ROLE OF MANDIBULAR ADVANCEMENT APPLIANCES IN SLEEP APNOEA AND SLEEP-

RELATED BREATHING DISORDERS

Niraj kumar(Junior resident)Maxillofacial prosthodonticsAIIMS-NEW DELHI

Introduction

- Sleep apnoea is a sleep disorder characterized by - pauses in breathing , or - periods of shallow breathing during sleep. - Each pause can last for a few seconds to several minutes and

they happen many times a night.

- most common form - loud snoring. - choking or snorting sound as breathing resumes. - disrupts normal sleep - those affected are often sleepy or tired during the day. - affects 1-6% of adults and 2% of children. - M:F (2:1) - most commonly (55-60years)

Signs and symptoms

- excessive daytime sleepiness (EDS) and impaired alertness.

- executive functioning - the way the person plans and initiates tasks.

- paying attention, working effectively and processing information when in a waking state.

- using memory and learning.

Risk factorsSleep apnoea can affect people regardless of sex, race, or age.

- however, risk factors include: - being male - excessive weight - age above 40 - enlarged tonsils or tongue - small jaw bone - family history of sleep apnoea - deviated septum

- alcohol, sedatives and tranquilizers may also promote sleep apnoea by relaxing throat muscles.

- smokers have sleep apnoea- 3 times the rate of people who have never smoked.

Mechanism

When breathing is paused

carbon dioxide builds up in the bloodstream

chemoreceptors in blood note the high carbon dioxide levels.

brain signals to wake the person and start breathing normally

restores oxygen levels and the person falls asleep again.

Diagnosis

- sleep apnea may be diagnosed by the evaluation of symptoms, risk factors and observation, (excessive daytime sleepiness and fatigue) but the gold standard for diagnosis is a formal sleep study (polysomnography).

Polysomnography

Polysomnography (PSG), a type of multi-parametric test used in the study of sleep and as a diagnostic tool in sleep medicine.

-test result is called a polysomnogram.

The PSG monitors many body functions including: - brain (EEG), - eye movements (EOG), - muscle activity or skeletal muscle activation (EMG) and - heart rhythm (ECG) during sleep.

Apnoea-hypopnea index (AHI)

apnoea - complete cessation – airflow -10 sec.hypopnea - decrease airflow - 50% - 10 sec.- AHI is calculated by dividing the number of apnea

events by the number of hours of sleep. - values are categorized as:• Normal: 0-4• Mild sleep apnea : 5 - 14• Moderate sleep apnea: 15-29• Severe sleep apnea: 30 or more

PREFFERED GROUP FOR TREATMENT WITH

INTRAORAL APPLIANCES

Management

Surgical therapy

Non-surgical therapies

-tracheostomy

-nasal surgeries

-maxillofacial surgery

-base of tongue resection

-hyoid repsitioning

-pharyngeal surgeries

-eliminating aggravating factors

-stimulation of upper airway

-pharmacological therapies

-CPAP

-INTRA-ORAL APPLIANCES

-tongue retaining devices-mandibular advancement splints

- Before treating a snoring problem, dentists should require the patient to complete an Epworth Sleepiness Scale, or (ESS).

- questionnaire used to determine the likelihood of dozing off in a variety of common daily situations.

Epworth Sleepiness Scale (ESS)

- scores on the ESS can range from 0 to 30.

- subjects scoring 10 or higher on the scale are considered hypersomnolent

referred to an appropriate medical center.

Intra-oral appliances

-two appliance categories have been documented as being effective in this therapy:

a) tongue-retaining devices, which retain the tongue anteriorly by means of an extra oral suction bulb, and b) mandibular advancement devices (MADs) -which retain the mandible anteriorly by means of dental anchorage.

Extra oral suction bulb

Mandibular advancement devices (MADs)

- MADs are constructed in a manner and with material that secures the mandible in its optimum position.

- the optimum mandibular position needs to be captured and transferred to the articulator with an accurate construction bite.

- therefore, dentists must consider the efficacy

and the safety of an MAD when selecting an appliance.

- since occlusal shifting appears to be the main potential detrimental effect,

- dentists should consider all available means

to monitor and minimize these changes.

