Method and device for cutting a crown restoration retaining form

Abstract

The application discloses a kind of crown prosthesis retained form cutting method and device, wherein the method includes: import prosthesis model, occlusal model and minimum thickness layer model, and based on prosthesis model, occlusal model and minimum thickness layer model are calculated, obtain complete deformation region;Based on complete deformation region, surface morphology weakening treatment is carried out to prosthesis model, obtain prosthesis model after surface morphology weakening treatment;Calculate the first collision deformation region of minimum thickness layer model and the prosthesis model and the second collision deformation region of occlusal model and the prosthesis model, and based on the first collision deformation region and the second collision deformation region, deformation processing is carried out, and deformation processing result is obtained;Deformation processing result is detected, and it is judged whether there is collision area.The application eliminates the collision area between models by deforming the prosthesis model, so as to ensure the minimum thickness and initial contour of the prosthesis, and improve the deformation quality.

Description

Technical Field

[0001] This invention relates to the field of computer technology, and in particular to a cutting method and apparatus for preserving the morphology of dental crown restorations. Background Technology

[0002] In clinical practice, the space between the prepared tooth and the opposing tooth for placing the restoration is limited. Different patients have different degrees of tooth wear and different dentition characteristics, which can lead to a phenomenon where the restoration model and the opposing tooth model penetrate each other after the restoration is generated during the design process, i.e., a collision area is created. To eliminate this collision area, we call the process of eliminating the collision area "cutting". Currently, there are usually two approaches to the cutting of the collision area between the restoration model and the opposing tooth model: one is based on Boolean operations of the model to remove the vertices of the collision area of ​​the restoration and regenerate a new surface; the other is based on deformation algorithms of the model to deform the relevant areas of the restoration model to a position where there is no collision with the opposing tooth model.

[0003] Model-based Boolean cutting allows for precise fitting of the prosthesis to the opposing jaw model, but this operation disrupts the original surface morphology of the prosthesis, losing feature points in relevant areas, often resulting in an unnatural appearance. Deformation-based cutting, on the other hand, is directly related to the deformation algorithm and its parameters. International dental CAD software employs various deformation-based cutting methods, each with different effects, but they generally suffer from at least one of the following problems: they significantly impact non-collision areas already designed by the prosthesis designer; the initial shape of the prosthesis is not well preserved when occlusal space is insufficient; and the minimum thickness requirement of the prosthesis is not considered during the cutting process. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art. This invention provides a cutting method and apparatus for preserving the shape of a dental crown restoration. It can eliminate collision areas between models by deforming the restoration model while preserving the outline shape of the restoration, and ensure the minimum thickness of the restoration.

[0005] To address the aforementioned technical problems, embodiments of the present invention provide a cutting method for preserving the morphology of a dental crown restoration, the method comprising:

[0006] Import the prosthesis model, the opposing jaw model, and the minimum thickness layer model generated from the preparatory model, and perform calculations based on the prosthesis model, the opposing jaw model, and the minimum thickness layer model to obtain the complete deformation area;

[0007] The surface morphology of the restoration model is weakened based on the complete deformation region to obtain the restoration model after surface morphology weakening.

[0008] Calculate the first collision deformation region between the minimum thickness layer model and the restoration model after surface morphology weakening treatment, and the second collision deformation region between the opposing jaw model and the restoration model after surface morphology weakening treatment, and perform deformation processing based on the first and second collision deformation regions to obtain the deformation processing result.

[0009] The deformation processing results are inspected to determine whether a collision area exists.

[0010] Optionally, the imported prosthesis model, opposing jaw model, and minimum thickness layer model generated from the prepared prosthesis model are used to calculate and obtain the complete deformation region, including:

[0011] Import the prosthesis model, the opposing jaw model, and the minimum thickness layer model generated by isometric calculation from the prepared prosthesis model, and obtain the collision area based on the prosthesis model, the opposing jaw model, and the minimum thickness layer model;

[0012] Find several vertices that are at a preset distance from the edge vertices of the collision area, and generate a deformation buffer based on these vertices;

[0013] Based on the topological relationship of the repair model, find the two-neighbor vertices of the boundary vertex of the deformation buffer, and use the two-neighbor vertices as fixed anchor points.

[0014] A complete deformation region is generated based on the deformation buffer, fixed anchor points, and collision areas.

[0015] Optionally, the step of finding several vertices that are at a preset distance from the edge vertices of the collision region and generating a deformation buffer based on these vertices includes:

[0016] The nearest neighbor search algorithm is used to find several vertices that are within a preset distance from the edge vertices of the collision region. The preset distance is positively correlated with the maximum collision depth of the collision region, and the formula for calculating the preset distance is as follows:

[0017] L = a * dm + b

[0018] Where L is the preset distance, dm is the maximum collision depth, and a and b are fitting parameters;

[0019] By removing duplicates from several vertices, a deformation buffer is obtained.

[0020] Optionally, the step of performing surface morphology weakening processing on the restoration model based on the complete deformed region to obtain a restoration model with weakened surface morphology includes:

[0021] Calculate the first collision region between the prosthesis model and the opposing jaw model, and the second collision region between the prosthesis model and the minimum thickness layer model;

[0022] Calculate the first maximum collision depth of the first collision region and the second collision region, and determine whether the first maximum collision depth is greater than a first preset depth threshold.

[0023] If the first maximum collision depth is greater than the first preset depth threshold, and the restoration model contains pit and fissure feature points in the molar and the first or second collision area, then the pit and fissure preprocessing deformation parameters are constructed using the complete deformation area to perform pit and fissure preprocessing deformation, and the first deformation processing result model is obtained.

[0024] Based on the first deformation processing result model, surface morphology weakening processing is performed to obtain the repair model after surface morphology weakening processing.

[0025] Optionally, the step of performing surface morphology weakening processing based on the first deformation processing result model to obtain a repair model after surface morphology weakening processing includes:

[0026] Calculate the third collision region between the first deformation result model and the jaw model, and the fourth collision region between the first deformation result model and the minimum thickness layer model.

[0027] Calculate the second maximum collision depth of the third and fourth collision regions, and determine whether the second maximum collision depth is greater than the second preset depth threshold.

