Method, system, and computer readable medium for making a composite denture base

Abstract

The application discloses a composite denture base manufacturing method, system and computer readable medium; the composite denture base manufacturing method comprises the following steps: obtaining an intraoral three-dimensional model and a CBCT image, performing rigid registration based on tooth hard tissue characteristics, identifying a region to be repaired, adjacent teeth and a crown-gum boundary, extracting alveolar bone surfaces and forming a soft tissue thickness distribution map, generating a non-uniform thickness metal veneer model, generating a resin base body model and a clasp model, setting a positioning structure and a connecting structure, respectively performing additive manufacturing and three-dimensional scanning detection, registration, connection and obtaining a composite denture base. The application solves the problem that the resin and the metal are easy to fall off, improves the connection stability and service life of the composite structure in a hot and humid oral environment with high load, improves the fitting degree through the non-uniform thickness design, and helps to improve the stress distribution, reduce local stress concentration and edge discomfort.

Description

Technical Field

[0001] This invention relates to the field of digital dental technology, and more specifically to a method, system, and computer-readable medium for manufacturing composite denture bases. Background Technology

[0002] The statements in this section are merely background information related to this application and do not necessarily constitute prior art.

[0003] With the development of digital dentistry, oral scanning, computer-aided design / manufacturing (CAD / CAM), and additive manufacturing (3D printing) have been widely introduced into the field of denture restoration. Taking removable dentures as an example, dentures typically include components such as a support structure, artificial teeth, and denture base. The denture base is used to cover the alveolar ridge and distribute occlusal forces, support the artificial teeth, and participate in the formation of retention and stability.

[0004] The denture base is the foundation structure of removable dentures (especially complete / partial removable dentures) that adheres to the patient's oral mucosa, alveolar ridge, and other tissue surfaces. It is typically used to: support and fix artificial teeth, restoring the shape and chewing function of missing teeth; cover the alveolar ridge and distribute occlusal forces, allowing for more even transmission of occlusal loads to the mucosa and bone tissue; and provide retention and stability through mechanisms such as adhesion between the base and mucosa, peripheral sealing (marginal seal), and thin liquid film retention, thus enhancing denture stability (especially in complete dentures). Structurally, the denture base usually includes a tissue surface (mucosal contact surface) and a polished surface (outer surface). The precision of the tissue surface fit and the quality of the peripheral sealing directly affect the retention force, comfort, and long-term stability.

[0005] In the prior art, Chinese patent CN120938640A discloses a method for manufacturing dental objects: obtaining a dental model; establishing a framework model (for installation onto abutment teeth); establishing a base model including a first part and a second part, wherein the framework model is sandwiched between the first part and the second part; establishing a dental prosthesis model; and manufacturing the base and framework separately and connecting them to obtain a dental object. Although this patented technology solves the problems of cumbersome, time-consuming, and aesthetically unappealing dental object manufacturing in the prior art by establishing framework and base models through digital modeling and 3D printing, the applicant discovered in the process of implementing this application that existing denture base manufacturing technologies still have at least the following technical problems:

[0006] 1. In the existing technology, the bonding strength between resin and metal interface is insufficient, especially in the hot and humid environment of the oral cavity and under the load of frequent chewing, which is particularly obvious and easy to age and debond.

[0007] 2. In the existing technology, if the denture base model is not made of metal framework and is made entirely of resin, the denture base is not rigid enough and can only withstand a small maximum chewing load. Moreover, resin is more prone to oxidation than metal, and the surface roughness increases, which affects the adsorption effect and is more likely to damage the oral mucosa.

[0008] 3. In the existing technology, the design of the retaining rings at both ends of the resin base body fails to accurately avoid the soft tissue of the gums, which can easily compress the gums and cause discomfort.

[0009] In view of this, how to solve the problems in the existing denture base manufacturing technology, such as easy detachment of resin and metal bonding, insufficient rigidity of pure resin base, resin oxidation affecting adsorption effect and mucosal damage, and easy compression of gingival soft tissue by clasps, has become the research topic to be solved by this invention. Summary of the Invention

[0010] The purpose of this invention is to provide a method, system, and computer-readable medium for manufacturing composite denture bases.

[0011] To achieve the above objectives, the first aspect of the present invention adopts the following technical solution: a method for manufacturing a composite denture base, the method comprising:

[0012] Acquire an intraoral 3D model and CBCT images, wherein the intraoral 3D model includes the crown surface and the outer gingival surface, and the CBCT images include alveolar bone images of the area to be repaired;

[0013] Rigid registration is performed based on the common hard tissue features of the teeth in the intraoral 3D model and CBCT images, so that the two are in the same coordinate system;

[0014] Identify the area to be repaired, the adjacent teeth at both ends of the area to be repaired, and the crown-gingival boundary of the adjacent teeth, and obtain the alveolar bone surface of the area to be repaired from CBCT images;

[0015] Calculate the distance from the alveolar bone surface to the outer surface of the gingiva to form a soft tissue thickness distribution map;

[0016] A metal veneer model is generated based on the alveolar bone surface, soft tissue thickness distribution map, and boundary of the area to be repaired. The metal veneer model is a non-uniform thickness structure, and its local thickness is determined according to the soft tissue thickness at the corresponding location.

[0017] Based on the area to be repaired and the adjacent teeth, a resin base model is generated to determine the denture placement direction and the undercut area of ​​the adjacent teeth. Under the constraint of the crown-gingival boundary, a clasp model that matches the undercut area of ​​the adjacent teeth is generated.

[0018] A positioning structure and a connection structure that cooperate with each other are set on the non-organic surface of the metal veneer and the connection surface of the resin base body;

[0019] The metal veneer and resin base body are manufactured using additive manufacturing technology. The metal veneer and resin base body, which meet the assembly accuracy requirements, are aligned using the positioning structure and connected using at least one of adhesive connection and mechanical interlocking connection to obtain a composite denture base.

[0020] The second aspect of this invention adopts the following technical solution: a composite denture base manufacturing system is proposed, the composite denture base manufacturing system comprising:

[0021] The data acquisition module is used to acquire intraoral 3D models and CBCT images;

[0022] The registration and analysis module is used to rigidly register the intraoral 3D model with CBCT images, identify the area to be repaired, adjacent teeth and crown-gingival boundary, obtain alveolar bone surface and form a soft tissue thickness distribution map.

