A skull-jaw teaching aid and method for simulating temporomandibular joint disorder

Abstract

The application discloses a skull-jaw teaching aid and method for simulating temporomandibular joint disorder, which comprises a skull component model and a mandibular body model, the skull component model is fixedly installed on an acrylic plate, the mandibular body model is connected with the skull component model through a disc model, a posterior disc ligament model and an anterior disc ligament model of a S area of a joint region, the mandibular body model can freely slide and rotate along a condylar process rotation track, the disc model is internally provided with a sliding rail, a sliding assembly is arranged on the condylar process of the mandibular body model, and the disc model, the posterior disc ligament model and the anterior disc ligament model are elastic components. The disc model can simulate the conversion between normal state, reducible anterior displacement and irreducible anterior displacement, and the influence of a disc anterior displacement on the opening movement range of the disc. The design can more truly simulate the pathological process of TMD, is helpful to deepening the understanding of the pathogenesis of the TMD by medical students and patients, and provides strong support for teaching and doctor-patient communication.

Description

Technical Field

[0001] This invention belongs to the field of teaching model technology, specifically relating to a craniomaxillary teaching aid and method for simulating temporomandibular joint disorder. Background Technology

[0002] Temporomandibular joint disorder (TMD) is a common oral and maxillofacial disease with a high incidence. Typical symptoms include joint pain, clicking, and limited mouth opening. It is often accompanied by joint locking, where one or both joints get stuck during natural opening or closing movements (usually not near the maximum opening position), preventing free movement. The patient needs to use their hand to assist the mandible and make appropriate adjustments before they can continue to open or close their mouth. It may be accompanied by pain, can recur, and seriously affects the patient's quality of life. Many patients with TMD exhibit structural changes in their joints, most commonly reducible and irreducible anterior disc displacement. These changes are clearly visible on magnetic resonance imaging (MRI). In a normal occlusal disc position, the medial disc zone is typically located between the posterior slope of the articular tubercle and the anterior slope of the condyle. In reducible anterior disc displacement, the disc shifts anteriorly, returning to its normal position in the maximum opening position. In irreducible disc displacement, the disc remains in its anteriorly displaced position for an extended period, failing to return to its normal position even in the maximum opening state. Besides positional changes, irreducible disc displacement may also exhibit morphological alterations due to prolonged abnormal positioning, such as lobulation or deformation. While MRI can capture these structural changes, MRI images are typically two-dimensional, meaning they only show a single plane of the patient's body (e.g., sagittal, coronal, or axial). For patients, relating these planar images to their perception of body structures in three-dimensional space can be challenging. Patients may not be able to intuitively understand how subtle changes shown on MRI images affect their bodily functions or cause symptoms such as pain, especially when these changes are dynamic processes (such as the movement of the articular disc during opening and closing). Two-dimensional static images are even less able to convey such dynamic changes.

[0003] Therefore, teaching aids for simulating temporomandibular joint disorders, especially anterior displacement of the temporomandibular joint disc and joint disc locks, are crucial for medical education, diagnosis, and treatment communication. Currently, craniomaxillary models are among the most common teaching aids for the temporomandibular joint. These are typically made of materials such as silicone, plastic, or metal, and include a skull model with a temporomandibular joint disc. Through rotational axes and connections, the model allows for opening and closing movements of the skull and mandibular body, simulating the structure of a normal human skull and temporomandibular joint. There are also joint movement simulators: these teaching aids usually contain mechanically or electronically driven joint structures, including the skull, mandible, power supply box, light source, strain gauges, and musculoskeletal elastomers. They simulate the movement of the masticatory muscles during temporomandibular joint movement, and the movement of the elastomers simulating muscles can be identified by color, used for teaching demonstrations of temporomandibular joint movement patterns. Alternatively, there are detachable models used for training manual reduction of the temporomandibular joint and joint aspiration training. While these teaching aids can simulate the normal structure and movement of the temporomandibular joint, they often fail to accurately represent the complexities of joint disorders. Therefore, developing a teaching aid capable of simulating these specific disorders would be an important direction for innovation. Currently, there are methods that use segmented magnets on the upper and lower jaws and articular discs, along with sliding rails in the joint area, to simulate anterior disc displacement on a two-dimensional magnetic plate. However, these methods do not demonstrate the physicochemical properties of the articular disc under physiological conditions, such as elasticity, and lack a demonstration of the role of joint ligaments during disc movement. Summary of the Invention

