A method for testing the mechanical properties of fixation of mandibular fractures in experimental animals

Abstract

The present invention discloses a method for testing the mechanical properties of fixation of mandibular fractures in experimental animals. The method comprises the following steps: 1) performing a CT scan on the head of the experimental animal; 2) reconstructing a three-dimensional model of the mandible; 3) designing a standard fixture model; 4) importing the three-dimensional models of the mandible and the standard fixture into 3-matic software, and performing Boolean subtraction and draft to obtain a personalized standard fixture; 5) manufacturing the personalized standard fixture by 3D printing; 6) fabricating a base; 7) assembling a mechanical testing device for mandibular fracture fixation: fixing the standard fixture of the physical model on the base, placing the mandible in the groove of the standard fixture of the physical model, and applying a vertical load on the dental arch of the mandible by the pressing component of an electronic universal testing machine to measure the bending strength of mandibular fracture fixation. In this method, the mandible is placed in the groove, preserving the intact original tissue structure, enabling more accurate measurement of the original tissue structure of the mandible, and obtaining more precise measurement results.

Description

Technical Field

[0001] The present invention relates to the technical field of mechanical property detection of mandibular fractures, and particularly to a method for testing the mechanical properties of fixation of mandibular fractures in experimental animals. Background Art

[0002] Due to the increase in traffic accidents, industrial accidents and sports injuries, the incidence of mandibular fractures has also been increasing, accounting for about 35% of maxillofacial fracture traumas, which will have a greater impact on mandibular mechanics, occlusal function and facial aesthetics. At present, the preferred treatment methods mainly focus on anatomical reduction and rigid internal fixation to ensure sufficient stability at the fracture site and promote the fracture healing process. With the development of material science and clinical technology, the methods of rigid internal fixation for mandibular fractures have also been expanded, including fixation with micro titanium plates and screws, and fixation with new biodegradable (poly-L-lactic acid) materials. However, the market application of new fixation strategies requires strict evaluation of the stability of the internal fixation system for mandibular fractures. An important experimental method is the in vitro biomechanical experimental test of experimental animal models. The electronic universal testing machine used in the experimental test only has standard fixtures for clamping conventional material structures, such as sheet-shaped, block-shaped, columnar, etc. However, for the mandible of experimental animals, there is no suitable clamping device for this complex biological tissue structure. At present, some scholars reduce the mandible to a block shape for mechanical testing, but this method destroys the original tissue structure and the obtained results are not very accurate. Another method is to design, process and manufacture special fixtures according to the shape and structure of the mandible by the manufacturer, but this processing cost is relatively expensive, and most experiments do not have such a large test budget. The development and application of 3D printing technology make it possible to design and manufacture personalized fixtures economically. Summary of the Invention

[0003] Aiming at the above deficiencies in the prior art, the present invention provides a method for testing the mechanical properties of fixation of mandibular fractures in experimental animals through personalized design and 3D printing technology.

[0004] To solve the above technical problems, the present invention adopts the following technical solutions:

[0005] A method for testing the mechanical properties of fixation of mandibular fractures in experimental animals, the method comprising the following steps:

[0006] 1) CT scan the head of the experimental animal to obtain the Dicom format data of the mandibular body;

[0007] 2) Import the Dicom format file into the medical image processing software Mimics, and reconstruct the three-dimensional model of the mandible by using threshold segmentation, mask editing, surface smoothing and 3D reconstruction methods;

[0008] 3) Designing a fixture standard body model in Solidworks, the fixture standard body model includes a standard fixture I and a standard fixture II, wherein the standard fixture I and the standard fixture II are vertically provided with a center hole for installing a bolt at the center position of the middle part, and the center holes on the standard fixture I and the standard fixture II are composed of a coaxial center hole I with a large diameter in the upper section and a through hole II with a small diameter in the lower section;

[0009] 4) Import the three-dimensional model of the mandible and the standard fixture into the 3-matic software, and set the horizontal position spacing between the standard fixture I and the standard fixture II according to the mechanical test requirements; perform Boolean subtraction and outward drafting operations on the mandible and the standard fixture I and the standard fixture II, and form grooves that penetrate the center hole on the upper parts of the standard fixture I and the standard fixture II to obtain personalized standard fixtures I and II, so as to ensure that the mandible can be installed in the grooves of the personalized standard fixtures I and II;

[0010] 5) 3D printing is performed on the personalized standard fixture I and standard fixture II to obtain the physical model of the standard fixture I and standard fixture II;

