Patent Publication Number: US-2021162156-A1

Title: Oral appliance

Description:
FIELD 
     The present disclosure relates broadly to an oral appliance for use in the treatment of sleep disorder breathing (SDB). 
     DEFINITIONS 
     In the specification and claims the term “comprising” shall be understood to have a broad meaning similar to the term “including” and will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps. This definition also applies to variations on the term “comprising” such as “comprise” and “comprises”. 
     In the specification and claims, the term “sleep disorder breathing” (SBD) refers to any condition where there is an abnormal breathing pattern during sleep. In some cases this abnormality is as a result of an upper airway obstruction during sleep, including but not limited to include snoring, upper airway resistance syndrome (UARS), and obstructive sleep apnea-hypopnea (OSA). Abnormal breathing can also occur in the absence of any airway obstruction during sleep in which the patient stops breathing for a period of time, known as an apneic event. 
     BACKGROUND 
     Over the past two decades, the medical and dental profession has become more aware of breathing disorders and in particular sleep disorder breathing as a major contributor to a number of health problems. Previously it was considered that snoring was a manifestation of a sleeping habit but it is now known that this leads to more severe disorders like Obstructive Sleep Apnea (OSA). OSA has been associated with the causes of heart disease, strokes and all as chronic daytime tiredness and spontaneous sleeping. The various forms of severity of OSA, snoring, and other syndromes have been described under the definition Sleep Disorder Breathing (SDB). 
     SDB comprises a wide spectrum of sleep-related breathing abnormalities; those related to an increase in upper airway resistance include snoring, upper airway resistance syndrome (UARS), and obstructive sleep apnea-hypopnea (OSA). Many clinicians regard SDB as a spectrum of diseases. This concept suggests that a person who snores may be exhibiting the first manifestation of SDB and that snoring should not be viewed as normal. This concept has support from experimental studies showing increasing airway collapsibility during sleep with progression from normal, snoring, UARS, and OSA. 
     Snoring is one of the most common aspects of SDB. After sleep apnea syndrome was recognized, snoring began to be viewed as an important clinical symptom. Although it is by far the most common symptom of sleep apnea, not all patients who snore have sleep apnea. 
     Pathogenesis of OSA involves a combination of reduced upper airway size and altered upper airway muscle activity, which causes oral tissue to collapse, and hence a blockage to occur. When a person is awake, muscles hold the pharyngeal airway open. These muscles can relax when sleeping. Other factors which are thought to contribute to OSA include weight, tongue size, soft palate volume, a retrognathic mandible, an anteroposterior discrepancy between the maxilla and the mandible, and obesity. 
     Snoring and OSA are often associated as generally both are caused by blockage of the pharyngeal airway by, for example, excess tissue when various muscles of the body, including the tongue, relax. As the tongue relaxes, it moves posteriorly, blocking the pharyngeal airway. When the pharyngeal airway is blocked, exhaled air is forced through the airway with increased velocity thereby causing vibration of the tongue, tissue, or other obstruction, thereby creating noise. 
     Snoring is caused by the partial obstruction of breathing during sleep while OSA occurs when the tongue and soft palate collapse onto the back of the throat and completely block the pharyngeal airway, thereby stopping breathing during sleep and restricting the flow of essential oxygen. Thus, a correlation between snoring and OSA is generally recognized in the medical community. 
     Snoring is common in people who breathe through their mouth when asleep. Mouth breathing causes the mandible to drop and decreases the area of the pharyngeal airway. It also causes the tongue to be pushed back into the throat, thereby creating the obstruction associated with SDB. 
     The traditional medical treatment for OSA has been the Continuous Positive Air Pressure Appliance (CPAP). CPAP treatment uses a positive air pressure to blow air through the nose and into the upper airways so as to prevent upper airway collapse during sleep. The positive air pressure is generated by a pump and is applied through a small mask which fits over the nose, nasal pillows or a mask that fits over the nose and mouth. 
     When pressure is applied to the nose, the uvula and soft palette partially block off the mouth. Some air may escape through the mouth, but if the mouth is kept closed a seal can be obtained. Air leaking through the mouth is known as “mouth leak” and is uncomfortable for the user. Mouth leak leads to a large unidirectional flow of air through the nose and out through the mouth driven by the positive air pressure of the CPAP. In some people this can cause an increase in nasal mucosal blood flux, mucosal drying and rebound congestion. CPAP humidification can generally avoid these problems. 
     Full face (oronasal) masks may be used to assist with mouth leak. Alternatively chinstraps may be used to hold the mouth closed. Neither solution is conducive to a comfortable night&#39;s sleep. Also, the tighter the full face mask, the more the mandible is forced back into the airway as well as compromising the tongue position. This makes the SDB and OSA worse. The problem is well known with the treatment of OSA. 
     It is important that the CPAP masks provide a good seal against the face and are kept firmly in place by head straps. In practice, this is uncomfortable and often results in poor compliance. Some patients feel claustrophobic whilst wearing masks. For this reason nasal only masks are preferred, but suffer from either mouth leak or inefficiency if the patient has a nasal obstruction. 
     Many patients cannot tolerate CPAP when their nasal breathing is obstructed. This may be due to a number of factors including nasal or sinus structure abnormalities like a deviated septum, swollen turbinates and problems with the upper palate and nasal congestion. 