[0004] To address the problems existing in the prior art, this invention provides a three-dimensional teaching aid capable of simulating specific disorders of temporomandibular joint disorder (TMD). It simulates the transitions of the articular disc between a normal state, reversible anterior displacement, and irreversible anterior displacement, as well as the impact of the disc's locking mechanism on the range of mouth opening during anterior disc displacement. This design more realistically simulates the pathological process of TMD, helping medical students and patients deepen their understanding of its pathogenesis and providing strong support for teaching and doctor-patient communication.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: a craniomaxillary teaching aid for simulating temporomandibular joint disorder, comprising a skull model and a mandibular body model. The skull model is mounted and fixed on an acrylic plate. The mandibular body model is connected to the skull model through a joint disc model, a posterior joint disc ligament model, and an anterior joint disc ligament model in the S-region of the joint. The mandibular body model can slide freely and rotate along the condyle rotation trajectory. A slide rail is provided inside the joint disc model, and a sliding component is provided on the condyle of the mandibular body model. The joint disc model, the posterior joint disc ligament model, and the anterior joint disc ligament model are elastic components.

[0006] Furthermore, the slide rail is a cylindrical track built into the articular disc, and the sliding assembly includes a built-in condylar slide rail and a built-in push rod of the condylar slide rail. The built-in push rod of the condylar slide rail can slide along the built-in condylar slide rail and can extend into the cylindrical track built into the articular disc.

[0007] Furthermore, a handle is installed on the push rod built into the condyle slide rail.

[0008] Furthermore, a first metal spring is installed at the junction of the articular tubercle and the glenoid fossa, and a second metal spring is installed near the glenoid fossa on the articular disc model. When the first metal spring and the second metal spring come into contact, a crisp metallic collision sound is produced.

[0009] Furthermore, the articular disc model is made of natural rubber or silicone, the skull composition model and the mandibular body model are made of biocompatible plastic; the posterior articular disc ligament model and the anterior articular disc ligament model are made of biocompatible polymer materials or high-strength fibers.

[0010] The skull and mandibular body models may be made of plaster or lightweight metal; the articular disc, posterior articular disc ligament, and anterior articular disc ligament models may be made of springs.

[0011] Furthermore, a lubricating layer is applied to the contact surface between the condyle and the articular disc model.

[0012] This invention also provides a method for simulating temporomandibular joint disorder. Based on the above-mentioned craniomaxillary manipulative for simulating temporomandibular joint disorder, the articular disc model is pulled in the closed position to cause the condylar articular disc to simulate anterior displacement of the articular disc. When the condyle slides forward to below the articular tubercle, i.e., in the maximum opening position, the condyle is moved away from the articular disc model. At this time, the articular disc model moves towards the glenoid fossa due to the elastic deformation of the posterior and anterior articular disc ligament models.

[0013] During the process from the closed position to the maximum opening position, the articular disc model maintains an anterior displacement state, and the condyle movement is restricted, simulating the joint lock during the opening process of the reducible disc anterior displacement;

[0014] In the closed position, the articular disc model is pulled so that the condyle enters the articular disc, simulating anterior displacement of the articular disc, thereby simulating irreversible anterior displacement of the articular disc.