CONSTRUCTION BITE

- the position in which a nonadjustable MAD holdsthe mandible is determined by the construction bite.

- before selecting the parameters of the construction bite, the dentist must carefullyweigh the advantages and disadvantages ofeach

each degree of mandibular downwardrotation.

- millimeter of mandibular forwardtranslation

&

a) forward mandibular translation - provides

beneficial longitudinal and sagittal stretching of the pharyngeal airway;

- however, each millimeter of forward movement increases the forces applied against the teeth and in the TMJ.

- These forces may alter the occlusion by : - changing the angulation of the teeth, - remodeling the condyle and fossa, and - shortening the inferior lateral pterygoid muscle.

therefore; mandibular advancement of about 70 % of the protrusive path

- has been shown to be effective in reducing SDB symptoms with minimal occlusal changes.

b) downward mandibular rotation - provides beneficial longitudinal stretching, but also causes detrimental backward compression

of the pharyngeal airway.

- therefore ; 5 mm appears to be a good compromise, for vertical opening since that amount of opening would give :

- a sufficient vertical raise , - without any compression of the airway in the pharyngeal region.

- once the desired parameters for the construction bite are selected, they can be captured and transferred to an articulator with the use of a George Gauge.

Horizontal component

Verticalcomponent

- patient closing into preset incisal notches, registering the desired anteroposterior and vertical mandibular position in impression material on a bitefork.

- more than 55 different appliances are available to dentists and this number continues to increase.

-the purpose of each of these appliances is the same - - to keep the pharyngeal airway open wide enough to prevent breathing efforts from causing snoring, apnoea or arousal.

- the MADs vary in four major areas:

- freedom of mandibular movement, - amount and rigidity of dental coverage, - amount of mandibular advancement and - amount of bite opening

a) freedom of mandibular movement

- an MAD that allows the mandible to move several millimeters laterally or vertically is less likely to produce TMDs, and is tolerated more readily by bruxers.

- however ; there is no published scientific evidence that an MAD that immobilizes the mandible is more likely to cause TMD or that it is less tolerable to bruxers in the short or long term than one that allows the mandible some freedom of movement.

b) amount and rigidity of dental coverage :

- the MAD uses the teeth as anchorage against this force, pushing the mandibular arch forward and the maxillary arch backward.

- such forces over time may change the angulation of the teeth, especially the incisors. - the more teeth held, the less force against each tooth.

- all the teeth in both arches should be recruited into the anchorage. This is particularly important in patients with missing

teeth or reduced alveolar bone support.

- any malocclusion resulting from

wearing a thermoplastic MAD is more likely to be the result of the inclination of the teeth rather than of changes in the TMJ.

-such resultant malocclusion usually isreversible if treatment is discontinued.

c) amount of mandibular advancement : - there is no direct correlation between the

amount of mandibular advancement and the efficacy of an MAD.

- several adjustable MADs have become availablethat can advance and retain the mandible upto 14 to 19 mm (exceeding 100 % of the protrusive range).

- unfortunately, results of these devices have beenapproximately the same as those obtained with a MAD at

70 % protrusion.

d) amount of bite opening

- as the mouth opens, the anterior attachment of the tongue swings not only down but also backwards.

- this backward movement carries the tongue toward the airway.

- for this reason, it has been concluded that MADsshould keep jaw opening to an “absolute minimum”.

- 2mm between the incisors.

- another advantage of

increasing the jaw opening is that it helps part the lips allowing a passage for oral breathing.

- this is important because patients with SDB need assistance in breathing when the nasal airway is inadequate.

“How do MADs keep the airway open?”

- as the mandible moves forward, so does the

tongue, and thus the airway enlarges.

while this explanation is accurate, it is an oversimplification of the mechanism.

- MADs expand the airway not only behind the tongue but also behind the soft palate. -the mechanism for this - velopharyngeal expansion is the pull on the palatoglossus muscle. - this muscle runs down and forward from the palate to

the tongue.

- this pull by the palatglossus muscle advances

the palate and increases its tension, making it less likely to collapse or vibrate as in apnea or snoring.

