Lower jaw advancing device with adjusting part

Abstract

The present invention relates to a mandibular advancement device with an adjustment portion, comprising an upper tray assembly, a lower tray assembly and an adjustment portion, the upper tray assembly comprising an upper bracket and an upper moldable member; the lower tray assembly comprises a lower bracket and a lower moldable part; the upper tray assembly and / or the lower tray assembly are / is made of at least two different materials; the adjusting part is configured to connect the upper tray assembly and the lower tray assembly in a buckling manner and adjust the position of the lower tray assembly relative to the position of the upper tray assembly; specifically, the buckling mode is that at least one protrusion is arranged on one side of the upper tray assembly and / or one side of the lower tray assembly, and the protrusions are configured to be connected with the upper support and the lower support in an extrusion mode.

Description

TECHNICAL FIELD

[0001] The present invention relates to mandibular advancement devices, and in particular to a device for preventing, reducing or eliminating snoring and / or obstructive sleep apnoea. BACKGROUND

[0002] There is a strong link between snoring and sleep apnoea and obstructive sleep apnoea (OSA), as snoring is often a common symptom or precursor to OSA. OSA is a sleep disorder characterised by pauses or reductions in breathing during sleep due to partial or complete obstruction of the upper airway. This obstruction is usually caused by the soft tissues relaxing during sleep, the tongue base and soft palate collapsing, resulting in restricted airflow. Snoring is essentially the vibration of the obstructed airflow within the restricted space, producing the characteristic noise. This obstruction can be partial or complete obstruction of the airway. When the airway is completely obstructed, sleep apnoea occurs, resulting in brief pauses in breathing, which can cause the brain and body to become oxygen deprived and disrupt normal sleep cycles. While snoring and sleep apnoea can be considered as common phenomena to some extent, when it occurs with increased frequency or severity to the extent that it affects sleep quality and health, it needs to be taken seriously. In particular, in the case of OSA, this obstruction can occur dozens or even hundreds of times per night, triggering multiple apnoeas each night, severely disrupting sleep. This not only causes the user to be excessively drowsy and inattentive during the day, but also increases the risk of chronic diseases such as cardiovascular disease, diabetes, etc.

[0003] Obstructive sleep apnoea (OSA) is not to be underestimated in its severity, as it can have a wide and serious impact on the health and life of the user. OSA is a common but underestimated sleep disorder, which can range from mild to severe in severity. Increased risk of cardiovascular disease is one of the signs, as continuous airway obstruction can cause blood oxygen levels to drop, causing blood pressure to rise and the cardiovascular system to be overloaded, thus increasing the risk of cardiovascular disease. In addition, OSA is also closely related to metabolic diseases such as diabetes and obesity, which can lead to cognitive function decline, emotional and mental health problems, and increased risk of dangerous behaviour and accidents. In the face of the severity of OSA, treatment becomes particularly important.

[0004] Currently, there are several options for treating snoring, sleep apnea, or obstructive sleep apnea (OSA). Among them, continuous positive airway pressure (CPAP) therapy is one of the most commonly used methods, but it has the disadvantages of inconvenience, adaptability problems, mask air leakage, and sleep disturbance. Therefore, some users turn to oral appliances as an alternative method. Among them, the mandibular advancement device (MAD) is a common oral appliance. The device improves sleep quality and reduces or eliminates the symptoms of snoring and / or sleep apnea by adjusting the position of the lower jaw relative to the upper jaw to increase airflow in the throat passage.

[0005] The main limitation of the mandibular advancement device is that the manufacturing process requires a custom model based on the user's teeth or oral cavity. Given the uniqueness of each person's oral structure and tooth position, the custom model aims to ensure the fit of the mandibular advancement device with the user's teeth and oral cavity to provide optimal effectiveness and comfort. However, this custom process usually requires assembly, molding, or adjustment by dental professionals and manufacturing laboratories, which not only takes time and effort, but also costs a lot.

[0006] With the development of digital technology, other methods of customizing mandibular advancement devices have emerged, such as oral scanning technology combined with computer-aided design and manufacturing (CAD / CAM) or three-dimensional printing technology. Although these methods shorten the manufacturing time, they still require the involvement of dental professionals and manufacturing laboratories. In addition, although these methods may have reduced some costs, the overall cost is still high. SUMMARY

[0007] In view of the above limitations, the present invention provides a durable, easy-to-wear, and easy-to-use mandibular advancement device. The device can adapt to the user's tooth structure and reduce production costs. Secondly, the goal of the present invention is to provide a comfortable solution that effectively alleviates the symptoms of snoring and / or sleep apnea. Most importantly, the present invention provides a simple-to-use mandibular advancement device that can be easily used and worn even by ordinary non-technical users without relying on dental professionals and manufacturing laboratories for expensive and time-consuming custom processes, thereby reducing the user's usage costs.

[0008] A mandibular advancement device with an adjustment portion, comprising:

[0009] The upper tray assembly is arched in shape to conform to the user's upper jaw curve;

[0010] The lower tray assembly is arched in shape to conform to the user's lower jaw curve;

[0011] The upper tray assembly includes an upper bracket and an upper shapeable component;

[0012] The lower tray assembly comprises a lower bracket and a lower moldable component;

[0013] The upper tray assembly and / or the lower tray assembly are made of at least two different materials;

[0014] An adjusting part is configured to connect the upper tray assembly and the lower tray assembly in a snap form, and to adjust the position of the lower tray assembly relative to the position of the upper tray assembly;

[0015] The snap form is specifically that the upper tray assembly and / or the lower tray assembly has at least one protrusion on one side, which is configured to extrude and connect the upper bracket and the lower bracket.

[0016] In one embodiment, the upper tray assembly is configured to contact the upper dental arch of the user.

[0017] In one embodiment, the lower tray assembly is configured to contact the lower dental arch of the user.

[0018] In one embodiment, the upper moldable component is configured to soften after being heated, so as to be adjusted and molded into a shape matching the upper dental arch of the user when the user bites.

[0019] In one embodiment, the lower moldable component is configured to soften after being heated, so as to be adjusted and molded into a shape matching the lower dental arch of the user when the user bites.