[0015] Furthermore, in the closed position, the articular disc model is pulled so that the push rod inside the condyle slide rail enters the internal cylindrical track of the articular disc to simulate anterior displacement of the articular disc; the condyle slides forward to below the articular tubercle, i.e., the maximum opening position, and the push rod inside the condyle slide rail is slid away from the articular disc model to disengage it from the internal cylindrical track of the articular disc. Due to the elastic deformation of the posterior articular disc ligament model and the anterior articular disc ligament model, the articular disc model recovers and moves towards the glenoid fossa. The first metal spring and the second metal spring are in contact and produce a crisp metallic collision sound, simulating the popping sound at the end of the opening of the reversible anterior displacement of the articular disc;

[0016] In the closed position, the articular disc model is pulled so that the push rod inside the condyle slide rail enters the internal cylindrical track of the articular disc to simulate anterior displacement of the articular disc; the push rod inside the condyle slide rail remains unchanged throughout the entire process to simulate irreversible anterior displacement of the articular disc.

[0017] Furthermore, the condyle moves along the condyle rotation trajectory at the articular disc model, simulating normal temporomandibular joint movement.

[0018] The device described in this invention offers excellent intuitiveness and educational value, promoting doctor-patient communication: through the intuitive operation of the built-in push rod and rotating knob, users can easily observe disc displacement and locking phenomena, as well as their impact on the range of mouth opening. This intuitiveness is crucial for medical education and training, enabling doctors, students, and patients to gain a deeper understanding of the pathogenesis and clinical manifestations of temporomandibular joint disorder (TMD). By using this educational tool, doctors can more visually demonstrate their TMD condition to patients, including disc displacement and locking phenomena. This visual communication method helps enhance patients' understanding and cooperation regarding their condition, improving the effectiveness of doctor-patient communication.

[0019] Adjustability: The built-in push rod of the teaching aid is adjustable, with a simple principle and easy operation. It can simulate different degrees of articular disc displacement and kinking, providing great convenience for medical research and clinical practice. The truncated skull model described in this invention saves materials and space, uses environmentally friendly materials, and has a lower cost compared to whole skull models and models with electronic devices, making it suitable for mass production. In addition, the device described in this invention fills the gap in the lack of teaching aids specifically for simulating temporomandibular joint disorder (TMD). Later, the intraocular and lateral displacement of the disc can be added to the craniofacial mold to simulate TMD caused by disc displacement from a three-dimensional perspective. Attached Figure Description

[0020] Figure 1 A schematic diagram of the external structure of a three-dimensional model of a skull with temporomandibular joint discs and ligaments (coronal and sagittal views);

[0021] Figure 2 This image shows a magnified view of the articular disc region and a diagram illustrating the movement trajectory of the joint during its open and closed states.

[0022] Figure 3 Rendering of the design for the built-in push rod for the front displacement of the repeatable disc.

[0023] Figure 4 MRI images of reducible anterior displacement of the articular disc in the closed and maximum opening positions (red arrows pointing to the articular disc).

[0024] Figure 5 Rendering of a built-in push rod design for non-returnable disc forward displacement

[0025] Figure 6 MRI images of reducible anterior displacement of the articular disc in the closed and maximum opening positions (red arrows pointing to the articular disc).

[0026] In the diagram: 1. Skull model; 2. Mandibular body model; 3. Acrylic plate; 4. Joint region S area; 5. Articular tubercle; 6. Condyle; 7. Articular disc model; 8. Posterior articular disc ligament model; 9. Anterior articular disc ligament model; 10. Condylar rotation trajectory; 11. Articular fossa; 12. First metal spring; 13. Second metal spring; 14. Internal cylindrical track of the articular disc; 15. Internal slide rail of the condyle; 16. Internal push rod of the condylar slide rail; 17. Internal push rod handle; 18. First fastening bolt (removable); 19. Second fastening bolt; 20. Third fastening bolt; 21. Fourth fastening bolt. Detailed Implementation

[0027] To fill the gap in the lack of teaching aids specifically designed to simulate temporomandibular joint disorder (TMD), this invention provides a craniomaxillary teaching aid that simulates TMD. Through a built-in push rod mechanism, the aid can simulate the transitions between the articular disc in its normal state, reversible anterior displacement, and non-reversible anterior displacement, as well as the effect of the articular disc's locking mechanism on the range of mouth opening during anterior disc displacement. This design allows medical students and patients to better understand and observe the mechanisms and evolution of TMD.