- an MAD’s efficacy is based on more than a simple cause – and - effect relationship betweenadvancement of the mandible and tongue.

- magnetic resonance images indicate that the airways in patients who have SDB are constricted more laterally than anteroposteriorly.

-moreover , the narrowest part of the pharyngeal airway usually is not behind the tongue but behind the soft palate; it is in the latter area that obstruction is most likely to start.

ANTICIPATED RESULTS

- results in the treatment of SDB with an MADare not uniform.

- when using a properly constructed MAD, a practitioners should anticipate :

- 90- 95 % success in treating primary snoring and - about 60 % success in treating moderate to severe OSAHS

- success in snoring treatment may be

considered its elimination or reduction to a level tolerable by a partner.

- success in OSAHS treatment may be considered a 50% reduction in the number of sleep-related obstructive breathing events per hour, as well as a severity no greater than mild.

- most authors believe that MADs should be used primarily in treating :

- snoring , and - mild-to-moderate but not severe OSAHS.

- because they are closer to mild cases, moderate cases are more likely than severe cases to be successfully treated,

- but the percentage of improvement cannot be predicted by the severity of the SDB.

- results obtained with mandibular advancement device that held mandible rigid at about 70 % protrusion and 5 mm bite opening.

- note that treatment response cannot be predicted from initial severity.

SUMMARY

- although MADs have earned an important place in SDB therapy, the mechanisms by which they

achieve their results have not been completely understood .

- since the efficacy of the various commercially available MADs varies, dentists must subject the claims of their promoters to scientific questioning and reasoning.

- since MAD therapy may last a lifetime,

dentists should be concerned not only with MADs’ efficacy but with their safety,

--- as the major untowardside effect appears to be a change in the occlusion.

- dentists should consider all available means to monitor and minimize these changes.

- A.Johal et al-British dental journal (2005)-Department of Orthodontics, (The Royal London School of Medicine and Dentistry)

The effect of a mandibular advancement splint in subjects with sleep-related breathing disorders.

Introduction

The treatment objectives for patients with sleep-related breathingdisorders should be to alleviate snoring in simple snorers and to resolve the clinical signs and symptoms in patients withobstructive sleep apnoea with normalisation of the respiratory disturbance index and oxyhaemoglobin saturation.

- for obstructive sleep apnoea, no currently available treatment provides the ideal combination of high rate success and patient compliance without complications.

- The majority of studies on the efficacy of mandibular advancement splints are case reports or series although recent publications report on prospective controlled trials investigating the differences between MAS and other treatment modalities.

-the present study is a retrospective report on the effects ofmandibular advancement splints in two distinct subject groups, -non-apnoeic snorers and -subjects with obstructive sleep apnoea.

Objective

- to assess the effectiveness of a mandibular advancement splint (MAS) in subjects with sleep-related breathing disorders using both objective and subjective outcome measures.

MATERIALS AND METHODS - twenty subjects with obstructive sleep apnoea (OSA) and six with

non-apnoeic snoring, diagnosed by overnight polysomnography, were fitted with a monobloc appliance between May1997 and March 2000.

The mandibular advancement splint (MAS) -alginate impressions of the upper and lower dentition and an

interocclusal wax registration, recorded in a position of maximum comfortable mandibular protrusion were obtained.

-A removable monobloc design was used . This consisted of a one-piece hard acrylic splint incorporating full occlusal coverage and an opening anteriorly to allow for mouth breathing. Additional retention was obtained from Adam’s cribs on the upper and lower first premolars and the upper first molars.

-Patients were instructed to wear the appliance at night-time only.

The mandibular advancement splint

- the respiratory disturbance index was calculated for each patient.

-A baseline respiratory disturbance index (RDI) score of below five was used to distinguish non-apnoeic snorers from those with obstructive sleep apnoea.

- All of the 26 subjects completed an Epworth Sleepiness Scale prior to fitting the appliance and at the time of the repeat sleep study.

Outcome questionnaires

-a single operator attempted to contact all subjects by telephone to complete an outcome questionnaire following the repeat sleep study.