[0020] The application also discloses a mandibular advancement device with an adjusting part, comprising:

[0021] The upper tray assembly comprises an upper bracket and an upper moldable component;

[0022] The lower tray assembly comprises a lower bracket and a lower moldable component;

[0023] The upper tray assembly and / or the lower tray assembly are made of at least two different materials;

[0024] An adjusting part is configured to connect the upper tray assembly and the lower tray assembly in a snap form, and to adjust the position of the lower tray assembly relative to the position of the upper tray assembly;

[0025] The snap form is specifically that the upper tray assembly and / or the lower tray assembly has at least one protrusion on one side, which is configured to extrude and connect the upper bracket and the lower bracket.

[0026] The upper bracket and the lower bracket have inner walls and outer walls, and the distance between the inner walls and the outer walls is at least a part of 0.3-8 mm.

[0027] In one embodiment, the protrusion is disposed on the outer wall surface of the upper bracket, and the protrusion receiving portion is disposed on the outer wall surface of the lower bracket and opposite to the protrusion.

[0028] In one embodiment, the protrusion is disposed on the outer wall surface of the lower bracket, and the protrusion receiving portion is disposed on the outer wall surface of the upper bracket and opposite to the protrusion.

[0029] In one embodiment, the upper and lower shapeable components are at least partially made of a flexible thermoplastic material.

[0030] In one embodiment, the upper and lower brackets are at least partially made of a relatively rigid material compared to the upper and lower shapeable components.

[0031] The present application also discloses a mandibular advancement device with an adjustment portion, comprising:

[0032] The upper tray assembly comprises an upper bracket and an upper shapeable component;

[0033] The lower tray assembly comprises a lower bracket and a lower shapeable component;

[0034] The upper tray assembly and / or the lower tray assembly are at least made of two different materials;

[0035] The adjustment portion is configured to connect the upper tray assembly and the lower tray assembly in a snap-in manner, and adjust the position of the lower tray assembly relative to the position of the upper tray assembly;

[0036] In one embodiment, the upper bracket and the lower bracket have inner walls, and the inner walls form an angle with the horizontal plane in the range of 20-150°.

[0037] In one embodiment, the sum of the weights of the upper bracket and the lower bracket is in the range of 3-50g.

[0038] In one embodiment, the weight of the mandibular advancement device as a whole is in the range of 8-80g.

[0039] In one embodiment, the snap-in structure of the adjustment portion is in the shape of I, F, E or symmetric E.

[0040] In one embodiment, the adjustment portion can adjust multiple gears.

[0041] The present application also discloses a mandibular advancement device with an adjustment portion, comprising:

[0042] The upper tray assembly comprises an upper bracket and an upper shapeable component;

[0043] The lower tray assembly comprises a lower bracket and a lower shapeable component;

[0044] The upper tray assembly and / or the lower tray assembly are made of at least two different materials;

[0045] An adjustment portion is configured to connect the upper tray assembly and the lower tray assembly in a snap form, and to adjust the position of the lower tray assembly relative to the position of the upper tray assembly;

[0046] The upper bracket and the lower bracket have an inner wall, an outer wall and a bottom wall;

[0047] The upper bracket and the lower bracket have one or more of the following properties:

[0048] The vertical distance between the inner wall, the outer wall and the bottom wall is 0.5-20mm;

[0049] The outer wall has a circumference ranging from 2-200mm;

[0050] The outer wall has an area ranging from 50-2000 square millimeters.

[0051] In one embodiment, the thickness of the bottom wall of the upper bracket and the lower bracket is 0.5-20mm.

[0052] In one embodiment, the upper tray assembly and / or the lower tray assembly comprise a passage column, and when the upper tray assembly and the lower tray assembly are combined, the gap between the upper and lower tray assemblies and the passage column collectively forms an airflow passage.

[0053] In one embodiment, the number of passage columns is odd.

[0054] In one embodiment, the number of airflow passages is even and symmetrical.

[0055] The lower jaw advancement device with an adjustment portion according to the present application has at least the following benefits:

[0056] 1) The mandibular advancement device usually needs to be finely adjusted in distance. Fine distance adjustment can effectively avoid the risk of over-adjustment, which may cause excessive advancement distance, causing pain and discomfort in the mandibular joint and oral cavity, and even causing problems such as temporomandibular joint disorder, oral ulcer, and other soft tissue contusion. Secondly, through fine adjustment, the mandibular advancement distance is gradually increased, and the user can more easily adapt to the device, making the wearing process more comfortable, thereby improving compliance and willingness to wear. In addition, fine distance adjustment gradually increases the mandibular advancement distance, which helps the user better adapt to the treatment process, ultimately improving the therapeutic effect of the device. There are other structures that can be finely adjusted on the market, but there are still many problems. For example, although the screw adjustment can be finely adjusted, the screw is prone to looseness due to the addition of an extra small part. Once it falls, it may enter the esophagus or even the airway from the oral cavity, posing a greater potential risk. There is another structure of an external connecting arm. If it is made of rigid material, it is easy to scratch the edge of the oral cavity; and if it is made of flexible material, it is prone to looseness and difficult to fix. The gear structure is similar to the buckle structure, but its composition is different. It usually needs to be pushed forward and backward to adjust the advancement distance, and the gear structure needs to be made of relatively rigid material to avoid looseness or wear. Commonly used is polycarbonate (PC) material. However, the mandibular advancement device usually needs to heat the plastic parts to shape the plastic parts, and PC material will produce bisphenol A when heated, thereby causing harm to the human body. In addition, the edges of the thinner gear are more difficult to align left and right, which may cause the left and right advancement distances to be inconsistent, thereby affecting the treatment effect. To solve these problems, the buckle structure of the present application is designed in the shape of I, F, E, and symmetric E. The special buckle design can not only ensure the wall thickness required in the production process, but also ensure the stability of the structure. Whether it is I-shaped, F-shaped, E-shaped, or symmetric E-shaped, they are a whole structure, which is fixed by buckling up and down, so it is easier to operate during jointing. The buckle structure of the present application provides a more reliable and flexible solution to meet the fine distance adjustment requirements of the mandibular advancement device and ensure the stability of the function of the mandibular advancement device, while also facilitating the operation and adjustment of the user.

[0057] 2) The present invention adopts a whole buckle structure, which allows multiple gear adjustment designs on the same bracket. This design allows users to adjust the forward distance of the lower tray assembly according to their individual circumstances, to select the most effective and comfortable position, thereby improving the compliance of the mandibular advancement device. Compared to using multiple different upper and lower bracket combinations, the present invention adopts I-shaped, F-shaped, E-shaped, and symmetric E-shaped buckle structures, which only require one pair of upper and lower brackets to achieve more precise and multi-gear forward distance adjustment. This design not only eliminates the need for multiple brackets, but also allows for more gear adjustment on the same bracket while ensuring the precision of the adjustment range. This innovation provides a more economical and simpler solution, greatly reducing cost and operational complexity.

