Molar impediment digital orthodontic correction device and design method thereof

Abstract

The invention relates to the technical field of orthodontics, and provides a molar impacted digital orthodontic correction device and a design method thereof.The design method comprises the following steps that a CBCT dental image of a patient is shot, three-dimensional tooth data of the patient is obtained according to the CBCT dental image of the patient, and the part, exposed to the oral cavity, of a second molar of the lower jaw is marked; based on the three-dimensional tooth data and the part, exposed to the oral cavity, of the mandibular second molar, the scheme of the correction device is designed; 3D printing is carried out according to the scheme design of the correction device. The design method of the mandibular second molar impacted digital orthodontic correction device based on the personalized 3D printing correction device is developed and is suitable for being used in the clinical environment that impacted molar exposure is insufficient, the correction device is manufactured through personalized design and 3D printing, the bonding retention force is improved, the stress application operation process is simplified, and the operation efficiency is improved. The treatment comfort of the patient is improved, and precise medical treatment is realized.

Description

Technical Field

[0001] The present invention relates to the technical field of oral orthodontics, and in particular to a digital orthodontic correction device for impacted molars and a design method thereof. Background Art

[0002] Impacted molars refer to the pathological condition in which the molars at the posterior part of the dentition cannot erupt to the normal functional position. Taking the impacted mandibular second molar as an example, the incidence rate among orthodontic patients is as high as 2%-3%. Mesial impacted mandibular second molars not only affect the neat arrangement of teeth, but also interfere with occlusion and reduce chewing function, which requires timely orthodontic treatment to correct.

[0003] Since the local space in the oral cavity of the impacted mandibular second molar is narrow and the amount of the impacted mandibular second molar exposed in the oral cavity is insufficient, the orthodontic treatment cycle is prolonged and the difficulty of orthodontic treatment increases. However, the existing orthodontic correction device for impacted mandibular second molars usually requires the exposure of the impacted molar to reach more than 5-6mm before the retention components can be bonded, and since the posterior section of the molar is relatively narrow, the force application range is limited, resulting in low correction efficiency. In addition, due to the non-personalized design of the orthodontic correction device, the patient's wearing comfort and treatment experience are greatly reduced. Summary of the invention

[0004] The present invention provides a digital orthodontic correction device for impacted molars and a design method thereof, aiming to solve the existing problems, be accurate and efficient, improve bonding retention force, have a good sustainable force application mode, increase the treatment comfort of patients, and realize precision medicine.

[0005] The present invention is implemented as follows: a design method for a digital orthodontic correction device for impacted molars, which comprises the following steps:

[0006] Step 1, take a CBCT dental and maxillofacial image of the patient, obtain the patient's three-dimensional tooth data based on the CBCT dental and maxillofacial image of the patient, and mark the part of the mandibular second molar exposed in the oral cavity;

[0007] Step 2: Design a correction device based on the three-dimensional tooth data and the portion of the mandibular second molar exposed in the oral cavity;

[0008] Step 3: Perform 3D printing according to the design of the correction device.

[0009] Preferably, obtaining the patient's three-dimensional dental data based on the patient's CBCT dental and maxillofacial images in step 1 includes: using an image data extraction system to receive the CBCT dental and maxillofacial images taken by the patient, segmenting the teeth based on artificial intelligence technology to obtain the patient's three-dimensional dental data, and marking the portion of the impacted mandibular second molar exposed to the oral cavity.

[0010] Preferably, the segmentation of teeth based on artificial intelligence technology comprises the following steps:

[0011] S1: read in and visualize the three-dimensional mesh model of the jaw;

[0012] S2: Extract meshes from the input three-dimensional mesh model of the tooth and jaw to reduce the number of meshes;

[0013] S3: Use Laplace smoothing algorithm to smooth the grid and eliminate the noise of the grid;

[0014] S4: Mark the grids and put the grids adjacent to the marked grids into the vector container;

[0015] S5: Access all the faces of the tooth mesh, group the mesh faces according to the minimum rule, and then achieve tooth segmentation.