     CPAP can have undesirable side effects that also lead to non-compliance or intolerance. Such side effects include nasal irritation that can cause congestion and mucosal dryness. This can lead to patients unconsciously taking off the mask prematurely. Nasal irritation is exacerbated by mouth leak. 
     Poor adherence or compliance (30-60%) to CPAP is a recognized limiting factor in treating OSA, leaving patients at risk for co-morbid conditions and impaired quality of life. Compliance to CPAP therapy is defined as CPAP for at least 4 hours for 70% of nights. This definition alone has an inherent non-compliance factor built in, as it would be optimal for the CPAP treatment to be used for the entire sleeping period to limit apnea and hypopnea events. 
     In conclusion, the CPAP treatment that is now widely used has many inherent disadvantages, but is accepted as the best that can be done for the SDB patient. 
     Alternatives for patients who are non-compliant include the use of intra-oral appliances or Dental Sleep Appliances (DSA). 
     DSAs for alleviation of SDB symptoms are considered less effective than CPAP and not suitable for more severe cases. However, they are more convenient, easier to use and certainly more portable. The compliance factor has brought the attention of the medical profession to view DSA&#39;s as the primary treatment for SDB for moderate to more severe cases who have a compliance issue with the CPAP regime. 
     There are many types of DSAs and the designs vary considerably. The most common are the Mandibular Advancement Devices (MAD). The principle behind the MAD devices is that advancing the mandible in an anterior position relative to the maxilla during sleep opens the pharyngeal airway by indirectly urging the tongue forward to stimulate activity of the muscles in the tongue and thereby also increases the forward rigidity of the tongue. Since the tongue attaches to the posterior portion of the mandibular symphysis, advancing the mandible forward relative to the maxilla also pulls the tongue forward, thus preventing the tongue from obstructing the pharyngeal airway. MADs therefore function to move the mandible, and hence the tongue forward to open the oropharynx. Snoring is believed to decrease proportionally with the increase in airway size or diameter. 
     Other MAD devices are in two parts that are hinged that are adjustably connectable to allow for titration of the amount of advancement. Others are formed from a single piece of thermoplastic with a living hinge. A recognized advantage of the hinged devices is that they allow the mouth to open for unrestricted breathing. It is considered very important that breathing is not restricted for mouth breathers as the object of the prior art MAD devices is to increase the amount of airflow. 
     Other devices are known as tongue retaining devices that work by pulling the tongue forward so as to open the airway, with less or no mandibular advancement when compared with the MAD devices. It will be appreciated that by pulling the tongue forward, it is also not possible to mouth breath and/or many devices block the mouth completely. Such devices are uncomfortable and have poor compliance. Further they are completely unsuitable for patients with nasal obstruction, congestion or irritation. 
     However, these MAD devices pose potentially damaging effects. Most single piece devices fit over both the maxillary and mandibular teeth and are typically held nearly stationary, thereby restricting movement, causing discomfort, and potential permanent repositioning of the jaw. 
     The temporomandibular joint (TMJ) is the joint that connects the mandible to the skull. The mandibular condyle is received within the superior synovial cavity The TMJ is flexible, allowing the mandible to move smoothly up and down and side to side and enabling a person to talk, chew and yawn. Muscles attached to and surrounding the TMJ control the position and movement of the mandible. 
     Continued use of devices that restrict the natural lateral movements as well as anterior and posterior movement of the mandible can potentially aggravate the TMJ and the related facial musculature. 
     Still further, mandibular advancement will clearly place stress on the TMJ as the mandibular condyle is anteriorly displaced relative to its normal position. This can lead to TMJ disorder. TMJ disorder covers a group of conditions that cause pain and dysfunction in the jaw joint and the muscles that control jaw movement. 
     There are therefore serious concerns within the dental community of the medium to long term effects of devices that over advance the mandible. These effects can cause adverse changes in occlusion, damage teeth and potential damage to the TMJ&#39;s. However, it is thought that the high priority in correcting snoring, SDB and health issues from OSA would make the medical practitioner and patient consider this a side effect that needs to be accepted for the overall benefits. 
     Patients with existing TMJ disorders are generally cautioned against using a MAD as such use can exacerbate the condition. A healthy TMJ is a prerequisite for MAD use. MADs are based on orthodontic appliance principles which are designed to correct a class II malocclusion. In a class II malocclusion there is a misalignment between the teeth of the dental arches and the upper teeth are forward of the lower teeth in what is commonly known as an overbite. Orthodontic appliances for the treatment of class II malocclusions in pre-adolescents advance the mandible and stimulate and enhance mandibular growth. The appliances also place and equal and opposite retractive force on the maxilla and restrains growth of the maxilla. 
     It is generally believed that the greater level of mandibular advancement caused by a MAD, the better the treatment effective for SDB. Advancement of between 50% and 75% of maximum mandibular protrusions is recommended. Physiological protrusion lengths are typically between about 7 mm to about 12 mm. The American Academy of Dental Sleep Medicine (AADSM) has published a report on what features define an effective oral appliance for the treatment of OSA. One of the features defined is that the appliance should permit protrusive advancement over a range of at least 5 mm. It is considered desirable to be able to gradually advance the mandible with treatment so as to reduce pain and soreness and alleviate TMJ pain. 