[0023] The model generation module is used to generate a non-uniform thickness metal veneer model with a continuous and smooth tissue surface, no through holes and no uneven texture structure, as well as to generate a resin base body model and a retaining ring model.

[0024] Manufacturing equipment for manufacturing the metal veneer and the resin base body according to the metal veneer model and the resin base body model, respectively;

[0025] The scanning and inspection module is used to acquire a scanned model of the manufactured metal veneer and to detect dimensional deviations.

[0026] The assembly module is used to align and connect the metal veneer, which meets the assembly accuracy requirements, to the resin base body through a positioning structure.

[0027] The third aspect of the present invention adopts the following technical solution: a computer-readable medium is provided, wherein a control program is stored in the computer-readable medium, and when the control program is executed by a processor, the processor performs the steps of the composite denture base manufacturing method as described in the first aspect of the present invention.

[0028] The relevant contents of this application are explained as follows:

[0029] This invention addresses existing problems in denture base manufacturing technology, such as easy detachment of resin-metal bonding, insufficient rigidity of pure resin bases, resin oxidation affecting adsorption and causing mucosal damage, and clasps easily compressing gingival soft tissue. It innovatively designs a composite denture base manufacturing method, a composite denture base manufacturing system, and a computer-readable medium. The resulting composite denture base improves tissue surface adsorption and fit stability, reduces local stress concentration, enhances comfort and durability, improves overall mechanical properties, and improves the coordination between clasp retention and gingival avoidance.

[0030] In the above-mentioned solution, through the implementation of the first aspect of the technical solution of the present invention, a method for manufacturing a composite denture base is proposed. This method involves first acquiring an intraoral three-dimensional model that characterizes the crown shape, the outer surface of the gingiva, and the boundary of the edentulous area, as well as CBCT images that characterize the alveolar bone surface and soft tissue thickness. These two types of data are then registered and fused using a unified coordinate system. Secondly, based on the registered intraoral three-dimensional model, the edentulous area to be restored and the adjacent teeth at both ends of the area are accurately identified. Simultaneously, the crown-gingiva boundary line is identified to limit the generation range of the clasps at both ends of the resin base body, preventing the clasps from infringing on the gingiva. Thirdly, based on the registered CBCT images and the intraoral three-dimensional model, the area to be restored is analyzed. The alveolar bone surface of the denture is precisely measured to obtain a thickness distribution map of the soft tissue at each location. Based on this map, a metal veneer model is generated to adhere to the gingiva. This veneer has a non-uniform thickness structure, with each region's thickness precisely matched to the corresponding soft tissue thickness. Next, a resin denture base model is generated based on the area to be restored and adjacent teeth. Following the constraints of the crown-gingival boundary, a clasp model is generated that avoids gingival soft tissue and stably fits with adjacent teeth. Finally, additive manufacturing technology is used to process the metal veneer and resin denture base, achieving precise registration through a positioning structure. A strong connection is then achieved using adhesives and / or mechanical interlocking structures, ultimately producing a composite denture base. In this composite denture base manufacturing method, the design of the metal veneer is driven by the alveolar bone surface and soft tissue thickness. Microstructure adsorption textures and / or edge sealing structures can be set on the tissue surface to make the metal veneer more suitable for forming a stable fit with the gingiva and maintaining a liquid film, thereby improving adsorption stability. The metal veneer adopts a non-uniform thickness design, with appropriate thickening in areas with thicker soft tissue or high occlusal stress, which helps to improve stress distribution and reduce local stress concentration and edge discomfort. The metal veneer serves as the tissue surface load-bearing layer, and the resin base body serves as the shape restoration and denture load-bearing layer. The combination of the two can improve the overall rigidity and bending and crack resistance. By identifying adjacent teeth and the crown-gingival boundary, clasps are generated at both ends of the resin base body, so that the clasps can form effective retention with adjacent teeth while avoiding invasion of the gingival area of ​​adjacent teeth. The composite denture base manufactured using this composite denture base manufacturing method solves the problem of easy detachment of resin and metal bonding, and greatly improves the connection stability and service life of the composite structure in the moist and hot environment of the oral cavity and high load environment. It not only ensures the smoothness of the tissue surface and prevents mucosal damage, but also improves the fit with non-uniform thickness design, which helps to improve the stress distribution and reduce local stress concentration and edge discomfort.

[0031] In the above solution, through the implementation of the second aspect of the technical solution of the present invention, by using the data acquisition module, registration and analysis module, model generation module, manufacturing equipment, scanning and detection module and assembly module in the proposed composite denture base manufacturing system, the entire process of digital, automated and precise manufacturing of composite denture bases can be realized, which can greatly improve the manufacturing efficiency and precision of denture bases, realize the standardized and large-scale production of composite denture bases, and comprehensively improve the mechanical strength, adsorption and retention force, wearing comfort and service life of dentures.

[0032] In the above solution, through the implementation of the third aspect of the technical solution of the present invention, a computer-readable medium is proposed to compile the composite denture base manufacturing method into a control program, store it in the computer-readable medium, and the controller calls the program to automatically execute the entire process.

[0033] In a further technical solution, the steps of identifying the area to be repaired and the adjacent teeth at both ends of the area based on the registered intraoral 3D model include:

[0034] In the steps of identifying the area to be repaired, the adjacent teeth located at both ends of the area to be repaired, and the crown-gingival boundary of the adjacent teeth, identifying the area to be repaired and the adjacent teeth includes:

[0035] The crown surfaces in the intraoral 3D model are segmented, and the tooth position sequence is determined according to the arrangement of each crown along the dental arch.

[0036] The consecutive missing tooth intervals are determined based on the tooth position sequence and the spatial interval between adjacent crowns, and the gingival region corresponding to the consecutive missing tooth intervals is determined as the area to be repaired;

[0037] The teeth located at both ends of the consecutive missing tooth interval and directly adjacent to it are identified as the adjacent teeth.