[0016] Preferably, the extraction rate of the grid extraction is 10%, that is, the number of grids is reduced by 10%.

[0017] Preferably, the smoothing of the grid using the Laplace smoothing algorithm comprises:

[0018] Find the set of 1-neighboring vertices for each vertex of the mesh:

[0019] G=<V,E>

[0020]

[0021] Where: G is the set of grids, V is the set of grid vertices, E is the coordinate set of grid vertices; L 1 (V i ) is the set of 1-neighborhood vertices of a mesh vertex, edge means there is at least one pair of vertices with common edges, V i is the i-th vertex in the mesh, V j For V i Mesh vertices that share edges;

[0022] Construct a 1-neighborhood array Array[n] for each vertex, where n is the number of 1-neighborhood vertices of each vertex;

[0023] Iterate over all vertices and modify the coordinates of each vertex according to the average value of the coordinates of all vertices in the neighborhood array Array[n], that is, use an umbrella operator:

[0024]

[0025] Where: U(V i ) is the average value of all vertex coordinates in the 1-neighborhood array Array[n], n is the number of 1-neighborhood vertices of each vertex, and k is the number of iterations.

[0026] Preferably, the step of making the grids adjacent to the marked grid enter the vector container comprises:

[0027] Mark a triangle mesh f on each tooth and find the triangle mesh f adjacent to each marked triangle mesh f i , store the ID, tag and curvature of each grid f into the corresponding structure array and put it into the vector container, where the curvature calculation expression is as follows:

[0028]

[0029] Where: H(f 1 ,f 2 ) is, f 1 and f 2 are two adjacent triangular meshes, n 1 and n 2 f 1 and f 2 The unit normal vector of f 1 or 2 non-public edges.

[0030] Preferably, the grouping of mesh facets comprises:

[0031] If the vector container is not empty, take out the triangle f with the largest curvature from the vector container. max , judge f max Is the access flag of true? If true, f max Delete from the vector container and continue iterating; if the access mark is false, set f max The access mark is TRUE, and f max Insert into the corresponding array and change f max Adjacent patches f marked as false i Put it into the vector container and continue iterating.

[0032] Preferably, the correction device comprises three parts, namely, a support part, a force-applying part and a correction part;

[0033] The support part is an elliptical metal bottom plate structure, the bottom plate is located on the distal surface of the mandibular first molar, the height is consistent with the cusp of the marked mandibular second molar, the curvature of the bottom plate is consistent with the distal surface of the mandibular first molar, and the support part is connected to the force-applying part through a connecting rod;

[0034] The force-applying part includes a sleeve, two independent connecting rods and a spring. The connecting rod near the supporting part is fixedly connected to the sleeve, and the connecting rod near the correction part is slidably connected to the sleeve. The two ends of the spring are respectively welded and fixed to the connecting rod and the sleeve near the correction part. The connection between the connecting rod near the correction part and the correction part is a rotatable structure, and the maximum rotation angle of the rotatable structure is designed to be 50 degrees.

[0035] The correction part is a metal structure, and its shape and size match the part of the marked mandibular second molar exposed in the oral cavity.

[0036] Preferably, the side of the base plate that contacts the tooth surface of the mandibular first molar is of a mesh hollow design.

[0037] Compared with the prior art, the present invention has the following beneficial effects:

[0038] 1. Increase the treatment comfort of patients. Personalized design and 3D printing of correction devices make it easy to design a special correction device that matches the part of the patient's mandibular second molar exposed in the oral cavity. The correction device matches the contact part of the tooth surface, which is highly comfortable and does not affect the patient's daily life.

[0039] 2. Accurate and efficient. The orthodontic device is designed according to the oral conditions of different patients. The support part is located on the distal surface of the mandibular first molar, and its height is consistent with the cusp of the marked mandibular second molar. The shape and size of the orthodontic part match the part of the marked mandibular second molar exposed in the oral cavity. The positioning is accurate, the bonding and retention are stable, the bonding and retention force is improved, and precision medical treatment is achieved.