     These recommendations have been based upon a number of factors and in particular pulse oximetry. Oximetry measures hemoglobin O 2  saturation. This measurement is based upon the generally held belief in the MAD art that simply physically opening up the airways and allowing more air to be breathed can treat SDB. 
     It may be appreciated that using an oral appliance designed for treating a class II malocclusion by advancing the mandible and retracting the maxilla would have the same effect on a person with normal occlusion. 
     It is the maxilla that determines the effective horizontal dimension of the pharynx and in particular the upper pharynx. Maxillary constriction has been reported to be associated with narrowing of the pharyngeal airway and may play a role in the etiology of OSA. Surgical maxillary expansion is an effective procedure for widening nasal cavities and decreasing nasal airway resistance which can lead to improvement in nasal breathing. 
     More recently, a modification to a conventional MAD was described in Australia Patents Numbers AU2012255625 and AU2015240431. The disclosed MAD&#39;s have a rigid U shaped body and an air inlet/outlet opening extending from the front of the U to allow for mouth breathing. The body has enclosed channels extending from the inlet at the front along the full length of the arms so as to in each arms that extend from the front to deliver inhaled air from the inlet to the posterior of the oral cavity in the vicinity of a junction between the hard and soft pallets. In this way, obstruction of the airway by the tongue or other soft tissue is bypassed. 
     The appliance has a lingual flange for engaging mandibular teeth for mandibular advancement. The appliance is considered to be particularly suitable for patients with nasal congestion or obstruction who are intolerant of CPAP. 
     WO2015/149127 describes a similar device in which the lingual flange is moveable by a screw device such that the degree of mandibular displacement can be titrated. 
     WO2017/020079 also describes a similar device to that above and further includes a removable tongue retainer for holding the tongue forward between the teeth. 
     WO2017/165918 further describes a device having air channels for delivering air to the posterior of the oral cavity. In this disclosure, the body is made in two parts connected via an adjustment mechanism so as to adjust the degree of mandibular displacement. 
     Each of the appliances described in the above patent documents must be custom made specifically for each individual. 3D scanning of the mouth of a user is described. The scanned information is then used to manufacture a customized device by additive manufacturing such as 3D printing of a metallic material such as titanium or stainless steel. Electron beam melting (EBM) is a technique that is specifically mentioned. This technique uses electron beams to build up metal powders layer by layer. The metal bodies are encased in a soft plastics material. 
     It is important that the enclosed channels that pass through the arms of the appliance are able to deliver a sufficient and uninterrupted flow of air to the posterior of the oral cavity. The rigid titanium body ensures that this occurs. The rigidity of the body also means that accurate scanning of a user&#39;s mouth must be made to ensure an accurate fit, comfort and compliance. 
     Conventional non-customized DSAs are injection molded from a flexible thermoplastics material such as ethylene vinyl acetate (EVA) that softens below 100° and is therefore self mouldable to a user&#39;s dentition. When moulding a user presses the teeth on the softened EVA. If air channels were in the arms of the body between the teeth there is a risk of distortion of the channels that may compromise uniformity of air flow. 
     It will be also appreciated that 3D scanning and custom manufacturing of the appliances by 3D printing of titanium as described above is time consuming and expensive. It follows that appliances manufactured thereby may be unavailable to many SDB sufferers. 
     SUMMARY 
     It has been appreciated that there is a desire for a less expensive appliance that may not need to be custom made and/or may provide the public with a useful choice. 
     The present disclosure therefore relates to an oral appliance for the treatment of sleep disorder breathing in a patient, the oral appliance comprising;
         a U shaped appliance body with a front section and two arms, the appliance body including an inner wall and an outer wall,   a web interconnecting the inner wall and the outer wall so as to define an upper dental arch receiving channel;   an air inlet opening for intake of air during inhalation;   an air outlet member configured in use to locate above the tongue with an air outlet for directing inhaled air between the tongue and the hard palette towards the posterior oral cavity; and   an air flow passageway between the air inlet opening and the air outlet member.       

     The oral appliance body is suitably manufactured from a soft and/or resilient material, suitably a thermoplastics material. 
     The oral appliance body, and in particular the arms suitably has a degree of compliance such that the oral appliance can be fitted to patient&#39;s with different size dental arches. 
     The thermoplastics material may soften at temperatures below 100° such that it is user mouldable. Such materials include ethylene vinyl acetate (EVA) that allows a user to soften the device in hot water and mould the device about the user&#39;s teeth as is well known with mouth guards. The oral apparatus may also have a core or frame from material that does not soften below 100° C. so as to provide structural support to the appliance. 
     Alternatively the oral appliance may be formed from a soft thermoplastics material that does not soften below 100° soft polymer but is soft and compliable at room temperature such as polyurethane or silicone. This may be compared to known oral appliances such as the MADs that are made from injection moulded ethylene vinyl acetate (EVA) or liquid silicon rubber (LSR). 
     Silicone is particularly suitable as it is pliable and does not require moulding to a user&#39;s teeth. This may improve comfort; allow the user some jaw movement that will also contribute to user comfort and thus compliance. 
