 1985pproximately 150 articles that describe variousral devices used in the treatment of sleep dis-rders have been published. The majority ofhese studies represent case series or case re-orts and a much smaller number are random-

zed controlled trials. It is generally acceptedhat treatment of OSA with oral appliances is aiable option for some patients with varying de-rees of short- and long-term improvement andide effects.

Oral appliance treatment includes, in orderf decreasing usage, adjustable and nonadjust-ble mandibular posturing devices, anteriorongue repositioners, and soft palate or uvula-ifting devices. Personal communication witheveral commercial laboratories (John’s Dentalaboratory, Great Lakes Orthodontics, Ltd., andpace Maintainers Laboratory) revealed that thedjustable or titratable advancement devicesere the most prescribed over the past severalears. An appliance that advances the tongue, orongue and mandible together with adjacent softissue, increases the posterior airway space, in-reases the activity of the genioglossal and lateralterygoid muscles,8 and effects a stretch induc-

ion of the pharyngeal motor system.9 Mandibu-ar advancement devices also alter position ofhe hyoid and modify the hypopharyngeal airway
pace. Soft palate or uvula lifters reduce soft
issue vibrations that result in snoring. With re-pect to the many variations of appliance de-igns, it is not possible to predict what device wille most effective for a particular patient.

The purpose of this article is to review theleep medicine literature with special attentiono the articles about randomized, controlledtudies. It discusses terminology, diagnostic im-ging, clinical procedures, patient communica-ion, and contraindications and complicationsf therapy with different types of adjustable andonadjustable oral appliances.

erminology

pnea is the cessation of airflow for at least 10seconds.

pnea index (AI) is the number of apneas perhour of sleep, with 5 or less considered nor-mal.

pnea-hypopnea index (AHI) is the number ofapneas and hypopneas per hour of sleep. Tenor less is usually considered to be normal.

entral sleep apnea is the cessation of airflow fromlack of respiratory effort.

pworth sleepiness scale (ESS) is a reliable andvalidated subjective assessment of daytimesleepiness. A score greater than 10 on thisself-administered questionnaire indicates ex-cessive sleepiness.

DA 510k is a premarket notification that a med-ical device manufacturer must submit to theFood and Drug Administration. It allows theFDA to determine whether the device is equiv-alent to one in commercial distribution be-fore May 28, 1976. New or modified devicesmust be supported with safety and effective-ness data that may include material composi-tion, biocompatibility, and clinical testing.ypopnea is an abnormal reduction of airflow forat least 10 seconds.ixed sleep apnea is the cessation of airflow start-ing as central followed by obstructive.ultiple sleep latency test (MSLT) is an objectivemeasure of daytime sleepiness. A time greaterthan 10 minutes is oftentimes defined as nor-mal.

bstructive sleep apnea (OSA) is the cessation ofairflow despite adequate effort to breath.

olysomnography is the science dealing with the
physiology of sleep and the definitive objec-

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75Oral Appliances and Sleep Apnea

tive means of diagnosis of sleep apnea andrelated disorders. Activities monitored duringa sleep study are brain waves (EEG), eye move-ments (EOG), muscle activity (EMG), heart-beat (EKG), blood oxygen levels (SaO2), andrespiration. Polysomnographic markers in-clude total sleep time, sleep efficiency, sleepstage distribution, arousal index (sleep frag-mentation), and snoring frequency and inten-sity.

espiratory disturbance index (RDI) is anotherterm for AHI. The usual definition of slightOSA is an RDI of 5 to 14, moderate OSA is anRDI of 15 to 30, and severe OSA is an RDI of�30.

leep stages are the intervals of non-REM andREM sleep. Non-REM sleep is divided intostages 1 to 4 with stage 1 being the lightestlevel and stage 4 very deep sleep. After pro-gression through all 4 stages in about 90 min-utes, stage REM begins. Dreams most oftenoccur and muscle tone decreases in this stage.The cycle repeats during the night with thelength of stage REM increasing until this stagepredominates by early morning.

noring is breathing through a narrowed upperairway space during sleep with harsh noises, as

igure 1. Noctural Airway-Patency ApplianceNAPA). The NAPA has FDA 510k clearance for OSA.Color version of figure is available online.)

