Lower jawbone biomechanical testing device and method

Abstract

The invention relates to a mandible biomechanical testing device and method, and belongs to the technical field of medical engineering.The mandible biomechanical testing device comprises a metal frame, a mandible testing area, a servo motor and pulleys; the mandible model used for simulating the mechanical characteristics of real bones is located in the mandible test area, and a masticatory muscle attachment area of the mandible model is provided with a muscle simulation structure to simulate the traction effect of masticatory muscles. The rigid rope is connected with the muscle simulation structure and then connected with a servo motor used for adjusting muscle force through a pulley used for adjusting the muscle traction direction, a condylar process fixing device is arranged at the position, corresponding to a condylar process, of the lower jawbone model so as to simulate the function of a fulcrum of chewing movement of the lower jawbone, and a loading column is arranged above the lower jawbone model. The muscle simulation structure and the loading column are provided with mechanical sensors to monitor muscle force and occlusal force in real time. The method is beneficial to providing an accurate biomechanical insight of mandible reconstruction for an oral clinician, and further optimizing a reconstruction scheme to improve the reconstruction prognosis of a patient.

Description

Technical Field

[0001] This invention discloses a novel biomechanical testing device for the mandible, which mainly relates to the biomechanical analysis of mandibular reconstruction and belongs to the field of medical engineering technology. Background Technology

[0002] Jawbone tumors, trauma, and osteomyelitis are common causes of jawbone defects. Jawbone defects not only severely impair a patient's physical function but also affect their mental health, significantly reducing their quality of life. To restore physiological function as much as possible after jawbone defect surgery and reshape the normal morphology of the maxillofacial region, reconstructive treatment is usually performed concurrently with jawbone resection surgery. Currently, autologous bone grafting combined with titanium plate fixation is the mainstream method for jawbone defect reconstruction. Extensive clinical follow-up data show that patients undergoing jawbone reconstruction often experience complications such as nonunion, bone resorption, titanium plate exposure, and titanium plate fracture. Numerous studies have confirmed that the occurrence of these complications is closely related to biomechanical factors during the jawbone reconstruction process.

[0003] Biomechanics aims to explore the relationship between biology and mechanics, explaining the intrinsic mechanisms of life sciences from a mechanical perspective. In the field of dentistry, biomechanical issues are widespread and cannot be ignored. In-depth research into oral biomechanics can powerfully promote the development of oral biomaterials and facilitate innovation in clinical oral medicine. The mandible, as the only movable bone in the face, has a complex biomechanical distribution. During daily physiological activities such as speech, chewing, and swallowing, it must withstand complex mechanical forces exerted by joints, muscles, and other soft tissues over a long period. After partial removal of the mandible due to lesions, the occlusal force and masticatory muscle force change due to the missing mandibular segment, resulting in a significant alteration in its biomechanical distribution and a highly complex biomechanical condition in patients after reconstruction. Studies have shown that a clear understanding of the biomechanical distribution characteristics after mandibular reconstruction is crucial for improving the long-term mechanical stability and survival rate of bone grafts. Furthermore, for novel technologies and methods applied to mandibular reconstruction, validating their safety and efficacy through biomechanical testing before conducting clinical trials is a key step in ensuring the reliability of clinical applications. Therefore, it is evident that biomechanical analysis of mandibular reconstruction has extremely high application value, both in theoretical research and clinical practice. Summary of the Invention

[0004] The purpose of this invention is to provide a mandibular biomechanical testing device and method to provide oral clinicians with accurate biomechanical insights into mandibular reconstruction and to further optimize reconstruction plans to improve patient reconstruction outcomes.