[0038] By implementing the above technical solutions, the tooth position sequence is determined in the intraoral three-dimensional model. The area to be repaired is determined by the continuous missing tooth position interval based on the tooth position sequence and the spatial interval between adjacent tooth crowns. The teeth located at both ends of the continuous missing tooth position interval and directly adjacent to it are identified as the adjacent teeth. This achieves accurate identification of the area to be repaired and the adjacent teeth, providing a precise positioning basis for the subsequent design of the denture base and clasps.

[0039] In a further technical solution, in the step of identifying the area to be repaired, the adjacent teeth located at both ends of the area to be repaired, and the crown-gingival boundary line of the adjacent teeth, identifying the crown-gingival boundary line includes:

[0040] Input the point cloud or mesh of the adjacent tooth region into the pre-trained semantic segmentation model to obtain crown labels and gingival labels;

[0041] The junction between the crown tag and the gingival tag is extracted, and a continuous curve is fitted to the junction to obtain the crown-gingival boundary line.

[0042] By implementing the above technical solutions, crown labels and gingival labels are obtained through a semantic segmentation model. The crown-gingival boundary line is obtained by continuously fitting the intersection of the crown label and the gingival label, thus achieving accurate identification of the crown-gingival boundary line. This provides precise boundary constraints for clasp generation, further preventing the clasp from infringing on the gingival area of ​​adjacent teeth and further improving effective retention.

[0043] In the step of rigid registration based on common hard tooth tissue features in the intraoral 3D model and CBCT images, the rigid registration includes:

[0044] Initial registration was performed based on the common hard dental tissue features in the intraoral 3D model and CBCT images;

[0045] The iterative nearest point algorithm is used for fine registration to obtain the rigid transformation relationship;

[0046] The rigid transformation relationship is applied as a whole to the alveolar bone surface extracted from the CBCT image, while maintaining the anatomical distance between the alveolar bone surface and the outer surface of the gingiva without any non-rigid change.

[0047] By implementing the above technical solutions, the initial registration of the intraoral 3D model and CBCT images is achieved. The iterative nearest point algorithm is used to obtain the rigid transformation relationship, and the rigid transformation relationship is used as a whole to ensure that the anatomical distance between the alveolar bone surface and the outer surface of the gingiva does not change in a non-rigid manner. This achieves the precise unification of the common hard tissue features of the teeth in the intraoral 3D model and CBCT images, so that the two are completely in the same correct coordinate system. This provides basic data support for the subsequent accurate analysis of alveolar bone surface and soft tissue thickness, and provides further data support for the generation of the resin base body and the personalized design of metal veneers, resulting in better fit and higher comfort.

[0048] In a further technical solution, the step of forming the soft tissue thickness distribution map includes:

[0049] The alveolar bone surface is triangularly meshed to obtain a set of triangular mesh elements {T}. i}, determine each triangular mesh element T i Center of gravity C i and the normal vector N towards the outer surface of the gum i ;

[0050] With C i Starting from N i The direction intersects with the outer surface of the gingiva to obtain the distance C along the direction. iThe nearest valid intersection point P i ;

[0051] The soft tissue thickness h at the corresponding location is calculated using the following formula. i :

[0052] h i =‖P i -C i ||;

[0053] Based on the soft tissue thickness h of each effective triangular mesh element i The soft tissue thickness distribution map H is formed.

[0054] By implementing the above technical solutions, the thickness is measured by intersecting the centroid and normal vector of the triangular mesh, and the shortest distance is taken when there is no unique intersection point. This achieves a dual improvement in the accuracy of data registration and the reliability of soft tissue thickness measurement, ensuring the accuracy of the soft tissue thickness distribution map, and further improving the stress distribution, reducing local stress concentration and edge discomfort.

[0055] In a further technical solution, the step of generating a metal veneer model based on the alveolar bone surface, soft tissue thickness distribution map, and the boundary of the area to be repaired includes generating the metal veneer model as follows:

[0056] The alveolar ridge crest line and soft tissue bearing area are determined based on the morphology of the alveolar bone surface;

[0057] The boundary of the soft tissue bearing area is projected onto the outer surface of the gingiva to obtain the outer boundary of the metal veneer.

[0058] The outer boundary is smoothed, and the edge of the metal veneer is rounded to transition with the tissue surface.

[0059] The local thickness of the metal veneer at each location is determined based on the soft tissue thickness distribution map, resulting in a metal veneer model with non-uniform thickness.

[0060] By implementing the above technical solutions, the alveolar crest area is determined, the soft tissue bearing area is expanded, the projection is made onto the gingival surface and the boundary is smoothed and rounded, and the veneer thickness is determined according to the thickness of the alveolar bone and soft tissue. This achieves the metal veneer boundary fitting the gingiva without local pressure, while the thickness is adapted to the intraoral tissue morphology to further reduce the local pressure of the edge on the gingiva.

[0061] In a further technical solution, the local thickness t of the metal veneer is 0.30mm to 1.00mm, and is determined according to the following range based on the soft tissue thickness h at the corresponding location:

[0062] When h ≤ 1.00 mm, t is 0.30 mm to 0.45 mm;

[0063] When 1.00mm<h≤2.00mm, t is 0.45mm to 0.70mm;

[0064] When h>2.00mm, t is 0.70mm to 1.00mm.

[0065] Through the implementation of the above technical solutions, the non-uniform veneer thickness of 0.30mm to 1.00mm is set in three ranges according to the soft tissue thickness, so as to achieve precise adaptation between the metal veneer thickness and the soft tissue thickness, further disperse the occlusal force and reduce stress concentration.

[0066] In a further technical solution, the local thickness t is determined according to the following piecewise relationships, where the units of h and t are both millimeters:

[0067] When 0≤h≤1.00, t=0.30+0.15h;

[0068] When 1.00<h≤2.00, t=0.45+0.25(h-1.00);

[0069] When h>2.00, t=min{0.70+0.15(h-2.00), 1.00}, this formula means that t takes the smaller value of the two values 0.70+0.15(h-2.00) and 1.00.

[0070] Through the implementation of the above technical solutions, the veneer thickness is calculated by setting the piecewise relationship, so as to realize continuous and refined adaptation of the metal veneer thickness with the soft tissue thickness, and further optimize the stress distribution and fitting effect.