caused by the vibrating of the soft palate. O

reatment outcomes are the subjective and objec-tive measures of patient responses to a partic-ular mode of therapy. Definitions of completeresponse, partial response, and failure varyamong investigators.

pper airway resistance syndrome is an incompleteupper airway obstruction without apneas orhypopneas. Snoring, inadequate sleep, anddaytime sleepiness characterize this condition.

iterature Review

ase Studies

n 1934, Pierre Robin10 first described the con-ept of advancing the mandible with a mono-lock functional appliance to treat airway ob-truction in infants with micrognathia. Hisethod was not accepted to any extent and itas not until 1985 that Meier-Ewert and cowork-rs11 next described an intraoral protractionevice for the treatment of sleep apnea. Manyrticles followed showing therapeutic efficacyn treating OSA with various one-piece, hardcrylic, nonadjustable advancement appli-nces.12-21 Soll and George12 described one ofhe first devices to receive FDA 510k clearanceor commercial distribution (Fig 1). An examplef a case series report with comparisons of initialnd progress conditions showed 71% of patients

igure 2. Silicone positioner appliance. The elasto-eric sleep appliance has FDA 510k clearance for
SA. (Color version of figure is available online.)

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n � 14) experienced normal breathing, de-ned as AHI �10, after appliance therapy.18 In992, Lyon and coworkers22 were the first to useone-piece silicone orthodontic positioner to

reat patients with snoring and mild to moderateleep apnea (Fig 2). This material was used toid patient comfort, which was sometimes a

igure 3. Herbst hardware variations. Standardlunger-tube (A). Telescopic connector (B). Theerbst appliance has FDA 510k clearance for OSA.

Color version of figure is available online.)

ource of complaint with hard acrylic appli- v

nces. Unlike applications in orthodontic finish-ng positioners, their appliance was designed toe passive and it did not intentionally exert anyooth-moving effects.23

Many appliances used to treat OSA are adjust-ble, the rationale being that single positionevices are sometimes uncomfortable or ineffec-ive thereby necessitating refabrication. The firstnvestigator to use a two-piece adjustable ad-ancement device with Herbst hardware wasider24 in 1988. His report was largely positiveut was based on a relatively subjective symptom

mprovement questionnaire without supportrom polysomnographic investigation. In sup-ort of the findings of Rider,24 Clark and co-orkers25 found the Herbst appliance to be ef-

ective in reducing the apnea index to a value of10 in 73% of patients (n � 24), while another

ike study reported a comparable reduction in3% of patients.26 Variations of the Herbst ap-liance used in the treatment of sleep apnea are

llustrated (Fig 3).Another type of device used to treat OSA

auses some clockwise mandibular rotationhile holding the tongue in a forward positionuring sleep.27-31 Tongue-retaining devicesTRD) are both pre- and custom-fabricated toaintain lingual protrusion with suction derived

rom a plastic bulb that is held between the lips

igure 4. Tongue-retaining device (TRD). (Color
ersion of figure is available online.)

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nd teeth (Fig 4). Tongue protrusion increaseshe oropharyngeal, velopharyngeal, and hypo-haryngeal cross-sectional areas of the upperirway, thereby improving airway patency andunction. This type of appliance is said to be ofarticular benefit in edentulous patients, in in-ividuals who have periodontally compromisedentitions, and in patients suffering from tem-oromandibular dysfunction (TMD).

Most case studies dealing with OSA use poly-omnography, and questionnaires to determinehe mean AHI with and without treatment, the

ean minimum arterial oxygen saturation, theleep stage distribution, and the subjective day-ime sleepiness. Schmidt-Nowara and cowork-rs32 reviewed 19 publications comprising caseeries and case reports that included a total of04 patients. Statistical analysis of the data ob-ained from 271 of the patients included in the9 publications showed that TRD, and fixed anddjustable mandibular advancement devices, allesulted in an improvement in the average AHI.imilar treatment results were obtained with aariety of appliances used to treat the 271 OSAatients who, on average, experienced a 56%eduction in their AHIs while 51% of patientschieved normal breathing (AHI �10) as a re-ult of their treatment. It should be recordedhat not all of the OSA patients reviewedchieved normal breathing and others did notmprove or even became worse. Some studies,ot all, showed that a statistically significant cor-elation exists between the levels of treatmentuccess and the value of the initial AHI. Fromhe above studies it is recommended that oralppliances be used as a first treatment option fornoring and mild OSA, and only for moderate toevere OSA if all alternate therapies fail.