[0040] 3. Suitable for clinical environments where the exposure of impacted molars is insufficient. The connection between the connecting rod and the correction part is a rotatable structure, and the maximum rotation angle of the rotatable structure is 50 degrees, which is convenient for adjusting the angle. Correction can also be performed when the exposure of impacted molars is insufficient.

[0041] 4. Good sustainable force application mode. The rotatable structure expands the force application range of the correction device, making it easier to apply force during the correction process. There is no need to frequently replace the correction device, which simplifies the force application process and improves the correction efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0043] Figure 1 It is a schematic diagram of the structure of the correction device of the present invention;

[0044] Figure 2 It is a structural schematic diagram of the force-applying portion of the correction device of the present invention;

[0045] Figure 3 It is a schematic diagram of the structure of the correction part of the correction device of the present invention;

[0046] Figure 4 It is a schematic diagram of a flow chart of an embodiment of the present invention. DETAILED DESCRIPTION

[0047] In order to more fully understand the technical content of the present invention, the technical solution of the present invention is further introduced and illustrated in conjunction with specific embodiments below, but is not limited thereto. The technical solution in the embodiment of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiment of the present invention. Obviously, the described embodiment is only a part of the embodiment of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making creative work are within the scope of protection of the present invention.

[0048] refer to Figure 1 to Figure 2 The design method of the digital orthodontic correction device for impacted molars comprises the following steps:

[0049] Step 1: Take a CBCT dental and maxillofacial image of the patient, obtain the patient's three-dimensional tooth data based on the CBCT dental and maxillofacial image, and mark the part of the mandibular second molar exposed in the oral cavity.

[0050] The image data extraction system receives the CBCT dental and maxillofacial images taken by the patient, which is an important data source for the design method and planning of the orthodontic device. The image data extraction system receives the CBCT dental and maxillofacial images taken by the patient, segments the teeth based on artificial intelligence technology, obtains the patient's three-dimensional tooth data, and displays and marks the part of the impacted mandibular second molar exposed in the oral cavity in red.

[0051] The segmentation of teeth based on artificial intelligence technology comprises the following steps:

[0052] S1: Read in and visualize the three-dimensional mesh model of the dental jaw.

[0053] S2: Extract meshes from the input three-dimensional mesh model of the tooth and jaw to reduce the number of meshes. The extraction rate of mesh extraction is 10%, that is, the number of meshes is reduced by 10%.

[0054] S3: Use the Laplace smoothing algorithm to smooth the grid and eliminate the noise of the grid.

[0055] Find the set of 1-neighboring vertices for each vertex of the mesh:

[0056] G=<V,E>

[0057]

[0058] Where: G is the set of grids, V is the set of grid vertices, E is the coordinate set of grid vertices; L 1 (V i ) is the set of 1-neighborhood vertices of a mesh vertex, edge means there is at least one pair of vertices with common edges, V i is the i-th vertex in the mesh, V j For V i Mesh vertices that share edges;

[0059] Construct a 1-neighborhood array Array[n] for each vertex, where n is the number of 1-neighborhood vertices of each vertex;

[0060] Iterate over all vertices and modify the coordinates of each vertex according to the average value of the coordinates of all vertices in the neighborhood array Array[n], that is, use an umbrella operator:

[0061]

[0062] Where: U(V i ) is the average value of all vertex coordinates in the 1-neighborhood array Array[n], n is the number of 1-neighborhood vertices of each vertex, and k is the number of iterations

[0063] S4: Mark the grids and put the grids adjacent to the marked grids into the vector container.