[0058] 3) The existing mandibular advancement device on the market still has the problem of easy detachment. A large number of users have feedback that the mandibular advancement device often separates from the teeth during sleep, causing the device to fall off. After testing and analysis, it was found that this detachment problem is mainly due to the need for the lower tray assembly to move forward relative to the upper tray assembly, and the user may move or unconsciously open and close their mouth during sleep, which can cause the mandibular advancement device to easily fall off. Therefore, to solve this problem, the upper and lower tray assemblies need to have sufficient support force in the front and back positions to ensure that the device remains in place during use. In addition, there are certain angle differences between each tooth, which are not necessarily perpendicular to the horizontal plane. For example, the front teeth (central incisors and lateral incisors) usually have a certain lip inclination relative to the horizontal vertical plane, with an inclination angle of about 10-25°; the inclination angle of the canine teeth (lip side) is usually between 5-15°; and the inclination angle of the molar teeth (lip side) is usually between 0-5°. The front teeth and canine teeth have a larger angle relative to the horizontal vertical plane, and the molar teeth have a smaller angle relative to the horizontal vertical plane, which results in different support forces required by different teeth during occlusion. The existing mandibular advancement device usually sets the inner and outer walls of the bracket perpendicular to the bottom wall, which cannot conform to the natural shape of the teeth, causing discomfort and easy detachment when worn. Another common mandibular advancement device bracket is only composed of a bottom wall without inner and outer walls in the front and back positions, which does not have sufficient support force, making it easier for teeth to slip out of the mandibular advancement device. After multiple tests on users with various tooth shapes, the present invention provides an improved bracket design. The bracket has inner and outer walls to provide sufficient support force. In addition, the inner wall of the bracket forms a certain angle with the bottom wall to adapt to the natural angle of the lip inclination of the front teeth, thereby better fitting the shape of the teeth. Through this structural design, the mandibular advancement device of the present invention shows significant stability during experiments, reducing the likelihood of device detachment. At the same time, this design improves the comfort and effectiveness of wearing, solving the main problems of existing products. BRIEF DESCRIPTION OF DRAWINGS

[0059] Figure 1 Structure diagram of the mandibular advancement device in one embodiment of the present application;

[0060] Figure 2 Structure exploded diagram of the mandibular advancement device in one embodiment of the present application;

[0061] Figure 3 Schematic diagram of the horizontal plane, the sagittal plane and the coronal plane in multiple embodiments of the present application;

[0062] Figure 4 Top view of the combination of the upper support and the lower support in multiple embodiments of the present application;

[0063] Figure 5 Sectional view of the support in one embodiment of the present application in the direction of A-A; Figure 3

[0064] Figure 6 Schematic diagram of the position of the passage column of the mandibular advancement device in one embodiment of the present application;

[0065] Figure 7 Schematic diagram of the number of passage columns of the mandibular advancement device in one embodiment of the present application;

[0066] Figure 8 Separation diagram of the upper support and the lower support in one embodiment of the present application;

[0067] Figure 9 Sectional view of the support in one embodiment of the present application in the direction of B-B; Figure 3

[0068] Schematic diagram of the sectional shape of the adjustment part in one embodiment of the present application; Figure 10

[0069] Structure exploded diagram of the mandibular advancement device in one embodiment of the present application; Figure 11

[0070] Schematic diagram of the sectional shape of the adjustment part in one embodiment of the present application; Figure 12

[0071] Schematic diagram of the sectional shape of the adjustment part in one embodiment of the present application; Figure 13

[0072] Enlarged schematic diagram of the sectional shape of the adjustment part in one embodiment of the present application; Figure 14

[0073] Structure exploded diagram of the mandibular advancement device in one embodiment of the present application; Figure 15

[0074] ​​Figure 16 a cross-sectional view of the adjustment portion in the second embodiment of the present application;

[0075] Figure 17 a cross-sectional view of the adjustment portion in the second embodiment of the present application;

[0076] Figure 18 a cross-sectional view of the adjustment portion in the second embodiment of the present application. DETAILED DESCRIPTION

[0077] In order to make the above objectives, features and advantages of the present application more clear and comprehensible, the specific embodiments of the present application will be described in detail below with reference to the accompanying drawings. In the following description, a large number of specific details are set forth in order to provide a thorough understanding of the present application. However, the present application can be implemented in many other different ways than those described herein, and those skilled in the art can make similar improvements without departing from the scope of the present application, so the present application is not limited to the specific embodiments disclosed below.

[0078] The present application provides a mandibular advancement device 1 with an adjustment portion 4, comprising an upper tray assembly 2, a lower tray assembly 3 and the adjustment portion 4. The upper tray assembly 2 and the lower tray assembly 3 are arched in shape to conform to the user's dentition curve. The upper tray assembly 2 is used to contact the user's upper dentition; the lower tray assembly 3 is used to contact the user's lower dentition.

[0079] The upper tray assembly 2 and / or the lower tray assembly 3 are made of at least two different materials. The materials of the upper tray assembly 2 and the lower tray assembly 3 have a wide range of choices, and plastic or polymer materials suitable for oral medical devices and can be molded can be used. These materials include but are not limited to polypropylene (PP), polycarbonate (PC), polyethylene terephthalate (PET), polymethyl acrylate (PMMA), polyphenyl sulfone (PPSU), polyethylene (PE), high-density polyethylene (HDPE), low-density polyethylene (LDPE), ethylene-vinyl acetate copolymer (EVA), thermoplastic polyurethane (TPU), styrene-ethylene-butylene-styrene (SEBS), styrene-ethylene-styrene (SEPS), silicone rubber, etc. Each component of the upper tray assembly 2 and the lower tray assembly 3 can be made of a single material or a combination of multiple materials. This multi-material combination design can take full advantage of the characteristics of different materials to meet the various needs of the mandibular advancement device 1 during use. The polymer material can contain various fillers, plasticizers, stabilizers, pigments and other additives to meet different performance requirements and manufacturing needs. For example, nanoscale fillers can be added to enhance the strength and hardness of the material, or antibacterial agents can be added to improve the hygiene performance of the oral appliance.