Since the review of Schmidt-Nowara and co-orkers32 of 19 publications in 1995, additionalase studies have shown that oral appliance ther-py has a valuable role to play in the treatmentf OSA.33-44 Thus, in a 2001 review article, Lind-an and Bondemark45 summarized data from

0 case series publications, dating back to 1985,n which 61% of 563 patients experienced aosttreatment AHI �10. This review reempha-ized the need for patients to return to theirhysicians for progress evaluation and polysom-ography, since symptoms such as snoring might

mprove while the degree of apnea actually wors-
ns. w
In other notable studies, Lowe and his co-orkers46 were the first to measure patient com-liance with a sensor, embedded in the body, oftitratable device of thermo-softening material.

n a trial group of 8 patients who wore thisppliance for 6.8 hours per night, awake videondoscopy showed that the most significant ef-ect obtained with the appliance in place was athe level of the velopharynx. In a further study ofong-term compliance, Pancer and coworkers41

eported that 86% of patients (n � 121) usedhe appliance every night for about 1 year afterelivery and that 87% of these patients were veryr moderately satisfied. A further study dealingith patient conformity in OSA patients re-orted a lesser degree of patient complianceith only 51% of patients (n � 53) continuing toear their advancement devices after 3 years.9

Despite their considerable contributions tour understanding of OSA, case studies of pa-ients who suffer from this condition raise ques-ions of validity. Shortcomings in these studiesnclude their retrospective design, the lack ofontrols, the generally small sample sizes, theariable definitions of treatment success, and thehort treatment durations used for progress eval-ations. The exclusion of patients with severepnea and the inclusion of patients who failed tomprove with other treatment modalities consti-ute a major source of bias in these case studies.

andomized, Controlled Studies

erguson and associates6 conducted a random-zed, crossover design study comparing a one-iece, hard acrylic, nonadjustable oral appli-nce, Snore-Guard™ (SG), to nCPAP in patientsith mild to moderate OSA. The amount ofdvancement of the lower jaw was set at 3 mmosterior to the position of maximal mandibularrotrusion and at 7 mm or greater vertical bitepening measured between the upper and lower

ncisors. The appliances used in both treatmentodalities studied were adjusted to maximize

atient comfort. In both instances the time pe-iod was limited to 4 months, with two 2-weekeriods during which no treatment was pro-ided. These periods of no treatment comprisedn initial period and an intervening 2-week
ash-out period. Twenty-one of the 27 patients

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ompleted the treatment protocol, which in-luded home sleep monitoring. Questionnairesesigned to evaluate symptoms, treatment effi-acy, side effects, and patient satisfaction weredministered during the wash-in period and athe end of therapy. The treatment of 48% of theG and 62% of nCPAP patients was considereduccessful (AHI �10/hr and with symptom re-ief), whereas 24% of SG patients and 38% ofCPAP patients were classified as compliance

ailures (discontinued treatment). In the finalnalysis, 28% of SG patients and none of theCPAP patients were classified as treatment fail-res (AHI � 10/hr and/or no relief of symp-oms). While patients preferred the SG treat-

ent to the nCPAP therapy, the former was nots effective as was the CPAP treatment in reliev-ng symptoms of excessive daytime sleepiness. Ithould be noted that SG currently has FDA 510klearance for snoring only.

In a recent study Ferguson and coworkers47

sed a randomized, crossover design protocol toompare an adjustable oral advancement mech-nism appliance (AMP) to nCPAP for the treat-ent of mild to moderate OSA. The advance-ent mechanism consisted of a titanium hingeith 5 adjustment holes that connected full-cov-rage upper and lower, hard acrylic splints. Thisesign permitted slight lateral movement of theandible as well as allowing unrestricted airflow

or breathing. The advancement was increasedntil snoring ceased and symptoms improved, or

he patient’s limit of tolerance was reached butot beyond 70% of maximum mandibular pro-

rusion. Both appliances were adjusted to maxi-ize comfort, and treatment time was 4 monthsith initial and intervening periods of 2 weeksuring which no treatment was provided. Homeleep monitoring and questionnaires, includingn Epworth questionnaire, were administereduring the intervening 2-week wash-in periodnd at the end of treatment. Follow-up questionst the end of subsequent posttreatment periodseported symptoms, treatment efficacy, side ef-ects, and patient satisfaction.