[0071] In a further technical solution, in the step of generating the metal veneer model according to the alveolar bone surface, the soft tissue thickness distribution map and the boundary of the region to be restored, generating the metal veneer model further includes performing finite element analysis on the metal veneer, determining the high-load region of the metal veneer according to the finite element analysis result, and increasing the local thickness of the metal veneer by 0.05mm to 0.30mm in the high-load region; the thickened local thickness does not exceed 1.00mm, and a smooth transition is formed between the high-load region and the adjacent region.

[0072] Through the implementation of the above technical solutions, local reinforcement of the high-stress region is realized, which further improves the bending and crack resistance performance and service life of the denture base.

[0073] In a further technical solution, in the step of generating the resin base main body model based on the region to be restored and the adjacent teeth, the step of generating the resin base main body model includes:

[0074] Establishing the outer shape of the resin base main body with the region to be restored and the outer boundary of the metal veneer as constraints;

[0075] A connecting surface that matches the non-organic surface of the metal veneer is formed on the side facing the metal veneer, and a positioning structure and a connecting structure are formed on the connecting surface;

[0076] An artificial tooth bearing area is formed on the side facing the artificial tooth to support the artificial tooth.

[0077] The overall thickness and smoothing processes are applied to form the main body model of the resin base.

[0078] By implementing the above technical solutions, the initial shape is established with the area to be repaired as the core, the connection surface of the matching metal veneer and the artificial tooth bearing area are set, and the thickness is smoothed, so as to further achieve precise matching between the resin base body and the metal veneer and reliably support the artificial tooth, thereby further ensuring the overall structural stability.

[0079] In a further technical solution, the step of generating the circlip model includes:

[0080] Determine the denture placement direction and undercut area of ​​adjacent teeth based on the surface morphology of adjacent teeth;

[0081] A retention point is selected in the undercut area of ​​the adjacent tooth, and a clasp is generated to connect the resin base body and the retention point;

[0082] The clasp body should not cross the crown-gingival boundary. The starting position of the clasp should be 0.2mm to 1.0mm from the crown side of the crown-gingival boundary, and the end of the clasp should be 0.2mm to 2.0mm from the crown-gingival boundary.

[0083] By implementing the above technical solutions, by setting safety constraint rules between the clasp body and the crown-gingival boundary, and by generating the clasp body according to the undercut of the adjacent tooth and the gingival boundary, the clasp can be effectively retained with the adjacent tooth while completely avoiding the soft tissue of the gingiva, thus further balancing retention performance and wearing comfort.

[0084] Further technical solutions include performing 3D scanning and dimensional deviation detection on the manufactured metal veneer, and compensating for or remanufacturing the metal veneer on the connecting surface of the resin base body based on the detection results. Specifically, this includes:

[0085] The scanned model of the metal veneer is registered with the design model of the metal veneer, and the dimensional deviation of the metal veneer connection surface is calculated.

[0086] When the dimensional deviation exceeds a preset deviation threshold and can be compensated by the connection surface to meet the assembly requirements, the connection surface of the resin base body is compensated according to the dimensional deviation.

[0087] When the dimensional deviation cannot meet the assembly requirements through the connection surface compensation, the metal veneer model is modified and the metal veneer is remanufactured.

[0088] By implementing the above technical solutions, deviations in the metal veneer connection surface can be corrected while ensuring the integrity of the metal veneer tissue surface (mucosal contact surface) without modification. This saves on expensive material costs and further improves the fitting accuracy between the metal veneer and the resin base body, significantly reducing scrap rate and rework costs.

[0089] In a further technical solution, a resin pad is provided on the tissue surface of the metal veneer in a predetermined contact area. The length of the resin pad along the dental arch direction is 8.0mm to 12.0mm, the buccal-palatal width is 3.0mm to 5.0mm, the central thickness is 0.30mm to 0.45mm, and the periphery gradually thins to no more than 0.10mm within a transition width of 1.0mm to 2.0mm, so that the outer surface of the resin pad forms a smooth transition with the tissue surface of the metal veneer where no resin pad is provided.

[0090] The resin pad is made of flexible dental resin material with a Shore A hardness of 65 to 75, and is bonded to the tissue surface of the metal veneer by an adhesive material with an adhesive layer thickness of 0.05 mm to 0.10 mm.

[0091] The resin pad does not alter the positioning structure, connection structure, or overall assembly relationship of the non-organic surface of the metal cladding.

[0092] The implementation of the above technical solutions mainly improves the local contact pressure in the bilateral maxillary missing areas. By setting a flexible resin pad in the predetermined load-bearing area of ​​the metal veneer tissue surface, the concentrated load transmitted from the rigid metal is transformed into a uniformly distributed surface load. At the same time, the edge of the resin pad smoothly connects with the metal tissue surface, without generating new stress concentration sources. It also does not change the positioning and connection structure of the non-tissue surface of the metal veneer, maintaining the overall assembly relationship of the composite denture base. After setting the resin pad, the peak contact pressure can be reduced by about 33% to 34%, effectively avoiding mucosal pressure pain and damage, and significantly improving the comfort of patients wearing it for a long time.

[0093] By implementing the above technical solutions, and through steps such as calculating the dimensional deviation of the metal veneer connection surface by 3D scanning of the metal veneer and compensating for the connection surface of the resin base body, manufacturing deviations can be effectively corrected, further improving the assembly accuracy and fit between the metal veneer and the resin base.

[0094] In a further technical solution, the registration and analysis module and the model generation module are implemented by a processor executing program instructions in a computer-readable medium; the manufacturing equipment includes metal additive manufacturing equipment and resin additive manufacturing equipment, and the scanning and detection module includes a three-dimensional scanning device. Through the implementation of the above technical solutions, the system can flexibly adapt to different hardware platforms, further ensuring operational stability and versatility.

[0095] Due to the application of the above-mentioned solution, the technical solution of this application has the following advantages and effects compared with the prior art:

[0096] 1. The composite denture base made using this composite denture base manufacturing method solves the problem of easy detachment of resin and metal bonding, and greatly improves the connection stability and service life of the composite structure in the oral cavity humid and hot environment and high load environment. It not only ensures the smoothness of the tissue surface and prevents mucosal damage, but also improves the fit with non-uniform thickness design, which helps to improve the stress distribution and reduce local stress concentration and edge discomfort.