[0080] In particular, please refer to Figures 1 to 4The upper tray assembly 2 comprises an upper bracket 21 and an upper moldable component 22. The upper moldable component 22 is made of a flexible thermoplastic material which can be softened after being heated, so as to be adjusted and molded into a shape matching the upper dental arch of the user when the user bites. The upper bracket is made of a relatively rigid material at least in part compared to the upper moldable component. The lower tray assembly 3 comprises a lower bracket 31 and a lower moldable component 32. The lower moldable component 32 is made of a flexible thermoplastic material which can be softened after being heated, so as to be adjusted and molded into a shape matching the lower dental arch of the user when the user bites. The lower bracket is made of a relatively rigid material at least in part compared to the lower moldable component. In the present application, the tray assembly 2, 3 comprises the upper tray assembly 2 and the lower tray assembly 3, the bracket 21, 31 comprises the upper bracket 21 and the lower bracket 31, and the moldable component 22, 32 comprises the upper moldable component 22 and the lower moldable component 32.

[0081] The present application allows the use of a simple heating method for the adaptability adjustment of the mandibular advancement device 1, preferably in the form of "boiled bite", the user only needs to heat the mandibular advancement device 1 in hot water, and then lightly bite the mandibular advancement device 1 with the mouth, so that it forms a good fit with the user's teeth.

[0082] The moldable components 31, 32 are softened after being heated, and the user can more easily adjust and adapt when wearing the mandibular advancement device 1 for the first time. This simple heating method allows the user to conveniently adjust the adaptability without professional technical knowledge, thereby improving the comfort and wearing experience of the user.

[0083] The brackets 21, 31 are made of a relatively rigid material to ensure the stability and support of the overall structure of the mandibular advancement device 1, while the moldable components 22, 32 are made of a thermoplastic material to provide comfort and plasticity. To ensure the stability of the mandibular advancement device 1 during use, the heat deformation temperature of the bracket 21, 31 material is higher than that of the moldable component 22, 32, so as not to affect the structure of the bracket 21, 31 during heating. The selection of such material combination aims to improve the balance stability and comfort, and ensure proper adjustment in accordance with the dental arch during use.

[0084] To further increase the comfort of the user wearing the mandibular advancement device 1, the mandibular advancement device 1 in the present embodiment is made of lightweight materials. As shown in Figure 5 The brackets 21, 31 have inner walls 211, 311, outer walls 212, 312 and bottom walls 213, 313, the overall weight of the bracket is in the range of 3-50g, the overall weight of the mandibular advancement device 1 is in the range of 8-80g, and the distance between the inner wall 211, 311 and the outer wall 212, 312 is at least a part of 0.3-8mm, i.e. Figure 5w1, the thickness of the bottom wall 213, 313 is 0.5-20mm, i.e. Figure 5 w2. Among them, preferably, the distance between the inner wall 211, 311 and the outer wall 212, 312 is 1-1.6mm, and the thickness of the bottom wall 213, 313 is 1-2mm. Through this design, both the required support force and rigidity of the mandibular advancement device 1 can be ensured, and the bracket 21, 31 is not too thick and heavy, thereby reducing the weight of the mandibular advancement device 1, reducing the burden on the oral cavity, and improving comfort.

[0085] The mandibular advancement device 1 on the market still has the problem of easy falling off. A large number of users have feedback that during sleep, the mandibular advancement device 1 often separates from the teeth, resulting in the device falling off. After testing and analysis, it is found that this falling off problem is mainly due to the need for the lower tray assembly 3 to move forward relative to the upper tray assembly 2, and the user may move or unconsciously open and close the mouth during sleep, which may cause the mandibular advancement device 1 to easily fall off. Therefore, in order to solve this problem, the upper and lower tray assemblies 2, 3 need to have sufficient support force in the front and back positions to ensure that the device can be stably maintained in place during use. In addition, there is a certain angle difference between each tooth, which is not necessarily perpendicular to the horizontal plane. For example, the front teeth (central incisors and lateral incisors) usually have a certain lip inclination relative to the horizontal vertical plane, and the inclination angle is about 10-25°; the inclination angle of the canine teeth (lip side direction) is usually between 5-15°; and the inclination angle of the molar teeth (lip side direction) is usually between 0-5°. The angles of the front teeth and canine teeth relative to the horizontal vertical plane are larger, and the angle of the molar teeth relative to the horizontal vertical plane is smaller, which causes the required support force of different teeth to be different during occlusion. The existing mandibular advancement device usually sets the inner and outer walls of the bracket to be perpendicular to the bottom wall. This design cannot conform to the natural shape of the teeth, resulting in discomfort and easy falling off when worn. Another common mandibular advancement device bracket is only composed of a bottom wall, without inner and outer walls in the front and back positions. This design does not have sufficient support force, making it easier for teeth to slide out of the mandibular advancement device. After multiple tests on users with various tooth shapes, the present application provides an improved bracket design, as shown in Figure 5 The bracket 21, 31 has an inner wall 211, 311 and an outer wall 212, 312 to provide sufficient support force. Among them, the vertical distance between the inner wall 211, 311, the outer wall 212, 312 and the bottom wall 213, 313 is 0.5-20mm, i.e. Figure 5h1, the circumference of the outer wall 212, 312 ranges from 2-200mm, and the area of the outer wall 212, 312 ranges from 50-2000mm2. In addition, the angle between the inner wall 211, 311 of the bracket and the horizontal plane (towards the same outer wall 212, 312, such as the direction of the inner wall 211 towards the outer wall 312) ranges from 20-150°, that is Figure 5 the angle α, to adapt to the natural angle of the anterior teeth tilting towards the lip, so as to better fit the shape of the teeth. Preferably, the angle between the inner wall 211, 311 of the bracket and the horizontal plane ranges from 45-90°. Through this structural design, the mandibular advancement device 1 of the present application shows remarkable stability in the experimental process, reducing the possibility of device falling off. At the same time, this design improves the comfort and effectiveness of wearing, solving the main problems of existing products.