[0005] To achieve the above objectives, the present invention provides a mandibular biomechanical testing device, comprising a metal frame, a mandibular testing area disposed within the metal frame, a servo motor disposed on one side of the mandibular testing area, and a pulley disposed above the mandibular testing area; a mandibular model for simulating the mechanical properties of real bones is located within the mandibular testing area, and a muscle simulation structure is provided in the masticatory muscle attachment area of ​​the mandibular model to simulate the masticatory muscle traction; a rigid rope is connected to the muscle simulation structure and then passes through the pulley for adjusting the direction of muscle traction and is connected to the servo motor for adjusting the magnitude of muscle force; a condyle fixation device is provided at the condyle position of the mandibular model to simulate the fulcrum of mandibular chewing movement; a loading column is provided above the mandibular model; and mechanical sensors are provided on the muscle simulation structure and the loading column to monitor the magnitude of muscle force and biting force in real time.

[0006] Preferably, it includes a computer terminal, which is used to control the output force of the servo motor, adjust the magnitude of muscle force, and adjust the direction of muscle traction through the pulley group; the mechanical sensor feeds back muscle force and bite force data to the computer terminal in real time.

[0007] Preferably, it includes an optical measuring instrument, which attaches optical markers to the reconstructed area of ​​the mandibular model to record the movement of the markers in three-dimensional space.

[0008] Preferably, it also includes a maxillary simplification device connected to the loading column, the position of which is adjustable.

[0009] Preferably, the condyle fixation device is a hemispherical metal groove that allows the condyle to rotate within the glenoid fossa.

[0010] Preferably, the mandibular model is made of polyurethane material.

[0011] Preferably, the muscle-simulating structure is a near-mandibular segment made of silicone material.

[0012] The present invention also provides a biomechanical testing method for the mandible, comprising the following steps: Generate a three-dimensional model of the reconstructed mandible; The mandibular model was 3D printed using polyurethane material. The mandibular model is installed into the testing device, and the pulling direction and force of the muscle simulation structure are adjusted by the pulley and the servo motor. Optical markers are attached to the reconstructed area of ​​the mandibular model, and the three-dimensional movement of the markers is recorded by the optical measuring instrument. The mechanical sensors monitor the magnitude of muscle force and biting force, and the data is fed back to the computer terminal. The output force of the servo motor is adjusted to simulate the traction effect of the masticatory muscles, thereby realizing the biomechanical analysis of the mandibular reconstruction scheme.

[0013] Preferably, the traction direction of the muscle simulation structure is adjusted by the pulley to conform to the traction direction of the masticatory muscles recorded in the patient's CT data.

[0014] Preferably, the optical measuring instrument is used to capture torsional motion and analyze the stress and displacement changes in the reconstructed area.

[0015] Compared with existing technical solutions, the present invention has the following beneficial effects: Based on further simulating the physiological characteristics of masticatory muscles, the device of this invention reproduces the chewing activity caused by muscle traction in real-world situations. By utilizing real-time feedback and adjustment from a computer terminal and a power control system, it simulates the central nervous system control and feedback regulation mechanism in the physiological chewing process of the mandible. It adopts a non-contact optical measurement system to overcome the errors of traditional strain measurement systems, thereby improving the accuracy of testing. Furthermore, by incorporating individual patient parameters, it enables personalized mandibular biomechanical prediction for different patients and different treatment plans. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the overall framework of the mandibular biomechanical testing device and method of the present invention; Figure 2 This is a schematic diagram of the combination of the mandibular model, the simplified maxillary device, and the temporomandibular joint fossa in the mandibular biomechanical testing device and method of the present invention. Figure 3 This is a three-dimensional schematic diagram of the rigid rope simulating muscle traction in a mandibular biomechanical testing device and method of the present invention. Figure 4 This is a frontal view of the rigid rope simulating muscle traction in the mandibular biomechanical testing device and method of the present invention; Figure 5 This is a side view schematic diagram of the rigid rope traction method simulating muscle in a mandibular biomechanical testing device and method of the present invention. Figure 6 This is a schematic diagram of the pulley and servo motor in the mandibular biomechanical testing device and method of the present invention; Figure 7 This is a physical diagram of the condylar fixation device in the mandibular biomechanical testing device and method of the present invention; Figure 8 This is a physical image of the optical measuring instrument used in the mandibular biomechanical testing device and method of the present invention.