     Suitably the oral appliance may be made by Slicone or other material by injection moulding. All the described appliances are injection moulded. EVA PU and LSR. So this needs to be technically a bit clearer. 
     The appliance body may be made in a number of different stock sizes so that a majority of the population can select an appliance that can be fitted over their upper arch with a reasonable fit. 
     The oral appliance has an air inlet opening and an air outlet. As will be described below, the disclosed oral appliance delivers air into the oral cavity with minimal interference from the tongue. For this reason, the terms inlet and outlet are used to describe the air flow direction when inhaling. The opposite flow direction occurs when exhaling. 
     The oral appliance is U shaped with an air inlet opening at the front so as to allow for mouth breathing. The air inlet may be any suitable shape or configuration. Suitably the air inlet has a cross sectional area for breathing that allows a patient to breathe fully through the mouth. This may be important for patients with nasal obstruction. The oral appliance also allows a person to partially breathe through the nose. 
     The air inlet opening may be formed in the front of the appliance body. 
     In another embodiment, the appliance comprises an air inlet member that extends forward of the front of the appliance body such that the air inlet opening is spaced from the body and the air inlet member forms part of the air flow passageway between the air inlet opening and the air outlet. 
     The air inlet member body may also define part of the air flow passageway. 
     Suitably the air inlet member is configured so as to allow a patient&#39;s lips to form a lip seal about the air inlet member. This prevents air from entering the oral cavity directly through the mouth rather than through the air inlet. In one aspect, the air inlet member has an elliptic cylindrical shape. 
     In another aspect, the air inlet member has an elliptic frustoconical shape with side walls that taper from the air inlet opening towards the appliance body. 
     The oral appliance has an air outlet member with a body that in use locates above the tongue and directs inhaled air between the tongue and the hard palette towards the posterior of the oral cavity and in particular the pharyngeal airway. 
     Suitably the air outlet member is configured that in use the air outlet delivers air at a location along a line extending between the anterior teeth and the molar region. 
     Suitably the air outlet member is configured to abut or be positioned close to the hard palette. Suitably the air outlet member has a degree of reliance such that it resiliently contacts or presses against the hard palette. This may assist in directing air flow above the tongue during inhalation so as to avoid obstruction thereby. It may also create a seal with the hard palette so as to prevent or minimise air passing above the air inlet member during exhalation to assist in directing air into the air outlet. 
     Suitably the air flow passageway between the air inlet and air outlet member includes a passageway part that is constricted with respect to the air outlet member. 
     Fluid flow through an abrupt constriction in a pipe results in a decrease in pressure of the fluid. Fluid flow also experiences a decrease in pressure when travelling through a bend in a pipe. Fluid pressure also drops when fluid flows through an abrupt expansion. 
     Whilst not wishing to be bound by theory, it is believed that the flow of air upon inhalation from the inlet member through the constricted part, bend in the constricted part and from the air outlet into the oral cavity experiences a decrease in pressure. This decrease in pressure results in a positive external pressure that may assist inhalation. 
     Suitably, the oral cross sectional flow area of the air inlet member before the constricted part may be between about 200 mm. to about 400 mm. 
     The cross sectional flow area of the constricted part may be between about 50 mm and about 100 mm. 
     Suitably, the oral appliance is configured to encourage the tongue into a forward position that corresponds to the natural resting position. When the tongue is in the natural resting position, the tip positions on the incisal papilla at the anterior part of the upper palate. With the tip of the tongue in this position, the dorsum of the tongue runs at the cervical third of the crowns and roots of the upper premolars. The base of the tongue goes downward at the molars, leading to insert at the hyoid bone. When the tip of the tongue is at its physiological position, its dorsum and base tend to reposition at their physiological positions as well, with the base descending at the molar area. 
     However, when mouth breathing, the tongue is in a lowered position to allow the patient to more easily breathe through the mouth. A disadvantage of this position is that the lowered tongue may partially block the airway. 
     The tip of the tongue is highly sensitive and haptically explores objects in the mouth and provides perception of size and shape of objects in the mouth. This is important for mastication and swallowing. The presence of the air outlet member in the oral cavity will generally evoke a spontaneous response for the tongue to find its way towards to touch and explore the air outlet member. 
     The arrangement of the air outlet member located above the tongue that directs air above the tongue allows the patient to inhale and exhale through the air inlet opening with the tongue in the elevated position. 
     The oral appliance may further comprise a lower dental arch receiving channel and the upper and lower dental arch receiving channels may be configured so that when the oral appliance is worn in the mouth, the patient&#39;s mandible is advanced. This further brings the tongue forward and may alleviate any obstruction of the pharyngeal airway. 
     Still further, the airflow generally bypasses saliva ducts such that mouth dryness is reduced or alleviated. 
     As discussed in the introductory section, there are a number of disadvantages with conventional MAD devices. It is generally believed that the further the mandibular advancement, the more effective is the MAD device. Generally mandibular advancement of between about 7 mm to about 12 mm is recommended. 
     On the other hand, in the present appliance, the tongue has already been voluntarily brought forward in view of the presence of the tongue such that less physical mandibular advancement may be required. For example, mandibular displacement of about 5 mm or less or between about 1 mm to about 3 mm may be sufficient. 