Twenty of the 24 patients completed thetudy, and 55% of AMP patients and 70% ofCPAP patients were assessed to be treatmentuccesses (AHI �10/h with relief of symptoms).
ive percent of the 20 patients treated with AMP, r
nd 30% with nCPAP, were compliance failuresdiscontinued treatment). Forty percent of theMP patients and none of the nCPAP patientsere treatment failures (AHI � 10/hr and/oro relief of symptoms). Two treatment failuresith AMP had an increase in AHI with this formf therapy. Both treatments reduced excessiveaytime sleepiness to the same degree. Thereas no significant difference in side effects be-

ween the treatments, but patients were moreatisfied with the oral appliance.

Bloch and colleagues48 used a randomized,ontrolled crossover design study to comparehe effectiveness and side effects of a fixed sin-le-piece, mandibular advancement deviceMonobloc) with those of an adjustable Herbstppliance with equal advancement. Twenty-fouruccessive patients with a diagnosis of OSA whoither refused CPAP, or declined to use it aftern initial trial period, participated in this study.his project was one of the first to compare theffectiveness of mandibular advance devices withifferent designs (Fig 5). Both appliances uti-

ized full coverage splints of hard acrylic, initiallyet at 75% of maximum protrusion, with theertical interincisal opening set at 5 to 10 mmor the Monobloc and at 4 to 6 mm for the

igure 5. Monobloc (A) and Herbst (B). Reprintedith permission from the American Journal of Respi-

48
atory and Critical Care Medicine.

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erbst. The appliances were adjusted to maxi-ize patient comfort and each patient was ran-

omly placed into 1 of 6 possible sequences ofreatment with the Herbst, Monobloc, or noreatment. Treatment was evaluated at weeklyntervals with a questionnaire and polysomnog-aphy.

Patient preference and trends of polysomno-raphic data showed the Monobloc to havereater patient acceptability and to be more ef-ective than the Herbst appliance in the treat-

ent of OSA. Reasons advanced for appliancereference were greater symptom relief, simplic-

ty, and lack of side effects. The Herbst appli-nce allows greater jaw opening than does theonobloc, and this clockwise jaw movement re-

ults in a posterior tongue movement that caniminish the effectiveness of this appliance in

reating OSA.In a randomized, controlled, three-period

rossover design study of OSA patients Mehtand coworkers49 compared the treatment effec-iveness of a custom-made, adjustable mandibu-ar advancement splint to a lower control plateith no protrusive effect. Protrusion was initially

et at the maximum tolerable limit of the pa-ients studied. Two separate, full coverage, hardcrylic splints were fabricated, each 1.5 to 2 mmhick, so as to minimize the vertical bite open-ng. The upper splints had bilateral flanges ex-ending inferiorly from the palatal aspect of the

olar region. These flanges engaged slots in theingual molar area of the mandibular splint andhe system used expansion screws to providencremental mandibular advancement. The ap-liance was adjusted to maximize comfort of theatients who were randomly placed into controlr treatment groups at weekly intervals. Fol-

ow-up polysomnography and an Epworth ques-ionnaire assessed objective and subjective treat-

ent outcomes.Partial (AHI �5/hr, or AHI reduced at least

0%, or symptom relief) or complete (AHI �5/r, symptom relief) improvement response waschieved in 62.5% of 24 patients who completedhe protocol with the active device. Treatmentailure (�50% reduction of AHI or no symptomelief) occurred in 37.5% of patients who worehe active device. Two patients discontinuedreatment and were deemed to be failures due toack of compliance. The majority of patients who
ore the active appliances reported reduced l
evel of snoring, improved sleep quality, and lessaytime sleepiness. In this short-term study, sub-

ective reports of compliance were high as 87.5%f patients who completed the protocol re-orted nightly use.