[0064] Mark a triangle mesh f on each tooth and find the triangle mesh f adjacent to each marked triangle mesh f i , store the ID, tag and curvature of each grid f into the corresponding structure array and put it into the vector container, where the curvature calculation expression is as follows:

[0065]

[0066] Where: H(f 1 ,f 2 ) is, f 1 and f 2 are two adjacent triangular meshes, n 1 and n 2 f 1 and f 2 The unit normal vector of f 1 or 2 non-public edges.

[0067] S5: Access all the faces of the tooth mesh, group the mesh faces according to the minimum rule, and then achieve tooth segmentation.

[0068] If the vector container is not empty, take out the triangle with the largest curvature from the vector container and determine whether the access mark is true. If it is true, delete it from the vector container and continue iterating. If the access mark is false, set the access mark to TRUE, insert it into the corresponding array, put the adjacent faces with false access marks into the vector container, and continue iterating.

[0069] Step 2: Design a corrective device based on the three-dimensional tooth data and the portion of the mandibular second molar exposed in the oral cavity.

[0070] The orthodontic device is divided into three parts, namely the support part, the force-applying part and the correction part: the support part is an elliptical metal base plate structure, the base plate is located on the distal surface of the mandibular first molar, the height is consistent with the cusp of the mandibular second molar marked in red, the curvature of the base plate is consistent with the distal surface of the mandibular first molar, the contact side of the base plate and the tooth surface of the mandibular first molar is a mesh hollow design to increase the bonding effect, and the support part is connected to the force-applying part through a connecting rod; the force-applying part includes three parts: a sleeve, two independent connecting rods and a spring. On the support part side, the sleeve and the connecting rod are an integrated structure and the two do not slide, while on the correction part side, the sleeve and the connecting rod can slide. The post-treatment position of the impacted mandibular second molar is digitally simulated, and the anteroposterior movement distance of the tooth is calculated, which is the length of the spring. The two ends of the spring are then welded and fixed to the sleeve and the connecting rod on the side of the correction part respectively; the correction part is a metal structure, and its shape and size are designed according to the part of the mandibular second molar exposed to the oral cavity marked in red. It is connected to the force-applying part through a connecting rod, and the connection between the connecting rod and the correction part is designed to be a rotatable structure. The maximum rotation angle is designed to be 50 degrees, so that the impacted molar can be moved distally while the molar can be rotated to adjust the rotation of the tooth, simplifying the treatment process and reducing the difficulty of treatment.

[0071] Step 3: Perform 3D printing according to the design of the correction device.

[0072] The support and correction parts designed by the digital design system are 3D printed. After printing, the parts are assembled and welded to finally complete the design and processing of the correction device.

[0073] The present invention develops a design method for a digital orthodontic appliance for impacted mandibular second molars based on a personalized 3D printed appliance. The method is suitable for clinical environments where the exposure of impacted molars is insufficient. The appliance is manufactured through personalized design and 3D printing, thereby improving the bonding retention force, simplifying the force application operation process, increasing the patient's treatment comfort, and achieving precision medicine.

[0074] The embodiments described above are only part of the embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any ordinary technician in the field can make equivalent replacements or changes according to the technical solutions and inventive concepts of the present invention within the technical scope disclosed by the present invention, and they should be covered by the protection scope of the present invention.

Claims

1. A method for designing a digital orthodontic appliance for impacted molars, characterized in that: The design method of the digital orthodontic correction device for impacted molars comprises the following steps: Step 1: Take a CBCT dental and maxillofacial image of the patient, obtain the patient's three-dimensional tooth data based on the CBCT dental and maxillofacial image, and mark the part of the mandibular second molar exposed in the oral cavity; Step 2: Design a correction device based on the three-dimensional tooth data and the portion of the mandibular second molar exposed in the oral cavity; Step 3: Perform 3D printing according to the design of the correction device.

2. The design method according to claim 1, characterized in that: The step 1 of obtaining the patient's three-dimensional dental data based on the patient's CBCT dental and maxillofacial images includes: using an image data extraction system to receive the patient's CBCT dental and maxillofacial images, segmenting the teeth based on artificial intelligence technology, obtaining the patient's three-dimensional dental data, and marking the portion of the impacted mandibular second molar exposed in the oral cavity.