     It will be appreciated that this lesser degree of displacement, will provide less strain on the TMJ and less retractive action of the maxilla. 
     The web suitably thickens from the front of the web to a point towards the trailing ends of the arms. This tends to fill in the space between the teeth of the upper and lower jaw. This in some respects resembles an airfoil and thickens the web. This arrangement puts more pressure on the rear molars thereby relaxing and exercising the joints and muscles. 
     Suitably, the thickened portions of the web are compressible. Compression may be achieved by providing a section of softer or more compressible material. Suitably compression is achieved by providing one or more holes through the trailing ends of the arms of the web. 
     The combination of the airfoil shape and the ability to compress that part of the web between the rear molars can alleviate TMJ pain and other discomfort that is felt by users of conventional rigid devices. 
     Further still the ability to compress the web allows movement of the users jaws relative to each other, further alleviating discomfort. 
     The present disclosure also relates to a method of treating symptoms of SDB in a patient comprising the steps of;
         providing an oral appliance as disclosed in all aspects herein and causing the patient to wear the oral appliance whilst sleeping.       

     In one aspect, the SBD is snoring. 
     In another aspect, the SBD is OSA. 
     Suitably, the appliance is worn during sleep for a minimum of three hours, suitably four hours, suitably five hours or more. 
     In one embodiment of the method, the oral appliance is used in combination with a CPAP machine in which the CPAP machine is connected to the air inlet opening of the oral appliance for blowing air into the mouth. 
     This is different to conventional CPAP therapy in which air is blown into the nose. With the disclosed method, air can be introduced into the oral cavity. This allows patients with nasal congestion and/or obstruction who are incompatible with conventional CPAP to be able to use CPAP. 
     Further, the oral appliance is held in place by the teeth within the arch receiving channels and the seal is provided by the lips about either the air inlet member that forms part of the oral appliance that receives an air outlet adapter from the CPAP machine or an air outlet adapter from the CPAP machine receives the air outlet member of the oral appliance. 
     In this way, the use of conventional CPAP masks may be avoided. The oral appliance bypasses the nasal cavity and any obstruction therein. 
     Also disclosed herein is a combination comprising an oral appliance of any one of claims  1  to  14  and an adapter having an air inlet and an air outlet and an air passage between the air inlet and the air outlet, wherein the air outlet is configured for fluid communication with the air inlet opening of the appliance and the air inlet is configured for fluid communication with an air supply. 
     Further, as discussed above, the oral appliance locates the tongue in an elevated position bringing the mandible forward. Whilst not wishing to be bound by theory, it is believed that the combination of bringing the tongue and mandible forward may have a positive effect on the airway, thereby allowing CPAP to be applied with a lower pressure than would be required with a conventional CPAP interface. 
     CPAP pressure reduction may avoid or reduce undesirable side effects such as air in the stomach, stomach pain or gas. Still further, many patients find it difficult to exhale against the positive pressure of the CPAP. 
     Alternately the described device can also be used in conjunction with a nasal CPAP, therefore positively ventilating through the nose and mouth while simultaneously advancing the mandible and the tongue. This combination (trilevel) positive ventilation would also require far less PAP and therefor have less leakage, minimal need for tight straps and air via oral ventilation will have minimal restriction from the tongue. As opposed to most MAD appliances which require substantial mandibular advancement accompanied by the detrimental effects previously stated. 
     According to another aspect of the disclosure there is provided a method of treating symptoms of SDB in a patient comprising the steps of;
         providing an oral appliance as disclosed in all aspects herein, fluidly connecting the air inlet member to a CPAP machine and causing air from to flow from the CPAP machine into the patient&#39;s mouth through the air inlet member and causing the patient to wear the oral appliance whilst sleeping.       