[0028] If the second maximum collision depth is greater than or equal to the second preset depth threshold, then the deep collision region deformation parameters are constructed using the complete deformation region to perform deep collision region deformation processing, thereby obtaining a repair model after surface morphology weakening processing.

[0029] Optionally, after constructing the deep collision region deformation parameters using the complete deformable region and performing deep collision region deformation processing, the method further includes:

[0030] After constructing the deep collision region deformation parameters using the complete deformation region and performing deep collision region deformation processing, a shallow collision region is generated.

[0031] The shallow collision region is subjected to shallow collision region deformation processing to obtain the first deformation processing result.

[0032] Optionally, the calculation of the first collision deformation region between the minimum thickness layer model and the restoration model after surface morphology weakening treatment, and the second collision deformation region between the opposing jaw model and the restoration model after surface morphology weakening treatment, and the deformation processing based on the first and second collision deformation regions to obtain the deformation processing result, includes:

[0033] Calculate the first collision deformation region between the minimum thickness layer model and the restoration model after surface morphology weakening treatment;

[0034] Calculate the second collision deformation region of the restoration model and the opposing jaw model after surface morphology weakening treatment;

[0035] Based on the first and second collision deformation regions, a deformation strategy is selected to deform the repair model after the surface morphology weakening treatment, and a second deformation processing result is obtained.

[0036] Optionally, the step of selecting a deformation strategy based on the first and second collision deformation regions to deform the repair model after surface morphology weakening treatment, and obtaining a second deformation processing result, includes:

[0037] Calculate the collision information of the first and second collision deformation regions;

[0038] Based on the collision information, a deformation strategy is selected using preset conditions to deform the repair model after the surface morphology has been weakened, thereby obtaining a second deformation processing result.

[0039] Optionally, detecting the deformation processing result to determine whether a collision region exists includes:

[0040] Based on the deformation processing results, collision detection is performed on the minimum thickness layer model, the restoration model after surface morphology weakening processing, and the opposing jaw model to determine whether there is a collision area. If a collision area exists, the collision area is further deformed.

[0041] In addition, embodiments of the present invention also provide a cutting device for preserving the morphology of a dental crown restoration, the device comprising:

[0042] Complete Deformation Area Module: Import the prosthesis model, the opposing jaw model, and the minimum thickness layer model generated from the preparatory model, and perform calculations based on the prosthesis model, the opposing jaw model, and the minimum thickness layer model to obtain the complete deformation area;

[0043] Surface morphology weakening module: Based on the complete deformation area, the restoration model is deformed to obtain a restoration model with weakened surface morphology.

[0044] Deformation module: Calculates the first collision deformation area between the minimum thickness layer model and the restoration model after surface morphology weakening treatment, and the second collision deformation area between the opposing jaw model and the restoration model after surface morphology weakening treatment, and performs deformation processing based on the first and second collision deformation areas to obtain the deformation processing result.

[0045] Detection module: Detects the deformation processing results to determine whether there is a collision area.

[0046] In this embodiment of the invention, local areas are first deformed to prevent the designed non-collision areas from being modified. Then, the concept of weakened morphology preservation is proposed. Even when the occlusal space is insufficient, the initial contour shape of the restoration can be maintained, satisfying the occlusal relationship while meeting the minimum thickness requirement of the restoration. Different deformation parameters are constructed to select different deformation strategies. By deforming the restoration model, the collision areas between models are eliminated, avoiding damage to the original surface morphology of the restoration and loss of feature points in related areas. This makes the cutting results appear more natural in morphology, and the deformation processing results can better meet the desired effect. Attached Figure Description

[0047] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0048] Figure 1 This is a schematic flowchart of the cutting method for preserving the morphology of a dental crown restoration in an embodiment of the present invention;

[0049] Figure 2 This is a schematic diagram of the structural composition of the cutting device for preserving the shape of the dental crown restoration in an embodiment of the present invention. Detailed Implementation

[0050] 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.

[0051] Example 1

[0052] Please see Figure 1 , Figure 1 This is a schematic flowchart of the cutting method for preserving the morphology of a dental crown restoration in an embodiment of the present invention.

[0053] like Figure 1 As shown, a cutting method for preserving the morphology of a dental crown restoration, the method comprising:

[0054] S11: Import the prosthesis model, the opposing jaw model, and the minimum thickness layer model generated from the preparatory body model, and perform calculations based on the prosthesis model, the opposing jaw model, and the minimum thickness layer model to obtain the complete deformation area;

[0055] In the specific implementation of this invention, the process of importing the prosthesis model, the opposing jaw model, and the minimum thickness layer model generated from the preparatory model, and calculating based on the prosthesis model, the opposing jaw model, and the minimum thickness layer model to obtain the complete deformation region includes: importing the prosthesis model, the opposing jaw model, and the minimum thickness layer model generated by isometric calculation from the preparatory model, and obtaining the collision region based on the prosthesis model, the opposing jaw model, and the minimum thickness layer model; finding several vertices that are at a preset distance from the edge vertices of the collision region, and generating a deformation buffer based on these vertices; finding the two-neighbor vertices of the boundary vertices of the deformation buffer based on the topological relationship of the prosthesis model, and using these two-neighbor vertices as fixed anchor points; and generating the complete deformation region based on the deformation buffer, the fixed anchor points, and the collision region.

[0056] Furthermore, the step of finding several vertices that are at a preset distance from the edge vertices of the collision region and generating a deformation buffer based on these vertices includes: finding several vertices that are at a preset distance from the edge vertices of the collision region based on a nearest neighbor query algorithm, wherein the preset distance is positively correlated with the maximum collision depth of the collision region, and the formula for calculating the preset distance is:

[0057] L = a * dm + b

[0058] Where L is the preset distance, dm is the maximum collision depth, and a and b are fitting parameters;

[0059] By removing duplicates from several vertices, a deformation buffer is obtained.