[0028] Please see Figures 1-6 This invention provides a technical solution: a three-dimensional skull model with a temporomandibular joint disc, including a skull component model 1 and a mandibular body model 2. The skull component model 1 is mounted and fixed on an acrylic plate 3. The mandibular body model 2 is connected to the skull component model 1 through a joint region S area 4, a joint disc model 7, a posterior joint disc ligament model 8, and an anterior joint disc ligament model 9. The mandibular body model 2 can slide freely and rotate along the condylar rotation trajectory 10. This craniomaxillary model simulating temporomandibular joint disorder can be used to simulate at least two conditions, namely... Figure 3 The reversible disk forward shift and Figure 5 The following is an example of an irreversible disk-front shift:

[0029] refer to Figure 3The articular disc model 7 has an internal cylindrical track 14 with a radius of a; the condyle 6 has an internal condyle slide rail 15 with a radius of b, where a > b; an internal condyle slide rail push rod 16 is installed on the internal condyle slide rail 15, and an internal push rod handle 17 is installed at the end of the internal push rod 16 to facilitate the sliding of the internal push rod 16 in the internal condyle slide rail 15. When the internal push rod 16 slides toward the articular disc model 7, manually pulling the articular disc can make the internal push rod 16 enter the internal cylindrical track 14, thereby fixing the articular disc model 7 away from the joint socket; a first metal spring 12 is installed at the junction of the articular tubercle 5 and the joint socket 11, and a second metal spring 13 is installed near the joint socket of the articular disc model 7. When the first metal spring 12 and the second metal spring 13 come into contact, a crisp metallic collision sound can be emitted;

[0030] Please see Figure 3 In the closed position, traction on the articular disc model 7 allows the condylar slide rail's built-in push rod 16 to enter the articular disc's built-in cylindrical track 14, thus simulating anterior displacement of the articular disc. Figure 4 As shown; when the condyle 6 slides forward to below the articular tubercle 5, i.e., at the maximum opening position, the push rod 16 built into the condyle slide rail is slid away from the articular disc model 7 to disengage it from the articular disc built-in cylindrical track 14. At this time, the articular disc model 7 moves towards the glenoid fossa due to the elastic deformation of the posterior articular disc ligament model 8 and the anterior articular disc ligament model 9. When the first metal spring 12 and the second metal spring 13 are in contact, they can produce a crisp metallic collision sound, simulating the popping sound at the end of the opening phase of the anterior displacement of the reversible articular disc. During the process from the closed position to the maximum opening position, the articular disc remains in an anterior displacement state, and the condyle movement is restricted. This process simulates the joint constriction during the opening process of the anterior displacement of the reversible disc.

[0031] Please see Figure 5 In the closed position, traction on the articular disc model 7 allows the condylar slide rail's built-in push rod 16 to enter the articular disc's built-in cylindrical track 14, thus simulating anterior displacement of the articular disc. Figure 6 As shown, the built-in push rod 16 of the condyle slide rail remains unchanged throughout the entire movement, thus simulating irreversible anterior displacement of the articular disc.

[0032] This invention has a simple structure and is easy and quick to operate. It uses a three-dimensional craniomaxillary model to simulate the state of different articular discs to simulate structural TMD in different situations in a timely and intuitive manner. Combined with the position and morphological changes of the articular discs in MRI images, it is convenient to popularize science to patients.

[0033] The articular disc model 7 is made of natural rubber or silicone. Natural rubber is a material with good elasticity and toughness, which can simulate the movement of the articular disc under real-world conditions. At the same time, natural rubber is also a relatively environmentally friendly material, derived from renewable resources. Silicone has excellent elasticity and durability, and can simulate the softness and elasticity of the articular disc. Furthermore, silicone is a non-toxic, odorless, and environmentally friendly material.