[0086] The upper tray assembly 2 and / or the lower tray assembly 3 comprises a passage column 5. As shown in Figure 6 , Figure 7 In the present application, the passage columns 5 located at the same position all belong to the same passage column 5. The passage columns 5 can be all arranged on the upper tray assembly 2, or all arranged on the lower tray assembly 3, or part on the upper tray assembly 2 and part on the lower tray assembly 3. When the upper tray assembly 2 and the lower tray assembly 3 are combined, the tray assemblies 2, 3 and the passage columns 5 together form an airflow passage 6, the height of the passage column 5 is between 0.5-25mm, and the area of the airflow passage 6 is between 2-500mm2. Therefore, when the user wears the mandibular advancement device 1, the device will not be completely closed, and the external airflow can enter the user's oral cavity from the airflow passage 6, without limiting the free flow of airflow in the user's oral cavity. At the same time, it also meets the use needs of users who are used to breathing through the mouth during sleep, avoiding the risk of suffocation.

[0087] Further, the number of passage columns 5 is odd, to ensure that the center of the mandibular advancement device 1 (i.e. the position of the user's anterior teeth) is always provided with a passage column 5, and the passage columns 5 are separated by airflow passages 6 on both sides, so the number of airflow passages 6 is even and the structure is symmetrical. When the upper and lower teeth are occluded, the anterior teeth, being longer, are usually the first to contact each other, so they will bear more pressure. By arranging the passage column 5 in the center of the mandibular advancement device 1, it is more conducive to the stability of the mandibular advancement device 1. In addition, the symmetrical structure of the airflow passage 6 is conducive to the stability of the airflow passing through, further improving the safety and stability of the mandibular advancement device 1.

[0088] The adjustment part 4 is configured to connect the upper tray assembly 2 and the lower tray assembly 3 in the form of buckling, and adjust the position of the lower tray assembly 3 relative to the position of the upper tray assembly 2. Wherein, as shown in Figure 8 , Figure 9As shown, the snap-fit ​​mechanism specifically includes at least one protrusion 41 on one side of the upper tray assembly 2 and / or the lower tray assembly 3, the protrusion 41 being configured to press-fit the upper support 21 and the lower support 31 together. The adjustment part 4 includes the protrusion 41 and the protrusion receiving part 42, and can be adjusted to multiple positions.

[0089] Specifically, such as Figure 10 As shown, the adjustment part 4, namely the protrusion 41 and the protrusion receiving part 42, adopts an I-shape, F-shape, E-shape, or symmetrical E-shape design. The mandibular advancement device 1 typically requires fine-tuning of the distance. Fine-tuning effectively avoids the risk of over-adjustment, which may lead to excessive advancement distance, causing soreness and discomfort in the temporomandibular joint and oral cavity, and may even trigger temporomandibular joint disorder, oral ulcers, and other soft tissue contusions. Secondly, by finely adjusting and gradually increasing the mandibular advancement distance, users can more easily adapt to the device, making the wearing process more comfortable, thereby improving compliance and willingness to wear it. Furthermore, fine-tuning the distance allows for a gradual increase in the mandibular advancement distance, helping users better adapt to the treatment process and ultimately improving the therapeutic effect of the device. Other finely adjustable structures exist on the market, but they still have many problems. For example, while bolt adjustment allows for fine-tuning, the added small parts make the bolt prone to loosening. If it falls out, it may enter the esophagus or even the airway from the mouth, posing a significant potential danger. Furthermore, bolts made of flexible materials are difficult to secure and prone to loosening; while those made of rigid materials can easily scratch the inside of the mouth if exposed. Similarly, another type of external connecting arm structure, if made of rigid materials, can easily scratch the inside of the mouth; while if made of flexible materials, it is prone to loosening and difficult to secure. The gear structure resembles a snap-fit ​​structure, but its composition differs. It typically requires force to push back and forth to adjust the forward movement distance, and gear structures usually need to be made of relatively rigid materials to prevent loosening or wear; polycarbonate (PC) is commonly used. However, the mandibular advancement device 1 usually requires heating to shape the malleable parts, and PC material produces bisphenol A (BPA) when heated, which can be harmful to the human body. In addition, the thinner gear edges are difficult to align left and right, which may lead to inconsistent left and right forward movement distances, thus affecting the treatment effect. To solve these problems, this invention employs specially designed snap-fit ​​structures such as I-shaped, F-shaped, E-shaped, and symmetrical E-shaped snap-fit ​​structures. These special snap-fit ​​designs ensure both the required wall thickness during manufacturing and the stability of the structure. Whether it's an I-shape, F-shape, E-shape, or symmetrical E-shape, they are all integral structures, fixed by interlocking at the top and bottom, making them easier to operate compared to the gear structure's method of adjusting distance by moving back and forth. The snap-fit ​​structure of this invention provides a more reliable and flexible solution, meeting the precise distance adjustment requirements of the mandibular advancement device and ensuring the stability of the mandibular advancement device 1's function, while also facilitating user operation and adjustment.

[0090] The present application adopts a whole buckle structure, so that the same bracket 21, 31 realizes multi-gear adjustment design. This design allows users to adjust the distance of the lower tray assembly 3 forward according to personal conditions, to select the most effective and comfortable position, thereby improving the compliance of the lower jaw advancement device 1. Compared with using multiple different upper and lower bracket combinations, the present application adopts I-shaped, F-shaped, E-shaped, symmetric E-shaped and other specially designed buckle structures, which only need a pair of upper and lower brackets 21, 31 to realize more precise and multi-gear forward distance adjustment. This design not only does not need multiple brackets, but also realizes more gear adjustment on the same bracket 21, 31, while ensuring the precision of the adjustment range. This innovation provides a more economical and more convenient solution, greatly reducing the cost and operation complexity.

[0091] The following describes several structures of the lower jaw advancement device 1 with the adjustment part 4 according to specific examples.

[0092] Example 1

[0093] The lower jaw advancement device 1 of the present embodiment includes an upper tray assembly 2, a lower tray assembly 3 and an adjustment part 4. The upper tray assembly 2 and the lower tray assembly 3 are arc-shaped to conform to the user's dentition curve. The upper tray assembly 2 includes an upper bracket 21 and an upper shapeable part 22, and the lower tray assembly 3 includes a lower bracket 31 and a lower shapeable part 32. The adjustment part 4 is configured to connect the upper tray assembly 2 and the lower tray assembly 3 in the form of a buckle, and adjust the position of the lower tray assembly 3 relative to the position of the upper tray assembly 2. The buckle form is that at least one protrusion 41 is provided on one side of the upper tray assembly 2 and / or the lower tray assembly 3, and the protrusion 41 is configured to extrude and connect the upper bracket 21 and the lower bracket 31. The adjustment part 4 includes the protrusion 41 and a protrusion receiving portion 42. In the present embodiment, the tray assembly 2, 3 includes the upper tray assembly 2 and the lower tray assembly 3, the bracket 21, 31 includes the upper bracket 21 and the lower bracket 31, and the shapeable part 22, 32 includes the upper shapeable part 22 and the lower shapeable part 32.