[0060] Specifically, the patient's oral cavity is scanned using a scanning device to obtain a preparatory model, a prosthesis model, and an opposing model. To meet the minimum thickness requirement of the prosthesis, the preparatory model needs to be equidistantly calculated to obtain a minimum thickness layer model. If the prosthesis collides with the minimum thickness layer, it indicates that the prosthesis does not meet the minimum thickness requirement in this collision area. This transforms the minimum thickness requirement of the prosthesis into eliminating the collision area between the prosthesis model and the minimum thickness layer model, thus the processing method is equivalent to eliminating the collision area between the prosthesis model and the opposing model. Therefore, the prosthesis model, the opposing model, and the minimum thickness layer model generated by equidistant calculation from the preparatory model are imported, and the collision area is obtained. The area where the prosthesis model penetrates into the opposing model is called the collision area. To reduce the impact on non-collision areas, only a portion of the model is deformed. Parameters are fitted according to actual business needs, and a preset distance is calculated based on the parameters. The preset distance is positively correlated with the maximum collision depth of the collision area. A nearest neighbor query algorithm can be used to find several vertices that are within the preset distance from the edge vertices of the collision area. By measuring different characteristics... The distance between eigenvalues ​​is used for classification. The nearest vertex that reaches a preset distance is used to determine whether to include it as an object. This algorithm obtains several vertices. The preset distance affects the deformation effect and the range of the deformation area. The preset distance is calculated as L = a * dm + b, where L is the preset distance, dm is the maximum collision depth, and a and b are fitting parameters. After all vertices are found, duplicate vertices are removed to obtain a deformation buffer. After calculating the deformation buffer, the two-neighbor vertices of the boundary vertices of the deformation buffer are found based on the topological relationship of the repair model. These two-neighbor vertices are used as fixed anchor points. Topological relationships mainly describe the simplified elements of spatial objects. Topology in mathematics is used to achieve a complete description of the location of simple or complex sets of objects in space. Based on the topological relationship of the repair model, two-neighbor vertices that meet the conditions can be found and used as fixed anchor points. Finally, the collision area, deformation buffer, and fixed anchor points are merged to form a complete deformation area. Deformation is performed on a specified local area to prevent the modification of designed non-collision areas.

[0061] S12: Based on the complete deformation region, perform surface morphology weakening processing on the restoration model to obtain a restoration model with weakened surface morphology.

[0062] In a specific implementation of this invention, the step of performing surface morphology weakening processing on the restoration model based on the complete deformation region to obtain a restoration model with weakened surface morphology includes: calculating a first collision region between the restoration model and the opposing jaw model and a second collision region between the restoration model and the minimum thickness layer model; calculating a first maximum collision depth between the first and second collision regions, and determining whether the first maximum collision depth is greater than a first preset depth threshold; if the first maximum collision depth is greater than the first preset depth threshold, and the restoration model is a molar and contains pit and fissure feature points in the first or second collision region, then pit and fissure pretreatment deformation parameters are constructed using the complete deformation region to perform pit and fissure pretreatment deformation to obtain a first deformation processing result model; and performing surface morphology weakening processing based on the first deformation processing result model to obtain a restoration model with weakened surface morphology.

[0063] Furthermore, the step of performing surface morphology weakening processing based on the first deformation processing result model to obtain a restoration model with weakened surface morphology includes: calculating the third collision region between the first deformation processing result model and the opposing jaw model and the fourth collision region between the first deformation processing result model and the minimum thickness layer model; calculating the second maximum collision depth of the third and fourth collision regions, and determining whether the second maximum collision depth is greater than a second preset depth threshold; if the second maximum collision depth is greater than or equal to the second preset depth threshold, then using the complete deformation region to construct deep collision region deformation parameters to perform deep collision region deformation processing, thereby obtaining a restoration model with weakened surface morphology.

[0064] Furthermore, after constructing deep collision region deformation parameters using the complete deformable region and performing deep collision region deformation processing, the method further includes: generating a shallow collision region by constructing deep collision region deformation parameters using the complete deformable region and performing deep collision region deformation processing; and performing shallow collision region deformation processing on the shallow collision region to obtain a first deformation processing result.

[0065] Specifically, in order to satisfy both the occlusal relationship between the restoration and the opposing jaw within a limited occlusal space, and to meet the minimum thickness requirement of the restoration, the surface morphology of the restoration needs to be weakened, retaining only the initial contour features. First, the first collision region between the restoration model and the opposing jaw model, and the second collision region between the restoration model and the minimum thickness layer model are calculated. Then, the first maximum collision depth of the first and second collision regions is calculated, and it is determined whether the first maximum collision depth is greater than a first preset depth threshold. If the first maximum collision depth is greater than the first preset depth threshold, and the restoration model contains pit and fissure feature points in the molar and the first or second collision region, then pit and fissure pretreatment deformation parameters are constructed using the complete deformation region for pit and fissure pretreatment deformation. For constructing the pit and fissure pretreatment deformation parameters, the initial Laplacian coordinates of the restoration are first determined, with the fixed anchor point as described in S11. The vertices of the pit and fissure regions in the first or second collision region are used as displacement anchor points. Then, the placement direction of the restoration is used as the deformation direction of the first collision region, and the deformation direction of the second collision region is opposite. The displacement value needs to meet the requirements of the weakened morphology and is calculated according to the following formula:

[0066] T(vi)=D(max)–((a–1) / a)*(H(max)–H(vi)),

[0067] Where T(vi) is the displacement value of vertex vi, D(max) is the maximum collision depth of the vertex in the region, a is the calculated coefficient, H(max)-H(vi) is the height difference between the vertex of maximum depth and vertex vi in ​​the crown placement direction, and the coefficient a is a quadratic equation about the maximum collision depth dm of the vertex within a certain range of the above-mentioned pit and fissure region, and its calculation formula is:

[0068] a = w1 * (dm) 2 +w2*dm+w3,

[0069] Where w1, w2, and w3 are parameter values ​​fitted according to actual needs, and dm is the maximum collision depth;