[0011] 6) making a base, the base being a rectangular parallelepiped, and a slide groove being arranged on the upper part of the base;

[0012] 7) Assemble the mandibular fracture fixation mechanical testing device: install the base on the base of the electronic universal testing machine, insert bolts into the center holes of the standard fixture I and the standard fixture II of the physical model respectively, and fix the standard fixture I and the standard fixture II of the physical model to the base by bolt connection respectively, and place the mandible in the grooves of the standard fixture I and the standard fixture II of the physical model. The pressure component of the electronic universal testing machine applies a vertical load on the dentition of the mandible to measure the bending strength of the mandibular fracture fixation.

[0013] As a preferred solution of the present invention, the slide groove is in a L structure.

[0014] As a preferred embodiment of the present invention, the mandibular angle of the mandible is installed in the groove of the standard fixture I of the physical model, and the mandibular body of the mandible is installed in the groove of the standard fixture II of the physical model.

[0015] As an improved solution of the present invention, the distance between the horizontal positions of the standard fixture I and the standard fixture II of the physical model is the distance between the mandibular angle and the mandibular body of the mandible.

[0016] As another improved solution of the present invention, the tops of the standard fixtures I and II are both provided with inwardly concave arc grooves, and the center hole and the groove are both located at the lower part of the arc grooves.

[0017] Compared with the prior art, the present invention has the following technical effects:

[0018] 1. By combining the design of personalized standard fixtures with 3D printing, this method manufactures a feasible mechanical measurement device for internal fixation of mandibular fractures in experimental animals. The mandible is placed in the groove of this mechanical measurement device, and the mandible preserves its complete original tissue structure, effectively avoiding damage to the mandibular tissue. Through this mechanical measurement device, the original tissue structure of the mandible can be measured more accurately, and the measurement results are more precise.

[0019] 2. The mechanical test device for mandibular fracture fixation used in the present invention has a lower manufacturing cost and stronger expandability, and can be extended and applied to fracture fixation tests in other orthopedic sub-specialty fields, which is beneficial for more experimental personnel to use. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 is a three-dimensional model diagram of the jawbone, Figure 1 where A in Figure 1 represents the mandibular angle, and

[0021] Figure 2 is a schematic structural diagram of the standard fixture I;

[0022] Figure 3 is a schematic cross-sectional diagram of the standard fixture I;

[0023] Figure 4 is a schematic structural diagram of the standard fixture II;

[0024] Figure 5 is a schematic cross-sectional diagram of the standard fixture II;

[0025] Figure 6 is a schematic structural diagram of the base;

[0026] Figure 7 is a schematic structural diagram of the bolt;

[0027] Figure 8 is a schematic cross-sectional diagram of the mechanical test mechanism for mandibular fracture fixation;

[0028] Figure 9 is a schematic structural diagram of the mandible placed on the mechanical test device for mandibular fracture fixation.

[0029] In the figure: 1 - standard fixture I; 2 - standard fixture II; 3 - central hole; 31 - central hole I; 32 - through hole II; 4 - groove; 5 - mandible; 6 - base; 7 - sliding groove; 8 - bolt; 9 - arc groove; 10 - nut. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0030] The present invention will be further described in detail below in conjunction with the drawings and specific embodiments.

[0031] A method for testing the mechanical properties of fracture fixation of the mandible of experimental animals, the method comprising the following steps:

[0032] 1) Perform a CT scan on the cranial part of the experimental animal to obtain the data of the mandibular body in Dicom format.

[0033] 2) Import the Dicom format file into the medical image processing software Mimics, and reconstruct the three-dimensional model of the mandible by methods such as threshold segmentation, mask editing, surface smoothing, and 3D reconstruction. As shown in Figure 1 shown, Figure 1 in which A represents the mandibular angle and B represents the body of the mandible.

[0034] 3) Design a fixture standard body model in Solidworks. The fixture standard body model includes a standard fixture Ⅰ1 and a standard fixture Ⅱ2. The standard fixture Ⅰ1 and the standard fixture Ⅱ2 are vertically provided with a central hole 3 for installing a bolt 8 at the central position in the middle. The central holes 3 on the standard fixture Ⅰ1 and the standard fixture Ⅱ2 are both composed of a central hole Ⅰ31 with a larger diameter in the upper section and a through hole Ⅱ32 with a smaller diameter in the lower section that are coaxial, as shown in Figures 2 - 5 shown.