[0097] 2. By using the data acquisition module, registration and analysis module, model generation module, manufacturing equipment, scanning and detection module, and assembly module in the proposed composite denture base manufacturing system in a coordinated manner, the entire process of composite denture base manufacturing can be digitized, automated, and precise, which can significantly improve the manufacturing efficiency and accuracy of denture bases, realize the standardized and large-scale production of composite denture bases, and comprehensively improve the mechanical strength, adsorption and retention force, wearing comfort, and service life of dentures. Attached Figure Description

[0098] Figure 1 This is a schematic flowchart of the composite denture base manufacturing method according to an embodiment of the present invention;

[0099] Figure 2 This is a schematic diagram of the unified coordinate system in an embodiment of the present invention;

[0100] Figure 3 This is a schematic diagram of triangular meshing of the registered alveolar bone surface in an embodiment of the present invention;

[0101] Figure 4 This is a schematic diagram of the segmented mapping curve in an embodiment of the present invention;

[0102] Figure 5 This is a schematic diagram of the high-load area of ​​the metal cladding in an embodiment of the present invention;

[0103] Figure 6 This is a schematic block diagram of the composite denture base manufacturing system in an embodiment of the present invention;

[0104] Figure 7 This is a schematic diagram of the intraoral three-dimensional model according to an embodiment of the present invention;

[0105] Figure 8 This is a schematic diagram of triangular meshing in an embodiment of the present invention;

[0106] Figure 9 This is a schematic diagram showing the exemplary finite element calculation results of the bilateral maxillary missing areas in an embodiment of the present invention;

[0107] Figure 10 This is a schematic diagram of the resin base body model in an embodiment of the present invention;

[0108] Figure 11 This is a schematic diagram of the resin base body model supporting artificial posterior teeth in an embodiment of the present invention;

[0109] Figure 12 This is a schematic diagram illustrating the generation of four retaining rings in an embodiment of the present invention;

[0110] Figure 13 This is a schematic diagram showing the average gap table on both sides before and after compensation in an embodiment of the present invention;

[0111] Figure 14 This is a schematic diagram showing the placement of localized resin pads on the tissue surface of bilateral maxillary metal veneers. Detailed Implementation

[0112] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, the specific embodiments of this application are described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of this application. However, this application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this application. Therefore, this application is not limited to the specific embodiments disclosed below.

[0113] The terms "first," "second," etc., used in this article do not specifically refer to order or sequence, nor are they intended to limit this case; they are merely used to distinguish components or operations described using the same technical terms.

[0114] The terms "connection" or "positioning" as used in this article can refer to two or more components or devices making direct physical contact with each other, or making indirect physical contact with each other, or to two or more components or devices operating or acting on each other.

[0115] The terms “include,” “including,” and “have” used in this article are all open-ended, meaning they include but are not limited to.

[0116] Unless otherwise specified, the terms used herein generally have their ordinary meaning in the context of the art, the subject matter, and the specific context. Certain terms used to describe this case will be discussed below or elsewhere in this specification to provide additional guidance to those skilled in the art in describing this case.

[0117] The terms “front,” “back,” “up,” “down,” “left,” and “right” used in this article are directional terms. In this case, they are only used to describe the positional relationship between the structures and are not intended to limit the specific direction of the protection scheme or its actual implementation.

[0118] The terminology used herein is for the purpose of describing specific embodiments only and is not intended to limit the scope of this work. Singular forms such as “a,” “this,” “this,” “the,” and “the” as used herein also include plural forms.

[0119] This application aims to address the shortcomings of existing denture bases, such as insufficient rigidity and short service life.

[0120] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. The parameters given in the embodiments are used to illustrate how to implement the technical relationships defined in the claims and do not constitute a limitation on the scope of protection. Unless otherwise specified, the units for distance and thickness are millimeters.

[0121] "Tissue surface" refers to the side of the metal veneer that faces and approaches the soft tissue of the area to be repaired after assembly; "non-tissue surface" refers to the side of the metal veneer that faces away from the tissue surface and connects to the resin base body. "Continuous smooth" means that the tissue surface does not have through holes or textured surfaces for mechanical interlocking with the resin base body; the tissue surface can achieve a continuous transition through finishing and polishing after additive manufacturing.

[0122] "Common hard tissue features of the tooth" refers to surface features of the crown or other hard tissues of the tooth that can be identified in both the intraoral 3D model and CBCT images. Rigid registration only includes rotation and translation, and does not include non-rigid deformations that change local scale and anatomical distance.

[0123] The "preset deviation threshold" can be set according to the accuracy of the additive manufacturing equipment, the connection method, and the assembly clearance requirements. Its function is to distinguish between direct assembly, situations that can be compensated by the resin connection surface, and situations that require remanufacturing of the metal veneer.

[0124] One embodiment of the present invention provides a method for manufacturing a composite denture base, the steps of which can be referred to... Figure 1As shown, S1 acquires an intraoral 3D model and CBCT images. The intraoral 3D model includes at least the crown surface and the outer gingival surface near the area to be repaired; the CBCT images cover at least the area to be repaired and its adjacent teeth at both ends, and include alveolar bone images. The intraoral 3D model can be a point cloud, a triangular mesh, or a surface model that can be converted into a point cloud / triangular mesh, and the CBCT images can be voxel data and surface models obtained by segmenting voxel data.

[0125] S2 performs rigid registration based on the features of dental hard tissue. The process involves initial registration followed by fine registration using an iterative nearest-point algorithm to ensure the intraoral 3D model and CBCT image are in the same coordinate system (see reference). Figure 2 (As shown). The point set corresponding to the hard tissue surface of the tooth in CBCT is used as the source point set, and the point set of the hard tissue surface of the tooth in the intraoral 3D model is used as the target point set; the nearest point y in the target point set is established for each source point. π(i) The optimal rotation matrix and translation vector are obtained by minimizing the sum of squared Euclidean distances between corresponding points. The objective function is:

[0126] ;

[0127] And it satisfies the rotation matrix constraint:

[0128] ;

[0129] Where M is the number of corresponding point pairs participating in fine registration, and π(i) represents the index of the target point corresponding to the source point. and These are the obtained optimal rotation matrix and translation vector, respectively.