[0034] The posterior disc ligament model 8 and the anterior disc ligament model 9 utilize biocompatible polymer materials, specifically polylactic acid (PLA) or polycaprolactone (PCL), which possess excellent biocompatibility and biodegradability, simulating the elasticity and toughness of ligaments. PLA or PCL can be naturally degraded within the human body, thus meeting environmental protection requirements. Alternatively, high-strength fibers such as carbon fiber or glass fiber can be used in the posterior disc ligament model 8 and the anterior disc ligament model 9. These high-strength fiber materials exhibit high strength and toughness, simulating the mechanical properties of ligaments. Furthermore, these fiber materials are environmentally friendly and recyclable.

[0035] Skull model 1 and mandibular body model 2 are made of biocompatible plastics, such as polylactic acid (PLA) or polycaprolactone (PCL). Biocompatible plastics have good biocompatibility, are non-toxic and environmentally friendly, and can be easily made into complex skull structures through 3D printing technology, while maintaining lightness and low cost.

[0036] The first metal spring 12 and the second metal spring 13 are made of aluminum, a lightweight metal with low density, excellent ductility and corrosion resistance. Aluminum is also non-toxic, environmentally friendly, and relatively inexpensive. Alternatively, titanium alloy can be used. Titanium alloy is a high-strength, low-density, and corrosion-resistant metal. Although titanium alloy is relatively more expensive, it has excellent mechanical properties and biocompatibility, making it suitable for applications requiring higher durability and safety. Brass can also be used. Brass is an alloy of copper and zinc, possessing good mechanical properties and corrosion resistance. It is also a non-toxic, environmentally friendly, and relatively inexpensive metal.

[0037] The fastening bolts are made of titanium alloy, which combines high durability and safety.

[0038] As an alternative, traditional materials such as plaster or lightweight metals (such as aluminum) can also be considered for model making. Plaster or lightweight metals can also meet the requirements of being lightweight, environmentally friendly, and cost-effective.

[0039] Simulating joint movement using mechanical devices: A mechanical device can be designed to simulate the movement of the temporomandibular joint through mechanical components (such as gears, slide rails, etc.). The mechanical device can precisely control the sliding and rotation of the mandibular body model to simulate various situations of anterior displacement of the articular disc. Ligaments can be replaced by springs.

[0040] The principles of this invention are applied to simulate joint movement using digital technology: Utilizing 3D reconstruction technology and computer simulation software, a precise craniomaxillary model can be constructed in a computer, simulating the interaction between the articular disc, ligaments, and bones. Various cases of anterior joint displacement can be accurately simulated, including reducible and non-reducible anterior disc displacement. Through digital technology, simulation parameters can be easily adjusted to more accurately simulate the symptoms of temporomandibular joint disorder in different patients.

[0041] The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made to the technical solution based on the technical concept proposed in this invention shall fall within the scope of protection of the claims of this invention.

Claims

1. A craniomaxillary manipulative simulating temporomandibular joint disorder, characterized in that, The system includes a skull model (1) and a mandibular body model (2). The skull model (1) is mounted and fixed on an acrylic plate (3). The mandibular body model (2) is connected to the skull model (1) through the articular disc model (7), the posterior articular disc ligament model (8), and the anterior articular disc ligament model (9) in the joint region S area (4). The mandibular body model (2) can slide freely and rotate along the condylar rotation trajectory (10). The articular disc model (7) is equipped with a sliding rail, and the mandibular body model (2) has a sliding rail inside. A sliding component is provided on the condyle (6); the articular disc model (7), the posterior articular disc ligament model (8), and the anterior articular disc ligament model (9) are elastic components; the slide rail is an internal cylindrical track (14) of the articular disc, and the sliding component includes an internal condyle slide rail (15) and an internal push rod (16) of the condyle slide rail. The internal push rod (16) of the condyle slide rail can slide along the internal condyle slide rail (15), and the internal push rod (16) of the condyle slide rail can extend into the internal cylindrical track (14) of the articular disc.