[0035] 4) Import the three-dimensional models of the mandible 5 and the fixture standard body into the 3-matic software. According to the mechanical test requirements, set the horizontal position spacing between the standard fixture Ⅰ1 and the standard fixture Ⅱ2. The horizontal position spacing is the distance between the mandibular angle of the mandible 5 and the body of the mandible; perform a Boolean subtraction and outward draft operation on the mandible 5 and the standard fixture Ⅰ1 and the standard fixture Ⅱ2. Grooves 4 penetrating the central hole 31 are formed on the upper parts of the standard fixture Ⅰ1 and the standard fixture Ⅱ2 to obtain personalized standard fixture Ⅰ1 and standard fixture Ⅱ2, so as to ensure that the mandible 5 can be installed and placed into the grooves 4 of the personalized standard fixture Ⅰ1 and the standard fixture Ⅱ2. The transverse dimension of the groove 4 gradually increases from bottom to top, and the upper opening is slightly larger than the lower opening, which is beneficial for the mandible 5 to be inserted and also beneficial for the mandible 5 to be pulled out from the groove 4. In this embodiment, concave arc-shaped grooves 9 are provided at the tops of the standard fixture Ⅰ1 and the standard fixture Ⅱ2. The central hole 3 and the groove 4 are both located below the arc-shaped groove 9. The arc-shaped groove 9 provided at the top can leave more space for installing the bolt 8 and placing the mandible 5, which is beneficial for the convenient installation and disassembly of the bolt 8 and the mandible 5.

[0036] 5) Perform 3D printing manufacturing on the personalized standard fixture Ⅰ1 and the standard fixture Ⅱ2 to obtain the physical model of the standard fixture Ⅰ1 and the standard fixture Ⅱ2.

[0037] 6) Manufacture a base 6. The base 6 is in the shape of a cuboid, and a chute 7 is provided on the upper part of the base 6. The transverse dimension of the lower part of the chute 7 is larger than that of the upper part, as shown in Figure 6As shown, the size of the slide groove 7 is slightly larger than the size of the bolt 8 to ensure that the bolt 8 can slide freely in the slide groove 7. The base 6 can be manufactured by 3D printing or other methods, such as mechanical processing. The slide groove 7 has a L structure, and the slide groove 7 of the L structure can be used in conjunction with the bolt 8 of the corresponding L structure. The structure of the bolt is as shown in FIG. Figure 7 As shown, the large end of the bolt 8 can be inserted into the lower part of the slide groove 7, and the entire bolt 8 can slide in the slide groove 7.

[0038] 7) Assemble the mandibular fracture fixation mechanical testing mechanism: install the base 6 on the base of the electronic universal testing machine, insert bolts 8 into the center holes 3 of the standard fixtures Ⅰ1 and Ⅱ2 of the physical model respectively, screw nuts 10 on the tops of the bolts 8, place the standard fixtures Ⅰ1 and Ⅱ2 of the physical model on the top of the base 6, insert the large ends of the bolts 8 into the lower part of the slide groove 7, slide the bolts 8 and the corresponding standard fixtures Ⅰ1 or Ⅱ2, and after sliding into place, tighten the nuts 10 on the bolts 8. The standard fixtures Ⅰ1 and Ⅱ2 of the physical model are respectively connected and fixed to the base 6 by the bolts 8 and nuts, that is, the standard fixtures Ⅰ1 and Ⅱ2 of the physical model are pressed onto the base 6 by tightening the nuts on the bolts 8, as shown in FIG. Figure 8 As shown; then the mandible 5 is installed and placed in the groove 4 of the standard fixture Ⅰ1 and the standard fixture Ⅱ2 of the physical model (that is, the mandibular angle of the mandible 5 is installed and placed in the groove 4 of the standard fixture Ⅰ1 of the physical model, and the mandibular body of the mandible 5 is installed and placed in the groove 4 of the standard fixture Ⅱ2 of the physical model), as shown Figure 9 As shown, the distance between the horizontal positions of the standard fixture Ⅰ1 and the standard fixture Ⅱ2 of the physical model is the distance between the mandibular angle of the mandible 5 and the mandibular body; the pressure component of the electronic universal testing machine applies a vertical load on the dentition of the mandible 5 to measure the bending strength of the mandibular fracture fixation.