A randomized, controlled, two-period cross-ver study was designed to compare an adjust-ble mandibular advancement device to an in-ctive one in a sample drawn from consecutiveatients with mild to moderate OSA.50 Two sep-rate hard acrylic splints were fabricated, each.5 to 2 mm thick, so as to minimize the verticalpening. The lower portion, with bilateral buc-al flanges, extended in a superior direction inhe molar region and abutted against bilateralxpansion screws anchored in the upper appli-nce, which was otherwise similar to the onellustrated (Fig 6). The appliances were adjustedo maximize patient comfort and each subjectncluded in the study was randomly placed into

of 2 treatment groups at 4-week intervals. Fol-ow-up polysomnography, Epworth, and symp-om questionnaires assessed objective and sub-ective treatment outcomes. The ESS and MSLTuestionnaires assessed subjective and objectivereatment outcomes, respectively. Patients expe-ienced significantly improved scores in botheasures with the active appliance in compari-

on with the control device after each treatment

igure 6. Mandibular advancement device with buc-al flanges. (Color version of figure is available on-
ine.)

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eriod. This study was the first to report a sig-ificant objective reduction in daytime sleepi-ess with a mandibular advancement appliance.olysomnography showed that the active deviceesulted in a 52% reduction in mean RDI andignificantly higher mean minimum arterial ox-gen saturation compared with the controls. Aseported in other studies, a proportion of pa-ients did not respond or only partially re-ponded to treatment with the mandibular ad-ancement device.

A randomized, controlled, two-period cross-ver design investigated the vertical dimensionf opening (VDO) on a mandibular advance-ent device.51 Twenty-three patients with a di-

gnosis of OSA completed this study in which 2eparate hard acrylic splints were fabricated withmm of interincisal opening for the first design

t the most comfortable protrusive position. Theecond design featured an additional 10-mmcrylic overlay to fit between 2-mm-thick splints,or a total of 14 mm of interincisal opening, athe same protrusion as used in the first design.uccal flanges extending from the lower splinttted against buccal blocks on the upper portion

o prevent posterior movement of the mandible.ollowing an initial period to maximize comfort,ach patient was randomized into 1 of 2 treat-ent groups at 2-week intervals with interveningash-out periods. Treatment outcomes were as-

essed with questionnaires and polysomnogra-hy. The investigators concluded that themount of vertical opening did not have anyarked effect on treatment efficacy, as deter-ined by objective and subjective measures, but

he patients preferred the device with the re-uced vertical opening.

Randerath and coworkers52 used a random-zed, controlled, two-period crossover designtudy to compare an adjustable mandibular ad-ancement device, adjusted to produce 66%aximum mandibular protrusion, to nCPAP.wenty patients with a diagnosis of mild to mod-rate OSA completed this study in which 2 thinhermoplastic splints were connected with a rel-tively new Herbst hardware design, adjustabley screw-type guide rods (Fig 3B). In contrast torevious studies, the appliance was not adjusted

o maximize comfort. Patients were randomizednto 1 of 2 treatment groups at 6-week intervals.
ach treatment period was evaluated with a e
uestionnaire and polysomnography. After 6eeks of treatment the AHI recorded with theCPAP therapy was significantly lower than thatoted with the mandibular advancement device.atients did, however, prefer the oral appliancend 30% of the individuals treated by this meanshowed a statistically significant reduction inHI (to �10).

iagnostic Imaging

any investigators have used cephalometricnalysis in an attempt to diagnose OSA or exam-ne treatment effects with oral appliances. Pa-ients with severe craniofacial anomalies such ashe Pierre Robin syndrome, who exhibit micro-nathia of the mandible and glossoptosis, tendo develop upper airway obstruction.53 The ma-ority of OSA patients, however, do not haveuch obvious anatomical deformities. Despitepecific limitations, which include a two-dimen-ional image taken with the patient in an uprightosition, lateral cephalometric radiographs haveeen used extensively to examine the possibleelationships that may exist between cranialorphology and OSA. Pae and coworkers54 dis-

ussed some of the shortcomings of radio-raphic cephalometry, while other workers55-62

ointed to skeletal and soft tissue morphologicaleatures that could be used to diagnose the pres-nce and severity of OSA. Skeletal featureshought to be of diagnostic importance in OSAnclude a retrognathic mandible, a narrow man-ibular arch, maxillary and mandibular retro-nathia, an increased lower facial height, aownward and forward positioned hyoid bone, aeduced size of the pharynx, and an increasedraniocervical angle. Those soft tissue entitieshat are visible in a sagittal cranial x-ray and that

ay be important in the diagnosis of OSA in-lude enlarged tonsils and adenoids, increasedongue and soft palate areas, and a reducedistance between the base of the tongue andosterior wall of the pharynx.