    
    
     
       DESCRIPTION OF THE FIGURES 
         FIG. 1  is a top front perspective view of one aspect of an oral appliance as disclosed herein; 
         FIG. 2  is a rear top perspective view of the same oral appliance shown in  FIG. 1 ; 
         FIG. 3  is a front view of the oral appliance shown in  FIG. 1 ; 
         FIG. 4  is a rear view of the oral appliance shown in  FIG. 1 ; 
         FIG. 5  is a side view of the oral appliance shown in  FIG. 1 ; 
         FIG. 6  is a cross section of the appliance shown in  FIG. 1   
         FIG. 7  is a top plan view of the oral appliance shown in  FIG. 1 ; 
         FIG. 8  is a bottom plan view of the oral appliance shown in  FIG. 1 ; 
         FIG. 9  is a top plan view of an oral appliance of a further disclosed aspect; 
         FIG. 10  is a schematic top plan view of the oral appliance shown in  FIG. 1  and the relationship with the positions of the teeth of a patient&#39;s upper arch; 
         FIG. 11  is a schematic view of tongue position relative to the oral appliance of  FIG. 1 ; 
         FIG. 12  is a front perspective view of an oral appliance of a still further disclosed aspect; 
         FIG. 13  is a rear perspective view of the oral appliance as shown in  FIG. 12 ; 
         FIG. 14  is a front view of the oral appliance as shown in  FIG. 12 ; 
         FIG. 15  is a rear view of the oral appliance as shown in  FIG. 12 ; 
         FIG. 16  is a side view of the oral appliance as shown in  FIG. 12 ; 
         FIG. 17  is a cross section view of the oral appliance as shown in  FIG. 12 ; 
         FIG. 18  is a top view of the oral appliance as shown in  FIG. 12 ; 
         FIG. 19  is a bottom view of the oral appliance as shown in  FIG. 12 ; 
         FIG. 20  is a cross section of a still further oral appliance as disclosed herein; 
         FIG. 21  is a front perspective view of a CPAP adapter for use with the disclosed oral appliances; 
         FIG. 22  is a rear perspective view of the adapter shown in  FIG. 21 ; 
         FIG. 23  is right end view of the adapter shown in  FIG. 21 ; 
         FIG. 24  is a left end view of the adapter shown in  FIG. 21 ; 
         FIG. 25  is a side view of the adapter shown in  FIG. 21 ; 
         FIG. 26  is a cross section view of the adapter shown in  FIG. 21 ; 
         FIG. 27  is a top plan view of the adapter shown in  FIG. 21 ; 
         FIG. 28  is a front perspective view of the oral appliance as shown in  FIG. 12  with the adapter as shown in  FIG. 21  fitted thereto; 
         FIG. 29  is a side view of the oral appliance adapted combination as shown in  FIG. 28 ; 
         FIG. 30  is a cross section view of the oral appliance adapted combination as shown in  FIG. 28 ; 
         FIG. 31  is a front perspective view of another embodiment of an oral appliance as disclosed herein; 
         FIG. 32  is a side view of the oral appliance as shown in  FIG. 31 ; 
         FIG. 33  is a front perspective view of the oral appliance as shown in  FIG. 33  with a CPAP adapter fitted thereto and 
         FIG. 34  is a side view of the oral appliance as shown in  FIG. 33  with the adapted shown in cross section. 
     
    
    
     DETAILED DESCRIPTION 
     An oral appliance and methods in accordance with this disclosure may manifest itself in a variety of forms. It will be convenient to hereinafter describe several embodiments of the invention in detail with reference to the accompanying drawings. The purpose of providing this detailed description is to instruct persons having an interest in the subject matter of the invention how to carry the invention into practical effect. However it is to be clearly understood that the specific nature of this detailed description does not supersede the generality of the preceding broad disclosure. 
       FIGS. 1 to 8  show a first aspect of an oral appliance  10 . The appliance  10  may be made of medical grade silicone that is a rubber material that is flexible and comfortable in the mouth. The flexibility can also accommodate users of different oral dimensions. The flexibility still further allows some movement that not only can provide comfort but can accommodate movement of the TMJ so as to reduce strain on the joint. 
     The appliance may also be made from a dual moulded having a base member that does not substantially soften at temperatures below 100° C. and a layer of a thermoplastic material such as ethylene vinyl acetate (EVA) that is softenable below 100° C. over the base member. 
     The base member may be a polyolefin such as polyethylene (PE), polypropylene (PP) or blends thereof. One example of a suitable polyolefin blend is a PE/polyurethane (PU) blend. 
     The base member confers a suitable level of rigidity on the base member but does have some flexibility and this enables the appliance to accommodate arches of varying width. 
     It will be appreciated that the flexibility allows for better fit whilst the mouldable outer layer provides a degree of customisation. 
     The appliance  10  includes a U shaped appliance body for mounting over the upper arch of a user. The appliance body  10  has a front section  12  and two arms  14 ,  16 . 
     The appliance  10  includes an inner wall  18  that is positioned on a lingual side of the patient&#39;s upper arch and an outer wall  20  that is positioned on the buccal side thereof. 
     The outer wall  20  is U shaped with a front  20   f  and two arms  20   a.  The inner wall  18  is U shaped with a front  18   f  and two arms  18   a.    
     The appliance body  10  also includes a U shaped web  22  interconnecting the inner wall  18  and the outer wall  20 . When the appliance  10  is in the mouth of a user, the web  22  lies in the occlusal plane between the dentition of the upper and the lower arches in use. 
     The inner  18 , outer wall  20  and web  22  define upper  24  and lower  26  arch receiving channels within which respectively the upper arch and associated dentition and the lower arch and associated dentition can be received (most clearly seen in  FIG. 4 ). 
     The inner wall  18  includes an upper portion  28  which projects up from the web  22  and a lower portion  30  which projects down from the web  22 . Similarly the outer wall  20  comprises an upper portion  32  above the web  22  and a lower portion  34  below the web  22 . 
     The inner wall  18  has a lingual surface  36  and a channel surface  38 . 
     The outer wall  20  has a front buccal surface  40  that is dimensioned so that it substantially covers the buccal aspects of the upper and lower posterior teeth. 
     The oral appliance  10  includes an air inlet member  44  extending forwardly from the front buccal surface  40  of the outer wall  20 . The air inlet member  44  is may be any suitable shape or configuration and may be elliptical or ovoid in cross section and is located generally centrally on the buccal surface  40 . The air inlet member  44  has a curved upper wall  46  and a curved lower wall  48  and an elliptical inlet  50  (as can be seen in  FIG. 3 ). The inlet  50  is surrounded by a lip  52  (as seen in  FIG. 6 ). 