[0039] The method combines the design of a personalized standard fixture with 3D printing to manufacture a feasible mechanical measurement device for internal fixation of mandibular fractures in experimental animals. The mandible 5 is installed in a groove 4 on the mechanical measurement device. The groove 4 fits the size of the clamping part at the bottom of the mandible 5, and the upper opening of the groove 4 is slightly larger than the size of the lower opening. After the mandible 5 is installed in the corresponding groove 4, the mandible 5 preserves the complete original tissue structure. The pressure component of the electronic universal testing machine is then pressed on the dentition of the mandible, and the pressure is gradually increased to bend the mandible 5 between the standard fixture Ⅰ1 and the standard fixture Ⅱ2 of the physical model, so that the bending strength of the mandibular fracture fixation can be measured. The method can more accurately measure the original tissue structure of the mandible through the mechanical measurement device, and the measurement result is more accurate.

[0040] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the spirit and scope of the technical solutions of the present invention, and they should all be covered within the scope of the claims of the present invention.

Claims

1. A mechanical property testing method for fixing mandibular fractures in experimental animals, characterized in that, The method comprises the following steps: 1) Perform CT scan on the skull of the experimental animal to obtain the mandibular body data in Dicom format; 2) Import the Dicom format file into the medical image processing software Mimics, and reconstruct the mandibular 3D model using threshold segmentation, mask editing, surface smoothing, and 3D reconstruction methods; 3) Designing a fixture standard body model in Solidworks, the fixture standard body model comprising a standard fixture I (1) and a standard fixture II (2), wherein the standard fixture I (1) and the standard fixture II (2) are vertically provided with a center hole (3) for installing a bolt (8) at the center position of the middle part, and the center hole (3) on the standard fixture I (1) and the standard fixture II (2) are both composed of a coaxial center hole I (31) with a large diameter at the upper section and a through hole II (32) with a small diameter at the lower section; 4) Import the three-dimensional model of the mandible (5) and the standard fixture into the 3-matic software, and set the horizontal position spacing between the standard fixture I (1) and the standard fixture II (2) according to the mechanical test requirements; perform Boolean subtraction and outward drafting operations on the mandible (5) and the standard fixture I (1) and the standard fixture II (2), and form a groove (4) penetrating the center hole I (31) on the upper part of the standard fixture I (1) and the standard fixture II (2), so as to obtain personalized standard fixtures I (1) and standard fixtures II (2), so as to ensure that the mandible (5) can be installed in the grooves (4) of the personalized standard fixtures I (1) and standard fixtures II (2); 5) 3D printing the personalized standard fixture I (1) and the standard fixture II (2) to obtain the physical model of the standard fixture I (1) and the standard fixture II (2); 6) manufacturing a base (6), wherein the base (6) is in the form of a rectangular parallelepiped, and a slide groove (7) is provided on the upper portion of the base (6); 7) Assemble the mandibular fracture fixation mechanical test device: install the base (6) on the base of the electronic universal testing machine, insert bolts (8) into the center holes (3) of the standard fixture I (1) and the standard fixture II (2) of the physical model respectively, and fix the standard fixture I (1) and the standard fixture II (2) of the physical model to the base (6) respectively by bolts (8), install the mandible (5) in the grooves (4) of the standard fixture I (1) and the standard fixture II (2) of the physical model, and the pressure component of the electronic universal testing machine applies a vertical load on the dentition of the mandible (5) to measure the bending strength of the mandibular fracture fixation.

2. The mechanical property testing method for fixing mandibular fractures of experimental animals according to claim 1, wherein: The slide groove (7) has a L structure.

3. The mechanical property test method for fixing mandibular fractures of experimental animals according to claim 1, characterized in that: The mandibular angle of the mandible (5) is installed and placed in the groove (4) of the standard fixture I (1) of the physical model, and the mandibular body of the mandible (5) is installed and placed in the groove (4) of the standard fixture II (2) of the physical model.

4. The mechanical property testing method for fixing mandibular fractures of experimental animals according to claim 1, wherein: The distance between the horizontal positions of the standard fixture I (1) and the standard fixture II (2) of the physical model is the distance between the mandibular angle of the mandible (5) and the mandibular body.

5. A mechanical property testing method for fixing mandibular fractures in experimental animals according to any one of claims 1 to 4, characterized in that: In step 4), concave arc grooves (9) are provided at the tops of the standard fixture I (1) and the standard fixture II (2), and the central hole (3) and the groove (4) are both located below the arc groove (9).

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