2. The craniomaxillary manipulative for simulating temporomandibular joint disorder according to claim 1, characterized in that, A handle (17) is provided on the built-in push rod (16) of the condyle slide rail.

3. The craniomaxillary manipulative for simulating temporomandibular joint disorder according to claim 1, characterized in that, A first metal spring (12) is installed at the junction of the joint tubercle (5) and the joint socket (11), and a second metal spring (13) is installed near the joint socket on the joint disc model (7). When the first metal spring (12) and the second metal spring (13) come into contact, a crisp metallic collision sound is emitted.

4. The craniomaxillary manipulative for simulating temporomandibular joint disorder according to claim 1, characterized in that, The articular disc model (7) is made of natural rubber or silicone, the skull composition model (1) and the mandibular body model (2) are made of biocompatible plastic; the posterior articular disc ligament model (8) and the anterior articular disc ligament model (9) are made of biocompatible polymer materials or high-strength fibers.

5. The craniomaxillary manipulative for simulating temporomandibular joint disorder according to claim 1, characterized in that, The skull model (1) and mandibular body model (2) are made of plaster or lightweight metal; the articular disc model (7), the posterior articular disc ligament model (8), and the anterior articular disc ligament model (9) are made of springs.

6. The craniomaxillary manipulative for simulating temporomandibular joint disorder according to claim 1, characterized in that, The contact surface between the condyle (6) and the articular disc model (7) is coated with a lubricating layer.

7. A method for simulating temporomandibular joint disorder, characterized in that, Based on the craniomaxillary manipulative for simulating temporomandibular joint disorder as described in any one of claims 1-6, the articular disc model (7) is pulled in the closed position to cause the condylar articular disc to simulate anterior displacement of the articular disc; when the condyle (6) slides forward to below the articular tubercle (5), that is, in the maximum opening position, the condyle is moved away from the articular disc model (7), at which time the articular disc model (7) moves towards the glenoid fossa due to the elastic deformation of the posterior articular disc ligament model (8) and the anterior articular disc ligament model (9); During the process from the closed position to the maximum opening position, the articular disc model (7) maintains an anterior displacement state, and the condyle (6) has limited movement, simulating the joint constriction during the opening process of the reversible disc anterior displacement; In the closed position, the articular disc model (7) is pulled so that the condyle (6) enters the articular disc, simulating anterior displacement of the articular disc, thereby simulating irreversible anterior displacement of the articular disc.

8. The method for simulating temporomandibular joint disorder according to claim 7, characterized in that, When the articular disc model (7) is in the closed position, the condyle slide rail built-in push rod (16) is pulled into the articular disc built-in cylindrical track (14) to simulate the anterior displacement of the articular disc; the condyle (6) slides forward to below the articular tubercle (5), that is, the maximum opening position, and the condyle slide rail built-in push rod (16) is slid away from the articular disc model (7) to make it disengage from the articular disc built-in cylindrical track (14). Due to the elastic deformation of the articular disc posterior ligament model (8) and the articular disc anterior ligament model (9), the articular disc model (7) moves towards the articular socket. The first metal spring (12) and the second metal spring (13) are in contact and emit a crisp metallic collision sound, simulating the popping sound at the end of the anterior displacement of the reversible articular disc. In the closed position, the articular disc model (7) is pulled so that the condyle slide rail built-in push rod (16) enters the articular disc built-in cylindrical track (14) to simulate the anterior displacement of the articular disc; the condyle slide rail built-in push rod (16) remains unchanged throughout the process to simulate the irreversible anterior displacement of the articular disc.

9. The method for simulating temporomandibular joint disorder according to claim 7, characterized in that, The condyle (6) moves along the condyle rotation trajectory (10) at the articular disc model (7) to simulate normal temporomandibular joint movement.

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