[0094] As shown in Figure 11 , the bracket 21, 31 has an inner wall 211, 311 and an outer wall 212, 312. The protrusion 41 is provided on the surface of the outer wall 212 of the upper bracket 21, and the protrusion receiving portion 42 is provided on the surface of the outer wall 312 of the lower bracket 31 and opposite to the protrusion 41.

[0095] In the present embodiment, the forward distance of each gear movement is set to 2mm, not only to achieve more stable fixing effect, but also to ensure that the protrusion 41 and the protrusion receiving portion 42 are easy to produce and not easy to break, and the protrusion 41 is set to symmetric E-shaped. As shown in Figure 12The overall width of the protrusion 41 is 5mm, the overall length is 5mm, and the length of the protruding edge of each E is 1mm, i.e. Figure 12 d1, and the length of the groove edge is 1mm, i.e. Figure 12 d2. When moving one gear each time, the forward movement distance is 2mm, i.e. d1+d2. Similarly, the protrusion receiving portion 42 corresponds to the protrusion 41 and has a symmetric E-shaped slot, the length of the protruding edge of each E is Figure 12 d3, and the length of the groove edge is Figure 12 d4. Figure 14 d1 of the protrusion 41 corresponds to d3 of the protrusion receiving portion 42, and d2 of the protrusion 41 corresponds to d4 of the protrusion receiving portion 42. In order to better fix and assemble, the ratio of d3 to d1 is 1-1.2, and the ratio of d4 to d2 is 1-1.2. In addition, after the protrusion 41 is connected with the protrusion receiving portion 42, the height of the overlapping part of the protrusion 41 and the protrusion receiving portion 42 is 0.5-20mm, i.e. Figure 14 h2. If the overlapping part is too small, the protrusion 41 and the protrusion receiving portion 42 are easy to separate by themselves; if the overlapping part is too large, the protrusion 41 and the protrusion receiving portion 42 need to move up and down a larger distance to separate, which is not convenient to operate. Therefore, it is preferred that the height of the overlapping part of the protrusion 41 and the protrusion receiving portion 42 is 3mm.

[0096] In other embodiments, the protrusion 41 and the protrusion receiving portion 42 use materials such as metal with thin wall thickness and stable connection, and the forward movement distance when moving one gear each time can be set to be less than 2mm, so as to achieve smaller and more precise distance adjustment. For example, the protrusion 41 is set to be E-shaped, as shown in Figure 13 the length of the protruding edge of each E in the protrusion 41 is 0.5mm, i.e. Figure 13 d1, and the length of the groove edge is 0.5mm, i.e. Figure 13 d2. When moving one gear each time, the forward movement distance is 1mm, i.e. d1+d2. Similarly, the protrusion receiving portion 42 corresponds to the protrusion 41 and has an E-shaped slot, the length of the protruding edge of each E is Figure 13 d3, and the length of the groove edge is Figure 13 d4.

[0097] Embodiment 2

[0098] The mandibular advancement device 1 of the embodiment comprises an upper tray assembly 2, a lower tray assembly 3 and an adjustment part 4. The upper tray assembly 2 and the lower tray assembly 3 are arched to conform to the curve of the user's dentition. The upper tray assembly 2 comprises an upper support 21 and an upper shapeable part 22, and the lower tray assembly 3 comprises a lower support 31 and a lower shapeable part 32. The adjustment part 4 is configured to connect the upper tray assembly 2 and the lower tray assembly 3 in the form of a buckle, and to adjust the position of the lower tray assembly 3 relative to the position of the upper tray assembly 2. The buckle form is that at least one protrusion 41 is provided on one side of the upper tray assembly 2 and / or the lower tray assembly 3, and the protrusion 41 is configured to extrude and connect the upper support 21 and the lower support 31. The adjustment part 4 comprises the protrusion 41 and a protrusion receiving part 42. In the embodiment, the tray assembly 2, 3 comprises the upper tray assembly 2 and the lower tray assembly 3, the support 21, 31 comprises the upper support 21 and the lower support 31, and the shapeable part 22, 32 comprises the upper shapeable part 22 and the lower shapeable part 32.

[0099] The difference between the embodiment and the embodiment 1 is that the protrusion 41 and the protrusion receiving part 42 of the adjustment part 4 are reversely arranged. As shown in the figure, the supports 21, 31 have inner walls 211, 311 and outer walls 212, 312. The protrusion 41 is arranged on the surface of the outer wall 312 of the lower support 31, and the protrusion receiving part 42 is arranged on the surface of the outer wall 212 of the upper support 21 and opposite to the protrusion 41. Figure 15

[0100] In the embodiment, the advancement distance of each gear is set to 2mm, not only to achieve more stable fixing effect, but also to ensure that the protrusion 41 and the protrusion receiving part 42 are easy to produce and not easy to break, and the protrusion 41 is arranged in a symmetrical E shape. As shown in the figure, the overall width of the protrusion 41 is 5mm, the overall length is 5mm, the length of each E protruding edge is 1mm, i.e. d1 in the figure, and the length of the groove edge is 1mm, i.e. d2 in the figure. The advancement distance of each gear is 2mm, i.e. d1+d2. Figure 16 Figure 16 Figure 16 Similarly, the protrusion receiving part 42 corresponds to the protrusion 41 and has a symmetrical E-shaped groove. The length of each E protruding edge is d3 in the figure, and the length of the groove edge is d4 in the figure. The d1 of the protrusion 41 corresponds to the d3 of the protrusion receiving part 42, and the d2 of the protrusion 41 corresponds to the d4 of the protrusion receiving part 42. In order to better fix and assemble, the ratio of d3 to d1 is 1-1.2, and the ratio of d4 to d2 is 1-1.2. In addition, after the protrusion 41 is connected with the protrusion receiving part 42, the height of the protrusion 41 coinciding with the protrusion receiving part 42 is 0.5-20mm, i.e. h in the figure. Figure 16 Figure 16 Figure 18 ​​​​​The height of the overlap between the protrusion 41 and the protrusion receiving portion 42 is preferably 3 mm. If the overlap is too small, the protrusion 41 and the protrusion receiving portion 42 can easily separate by themselves; if the overlap is too large, the protrusion 41 and the protrusion receiving portion 42 need to move a large distance up and down to separate, which is inconvenient. Therefore, the height of the overlap between the protrusion 41 and the protrusion receiving portion 42 is preferably 3 mm.