[0070] After obtaining the aforementioned pit and fissure pretreatment deformation parameters, Laplace deformation is performed based on these parameters. First, pit and fissure pretreatment deformation is completed to obtain the first deformation processing result model. The third collision region between the first deformation processing result model and the opposing jaw model, and the fourth collision region between the first deformation processing result model and the minimum thickness layer model are calculated. The second maximum collision depth of the third and fourth collision regions is calculated. After completing the pit and fissure pretreatment deformation, a threshold needs to be set for the depth of the remaining regions. Therefore, it is determined whether the second maximum collision depth is greater than the second preset depth threshold. If the second maximum collision depth is greater than or equal to the second preset depth threshold, deep collision region deformation parameters are constructed using the complete deformation region for deep collision region deformation processing. For the deep collision region deformation parameters, the deep collision region... The Laplacian coordinates and fixed anchor points in the deformation parameters are the same as those in the pit and fissure preprocessing deformation parameters. The displacement anchor points are a series of shape value high points similar to tooth ridges along the average normal direction of the vertices within the region. The displacement direction of the third collision region is the average normal of the vertices within the region, and the deformation direction of the fourth collision region is the opposite direction of the average normal of the vertices within the region. For the displacement values ​​of the displacement anchor points, the displacement values ​​of convex and concave surfaces are different due to the different surface morphologies of the regions. The ideal shape of the concave surface after deformation is close to the collision target model. Therefore, for the concave surface, the displacement value T(vi) = D(vi), where D(vi) is the collision depth of vertex vi. The displacement value of the convex surface needs to meet the requirements of the weakened shape and can be calculated using the following formula:

[0071] T(vi)=D(vi)+(H(max)-H(vi)) / a,

[0072] Where T(vi) is the displacement value of vertex vi, D(vi) is the collision depth of vertex vi, a is the calculated coefficient, the calculation formula of a is consistent with that of pit and fissure pretreatment deformation, and H(max)-H(vi) is the height difference between the vertex with the maximum depth and vertex vi in ​​the average normal direction of the region.

[0073] Based on the constructed deep collision region deformation parameters, the prosthesis model after pit and fissure pretreatment deformation is further deformed, completing the surface morphology weakening treatment of the prosthesis model and obtaining the surface morphology weakened prosthesis model. After performing deep collision region deformation, shallow collision regions are generated. Therefore, shallow collision region deformation treatment needs to be performed on the shallow collision region construction parameters. The fifth collision region between the prosthesis model after deep collision region deformation treatment and the opposing jaw model and the sixth collision region between the prosthesis model after deep collision region deformation treatment and the minimum thickness layer model are calculated. The Laplacian coordinates in the shallow collision region deformation parameters are the Laplacian coordinates of the prosthesis model after deep collision region deformation. The fixed anchor point of the fifth collision region is the two neighboring vertices not in the deformation region and the sixth collision region when the shallow collision region deformation strategy is executed during the deformation process. The fixed anchor point of the sixth collision region is... The two neighboring vertices not in the deformation region and the fifth collision region during the deformation process when the shallow collision region deformation strategy is executed are considered. The displacement anchor points are all vertices in the fifth and sixth collision regions. The displacement direction of the fifth collision region is the average normal of the vertices in the region, and the deformation direction of the sixth collision region is the opposite direction of the average normal of the vertices in the region. The displacement value of all displacement anchor points is the maximum collision depth D(max) of the collision region. In order to avoid incomplete dissipation of deformation energy and calculation errors, an offset o is also required. The value of the offset is set according to the actual needs. The final displacement value is: D(vi) = D(max) + o. After completing the construction of the shallow collision region deformation parameters, the shallow collision region is deformed to eliminate the region. For the surface morphology weakening treatment, it can prevent the deformation displacement of the maxillofacial pit and groove region from being too large and can maximize the use of space to achieve the effect of preserving the basic contour features.

[0074] S13: Calculate the first collision deformation region between the minimum thickness layer model and the restoration model after surface morphology weakening treatment, and the second collision deformation region between the opposing jaw model and the restoration model after surface morphology weakening treatment, and perform deformation processing based on the first collision deformation region and the second collision deformation region to obtain the deformation processing result.

[0075] In the specific implementation of this invention, the calculation of the first collision deformation region between the minimum thickness layer model and the restoration model after surface morphology weakening treatment, and the second collision deformation region between the opposing jaw model and the restoration model after surface morphology weakening treatment, and the deformation processing based on the first and second collision deformation regions to obtain the deformation processing result, includes: calculating the first collision deformation region between the minimum thickness layer model and the restoration model after surface morphology weakening treatment; calculating the second collision deformation region between the restoration model after surface morphology weakening treatment and the opposing jaw model; selecting a deformation strategy based on the first and second collision deformation regions to perform deformation processing on the restoration model after surface morphology weakening treatment, and obtaining the second deformation processing result.

[0076] Furthermore, the step of selecting a deformation strategy based on the first and second collision deformation regions to deform the repair model after surface morphology weakening treatment and obtain a second deformation processing result includes: calculating the collision information of the first and second collision deformation regions; and selecting a deformation strategy based on the collision information using preset conditions to deform the repair model after surface morphology weakening treatment and obtain a second deformation processing result.

[0077] Specifically, it is generally impossible to deform the model to the predetermined result in one go. Therefore, after the surface morphology weakening treatment of the prosthesis model is completed, the remaining collision deformation areas need to be deformed. First, the first collision deformation area between the minimum thickness layer model and the prosthesis model after surface morphology weakening treatment is calculated; the second collision deformation area between the prosthesis model after surface morphology weakening treatment and the opposing jaw model is calculated; collision information is calculated based on the first and second collision deformation areas; based on the collision information, it is determined whether the remaining collision area is a deep collision using preset conditions. If it is a deep collision, deep collision area deformation parameters are constructed for deep collision area deformation treatment. The constructed deep collision area deformation parameters are the same as those in step S13 above, and will not be repeated here. If it is not a deep collision, shallow collision area deformation parameters are constructed for shallow collision area deformation treatment. The Laplacian coordinates in the constructed shallow collision area deformation parameters are the Laplacian coordinates of the prosthesis after surface morphology weakening treatment, and the other parameters are the same as those in step S13 above, and will not be repeated here. This completes the basic process of deformation treatment.

[0078] S14: Detect the deformation processing result to determine whether there is a collision area.

[0079] In the specific implementation of this invention, the step of detecting the deformation processing result and determining whether there is a collision area includes: performing collision detection on the minimum thickness layer model, the restoration model after surface morphology weakening treatment, and the opposing jaw model based on the deformation processing result to determine whether there is a collision area. If there is a collision area, the deformation processing is continued on the collision area.

[0080] Specifically, after each deformation strategy is executed, it is necessary to check the collision situation of the minimum thickness layer model, the restoration model after surface morphology weakening treatment, and the opposing jaw model to determine whether there is still a collision area. If there is still a collision area, the deformation strategy is selected again for deformation. This process is repeated until the collision area is completely eliminated. Only when the collision area is completely eliminated can the final deformation result be obtained.