[0130] x i Let i be the i-th point in the source point set;

[0131] y π(i) For the target point set with x i The corresponding nearest point;

[0132] M is the number of point pairs participating in the registration;

[0133] This represents the square of the Euclidean distance.

[0134] Furthermore, after obtaining the final rigid transformation relationship, this relationship is applied globally to the alveolar bone surface extracted from the CBCT image. Since the transformation only involves rotation and translation, the geometric scale of the alveolar bone surface itself and its spatial relationship with the hard dental tissues do not undergo non-rigid changes.

[0135] S3 identifies the area to be repaired, adjacent teeth, and the crown-gingival boundary. It segments the crown surface in the intraoral 3D model and forms a tooth position sequence based on the arrangement of the crowns along the dental arch. When the spatial interval between adjacent crowns is greater than a set threshold, such as 4.0mm or 5.0mm, and there are consecutive missing teeth in the tooth position sequence, a consecutive missing tooth position interval is determined. The gingival region corresponding to this interval is the area to be repaired, and the teeth located at both ends of this interval and directly adjacent to it are considered adjacent teeth.

[0136] Semantic segmentation of the crown-gingiva region is performed on adjacent teeth. The pre-trained semantic segmentation model takes the point cloud or mesh of adjacent teeth as input and outputs crown and gingiva labels for each point or mesh surface. The intersection points of the two types of labels are extracted, discrete outliers are removed, and continuous curve fitting is performed to obtain closed or semi-closed crown-gingiva boundaries. These boundaries are used to limit the path, starting position, and ending point of the clasp. The application of the pre-trained semantic segmentation model and other deep neural network models, including their pre-training weights, network structures, and standardized interfaces, are all existing technologies widely disclosed and used in the fields of computer vision and deep learning. They are fundamental technical means widely used in this field and will not be elaborated further here.

[0137] S4 extracts the alveolar bone surface and generates a soft tissue thickness distribution map. The registered alveolar bone surface is then triangulated to obtain a set of triangular mesh elements {T}. i For each valid triangular mesh element T i Calculate its centroid C i And determine the normal vector N pointing to the outer surface of the gingiva based on the mesh orientation. i .

[0138] refer to Figure 3 As shown, with C i Starting from N i An intersection ray is emitted from the direction indicated by the ray and intersects with the outer surface of the gingiva. If multiple intersection points are obtained, the ray along the N direction is selected. i positive direction distance C i The nearest intersection point P located within the area to be repaired i If no valid intersection point is found, the mesh cell is marked as an invalid cell and does not participate in thickness mapping, or it is interpolated based on adjacent valid cells.

[0139] The thickness h of the soft tissue at the corresponding location i For valid intersection point P i With center of gravity C i Euclidean distance between them:

[0140] h i =‖P i -C i ||;

[0141] h of each effective triangular mesh cell i A soft tissue thickness distribution map H is generated by writing a mesh onto the alveolar bone surface and continuously displaying or interpolating the mesh based on its adjacency relationship.

[0142] ;

[0143] S5 generates a non-uniform thickness metal veneer model, and the soft tissue thickness distribution map H is used to determine the basic local thickness of the metal veneer at each location. This thickness map is jointly determined by the rigidly registered alveolar bone surface and the gingival surface of the intraoral 3D model, rather than being inferred solely from the curvature of the gingival surface.

[0144] Furthermore, the alveolar ridge crest line is determined based on the morphology of the alveolar bone surface, and the soft tissue support area is determined by the alveolar ridge crest line and the boundary of the area to be repaired. The boundary of the soft tissue support area is projected onto the outer surface of the gingiva along the local projection direction to form the outer boundary of the metal veneer. The outer boundary is smoothed, and a rounded transition is set at the edge of the metal veneer.

[0145] The local thickness t of the metal veneer base is determined based on the soft tissue thickness h at the corresponding location, and t ranges from 0.30 mm to 1.00 mm. According to the segmentation relationship defined in the claims, the following continuous mapping can be used:

[0146] ;

[0147] This piecewise relationship is continuous at h=1.00mm and h=2.00mm, yielding t=0.45mm and t=0.70mm respectively. As h continues to increase, the local thickness gradually increases, limited by an upper limit of 1.00mm. t ranges from 0.30mm to 1.00mm, and its values ​​can be 0.30mm, 0.40mm, 0.50mm, 0.60mm, 0.70mm, 0.80mm, 0.90mm, 0.95mm, 1.0mm, etc.

[0148] Figure 4 The piecewise mapping curve is shown.

[0149] Furthermore, finite element analysis was performed on the metal cladding based on the base thickness model to identify high-load areas (see reference). Figure 5 (As shown). The finite element analysis results are used to determine the locations requiring local thickening without altering the structural relationship of the tissue surface being continuous, smooth, without through-holes, and without any uneven textures used for connection. The thickening amount Δt in the high-load area is 0.05 mm to 0.30 mm, and the local thickness after thickening does not exceed 1.00 mm, which can be expressed as:

[0150] ;

[0151] Where u is the position parameter of the metal cladding surface, and Δt(u) takes a non-zero value only in the high load region.

[0152] Δt is 0.05mm to 0.30mm, specifically 0.05mm, 0.10mm, 0.15mm, 0.20mm, 0.25mm, 0.30mm, etc.

[0153] The metal cladding includes a tissue surface facing the soft tissue and a non-tissue surface facing the resin base body. The tissue surface is finished and polished to form a continuous, smooth curved surface. Positioning and connecting structures are both located on the non-tissue surface and do not penetrate the tissue surface. The positioning structures restrict the relative positional freedom during assembly, while the connecting structures form an adhesive and / or mechanical interlocking connection with the resin base body.

[0154] The S6 generator produces a model of the resin base and clasp, establishing the shape of the resin base using the area to be restored and the outer boundary of the metal veneer as constraints. A connecting surface is formed on the side of the resin base facing the metal veneer, matching the non-tissue surface of the metal veneer, and positioning and mating structures corresponding to the positioning and connecting structures are provided. The side of the resin base away from the metal veneer forms the artificial tooth bearing area for supporting the artificial tooth.