[0101] In other embodiments, the protrusion 41 and the protrusion receiving portion 42 use a material with a thin wall thickness and stable connection, such as metal, and the forward movement distance for each gear is less than 2 mm, so as to achieve a smaller and more precise distance adjustment. For example, the protrusion 41 is set to be E-shaped, as shown in FIG. 4, the length of the protruding edge of each E in the protrusion 41 is d1, and the length of the groove edge is d2. Figure 17 Figure 17 In other embodiments, the protrusion 41 and the protrusion receiving portion 42 use a material with a thin wall thickness and stable connection, such as metal, and the forward movement distance for each gear is less than 2 mm, so as to achieve a smaller and more precise distance adjustment. For example, the protrusion 41 is set to be E-shaped, as shown in FIG. 4, the length of the protruding edge of each E in the protrusion 41 is d1, and the length of the groove edge is d2. Figure 17 Figure 17 In other embodiments, the protrusion 41 and the protrusion receiving portion 42 use a material with a thin wall thickness and stable connection, such as metal, and the forward movement distance for each gear is less than 2 mm, so as to achieve a smaller and more precise distance adjustment. For example, the protrusion 41 is set to be E-shaped, as shown in FIG. 4, the length of the protruding edge of each E in the protrusion 41 is d1, and the length of the groove edge is d2. Figure 17

[0102] In addition, the technical features in each of the above embodiments can be combined as needed to obtain a mandibular advancement device 1 including all or part of the above technical features.

[0103] The mandibular advancement device 1 with the adjustment portion 4 according to the present application has at least the following beneficial effects:

[0104] ​​​1) The mandibular advancement device 1 generally needs to be finely adjusted in distance. Fine distance adjustment can effectively avoid the risk of over-adjustment, which may cause excessive advancement distance, causing pain and discomfort in the temporomandibular joint and the oral cavity, and even causing temporomandibular joint disorders, oral ulcers, and other soft tissue injuries. Secondly, through fine adjustment, the mandibular advancement distance is gradually increased, and the user can more easily adapt to the device, making the wearing process more comfortable, thereby improving compliance and willingness to wear. In addition, fine distance adjustment gradually increases the mandibular advancement distance, which helps the user better adapt to the treatment process and ultimately improves the therapeutic effect of the device. There are other structures on the market that can be finely adjusted, but there are still many problems. For example, although the screw adjustment can be finely adjusted, the screw is prone to loosening due to the addition of an extra small part. Once it falls, it may enter the esophagus or even the airway from the oral cavity, posing a greater potential risk. There is another structure of an external connecting arm. If it is made of rigid material, it is easy to scratch the edge of the oral cavity; if it is made of flexible material, it is prone to looseness and is difficult to fix. The gear structure is similar to the buckle structure, but its composition is different. It usually needs to be pushed forward and backward to adjust the advancement distance, and the gear structure needs to be made of relatively rigid material to avoid loosening or wear. Commonly used is polycarbonate (PC) material. However, the mandibular advancement device usually needs to heat the plastic parts to shape the plastic parts, and PC material will produce bisphenol A when heated, thereby causing harm to the human body. In addition, the edges of the thinner gear are more difficult to align left and right, which may cause the left and right advancement distances to be inconsistent, thereby affecting the treatment effect. To solve these problems, the present invention adopts a buckle structure with special designs such as I-shaped, F-shaped, E-shaped, and symmetric E-shaped. The special buckle design can ensure the required wall thickness during production and ensure the stability of the structure. Whether it is I-shaped, F-shaped, E-shaped, or symmetric E-shaped, they are a whole structure, which is fixed by buckling up and down, so it is easier to operate during engagement. The buckle structure of the present invention provides a more reliable and flexible solution to meet the fine distance adjustment requirements of the mandibular advancement device 1 and ensure the stability of the mandibular advancement device 1, while also facilitating the user's operation and adjustment.

[0105] 2) The invention adopts a whole buckle structure, which allows multiple gear adjustment design on the same bracket. This design allows users to adjust the forward distance of the lower tray assembly 3 according to their individual conditions to select the most effective and comfortable position, thereby improving the compliance of the lower jaw forward movement device 1. Compared with using multiple different upper and lower bracket combinations, the invention adopts I-shaped, F-shaped, E-shaped, and symmetric E-shaped buckle structures, which only require one pair of upper and lower brackets 21, 31 to achieve more precise and multi-gear forward distance adjustment. This design not only eliminates the need for multiple brackets, but also allows for more gear adjustment on the same bracket while ensuring the precision of the adjustment range. This innovation provides a more economical and simpler solution, greatly reducing the cost and operation complexity.

[0106] 3) The mandibular advancement devices on the market still have the problem of easy falling off. A large number of users have feedback that the mandibular advancement device often separates from the teeth during sleep, resulting in the device falling off. After testing and analysis, it is found that this falling off problem is mainly due to the need for the lower tray assembly to move forward relative to the upper tray assembly, and the user may move or unconsciously open and close the mouth during sleep, which may cause the mandibular advancement device to easily fall off. Therefore, in order to solve this problem, the upper and lower tray assemblies 2, 3 need to have sufficient support force in the front and back positions to ensure that the device can be firmly maintained in place during use. In addition, there is a certain angle difference between each tooth, which is not necessarily perpendicular to the horizontal plane. For example, the front teeth (central incisors and lateral incisors) usually have a certain lip inclination relative to the horizontal vertical plane, and the inclination angle is about 10-25°; the inclination angle of the canine teeth (lip side direction) is usually between 5-15°; the inclination angle of the molar teeth (lip side direction) is usually between 0-5°. The angles of the front teeth and canine teeth relative to the horizontal vertical plane are larger, and the angle of the molar teeth relative to the horizontal vertical plane is smaller, which causes the support forces required by different teeth to be different during occlusion. The inner and outer walls of the existing mandibular advancement device are usually designed to be perpendicular to the bottom wall, which cannot conform to the natural shape of the teeth, resulting in discomfort and easy falling off when worn. Another common mandibular advancement device support is only composed of a bottom wall without inner and outer walls in the front and back positions, which does not have sufficient support force, making it easier for teeth to slide out of the mandibular advancement device. After multiple tests on users with various tooth shapes, the present application provides an improved support design. The support 21, 31 has an inner wall 211 and an outer wall 212 to provide sufficient support force. In addition, the inner wall 211 of the support 21, 31 forms a certain angle with the bottom wall 212 to adapt to the natural angle of the lip inclination of the front teeth, thereby better fitting the shape of the teeth. Through this structural design, the mandibular advancement device 1 of the present application shows significant stability during the experiment, reducing the possibility of device falling off. At the same time, this design improves the comfort and effectiveness of wearing, solving the main problems of existing products.