[0081] In this embodiment of the invention, local areas are first deformed to prevent the designed non-collision areas from being modified. Then, the concept of weakened morphology preservation is proposed. Even when the occlusal space is insufficient, the initial contour shape of the restoration can be maintained, satisfying the occlusal relationship while meeting the minimum thickness requirement of the restoration. Different deformation parameters are constructed to select different deformation strategies. By deforming the restoration model, the collision areas between models are eliminated, avoiding damage to the original surface morphology of the restoration and loss of feature points in related areas. This makes the cutting results appear more natural in morphology, and the deformation processing results can better meet the desired effect.

[0082] Example 2

[0083] Please see Figure 2 , Figure 2 This is a schematic diagram of the structural composition of the cutting device for preserving the shape of the dental crown restoration in an embodiment of the present invention.

[0084] like Figure 2 As shown, a cutting device for preserving the morphology of a dental crown restoration includes:

[0085] Complete Deformation Area Module 21: Import the prosthesis model, the opposing jaw model, and the minimum thickness layer model generated from the preparatory body model, and perform calculations based on the prosthesis model, the opposing jaw model, and the minimum thickness layer model to obtain the complete deformation area;

[0086] In the specific implementation of this invention, the process of importing the prosthesis model, the opposing jaw model, and the minimum thickness layer model generated from the preparatory model, and calculating based on the prosthesis model, the opposing jaw model, and the minimum thickness layer model to obtain the complete deformation region includes: importing the prosthesis model, the opposing jaw model, and the minimum thickness layer model generated by isometric calculation from the preparatory model, and obtaining the collision region based on the prosthesis model, the opposing jaw model, and the minimum thickness layer model; finding several vertices that are at a preset distance from the edge vertices of the collision region, and generating a deformation buffer based on these vertices; finding the two-neighbor vertices of the boundary vertices of the deformation buffer based on the topological relationship of the prosthesis model, and using these two-neighbor vertices as fixed anchor points; and generating the complete deformation region based on the deformation buffer, the fixed anchor points, and the collision region.

[0087] Furthermore, the step of finding several vertices that are at a preset distance from the edge vertices of the collision region and generating a deformation buffer based on these vertices includes: finding several vertices that are at a preset distance from the edge vertices of the collision region based on a nearest neighbor query algorithm, wherein the preset distance is positively correlated with the maximum collision depth of the collision region, and the formula for calculating the preset distance is:

[0088] L = a * dm + b

[0089] Where L is the preset distance, dm is the maximum collision depth, and a and b are fitting parameters;

[0090] By removing duplicates from several vertices, a deformation buffer is obtained.

[0091] Specifically, the patient's oral cavity is scanned using a scanning device to obtain a preparatory model, a prosthesis model, and an opposing model. To meet the minimum thickness requirement of the prosthesis, the preparatory model needs to be equidistantly calculated to obtain a minimum thickness layer model. If the prosthesis collides with the minimum thickness layer, it indicates that the prosthesis does not meet the minimum thickness requirement in this collision area. This transforms the minimum thickness requirement of the prosthesis into eliminating the collision area between the prosthesis model and the minimum thickness layer model, thus the processing method is equivalent to eliminating the collision area between the prosthesis model and the opposing model. Therefore, the prosthesis model, the opposing model, and the minimum thickness layer model generated by equidistant calculation from the preparatory model are imported, and the collision area is obtained. The area where the prosthesis model penetrates into the opposing model is called the collision area. To reduce the impact on non-collision areas, only a portion of the model is deformed. Parameters are fitted according to actual business needs, and a preset distance is calculated based on the parameters. The preset distance is positively correlated with the maximum collision depth of the collision area. A nearest neighbor query algorithm can be used to find several vertices that are within the preset distance from the edge vertices of the collision area. By measuring different characteristics... The distance between eigenvalues ​​is used for classification. The nearest vertex that reaches a preset distance is used to determine whether to include it as an object. This algorithm obtains several vertices. The preset distance affects the deformation effect and the range of the deformation area. The preset distance is calculated as L = a * dm + b, where L is the preset distance, dm is the maximum collision depth, and a and b are fitting parameters. After all vertices are found, duplicate vertices are removed to obtain a deformation buffer. After calculating the deformation buffer, the two-neighbor vertices of the boundary vertices of the deformation buffer are found based on the topological relationship of the repair model. These two-neighbor vertices are used as fixed anchor points. Topological relationships mainly describe the simplified elements of spatial objects. Topology in mathematics is used to achieve a complete description of the location of simple or complex sets of objects in space. Based on the topological relationship of the repair model, two-neighbor vertices that meet the conditions can be found and used as fixed anchor points. Finally, the collision area, deformation buffer, and fixed anchor points are merged to form a complete deformation area. Deformation is performed on a specified local area to prevent the modification of designed non-collision areas.

[0092] Surface morphology weakening module 22: Based on the complete deformation area, the surface morphology of the restoration model is weakened to obtain the restoration model after surface morphology weakening.

[0093] In a specific implementation of this invention, the step of performing surface morphology weakening processing on the restoration model based on the complete deformation region to obtain a restoration model with weakened surface morphology includes: calculating a first collision region between the restoration model and the opposing jaw model and a second collision region between the restoration model and the minimum thickness layer model; calculating a first maximum collision depth between the first and second collision regions, and determining whether the first maximum collision depth is greater than a first preset depth threshold; if the first maximum collision depth is greater than the first preset depth threshold, and the restoration model is a molar and contains pit and fissure feature points in the first or second collision region, then pit and fissure pretreatment deformation parameters are constructed using the complete deformation region to perform pit and fissure pretreatment deformation to obtain a first deformation processing result model; and performing surface morphology weakening processing based on the first deformation processing result model to obtain a restoration model with weakened surface morphology.

[0094] Furthermore, the step of performing surface morphology weakening processing based on the first deformation processing result model to obtain a restoration model with weakened surface morphology includes: calculating the third collision region between the first deformation processing result model and the opposing jaw model and the fourth collision region between the first deformation processing result model and the minimum thickness layer model; calculating the second maximum collision depth of the third and fourth collision regions, and determining whether the second maximum collision depth is greater than a second preset depth threshold; if the second maximum collision depth is greater than or equal to the second preset depth threshold, then using the complete deformation region to construct deep collision region deformation parameters to perform deep collision region deformation processing, thereby obtaining a restoration model with weakened surface morphology.