     In another aspect, the air inlet may be ovoid. The air inlet may also comprises a plurality of inlet aperatures. 
     The curvature of the upper and lower walls  46 ,  48  of the air inlet member  44  is designed for a user&#39;s lips to fit comfortably around so as to be able to form a lip-seal around the air inlet member  44 . This means that the only way that air can pass into the mouth is through the air inlet  50 . It will be appreciated that other shapes or configurations of the air inlet member may be suitable for the purpose. 
     As can be seen in the cross section in  FIG. 6 , the upper  46  and lower walls  48  define an air passage  54  that extends through the outer wall  20 . 
     The frontal portion of the inner wall  18   f  inclines rearwardly away from the outer wall  20  as it extends up from the web  22  at an angle of about 30 to 40 degrees. This matches the curvature of the lingual side of the maxillary teeth. 
     The lower portion of the inner wall  18  includes a tongue elevator  70  (shown in  FIGS. 2 and 4 ). The lower part  18   l  of the inner wall  18  has a lower terminal edge region that is thickened to form the tongue elevator  70 . The tongue elevator  70  forces the tongue to hold an upwards position that further assists in bringing the tongue forward so as to open the airway. 
     At substantially centrally in the upper part  28  of the inner wall  18  there is a rearward facing extended part that forms an air outlet member  56 . The air outlet member  56  has an outlet body  58 . The outlet body  58  has an upper wall  60  that is concave in the transverse direction and a lower wall  62  that is also concave in the transverse direction. 
     The outlet body  58  further comprises opposing side edges  64 ,  66  and a posteriorly facing elliptical air outlet  68 . As seen in  FIG. 7 , the side edges  64 ,  66  of the outlet body  58  diverge outwardly towards the air outlet  68 . The elliptical outlet  68  has an upper edge  69  that is convex in the transverse direction and a lower edge  72  that is convex in the transverse direction. The outlet body  58  is also arcuate about a radial centre along the longitudinal axis of the body. 
     The air outlet member  56  is configured such that in use the air outlet locates horizontally adjacent or close to the hard palate at a position between the molars, suitably in the region of the second premolar PM and first molar M as shown in  FIG. 10 . This places the air outlet  68  above the tongue about the middle part of the hard palate. 
     The curvature of the upper wall  60  of the air outlet body  58  substantially corresponds to that of a user&#39;s hard palate for comfort. 
     The air outlet member  56  has a degree of resilience such that it may comfortably press against the patient&#39;s palate so as to prevent or obstruct air from passing above the air outlet member  56  and the palate during exhalation so as to optimise air flowing into the air outlet  68 . 
     The air outlet  68  is configured to extend substantially across the width of the hard palate at that point. In this way air enters the oral cavity uniformly across the cavity. 
     An air flow passageway  71  is defined between the air inlet  50  and the air outlet  68 . The air flow passageway  71  has an inlet part  73  defined by the air inlet member and an outlet part  75  defined by the air outlet member body  58 . The oral appliance  10  includes a curved intermediate part of  74  of constant cross section. The part  74  has an inner facing part and an outer part. The inner part receives the tip of a user&#39;s tongue. The tongue is highly responsive to objects in the mouth and will haptically explore the air outlet member  56  and part  74 . This further brings the tongue forward. Further advantages of this tongue placement will be described below. 
     The diameter of the intermediate part  74  is constant and about 6 mm to 8 mm. The width of the air inlet is about 23 mm to 26 mm. 
     Fluid flow through an abrupt constriction in a pipe results in a decrease in pressure of the fluid. Fluid flow also experiences a decrease in pressure when travelling through a bend in a pipe. Fluid pressure also drops when fluid flows through an abrupt expansion. 
     Whilst not wishing to be bound by theory, it is believed that the flow of air upon inhalation from the inlet member through the constriction in intermediate part  74  and the bend therein. This decrease in pressure results in a positive external pressure that may assist inhalation. 
     As discussed above, the oral appliance  10  encourages the tongue forward adjacent the air outlet member  56 . This corresponds to the normal rest position nasal for breathing (subject to the thickness of the air outlet member). Under normal circumstances, such a tongue position would inhibit mouth breathing and the tongue would be forced into the lower position of a mouth breather in which the tip rests against the maxillary teeth. However, with the present appliance, air is delivered above the tongue at a position about half way along the hard palate and bypasses any such inhibition, whilst encouraging forward location of the tongue T. This is schematically shown in  FIG. 11 . 
     The air outlet member  56  is also flexible that allows the tongue to press up against it. A patient may be encouraged to do this so as to exercise and train the tongue to adopt the correct position, when the appliance is not being worn. 
     Whilst not wishing to be bound by theory it is believed that the positive pressure delivered to the mouth through the air outlet member  56  combined with shape and configuration of upper part of the air outlet member against the hard palette and further the activity of the tongue against the air outlet member  56  may assist in expansion of the maxilla. The lateral wall of each nasal cavity mainly consists of the maxilla. Thus expansion of the maxilla may increase the size of the nasal cavity, thereby reducing nasal obstruction. This in turn may over time alleviate at least partially the symptoms of OSA. 