[0107] The technical features of the above-described embodiments can be combined in any manner. In order to make the description concise, not all possible combinations of the technical features in the above-described embodiments are described, but as long as the combinations of the technical features do not contradict, they should be considered within the scope of the present disclosure.

[0108] The above embodiments only express several implementation manners of the present application, and the description is more specific and detailed, but it should not be understood as a limitation on the scope of the patent. It should be noted that for ordinary skilled persons in the art, without departing from the concept of the present application, several modifications and improvements can be made, which are within the scope of protection of the present application. Therefore, the protection scope of the patent of the present application should be subject to the appended claims.

Claims

1. A mandibular advancement device having an adjustment portion, comprising: an upper tray assembly shaped to conform to a user's upper dental arch; a lower tray assembly shaped to conform to a user's lower dental arch; the upper tray assembly comprising an upper support and an upper moldable component; the lower tray assembly comprising a lower support and a lower moldable component; the upper tray assembly and / or the lower tray assembly being made of at least two different materials; an adjustment portion configured to connect the upper tray assembly and the lower tray assembly in a snap-fit manner and to adjust the position of the lower tray assembly relative to the position of the upper tray assembly; wherein the snap-fit manner is specifically that the upper tray assembly and / or the lower tray assembly has at least one protrusion on one side thereof, the protrusion being configured to press-fit connect the upper support and the lower support.

2. The mandibular advancement device of claim 1, wherein, the upper tray assembly is configured to contact a user's upper dental arch.

3. The mandibular advancement device of claim 1, wherein, the lower tray assembly is configured to contact a user's lower dental arch.

4. The mandibular advancement device of claim 1, wherein, the upper moldable component is configured to soften upon being heated so as to adjust and mold to a shape that matches a user's upper dental arch when the user bites.

5. The mandibular advancement device of claim 1, wherein, the lower moldable component is configured to soften upon being heated so as to adjust and mold to a shape that matches a user's lower dental arch when the user bites.

6. A mandibular advancement device having an adjustment portion, comprising: an upper tray assembly comprising an upper support and an upper moldable component; a lower tray assembly comprising a lower support and a lower moldable component; the upper tray assembly and / or the lower tray assembly being made of at least two different materials; an adjustment portion configured to connect the upper tray assembly and the lower tray assembly in a snap-fit manner and to adjust the position of the lower tray assembly relative to the position of the upper tray assembly; wherein the snap-fit manner is specifically that the upper tray assembly and / or the lower tray assembly has at least one protrusion on one side thereof, the protrusion being configured to press-fit connect the upper support and the lower support; wherein the upper support and the lower support have an inner wall and an outer wall, and the distance between the inner wall and the outer wall is at least partially in the range of 0.3-8 mm.

7. The mandibular advancement device of claim 6, wherein, the protrusion is disposed on the outer wall surface of the upper support, and the protrusion receiving portion is disposed on the outer wall surface of the lower support and is opposite to the protrusion.

8. The mandibular advancement device of claim 6, wherein, the protrusion is disposed on the outer wall surface of the lower support, and the protrusion receiving portion is disposed on the outer wall surface of the upper support and is opposite to the protrusion.

9. The mandibular advancement device of claim 6, wherein, the upper moldable component and the lower moldable component are at least partially made of a flexible thermoplastic material.

10. The mandibular advancement device of claim 6, wherein, the upper support and the lower support are at least partially made of a relatively rigid material compared to the upper moldable component and the lower moldable component.

11. A mandibular advancement device having an adjustment portion, comprising: an upper tray assembly comprising an upper support and an upper moldable component; a lower tray assembly comprising a lower support and a lower moldable component; the upper tray assembly and / or the lower tray assembly being made of at least two different materials; an adjustment portion configured to connect the upper tray assembly and the lower tray assembly in a snap-fit manner and to adjust the position of the lower tray assembly relative to the position of the upper tray assembly; The upper support and the lower support have inner walls, and the inner walls form an angle with the horizontal plane in the range of 20-150°.

12. The mandibular advancement device of claim 11, wherein, The sum of the weights of the upper support and the lower support is in the range of 3-50g.

13. The mandibular advancement device of claim 11, wherein, The weight of the whole mandibular advancement device is in the range of 8-80g.

14. The mandibular advancement device of claim 11, wherein, The buckle structure of the adjustment part adopts I shape, F shape, E shape or symmetric E shape.

15. The mandibular advancement device of claim 11, wherein, The adjustment part can adjust multiple gears.

16. A mandibular advancement device with an adjustment part, comprising: The upper tray assembly comprises an upper support and an upper shapeable component; The lower tray assembly comprises a lower support and a lower shapeable component; The upper tray assembly and / or the lower tray assembly are made of at least two different materials; The adjustment part is configured to connect the upper tray assembly and the lower tray assembly in the form of a buckle, and adjust the position of the lower tray assembly relative to the position of the upper tray assembly; The upper support and the lower support have inner walls, outer walls and bottom walls; The upper support and the lower support have one or more of the following characteristics: The vertical distance between the inner walls, the outer walls and the bottom walls is in the range of 0.5-20mm; The outer wall circumference is in the range of 2-200mm; The area of the outer wall is in the range of 50-2000 square millimeters.

17. The mandibular advancement device of claim 16, wherein, The thickness of the bottom wall of the upper support and the lower support is in the range of 0.5-20mm.

18. The mandibular advancement device of claim 16, wherein, The upper tray assembly and / or the lower tray assembly comprise a passage column, and when the upper tray assembly and the lower tray assembly are combined, the gap between the upper and lower tray assemblies and the passage column collectively forms an air flow passage.

19. The mandibular advancement device of claim 18, wherein, The number of passage columns is odd.

20. The mandibular advancement device of claim 18, wherein, The number of air flow passages is even and symmetric.

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