- the questionnaire was designed to assess - snoring; - sleepiness; - complications of MAS therapy; - the partner’s experience and - comparison to nasal-CPAP, if relevant.

RESULTS

-all categories of obstructive sleep apnoea (mild, moderate, severe) improved as a result of treatment, with an overall reduction in the numbers of subjects with OSA, from 20 to 13.

-thus, the numbers of subjects with non-apnoeic snoring increased from six to 13 as a result of intervention.

- no statistically significant change was observed in the

Epworth Sleepiness Scale scores in either subject group.

- However, subjects with obstructive sleep apnoea demonstrated a reduction in median respiratory disturbance index following mandibular advancement splint therapy.

DISCUSSION

- two of the most commonly used measures in assessing treatment outcomes in sleep-related breathing disorders are the Epworth sleepiness scale (ESS) and the respiratory disturbance index (RDI).

- despite their subjective nature, questionnaire outcome measures are also widely used.

- Polysomnography is regarded as the ‘gold standard’ for diagnosing obstructive sleep apnoea (OSA) and is recommended for the evaluation of treatment efficacy in moderate to severe OSA subjects treated with mandibular advancement splints.

- However, the technique is expensive and not readily available, requiring a special sleep laboratory and trained technical support.

CONCLUSION

- the monobloc appliance significantly improved the respiratory disturbance index in the obstructive sleep apnoea subjects.

-86 % of the subject’s partners reported better quality of sleep following mandibular advancement splint therapy.

-some subjects had increased respiratory disturbance index scores following splint therapy. This highlights the need for an objective assessment in the follow-up of patients treated with mandibular advancement splints.

-J. Lamont, D. R. Baldwin, K. D. Hay and A. G.Veale-School of Dentistry, University of Otago, Dunedin, New Zealand-European Journal of Orthodontics (1998)

Effect of two types of mandibular advancement splints on snoring and obstructive sleep apnoea

INTRODUCTION - Treatment options for obstructive sleep apnoea (OSA) are limited. - Mandibular advancement splints have been proposed as an alternative in patients who have simple snoring or mild OSA but data on effectiveness are conflicting . -This may be a result of differing splint designs and research methodology.

-the aim of this study was to measure the effect of two types of splints on

daytime sleepiness, snoring and domiciliary sleep in a sample of patients who might benefit from an alternative

treatment to a CPAP device, i.e. those with snoring alone or OSA with intolerance of the CPAP.

Subjects and methods

-twenty-four subjects (21 male, 3 female) - who had been fitted with one or other of two different types of

splints were enrolled consecutively. -All patients were snorers and seven were known to have OSA, but were unable to tolerate the CPAP device.

• Mandibular advancement splints (MAS) -both devices reposition the mandible forward and open the

vertical dimension of occlusion to a variable degree depending on individual anatomy.

- Type A - devices produced maximal mandibular protrusion, with a 3–4 mm inter-incisal opening depending on the patient’s overbite.

- Type B - permitted up to 70 % maximal protrusion, and an opening of 6–9

mm, depending on the overbite.

- They both contained a breathing slot anteriorly. The devices were made of transparent, soft acrylic resin which is physiologically harmless, insoluble in water, odour-free, and inactive

Statistics: -the Wilcoxon signed rank test, and Mann– Whitney U-tests were applied for paired and unpaired non-parametric data.

Results:

-twenty-three subjects aged 31–70 years completed the study. One female was unable to tolerate the MAS and was withdrawn from this study.

Apnoea/hypopnoea indices and ESS before and after use of the mandibular advancement splints

DISCUSSION - the efficacy of mandibular advancement splints in snoring and

OSA quoted in previous reports is variable . -it is likely that this is related to differences in splint design as

well as patient selection. -the present study showed that both splints produced

a reduction in daytime sleepiness and number of apnoeas. - type B was effective in reducing all measures of sleep apnoea,

including oxygen saturation and snoring.

-the differences in efficacy underlines the need for research into the most effective design.

Conclusions - the selection of patients in whom splints are the most

appropriate therapy has not yet been widely agreed. - However, in view of the marked improvement in symptoms for

patients with snoring alone shown by the present study and those of others, splints may be an appropriate non-invasive first line therapy for such cases.