3. The design method according to claim 2, characterized in that: The segmentation of teeth based on artificial intelligence technology comprises the following steps: S1: read in and visualize the three-dimensional mesh model of the jaw; S2: Extract meshes from the input three-dimensional mesh model of the tooth and jaw to reduce the number of meshes; S3: Use Laplace smoothing algorithm to smooth the grid and eliminate the noise of the grid; S4: Mark the grids and put the grids adjacent to the marked grids into the vector container; S5: Access all the faces of the tooth mesh, group the mesh faces according to the minimum rule, and then achieve tooth segmentation.

4. The design method according to claim 3, characterized in that: The extraction rate of the grid extraction is 10%, that is, the number of grids is reduced by 10%.

5. The design method according to claim 3, characterized in that: The smoothing process of the grid by using the Laplace smoothing algorithm comprises: Find the set of 1-neighboring vertices for each vertex of the mesh: G=<V,E> Where: G is the set of grids, V is the set of grid vertices, E is the coordinate set of grid vertices; L 1 (V i ) is the set of 1-neighborhood vertices of a mesh vertex, edge means there is at least one pair of vertices with common edges, V i is the i-th vertex in the mesh, V j For V i Mesh vertices that share edges; Construct a 1-neighborhood array Array[n] for each vertex, where n is the number of 1-neighborhood vertices of each vertex; Iterate over all vertices and modify the coordinates of each vertex according to the average value of the coordinates of all vertices in the neighborhood array Array[n], that is, use an umbrella operator: Where: U(V i ) is the average value of all vertex coordinates in the 1-neighborhood array Array[n], n is the number of 1-neighborhood vertices of each vertex, and k is the number of iterations.

6. The design method according to claim 3, characterized in that: The step of making the grids adjacent to the marked grid enter the vector container comprises: Mark a triangle mesh f on each tooth and find the triangle mesh f adjacent to each marked triangle mesh f i , store the ID, tag and curvature of each grid f into the corresponding structure array and put it into the vector container, where the curvature calculation expression is as follows: Where: H(f1,f2), f1 and f2 are two adjacent triangle meshes, n1 and n2 are the unit normal vectors of f1 and f2, and d is the non-common edge of f1 or f2.

7. The design method according to claim 3, characterized in that: The mesh patches are grouped as follows: If the vector container is not empty, take out the triangle f with the largest curvature from the vector container. max , judge f max Is the access flag of true? If true, f max Delete from the vector container and continue iterating; if the access mark is false, set f max The access mark is TRUE, and f max Insert into the corresponding array and change f max Adjacent patches f marked as false i Put it into the vector container and continue iterating.

8. A correction device prepared by the design method according to any one of claims 1 to 7, characterized in that: It consists of three parts, namely the support part, the force-applying part and the correction part; The support part is an elliptical metal bottom plate structure, the bottom plate is located on the distal surface of the mandibular first molar, the height is consistent with the cusp of the marked mandibular second molar, the curvature of the bottom plate is consistent with the distal surface of the mandibular first molar, and the support part is connected to the force-applying part through a connecting rod; The force-applying part includes three parts: a sleeve, two independent connecting rods and a spring. The connecting rod near the supporting part is fixedly connected to the sleeve, and the connecting rod near the correction part is slidably connected to the sleeve. Both ends of the spring are respectively welded and fixed to the connecting rod and the sleeve near the correction part. The connection between the connecting rod near the correction part and the correction part is a rotatable structure. The correction part is a metal structure, and its shape and size match the part of the marked mandibular second molar exposed in the oral cavity.

9. The correction device according to claim 8, characterized in that The maximum rotation angle of the rotatable structure is designed to be 50 degrees, and the side of the base plate that contacts the tooth surface of the mandibular first molar is a mesh hollow design.

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