In contrast to the findings of others, Rose andoworkers63 examined the lateral cephalographsf 106 consecutive OSA patients and found noirect correlation existed between cephalomet-ic parameters and the severity of OSA, with the
xception of the position of the hyoid bone. The

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ownward and forward position of the hyoidone relative to the mandibular plane was re-orted in a number studies and it is postulated

hat this movement is an adaptation to alteredead and tongue posture.33,64,65

A comparison of lateral cephalograms takenor patients with snoring and OSA, before andfter 2 years of treatment with a mandibularrotruding device, showed pharyngeal volume

o increase by about 10% during the period ofreatment.66 One explanation for this relativencrease in size is the reduction of soft tissuedema, about one-half in the velum, which oc-urs as the frequency and intensity of the vibra-ions, due to the snoring, decreases. Two years ofreatment with a mandibular protruding deviceas associated with a moderate mandibular ro-

ation, a proclination of lower incisors, and nohange in mandibular length. The distances be-ween the hyoid bone and 2 reference lines, theasal and the mandibular line, increased signif-

cantly during the period of treatment. Another-year study of the effects of OSA treatment onranial form found a significant decrease inverbite and overjet and, in contrast to the pre-ious study, an increase in mandibular length.67

Investigators have also employed 3-dimen-ional imaging techniques to evaluate the pha-yngeal region of OSA patients. Lowe and co-orkers58 used computed tomography (CT) to

how the correlation of tongue and soft palateolumes with the body mass index. A magneticesonance imaging (MRI) study reported on theffects that nCPAP treatment has on cranialorphology. This study published findings that

ncluded an increase in pharyngeal volume, aecrease in tongue volume, and a decrease inpper airway edema.68 Examination of cross-sec-

ional areas of the hypopharynx, oropharynx,nd velopharynx, by using video endoscopy withnd without a mandibular protruding device ap-liance, showed that treatment with this deviceesulted in a significant increase in space at theevel of the velopharynx.46

linical Approach to Obstructive Sleep Apnea

he following treatment guidelines are based onecommendations from the American Sleep Dis-rders Association.69 A flowchart illustrating as-ignment to treatment alternatives is shown in
igure 7.
. The physician has the responsibility to diag-nose OSA and recommend an appropriatecourse of treatment. Diagnostic criteria in-clude clinical signs, symptoms, and results ofpolysomnography. The medical providershould be aware of basic dental conditionssuitable for oral appliance therapy.

. The patient is referred to a dentist or dentalspecialist who practices in this field. A pre-scription requests further evaluation of thedental status and fabrication of an oral appli-ance, if appropriate. A diagnostic report isalso forwarded.

. At the initial dental evaluation, medical anddental histories should be taken. The clini-cian should explain the rationale, advan-tages, and disadvantages of treatment, to-gether with a review of informed consent.

. During the initial appointment, a clinical ex-amination notes:a. Soft tissue facial features and facial type.b. Physiologic activity including abnormal

habits.c. Temporomandibular joint health, occlu-

sion, range of mandibular movement,and abnormal attrition.

d. Teeth present and restorations with spe-cial attention to full coverage crowns.

e. Periodontal status assisted by full mouthseries or panoramic radiograph no morethan 6 months old.

f. Intraoral soft tissue health and presenceof abnormal muscle attachments.

Although records may be included in thisppointment, many clinicians and patients pre-er to wait until consideration of the advantagesnd the disadvantages of home treatment arenown.

. A records appointment is scheduled to takeimpressions for study, and work models, pho-tographs, a mandibular advancement regis-tration, and an optional cephalometric ra-diograph. A George Gauge™ (Great LakesOrthodontics; Fig 8) is useful to take a biteregistration at or about 75% of the maximumprotrusion.