[0155] The denture placement direction is determined based on the surface morphology of adjacent teeth, and the undercut areas on the adjacent tooth surfaces are calculated according to this placement direction. Retention points are selected within the undercut areas, and clasps are generated extending from the resin base to the retention points. The clasp path is constrained by the crown-gingival margin, ensuring that the clasp body does not cross this margin.

[0156] Furthermore, the starting position of the clasp is located 0.2mm to 1.0mm (which can be 0.2mm, 0.4mm, 0.5mm, 0.6mm, 0.7mm, 0.8mm, 0.9mm, 1.0mm, etc.) on the crown side of the crown-gingival boundary, and the end of the clasp is maintained at a distance of 0.2mm to 2.0mm (which can be 0.2mm, 0.5mm, 0.8mm, 1.0mm, 1.0mm, 1.3mm, 1.5mm, 2.0mm, etc.) from the crown-gingival boundary. This distance is determined along the local normal of the adjacent tooth surface or the shortest distance on the adjacent tooth surface, and the clasp path always remains on the crown side of the boundary.

[0157] S7 provides positioning and connecting structures. These structures are designed to mate with each other on the non-organic surface of the metal veneer and the connecting surface of the resin base body. The positioning structures, used for registration, restrict the relative positional freedom during assembly. The connecting structures form adhesive and / or mechanical interlocking connections with the resin base body. Mechanical interlocking connections can be achieved by providing bosses on the non-organic surface of the metal veneer and grooves on the resin base body, or by using corresponding slots and protrusions. Conventional mechanical connection methods can be used for these positioning and connecting structures. Alternatively, positioning and connection can be achieved through adhesive bonding.

[0158] The S8 is manufactured using additive manufacturing and subjected to 3D scanning inspection. Both the metal veneer and the resin base are manufactured using additive manufacturing technology. The metal veneer can be formed using metal additive manufacturing equipment suitable for dental metal parts, followed by support removal, tissue surface finishing, and polishing. The resin base can be formed using resin additive manufacturing equipment, and cleaning and post-processing are performed according to the resin material used.

[0159] After the metal veneer manufacturing is completed, a 3D scanning device is used to obtain a scanned model S, which is then rigidly registered with the metal veneer design model D. At the sampling point k corresponding to the connection surface, the dimensional deviation d... k This can be represented as the scanning model points and design model points along the design model normal vector n. k Signed distance:

[0160] ;

[0161] Among them, s k For the coordinates of the sampling points of the scanning model, The coordinates of the points corresponding to the design model are given, and ⋅ represents the vector dot product.

[0162] S9 registers, connects, and obtains the composite denture base. The dimensional deviations at each sampling point on the connection surface are compared with a preset deviation threshold. If the deviation does not exceed the threshold, assembly can proceed directly. If the deviation exceeds the threshold but can be compensated for through the connection surface to meet assembly requirements, reverse compensation is performed on the connection surface of the resin base body based on the deviation field. An example compensation amount is:

[0163] ;

[0164] Where α is the compensation coefficient, satisfying 0 < α ≤ 1.

[0165] When local deviations, overall warping, or positioning structural deviations cannot be compensated by the resin base body connection surface to meet assembly requirements, the metal veneer model is modified and the metal veneer is remanufactured.

[0166] In another embodiment, without altering the overall continuous smoothness of the metal veneer's tissue surface, left and right resin pads are respectively provided in localized areas on both sides of the metal veneer's tissue surface where it contacts the gum line. The resin pads are located in localized contact areas inside the edge of the metal veneer, do not penetrate the metal veneer, and do not replace positioning or connecting structures located on non-tissue surfaces.

[0167] In this embodiment, the length of the resin pad along the dental arch direction is 5.5mm to 8.0mm (it can be 5.5mm, 6mm, 6.5mm, 7mm, 7.5mm, 8mm, etc.), the buccal-lingual width is 2.0mm to 4.0mm (it can be 2mm, 2.5mm, 3mm, 3.5mm, 4mm, etc.), and the center thickness is 0.20mm to 0.50mm (it can be 0.2mm, 0.3mm, 0.35mm, 0.4mm, 0.5mm, etc.), with a preferred center thickness of approximately 0.35mm. The resin pad can be formed of an elastic or flexible resin material compatible with the resin base body, and after assembly, it makes partial contact with the alveoli on both sides of the missing area to provide a cushioning effect under occlusal load.

[0168] Another embodiment of the present invention proposes a composite denture base manufacturing system, such as Figure 6 As shown, the composite denture base manufacturing system includes a data acquisition module, a registration and analysis module, a model generation module, manufacturing equipment, a scanning and inspection module, and an assembly module.

[0169] The data acquisition module receives intraoral 3D models and CBCT images. The registration and analysis module is used for common tooth hard tissue feature identification, initial registration, iterative nearest-point fine registration, identification of the area to be restored, identification of adjacent teeth, extraction of the crown-gingival boundary, extraction of alveolar bone surface, and calculation of soft tissue thickness distribution maps.

[0170] The model generation module generates a non-uniform thickness metal veneer model with a continuous, smooth tissue surface, no through holes, and no uneven texture, based on the alveolar bone surface, soft tissue thickness distribution map, and the boundary of the area to be repaired. It also generates the resin base model and clasp model. The registration and analysis module and the model generation module are implemented by the processor executing program instructions in a computer-readable medium.

[0171] The manufacturing equipment includes metal additive manufacturing equipment and resin additive manufacturing equipment, which manufacture the metal veneer and resin base body based on the metal veneer model and resin base body model, respectively. The scanning and inspection module includes a 3D scanning device for obtaining a scanned model of the manufactured metal veneer and performing dimensional deviation detection. The assembly module is used to align and connect the metal veneer, which meets the assembly accuracy requirements, to the resin base body using a positioning structure.