- as the splints may not produce adequate improvement in AHI in

some patients, it is important that objective screening for OSA, possibly using oximetry or a more comprehensive sleep study, should also be employed.

- In patients with OSA, it is clear that with splint therapy both symptoms and the AHI may be reduced to acceptable levels in some patients, but further work is needed to evaluate long-term efficacy and patients need to be studied with a device in place.

- The present study confirms the findings of others

that mandibular advancement splints may be a useful alternative or adjunct to the use of the CPAP device in selected patients with snoring and mild OSA.

Efficacy of two mandibular advancement appliances in the management of snoring and mild moderate sleep apnea: A cross-over randomized study

- Luc Gauthier , Luc Laberge , Michel Beaudry , Mario Laforte - Faculty of Dental Medicine, University of Montreal. - Sleep Medicine 10 (2009)

Introduction -mandibular advancement appliances (MAA) are indicated in the

treatment of snoring and mild - moderate obstructive sleep apnea syndrome (OSAS) .

- although many studies have demonstrated that Continuous Positive Airway Pressure (CPAP) is recognized as the ‘‘gold standard.” -yet, MAA remain a valid alternative preferred by several

subjects . -surprisingly few studies have compared the efficiency of two MAA using

the : - apnea/hypopnea index (AHI) or - the respiratory disturbance index (RDI) or even - patient or sleep partner satisfaction as outcomes .

Also , most of these studies include a large range of severity, from very mild to highly severe OSAS subjects.

- the present study aimed to assess the efficacy and patient/sleep partner satisfaction with two MAA in subjects with mild-moderate RDI .

(apnea + hypopnea + respiratory effort-related arousal per hour of sleep, RERA).

- the null hypothesis is that the Klearway is equivalent to the Silencer for the management of OSAS patients.

- the alternative hypothesis is that one appliance is superior.

Material and methods

- in a prospective, single blind cross-over and randomized study comparing two MAA ;16 subjects were enrolled from the sleep disorders clinic of a hospital for a six-month period (three months for each MAA) and a follow- up interview.

- inclusion criteria included: - a history of snoring, the presence of natural teeth on both dental arches. - exclusion criteria were: - previous treatment for OSAS, caries, periodontal disease, jaw pain or mandibular movement limitations

- appliances: - the two commercially produced MAA used in the study were the Klearway and the Silencer . -both MAA offer an interincisal space of 9–12 mm.

- subjects wore each MAA for two consecutive 12-week periods .

-the bite was taken on average at - 6.5 mm for the Silencer and at - 8.5 mm for the Klearway, and the maximal advancement was on average - 10.5 mm for the Silencer and - 12.5 mm for the Klearway.

-the advancements were made by patients twice a week and verified by a dentist every four weeks.

Success criteria and statistical analysis

- Sleep apnea treatment success criteria used was the 50% RDI reduction.

- ANOVAs for repeated measures were used to evaluate

treatment effects. Paired comparisons were then used to assess differences between Klearway and Silencer.

- p value 60.05 was used to assess the significance level. Data

are presented as mean values ± standard error.

Results

Discussion

- the present study confirms that both the Klearway and Silencer are effective but similar in their capacity to reduce RDI in a population of subjects with mild-moderate OSAS, previously untreated with CPAP.

- Moreover, subjects’ sleep quality and quality of life were significantly improved. -The Silencer is made with an advancement mechanism that provides more oral space for the tongue compared to the Klearway, so it remains to be demonstrated whether the differences between efficacy of the appliances is related to tongue space.

-The clinical relevance of this effect needs to be reproduced.

Conclusion

- The present results confirm that both types of MAA are indicated in the management of mild-moderate OSAS.

- Since both MAA decreased RDI and subjective daytime sleepiness in a similar manner, the choice of an oral appliance needs to be weighted giving due consideration to :

- the benefit of RDI reduction (in favor of the Silencer) - over benefit of subject compliance (in favor of the

Klearway).

-The long term benefit of a better RDI reduction vs. a better patient compliance needs to be assessed in prospective studies.

Thank you