[0017] Reference numerals: 1. Mandibular test area; 2. Servo motor; 3. Pulley; 4. Maxillary simplification device; 5. Micrognathia adjustment structure; 6. Loading column; 7. Condylar fixation device; 8. Muscle simulation structure. Detailed Implementation

[0018] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] This invention discloses a biomechanical testing device and method for the mandible, aiming to analyze and evaluate the mechanical properties of the mandible by simulating the traction of the masticatory muscles. This provides oral clinicians with accurate biomechanical insights into mandibular reconstruction, further optimizing reconstruction plans to improve patient outcomes. The device integrates multiple structures, including a metal frame (based on aluminum alloy), a mandibular model, a muscle simulation structure 8 (load-bearing structure), a condylar fixation device 7 (simplified temporomandibular joint structure), an optical measuring instrument, a mechanical sensor, a simplified temporomandibular joint structure, a simplified maxillary device 4, a servo motor 2, and a computer terminal, forming a complete mechanical testing platform.

[0020] The mandibular test area 1 is located inside a metal frame. The mandibular model is a 3D-printed model based on polyurethane material, whose physiological characteristics closely resemble those of real bones. Various components are arranged within the mandibular test area 1. A muscle simulation structure 8 is installed on the mandibular model. This silicone-based muscle simulation structure 8, fitted to the attachment area of ​​the masticatory muscles, simulates the proximal segment of the masticatory muscles. One end of the muscle simulation structure 8 is connected to the mandibular model, with a mechanical sensor in the connection area providing real-time feedback to a computer terminal. The other end is connected to a rigid cable. This rigid cable, which pulls the muscle simulation structure 8, is connected to a servo motor 2 via three pairs of pulleys 3. The servo motor 2 is located on one side of the mandibular test area 1, and the pulleys 3 are positioned above it. Adjusting the position of the pulleys 3 allows for control of muscle direction. The connection area of ​​the muscle simulation structure 8 is equipped with a mechanical sensor, providing real-time feedback to the computer terminal for monitoring muscle force.

[0021] The simplified maxillary device 4 is connected to a loading post 6, the position of which is adjustable to correspond to the occlusal region. The loading posts 6 are located on one side, one anterior and one posterior, corresponding to the anterior and molar regions of the mandible, respectively. Each loading post 6 is equipped with a force sensor to detect the occlusal force in the anterior and molar regions of the mandible. The position of the loading posts 6 and the force feedback mechanism ensure the physiological occlusal relationship between the mandibular model and the maxillary structure.

[0022] The simplified temporomandibular joint structure (condylar fixation device 7, temporomandibular joint fossa) is a hemispherical metal groove used to fix the mandibular condyle. The condyle can rotate within the fossa, simulating the fulcrum role of the mandible's chewing movements. The micrognathiac adjustment structure 5 contacts the mandibular model through the condylar fixation device 7, further simplifying and stabilizing the mandibular movement.

[0023] An optical measuring instrument is mounted in front of the test area and is attached to the reconstructed area of ​​the mandibular model using optical markers. The movement of the markers in three-dimensional space is recorded. This system uses passive optical marking, requires no glue, avoids affecting bone surface features or mechanical properties, and can capture torsional motion, enabling precise measurement of the reconstructed area.

[0024] Mechanical sensors are positioned on the connection area of ​​the muscle simulation structure 8 and the loading column 6 to record the magnitude of muscle force and biting force in real time, and feed the data back to the computer terminal. The computer terminal controls the output force of the servo motor 2, adjusts the magnitude of the muscle force, and adjusts the direction of muscle traction through the pulley 3 to make it conform to the direction of masticatory muscle traction recorded in the patient's CT data.

[0025] The biomechanical testing method for the mandible of this invention is as follows: Before the operation, a reconstruction surgical plan for the patient is formulated using digital surgical technology. A three-dimensional model of the reconstructed mandible is generated using three-dimensional software and exported as an STL file. The model is then printed using 3D printing technology, with polyurethane, which is close to the physiological properties of bone, as the printing material, to obtain a reconstructed mandible model made of polyurethane material.