       FIG. 9  shows an alternative oral appliance  110  in which the air inlet member  144  is tapered from the air inlet opening  150  towards the appliance  110 . 
     Further the upper and lower arch receiving channels are configured for mandibular advancement (see  FIG. 6 ). This physically brings the mandible and tongue forward and further opens the pharyngeal airway. 
       FIGS. 12 to 19  show an oral appliance  210  of another aspect of the disclosure. The same reference numbers will be used to define the same features. 
     The oral appliance  210  is substantially the same as the oral appliance of  FIG. 1  with the addition of three compressible channels  212  in the web  22  of each arm  14 ,  16 . The channels may be open or closed. The channels are compressible that further allows relative movement of the jaw so as to reduce strain on the TMJ. 
     The air outlet member body  256  and the air outlet  268  each have a different configuration that may best be seen by comparing the cross section views in  FIGS. 11 and 17 . 
     Air outlet member body  256  has an upper wall  260  and a lower wall  262  that are diverging rather than parallel. The air outlet member body  256  is also at an angle of about 30 to 45 degrees to the horizontal rather than parallel. The air outlet body  256  is shorter and extends back to the premolars. 
     The space S where the tip of the tongue sits is larger than that in  FIG. 11  that may facilitate further correct tongue placement. 
       FIG. 20  shows yet a further oral appliance  340  similar to that of  FIGS. 12 to 19  but having a singular air channel  350 . 
       FIGS. 21 to 26  show an adapter  300  that may be used to connect the oral appliance to an outlet tube of a CPAP machine. 
     The adapter  300  has cylindrical air inlet member  302  with an inlet  304 . The inlet member  302  is configured for fluid connection to a CPAP air outlet tube. The inlet member  302  may receive or be received by the CPAP tube. 
     The adapter  300  has an outlet member  306  of elliptical cross section that is configured for fluid connection to the air inlet member  44  of the oral appliances  10 ,  210 . The air inlet member  44  may receive or be received by the air outlet member  306 . 
     The inlet member  302  and outlet member  306  are separated by an elliptical flange  308  that in use acts as a stop against a patient&#39;s lips. 
       FIGS. 28 to 30  show the adapter  300  connected to the appliance  210 . It will be appreciated that such an arrangement may be more comfortable to a user than a nasal of full face mask. Seals against the face and chin straps are not required. 
     As can be seen in  FIG. 30  there is a sudden contraction C in the in-flow direction from the air inlet member  302  to the air outlet member  306 . Sudden contractions in pipes cause a marked drop in pressure due to an increase in velocity and loss of energy to turbulence. 
       FIGS. 31 and 32  show an oral appliance  410  of another aspect of the disclosure. The same reference numbers will be used to define the same features. 
     The oral appliance  410  is substantially the same as the oral appliance of  FIG. 1  with the addition of an upper tab  412  formed on the upper wall  46  of the air inlet  44 , and a lower tab  414  formed on the lower wall  48  of the air inlet  44 . 
       FIGS. 33 to 34  show an adapter  400  of another aspect connected to the appliance  410 . The same reference numbers will be used to define the same features. 
     The adapter  400  is substantially the same as the adapter of  FIGS. 21 to 26  with the addition of an upper groove  416  and a lower groove  418  formed on an internal surface of the outlet member  306 , positioned adjacent to the elliptical flange  308 . The upper recess  416  is configured to engage with the upper tab  412  of the oral appliance and the lower recess  428  is configured to engage with the lower tab  414  to thereby releasably secure the air inlet member  306  of the adapter  400  to the appliance  410 . The walls of the adapter are sufficiently resilient so as to provide for a snap fit engagement with the appliance  410 . 
     Mandibular advancement for a person having a normal bite will put some strain on the temporomandibular joints (TMJ). The flexibility of the silicone material or the material of a base member where the oral appliance is dual moulded allows some relative movement of the mandible that may at least partially alleviate such strain. However, this strain is significantly less than the art known MAD devices. Common side effects of art known MAD devices include TMJ discomfort or pain and myofascial pain. Long term advancement can cause TMJ damage and dysfunction. 
     The combination of forward tongue position and minimal mandibular advancement of the present appliances allows opening of the pharyngeal airway to extents comparable with known art MADs that significantly advance the mandible. Thus there is less strain on the TMJ with use of the present appliances than with art known MADs. This allows for more patient comfort which generally translates to higher patient compliance. This location of the tongue also reciprocates retrusive action of the maxilla. 
     The oral appliance may also be used in conjunction with a CPAP machine whereby the CPAP air tube is connected to the air outlet member. 
     It will be appreciated that the disclosed oral appliances do not require custom fabrication fitting by virtue of the flexibility of the thermoplastics material. The oral appliances may be easily manufactured by injection moulding at a fraction of the cost of custom made devices. Alternately, with the dual moulded ready-made device can be custom fitted with the above features. 
     The configuration of the air outlet member promotes voluntary forward positioning of the tongue that opens the airway. This may reduce the amount of mandibular advancement required. This in turn reduces stress on the TMJ. Stress on the TMJ is further reduced by the flexibility of the appliance. 
     It will be appreciated that various changes and modifications may be made to the appliances and methods as disclosed herein without departing from the spirit and scope thereof.