. The clinician selects an appliance for labora-tory fabrication and delivers the completedappliance with home care instructions ac-cording to the manufacturer’s specifications.
Approximately 18 commercially available de-

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vices have FDA 510k market clearance forOSA. About twice that number have FDAclearance for snoring.

. Following placement of the chosen appli-ance patients should be seen after 1 week,after 1 month, and as required for progressevaluations that include notation of symp-toms, sore spot adjustments, and modifica-tions of the advancement position. A 1-piecedevice may need to be sectioned and refab-ricated at the laboratory at a new advance-

Figure 7. Flowchart

ment registration.

. The patient should return to the physicianfor follow-up assessment when the patientand/or bed partner reports a subjective im-provement in sleep quality or after no longerthan several months. Follow-up polysomnog-raphy is not indicated for patients with eitherprimary snoring or mild OSA if symptomsimprove. As the degree of improvement var-ies and some patients show no improvementor worsen, the appliance may need to bemodified, refabricated with an alternate de-

atment alternatives.

sign, or discontinued.

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. To monitor an effective oral appliance, recalldental appointments are made every 6months for 2 years and then annually. Theocclusion, dental and periodontal condition,temporomandibular joint (TMJ) status, andsigns and symptoms of reoccurring OSA areall monitored. Referrals to the physician incharge’s office are made as required.

reatment Considerations

efore placing an appliance to treat OSA clini-ians should explain the possible side effects ofreatment including the possibility that the ap-liance may loosen or break dental restorations.xcess salivation, xerostomia, TMJ pain, sore-ess of the masseter muscle, and tooth discom-

ort are usually of minor intensity. These symp-oms tend to occur at the inception of treatmentnd they usually ameliorate with time. Patientshat are treated with a mandibular protrudingevice for OSA may find that when they wear theppliance their occlusion feels different for ahort while after the appliance is removed. Moreermanent, but usually relatively minor, occlusalhanges have also been reported.66,67 More sig-ificant effects, such as the change in overjet

rom 2 mm to an edge-to-edge incisor relation-hip shown in a 5-year-progress cephalometricadiograph, are less commonly seen (Fig 9). Theelationship that exists between the degree of

igure 8. Gauge for registering mandibular anteriordvancement.

nwanted tooth movement and conventional (

ersus heat-softening acrylics is currently beingiscussed.70

Mandibular protrusion devices should onlye used when a patient has at least 8 teeth inach arch and is able to demonstrate a mandib-lar protrusion of at least 5 mm and a bitepening of greater than 25 mm. Appliances maye used in combination with partial dentureshat replace no more than 4 teeth. Patients withdentulous maxillary arches and at least 8 teethn the mandibular arch may be able to wearome mandibular protrusion devices, especiallyhose that are fabricated with heat-softeningcrylics. Totally edentulous patients are usuallyot good candidates for mandibular reposition-rs, but tongue retaining devices may be used in

igure 9. Cephalometric tracings of occlusalhanges. Pretreatment (A) and five years progress
B).

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igure 10. Advancement components. PM Positioner (A). Klearway (B). EMA (C). TAP (D). Snore-Aid (E).
ilencer (F). All have FDA 510k clearance for OSA. (Color version of figure is available online.)

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dentulous patients, although these appliancesnly have FDA clearance for snoring, not OSA.

Whereas slight TMJ discomfort can be re-ieved with forward mandibular positioning,

SA patients who present with more severe TMJain probably are not good candidates for treat-ent with mandibular protrusion appliances.

atients with significant bruxism can frequentlyamage mandibular protrusion devices and thusake this treatment approach costly and ineffi-

ient, while very obese patients, with some ex-eptions, are best treated by other means thanandibular protrusion.

ppliance Design

ral appliances that are used to treat OSA cane either fixed, or adjustable sagittally at a ver-ical opening that ranges from 1 to about 10 mmhen measured in the incisor region. L’Estrangend his coworkers71 recommended minimizinghe vertical opening to limit posterior displace-

ent of the tongue and soft palate. In contrastther investigators reporting on the findings of aandomized study concluded that the amount ofertical opening did not have any marked effectn treatment efficacy as determined by objectivend subjective measures.51 Patients, however,referred devices with reduced vertical opening.n another randomized study, patients preferredone-piece Monobloc with 5 to 10 mm of verti-