[0095] Furthermore, after constructing deep collision region deformation parameters using the complete deformable region and performing deep collision region deformation processing, the method further includes: generating a shallow collision region by constructing deep collision region deformation parameters using the complete deformable region and performing deep collision region deformation processing; and performing shallow collision region deformation processing on the shallow collision region to obtain a first deformation processing result.

[0096] Specifically, in order to satisfy both the occlusal relationship between the restoration and the opposing jaw within a limited occlusal space, and to meet the minimum thickness requirement of the restoration, the surface morphology of the restoration needs to be weakened, retaining only the initial contour features. First, the first collision region between the restoration model and the opposing jaw model, and the second collision region between the restoration model and the minimum thickness layer model are calculated. Then, the first maximum collision depth of the first and second collision regions is calculated, and it is determined whether the first maximum collision depth is greater than a first preset depth threshold. If the first maximum collision depth is greater than the first preset depth threshold, and the restoration model contains pit and fissure feature points in the molar and the first or second collision region, then pit and fissure pretreatment deformation parameters are constructed using the complete deformation region for pit and fissure pretreatment deformation. For constructing the pit and fissure pretreatment deformation parameters, the initial Laplace coordinates of the restoration are first determined, with the fixed anchor point as described in the complete deformation region module 21. The vertices of the pit and fissure regions in the first or second collision region are used as displacement anchor points. Then, the placement direction of the restoration is used as the deformation direction of the first collision region, and the deformation direction of the second collision region is opposite. The displacement value needs to meet the requirements of the weakened morphology and is calculated according to the following formula:

[0097] T(vi)=D(max)–((a–1) / a)*(H(max)–H(vi)),

[0098] Where T(vi) is the displacement value of vertex vi, D(max) is the maximum collision depth of the vertex in the region, a is the calculated coefficient, H(max)-H(vi) is the height difference between the vertex of maximum depth and vertex vi in ​​the crown placement direction, and the coefficient a is a quadratic equation about the maximum collision depth dm of the vertex within a certain range of the above-mentioned pit and fissure region, and its calculation formula is:

[0099] a = w1 * (dm) 2 +w2*dm+w3,

[0100] Where w1, w2, and w3 are parameter values ​​fitted according to actual needs, and dm is the maximum collision depth;

[0101] After obtaining the aforementioned pit and fissure pretreatment deformation parameters, Laplace deformation is performed based on these parameters. First, pit and fissure pretreatment deformation is completed to obtain the first deformation processing result model. The third collision region between the first deformation processing result model and the opposing jaw model, and the fourth collision region between the first deformation processing result model and the minimum thickness layer model are calculated. The second maximum collision depth of the third and fourth collision regions is calculated. After completing the pit and fissure pretreatment deformation, a threshold needs to be set for the depth of the remaining regions. Therefore, it is determined whether the second maximum collision depth is greater than the second preset depth threshold. If the second maximum collision depth is greater than or equal to the second preset depth threshold, deep collision region deformation parameters are constructed using the complete deformation region for deep collision region deformation processing. For the deep collision region deformation parameters, the deep collision region... The Laplacian coordinates and fixed anchor points in the deformation parameters are the same as those in the pit and fissure preprocessing deformation parameters. The displacement anchor points are a series of shape value high points similar to tooth ridges along the average normal direction of the vertices within the region. The displacement direction of the third collision region is the average normal of the vertices within the region, and the deformation direction of the fourth collision region is the opposite direction of the average normal of the vertices within the region. For the displacement values ​​of the displacement anchor points, the displacement values ​​of convex and concave surfaces are different due to the different surface morphologies of the regions. The ideal shape of the concave surface after deformation is close to the collision target model. Therefore, for the concave surface, the displacement value T(vi) = D(vi), where D(vi) is the collision depth of vertex vi. The displacement value of the convex surface needs to meet the requirements of the weakened shape and can be calculated using the following formula:

[0102] T(vi)=D(vi)+(H(max)-H(vi)) / a,

[0103] Where T(vi) is the displacement value of vertex vi, D(vi) is the collision depth of vertex vi, a is the calculated coefficient, the calculation formula of a is consistent with that of pit and fissure pretreatment deformation, and H(max)-H(vi) is the height difference between the vertex with the maximum depth and vertex vi in ​​the average normal direction of the region.

[0104] Based on the constructed deep collision region deformation parameters, the prosthesis model after pit and fissure pretreatment deformation is further deformed, completing the surface morphology weakening treatment of the prosthesis model and obtaining the surface morphology weakened prosthesis model. After performing deep collision region deformation, shallow collision regions are generated. Therefore, shallow collision region deformation treatment needs to be performed on the shallow collision region construction parameters. The fifth collision region between the prosthesis model after deep collision region deformation treatment and the opposing jaw model and the sixth collision region between the prosthesis model after deep collision region deformation treatment and the minimum thickness layer model are calculated. The Laplacian coordinates in the shallow collision region deformation parameters are the Laplacian coordinates of the prosthesis model after deep collision region deformation. The fixed anchor point of the fifth collision region is the two neighboring vertices not in the deformation region and the sixth collision region when the shallow collision region deformation strategy is executed during the deformation process. The fixed anchor point of the sixth collision region is... The two neighboring vertices not in the deformation region and the fifth collision region during the deformation process when the shallow collision region deformation strategy is executed are considered. The displacement anchor points are all vertices in the fifth and sixth collision regions. The displacement direction of the fifth collision region is the average normal of the vertices in the region, and the deformation direction of the sixth collision region is the opposite direction of the average normal of the vertices in the region. The displacement value of all displacement anchor points is the maximum collision depth D(max) of the collision region. In order to avoid incomplete dissipation of deformation energy and calculation errors, an offset o is also required. The value of the offset is set according to the actual needs. The final displacement value is: D(vi) = D(max) + o. After completing the construction of the shallow collision region deformation parameters, the shallow collision region is deformed to eliminate the region. For the surface morphology weakening treatment, it can prevent the deformation displacement of the maxillofacial pit and groove region from being too large and can maximize the use of space to achieve the effect of preserving the basic contour features.