[0026] By combining patient CT data, the direction of masticatory muscle traction and maximum muscle strength of a specific patient are quantified, and the relevant quantitative parameters are transferred to the testing platform. The simulated masticatory muscles include three main pairs of muscles: the lateral pterygoid, temporalis, and masseter. Since the lateral pterygoid mainly plays a stabilizing role during mouth closure, it is not included. A muscle simulation structure 8 is selected to simulate the prognathic segment of the masticatory muscles. Silicone can well simulate the biomechanical properties of muscles. One end of the muscle simulation structure 8 is connected to the mandible, and the connection area has a mechanical sensor that provides real-time feedback to the computer terminal. The other end is connected to a rigid rope, which is connected to a servo motor 2. The servo motor 2 is controlled by the computer terminal to adjust the output force to regulate the magnitude of the muscle force. The direction of the muscle force is adjusted by a pulley 3 through which the rigid rope passes. The adjusted muscle direction should conform to the patient's CT scan.

[0027] The maxilla is simplified into two adjustable loading posts 6, which can contact the anterior and molar regions of the mandible respectively. When the mandible is pulled by muscles, it interacts with the loading posts 6. Each loading post 6 is equipped with a mechanical sensor to provide real-time feedback on the occlusal force in the occlusal region. A 3D-printed polyurethane model of the mandible contacts the simplified maxilla device 4, thereby simulating the physiological occlusal mechanism. The output force of the three main masticatory muscles is controlled by a computer terminal to achieve a specific occlusal force in the occlusal region.

[0028] The condyle of the mandible is placed in a simplified temporomandibular joint fossa (condyle fixation device 7), and the condyle can rotate inside the joint fossa, which acts as a fulcrum for chewing. During testing, a polyurethane mandibular model is placed in a suitable position on the testing platform, requiring the condyle to be located within the simplified temporomandibular joint fossa. The position of the mandibular model and the maxillary structure should correspond to their relative positions during chewing. The muscle direction and force are adjusted, and a rigid rope is driven by a servo motor 2 to transmit force. The rigid rope is connected to the end of the muscle simulation structure 8 (the silicone shape mimics the shape of the masticatory muscles attached to the mandible). The muscle simulation structure 8 transmits force to the mandibular model. After being pulled by the muscle simulation structure 8, the mandibular model interacts with the simplified maxillary device 4 under the fulcrum of the temporomandibular joint fossa. The magnitude of the occlusal force in the occlusal area can be recorded by the mechanical sensor equipped on the maxillary loading column 6. According to the principle of force interaction, the mandible is subjected to an equal and opposite force, which is similar to the occlusal force during physiological chewing.

[0029] In addition, for the jawbone reconstruction area that is of great interest, non-contact and precise measurement can be achieved through an optical measuring instrument. The optical measuring instrument attaches an optical marker to the reconstruction area, and the optical camera records and analyzes the positional changes of the optical marker before and after the test to obtain the stress and displacement changes in the reconstruction area.

[0030] This invention, by simulating the traction of the masticatory muscles and the distribution of biting forces, enables biomechanical analysis of mandibular reconstruction plans, predicting weak points and key areas of concern. This effectively guides surgeons in biomechanically optimizing mandibular reconstruction plans. Furthermore, this device can be used to evaluate the safety of novel reconstruction methods or materials, and can also be applied before clinical trials to effectively assess their safety, thus contributing to the development and breakthroughs of new maxillofacial surgical techniques.

[0031] In the accompanying drawings of this invention, the thick green line represents the temporalis muscle, the thick blue line represents the masseter muscle, the thick red line represents the medial pterygoid muscle, and the lateral pterygoid muscle is omitted. It's not simply a matter of using a rope for traction; a silicone material is also present between the end of the rope and the mandible. This silicone material needs to be molded to the physiological shape of a muscle. This silicone material is used to further simulate the area where the masticatory muscles attach to the mandible, thus further recreating the realistic scenario of the masticatory muscles acting on the mandible.