al opening between the incisors to a Herbstith between 4 and 6 mm of bite opening.48

atient preference and results of polysomno-raphic data indicate that the Monobloc appli-nce is more effective, in comparison with theerbst appliance, in treating OSA. Georgeaintains that non-rigid devices that cause man-

ibular advancement but permit some degree ofovement also cause a suppression of the

ongue-protruding muscles and that this allowshe tongue to retract from the teeth and to be

ore vulnerable to airway suction.70

In addition to Herbst hardware, the advance-ent mechanisms employed in adjustable man-

ibular advancement devices include expansioncrews, rapid maxillary expansion screws (RME)ith connector arms, elastic straps, and otheresigns (Fig 10). The connector arms that areelded to the body of the RME are designed to

upport a quasi-static intraarch load mainly par-
llel to the direction of opening. When used as (
n interarch connector for mandibular advance-ent, additional torsional forces that are ex-

ressed at the solder joints occasionally causeremature failure of the appliance. Soldering andditional reinforcement wire to the anteriorortion of the connector arms at the laboratoryinimize this type of failure (Fig 11).Appliances that are used to treat OSA may be

onstructed of a variety of materials that includeard methyl methacrylates, soft silicone elas-

omers, heat-softening acrylics, and hard ther-oformed plastics that are lined with soft vinyl

ubber. Since replacing vulcanite in the early940s, hard methyl methacrylate has been exten-ively used in many types of dental appliances.72

hile silicones can provide any desired degreef softness, their propensity to tear makes themoor choices when they are used in combinationith embedded wires or clasps. Heat-softeningcrylics are relatively new on the market andhey have not been given a great deal of expo-ure in the literature other than when they arepplied as soft denture reliners.73,74

Heat-softening polymers have glass transitionemperatures (Tg) that range from 25°C to ap-roximately 40°C, and soften sufficiently inarm water to allow minor undercuts to be en-aged, which improves retention. Hard acrylicsuch as methyl or ethyl methacrylate have Tgalues that range from 65°C to over 100°C. A-point bending test (ASTM D790-92, standardest methods for flexural properties of unrein-orced and reinforced plastics and electrical in-

igure 11. Stabalizing bar in Klearway appliance.
Color version of figure is available online.)

sidtoAsstciPamaaci

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ulating materials) is used to assess material flex-bility. Bending experiments are performed inistilled water at different temperatures and,

ypically, the bending modulus drops by a factorf 2 for every 10°F rise in temperature (Fig 12).

typical heat-softening polymer used to con-truct dental splints and sleep appliances con-ists of a liquid/powder system. Water absorp-ion is more significant with heat softening thanonventional acrylics; consequently, heat-soften-ng polymers should be stored dry between uses.atients should be advised that heat softening,nd even hard acrylic, devices may need replace-ent after a period of 1 to 3 years, which may beconcern should insurance coverage not be

vailable. Current research is developing plasti-izer-free compositions that, in theory, shouldmprove their long-term durability.

ummary

ral appliances are a treatment option in theanagement of sleep apnea syndromes. Whileany patients experience a complete or partial

esolution of their symptoms, some do not im-

Figure 12. Comparision of heat-softening acrylics.

rove or may even become worse. It is thereforemperative that physicians conduct progressvaluations while the respective dental care pro-ider continues to make adjustments to optimizehe effectiveness of the chosen appliance.

Since the first nonadjustable, hard acrylic appli-nces were developed to treat OSA, a variety ofemovable devices have been designed to providemproved patient comfort and hence, hopefully,atient compliance. The trend has been towarddjustable devices, while the materials now beingsed to construct mandibular protrusion devices

nclude heat-softening acrylics and plastics withoft liners. It should be noted, however, that in aecent randomized trial, patients preferred a sin-le-piece Monobloc appliance to a continuouslydjustable Herbst constructed of the same hardcrylic composition. It is not always the case thatard acrylics are necessarily more uncomfortable

han heat-softening acrylics and plastics with softiners.

Future research will help to identify the typesf patients who are suitable for a specific kind ofSA treatment.

(Color version of figure is available online.)

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cknowledgmentshe author thanks The Academy of Dental Sleep Medicine,reat Lakes Orthodontics Ltd, and Space Maintainers Lab-ratory for providing photographs.

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