[0105] Deformation module 23: Calculates the first collision deformation area between the minimum thickness layer model and the restoration model after surface morphology weakening treatment, and the second collision deformation area between the opposing jaw model and the restoration model after surface morphology weakening treatment, and performs deformation processing based on the first collision deformation area and the second collision deformation area to obtain the deformation processing result.

[0106] In the specific implementation of this invention, the calculation of the first collision deformation region between the minimum thickness layer model and the restoration model after surface morphology weakening treatment, and the second collision deformation region between the opposing jaw model and the restoration model after surface morphology weakening treatment, and the deformation processing based on the first and second collision deformation regions to obtain the deformation processing result, includes: calculating the first collision deformation region between the minimum thickness layer model and the restoration model after surface morphology weakening treatment; calculating the second collision deformation region between the restoration model after surface morphology weakening treatment and the opposing jaw model; selecting a deformation strategy based on the first and second collision deformation regions to perform deformation processing on the restoration model after surface morphology weakening treatment, and obtaining the second deformation processing result.

[0107] Furthermore, the step of selecting a deformation strategy based on the first and second collision deformation regions to deform the repair model after surface morphology weakening treatment and obtain a second deformation processing result includes: calculating the collision information of the first and second collision deformation regions; and selecting a deformation strategy based on the collision information using preset conditions to deform the repair model after surface morphology weakening treatment and obtain a second deformation processing result.

[0108] Specifically, it is generally impossible to deform the model to the predetermined result in one go. Therefore, after the surface morphology weakening treatment of the prosthesis model is completed, the remaining collision deformation areas need to be deformed. First, the first collision deformation area between the minimum thickness layer model and the prosthesis model after surface morphology weakening treatment is calculated; the second collision deformation area between the prosthesis model after surface morphology weakening treatment and the opposing jaw model is calculated; collision information is calculated based on the first and second collision deformation areas; based on the collision information, it is determined whether the remaining collision area is a deep collision using preset conditions. If it is a deep collision, deep collision area deformation parameters are constructed for deep collision area deformation treatment. The constructed deep collision area deformation parameters are the same as those in step S13 above, and will not be repeated here. If it is not a deep collision, shallow collision area deformation parameters are constructed for shallow collision area deformation treatment. The Laplacian coordinates in the constructed shallow collision area deformation parameters are the Laplacian coordinates of the prosthesis after surface morphology weakening treatment, and the other parameters are the same as those in step S13 above, and will not be repeated here. This completes the basic process of deformation treatment.

[0109] Detection module 24: Detects the deformation processing result and determines whether there is a collision area.

[0110] In the specific implementation of this invention, the step of detecting the deformation processing result and determining whether there is a collision area includes: performing collision detection on the minimum thickness layer model, the restoration model after surface morphology weakening treatment, and the opposing jaw model based on the deformation processing result to determine whether there is a collision area. If there is a collision area, the deformation processing is continued on the collision area.

[0111] Specifically, after each deformation strategy is executed, it is necessary to check the collision situation of the minimum thickness layer model, the restoration model after surface morphology weakening treatment, and the opposing jaw model to determine whether there is still a collision area. If there is still a collision area, the deformation strategy is selected again for deformation. This process is repeated until the collision area is completely eliminated. Only when the collision area is completely eliminated can the final deformation result be obtained.

[0112] In this embodiment of the invention, local areas are first deformed to prevent the designed non-collision areas from being modified. Then, the concept of weakened morphology preservation is proposed. Even when the occlusal space is insufficient, the initial contour shape of the restoration can be maintained, satisfying the occlusal relationship while meeting the minimum thickness requirement of the restoration. Different deformation parameters are constructed to select different deformation strategies. By deforming the restoration model, the collision areas between models are eliminated, avoiding damage to the original surface morphology of the restoration and loss of feature points in related areas. This makes the cutting results appear more natural in morphology, and the deformation processing results can better meet the desired effect.

[0113] Those skilled in the art will understand that all or part of the steps in the various methods of the above embodiments can be implemented by a program instructing related hardware. The program can be stored in a computer-readable storage medium, which may include: read-only memory (ROM), random access memory (RAM), disk or optical disk, etc.

[0114] Furthermore, the cutting method and apparatus for preserving the morphology of a dental crown restoration provided by the embodiments of the present invention have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only for the purpose of helping to understand the method and core ideas of the present invention. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A cutting method for preserving the morphology of a dental crown restoration, characterized in that, The method includes: Import the prosthesis model, the opposing jaw model, and the minimum thickness layer model generated from the preparatory model, and perform calculations based on the prosthesis model, the opposing jaw model, and the minimum thickness layer model to obtain the complete deformation area; The surface morphology of the restoration model is weakened based on the complete deformation region to obtain the restoration model after surface morphology weakening. Calculate the first collision deformation region between the minimum thickness layer model and the restoration model after surface morphology weakening treatment, and the second collision deformation region between the opposing jaw model and the restoration model after surface morphology weakening treatment, and perform deformation processing based on the first and second collision deformation regions to obtain the deformation processing result. The deformation processing results are inspected to determine whether a collision area exists; The process of importing the prosthesis model, the opposing jaw model, and the minimum thickness layer model generated from the preparatory model, and calculating based on the prosthesis model, the opposing jaw model, and the minimum thickness layer model to obtain a complete deformation region, includes: importing the prosthesis model, the opposing jaw model, and the minimum thickness layer model generated by isometric calculation from the preparatory model, and obtaining the collision region based on the prosthesis model, the opposing jaw model, and the minimum thickness layer model; finding several vertices that are at a preset distance from the edge vertices of the collision region, and generating a deformation buffer based on these vertices; finding the two-neighbor vertices of the boundary vertices of the deformation buffer based on the topological relationship of the prosthesis model, and using these two-neighbor vertices as fixed anchor points; and generating a complete deformation region based on the deformation buffer, the fixed anchor points, and the collision region. The step of performing surface morphology weakening processing on the restoration model based on the complete deformation region to obtain a restoration model with weakened surface morphology includes: calculating a first collision region between the restoration model and the opposing jaw model and a second collision region between the restoration model and the minimum thickness layer model; calculating a first maximum collision depth between the first and second collision regions and determining whether the first maximum collision depth is greater than a first preset depth threshold; if the first maximum collision depth is greater than the first preset depth threshold, and the restoration model is a molar and contains pit and fissure feature points in the first or second collision region, then pit and fissure pretreatment deformation parameters are constructed using the complete deformation region to perform pit and fissure pretreatment deformation to obtain a first deformation processing result model; and performing surface morphology weakening processing based on the first deformation processing result model to obtain a restoration model with weakened surface morphology.