[0032] This invention preferably employs the PONTOS optical measuring instrument, which tracks and identifies optical markers (2.5 mm diameter reflection points) applied to the surface of the object under study. Theoretically, the number of optical markers is unlimited, and it can record the movement of these markers over time in three-dimensional space. This method is superior to other measurement methods using strain gauges because it does not require direct application of the testing equipment to the bone, which would otherwise interact with the bone surface and distort the results. Passive optical marking does not affect the characteristics or mechanical properties of the mandible, which is a significant advantage. Furthermore, no glue is required, which is crucial on irregular bone surfaces. The movement of each marker point can be detected, allowing focus on any desired region of interest. The instrument also allows for 3D reconstruction of the relative movements of different groups of markers. The PONTOS optical measuring instrument can also capture torsional motion, which is often very challenging to detect with traditional measurement methods, and torsional motion can also affect bone healing in osteotomy gaps.

[0033] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A biomechanical testing device for the mandible, characterized in that, The device includes a metal frame, a mandibular test area (1) located within the metal frame, a servo motor (2) located on one side of the mandibular test area (1), and a pulley (3) located above the mandibular test area (1). A mandibular model for simulating the mechanical properties of real bones is located within the mandibular test area (1). The masticatory muscle attachment area of ​​the mandibular model is provided with a muscle simulation structure (8) to simulate the masticatory muscle traction. A rigid rope is connected to the muscle simulation structure (8) and then connected to the servo motor (2) for adjusting the muscle force through the pulley (3) for adjusting the direction of muscle traction. A condyle fixation device (7) is provided at the condyle position of the mandibular model to simulate the fulcrum of mandibular chewing movement. A loading column (6) is provided above the mandibular model. The muscle simulation structure (8) and the loading column (6) are provided with mechanical sensors to monitor the magnitude of muscle force and biting force in real time.

2. The mandibular biomechanical testing device according to claim 1, characterized in that, The system includes a computer terminal, which controls the output force of the servo motor (2), adjusts the muscle force, and adjusts the muscle traction direction through the pulley (3) group; the mechanical sensor feeds back the muscle force and bite force data to the computer terminal in real time.

3. The mandibular biomechanical testing device according to claim 2, characterized in that, It includes an optical measuring instrument, which attaches optical markers to the reconstructed area of ​​the mandibular model to record the movement of the markers in three-dimensional space.

4. The mandibular biomechanical testing device according to claim 3, characterized in that, It also includes a maxillary simplification device (4), which is connected to the loading column (6), the position of which is adjustable.

5. The mandibular biomechanical testing device according to claim 4, characterized in that, The condyle fixation device (7) is a hemispherical metal groove that allows the condyle to rotate within the glenoid fossa.

6. The mandibular biomechanical testing device according to claim 5, characterized in that, The mandibular model is made of polyurethane material.

7. The mandibular biomechanical testing device according to claim 6, characterized in that, The muscle-simulating structure (8) is a near-jawbone segment made of silicone material.

8. A method for using the mandibular biomechanical testing device according to any one of claims 3-7, characterized in that, Includes the following steps: Generate a three-dimensional model of the reconstructed mandible; The mandibular model was 3D printed using polyurethane material. The mandibular model is installed in the testing device, and the pulling direction and force of the muscle simulation structure (8) are adjusted by the pulley (3) and the servo motor (2); Optical markers are attached to the reconstructed area of ​​the mandibular model, and the three-dimensional movement of the markers is recorded by the optical measuring instrument. The mechanical sensors monitor the magnitude of muscle force and biting force, and the data is fed back to the computer terminal. Adjust the output force of the servo motor (2) to simulate the traction effect of the masticatory muscles and realize the biomechanical analysis of the mandibular reconstruction scheme.

9. A biomechanical testing method for the mandible according to claim 8, characterized in that, The traction direction of the muscle simulation structure (8) is adjusted by the pulley (3) to conform to the traction direction of the masticatory muscle recorded in the patient's CT data.

10. A biomechanical testing method for the mandible according to claim 9, characterized in that, The optical measuring instrument captures torsional motion and analyzes stress and displacement changes in the reconstructed area.

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