2. The cutting method for preserving the morphology of a dental crown restoration according to claim 1, characterized in that, The process of finding several vertices that are at a preset distance from the edge vertices of the collision region and generating a deformation buffer based on these vertices includes: The nearest neighbor search algorithm is used to find several vertices that are within a preset distance from the edge vertices of the collision region. The preset distance is positively correlated with the maximum collision depth of the collision region, and the formula for calculating the preset distance is as follows: ， Where L is the preset distance, dm is the maximum collision depth, and a and b are fitting parameters; By removing duplicates from several vertices, a deformation buffer is obtained.

3. The cutting method for preserving the morphology of a dental crown restoration according to claim 1, characterized in that, The step of performing surface morphology weakening processing based on the first deformation processing result model to obtain a repair model after surface morphology weakening processing includes: Calculate the third collision region between the first deformation result model and the jaw model, and the fourth collision region between the first deformation result model and the minimum thickness layer model. Calculate the second maximum collision depth of the third and fourth collision regions, and determine whether the second maximum collision depth is greater than a second preset depth threshold. If the second maximum collision depth is greater than or equal to the second preset depth threshold, then the deep collision region deformation parameters are constructed using the complete deformation region to perform deep collision region deformation processing, thereby obtaining a repair model after surface morphology weakening processing.

4. The cutting method for preserving the morphology of a dental crown restoration according to claim 3, characterized in that, After constructing the deep collision region deformation parameters using the complete deformable region and performing deep collision region deformation processing, the method further includes: After constructing the deep collision region deformation parameters using the complete deformation region and performing deep collision region deformation processing, a shallow collision region is generated. The shallow collision region is subjected to shallow collision region deformation processing to obtain the first deformation processing result.

5. The cutting method for preserving the morphology of a dental crown restoration according to claim 1, characterized in that, The calculation of the first collision deformation region between the minimum thickness layer model and the restoration model after surface morphology weakening treatment, and the second collision deformation region between the opposing jaw model and the restoration model after surface morphology weakening treatment, and the deformation processing based on the first and second collision deformation regions to obtain the deformation processing result, includes: Calculate the first collision deformation region between the minimum thickness layer model and the restoration model after surface morphology weakening treatment; Calculate the second collision deformation region of the restoration model and the opposing jaw model after surface morphology weakening treatment; Based on the first and second collision deformation regions, a deformation strategy is selected to deform the repair model after the surface morphology weakening treatment, and a second deformation processing result is obtained.

6. The cutting method for preserving the morphology of a dental crown restoration according to claim 5, characterized in that, The deformation strategy selected based on the first and second collision deformation regions is used to deform the repair model after surface morphology weakening treatment, thereby obtaining a second deformation processing result, including: Calculate the collision information of the first and second collision deformation regions; Based on the collision information, a deformation strategy is selected using preset conditions to deform the repair model after the surface morphology has been weakened, thereby obtaining a second deformation processing result.

7. The cutting method for preserving the morphology of a dental crown restoration according to claim 1, characterized in that, The step of detecting the deformation processing result to determine whether a collision region exists includes: Based on the deformation processing results, collision detection is performed on the minimum thickness layer model, the restoration model after surface morphology weakening processing, and the opposing jaw model to determine whether there is a collision area. If a collision area exists, the collision area is further deformed.

8. A cutting device for preserving the morphology of a dental crown restoration, characterized in that, The device includes: Complete Deformation Area Module: Import the prosthesis model, the opposing jaw model, and the minimum thickness layer model generated from the preparatory model, and perform calculations based on the prosthesis model, the opposing jaw model, and the minimum thickness layer model to obtain the complete deformation area; Surface morphology weakening module: Based on the complete deformation area, the surface morphology of the restoration model is weakened to obtain the restoration model after surface morphology weakening. Deformation module: Calculates the first collision deformation area between the minimum thickness layer model and the restoration model after surface morphology weakening treatment, and the second collision deformation area between the opposing jaw model and the restoration model after surface morphology weakening treatment, and performs deformation processing based on the first and second collision deformation areas to obtain the deformation processing result. Detection module: Detects the deformation processing results to determine whether there is a collision area; The process of importing the prosthesis model, the opposing jaw model, and the minimum thickness layer model generated from the preparatory model, and calculating based on the prosthesis model, the opposing jaw model, and the minimum thickness layer model to obtain a complete deformation region, includes: importing the prosthesis model, the opposing jaw model, and the minimum thickness layer model generated by isometric calculation from the preparatory model, and obtaining the collision region based on the prosthesis model, the opposing jaw model, and the minimum thickness layer model; finding several vertices that are at a preset distance from the edge vertices of the collision region, and generating a deformation buffer based on these vertices; finding the two-neighbor vertices of the boundary vertices of the deformation buffer based on the topological relationship of the prosthesis model, and using these two-neighbor vertices as fixed anchor points; and generating a complete deformation region based on the deformation buffer, the fixed anchor points, and the collision region. The step of performing surface morphology weakening processing on the restoration model based on the complete deformation region to obtain a restoration model with weakened surface morphology includes: calculating a first collision region between the restoration model and the opposing jaw model and a second collision region between the restoration model and the minimum thickness layer model; calculating a first maximum collision depth between the first and second collision regions and determining whether the first maximum collision depth is greater than a first preset depth threshold; if the first maximum collision depth is greater than the first preset depth threshold, and the restoration model is a molar and contains pit and fissure feature points in the first or second collision region, then pit and fissure pretreatment deformation parameters are constructed using the complete deformation region to perform pit and fissure pretreatment deformation to obtain a first deformation processing result model; and performing surface morphology weakening processing based on the first deformation processing result model to obtain a restoration model with weakened surface morphology.

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