[0172] Another embodiment of the present invention provides a computer-readable medium storing a control program. When the control program is executed by a processor, the processor sequentially performs data acquisition, rigid registration, region identification, alveolar bone surface extraction, soft tissue thickness distribution map formation, metal veneer model generation, resin base body and clasp model generation, scanning deviation analysis, and connection surface compensation data generation. The processor executes the program instructions in the computer-readable medium to implement the registration and analysis, model generation, and deviation compensation logic.

[0173] The implementation of the technical solution of the present invention will be described below with specific detailed embodiments.

[0174] Example 1:

[0175] Example 1 illustrates an intraoral case where two consecutive posterior teeth are missing on each of the left and right sides of the maxilla, for a total of four posterior teeth. Specifically, the second premolar and first molar on the left side of the maxilla are consecutively missing, as are the second premolar and first molar on the right side of the maxilla. The left and right first premolars serve as the mesial adjacent teeth of the corresponding areas to be restored (10), and the left and right second molars serve as the distal adjacent teeth of the corresponding areas to be restored. Thus, the areas to be restored include a first sub-area to be restored on the left side of the maxilla and a second sub-area to be restored on the right side of the maxilla. Both sub-areas participate in the overall design of the composite denture base.

[0176] refer to Figure 7 As shown, an intraoral 3D model covering the maxillary dental arch 15, adjacent teeth (16, 17) on both sides, and the outer surface of the gingiva 20 in the bilateral missing areas was obtained. CBCT images covering the maxillary dental arch and alveolar bone were also acquired. Using the common hard tissue surface of the bilateral first premolars 18, second molars 19, and the anterior teeth as registration features, initial registration of feature points was performed first, followed by fine registration using the iterative nearest-point algorithm. After registration, both sides of the missing areas were in the same coordinate system.

[0177] refer to Figure 8 As shown, triangular meshing was performed on the alveolar bone surfaces of the left and right missing areas. The first sub-region to be restored on the left side (25) formed approximately 27,600 triangular mesh units, of which 24,960 mesh units achieved effective intersections; the second sub-region to be restored on the right side formed approximately 28,100 triangular mesh units, of which 25,340 mesh units achieved effective intersections. The soft tissue thickness on the left side ranged from 0.68 mm to 3.22 mm, with a median of 1.71 mm; the soft tissue thickness on the right side ranged from 0.72 mm to 3.35 mm, with a median of 1.79 mm.

[0178] Based on the segmented thickness relationship, the basic thickness fields of the left and right metal veneers are generated respectively, and the connecting surfaces corresponding to the two metal veneers are incorporated into the same assembly coordinate system in the resin base body model. The thickness mapping results at representative positions on both sides are shown in Table 1.

[0179] Table 1. Representative thickness mapping results of the bilateral maxillary missing areas

[0180]

[0181] Finite element analysis was performed on the assembly model of the bilateral metal veneers and resin base. A vertical load of 120 N was applied to the load-bearing areas of the left and right artificial teeth, directed along the long axis of the corresponding posterior teeth, for a total load of 240 N. The contact areas between adjacent teeth were set according to the constraint relationship after the denture was in place. Three calculation groups were set up: Comparative Example 1 used a metal veneer with a uniform thickness of 0.40 mm; Example 1-B used only soft tissue thickness segmentation mapping; Example 1-C, based on Example 1-B, increased the thickness of the bilateral high-load areas by 0.10 mm to 0.20 mm, with the increased local thickness not exceeding 1.00 mm.

[0182] Table 2. Exemplary finite element calculation results for bilateral maxillary amputation areas.

[0183]

[0184] From Table 2 and Figure 9 It is evident that under bilateral loading conditions, segmented mapping of soft tissue thickness can simultaneously reduce the maximum equivalent stress and maximum displacement of the left and right metal veneers. Further local thickening based on the finite element results for each side further reduces bilateral stress and displacement. The slight differences between the left and right sides are mainly due to the incomplete asymmetry in the distribution of alveolar bone surface and soft tissue thickness on both sides.

[0185] Example 2: Generation of the model of the bilateral resin base body of the maxilla, the artificial tooth bearing area and the clasp.

[0186] Under the constraints of the bilateral sub-regions to be repaired and the outer boundaries of the bilateral metal veneers obtained in Example 1, Example 2 establishes an integral resin base body model 30 (see Figure 10 The resin base body is formed on the left and right sides to support the two artificial posterior teeth 35 (see...). Figure 11 The artificial tooth bearing area 40 is formed, and a connecting surface 45 is formed on the side facing the non-tissue surface 50 of the corresponding metal veneer. Both the left and right connecting surfaces are provided with positioning and mating structures that cooperate with the positioning and connecting structures of the corresponding metal veneer.

[0187] A common denture placement direction was determined based on the overall maxillary dental arch morphology, and the undercut areas of the first premolar and second molar on both the left and right sides relative to this placement direction were calculated. For each sub-region to be restored, retention points were selected on the mesial and distal adjacent teeth, thereby generating four clasps 55 (see...). Figure 12 (i) refers to the left near-center tether 56, the left far-center tether 57, the right near-center tether 58, and the right far-center tether 59.

[0188] The main paths of the four clasps 55 are all constrained by the crown-gingival margin of the corresponding adjacent teeth, and none of them cross the crown-gingival margin. Exemplary parameters for the starting and ending positions of each clasp are shown in Table 3.

[0189] Table 3. Positional parameters of the maxillary bilateral clasps relative to the crown-gingival boundary.

[0190]

[0191] The tissue surfaces of the left and right metal veneers remain continuous and smooth; the edges of the metal veneers smoothly transition to the tissue surfaces with an arc of radius 0.50mm to 0.80mm. Positioning and connecting structures are only located on the non-tissue surfaces of each metal veneer and cooperate with corresponding structures on the integral resin base body.

[0192] After generating models of the bilateral artificial tooth bearing areas, connecting surfaces, and four clasps, the overall denture model is subjected to interference checks along the common placement direction. When unexpected interference occurs between the clasp body, metal veneer edge, or resin base body and adjacent teeth, the clasp path or local shape of the resin base body is adjusted first, without making non-rigid modifications to the anatomical distance between the alveolar bone surface and the outer gingival surface.

[0193] Example 3: Additive manufacturing, scanning inspection and connection surface compensation of bilateral maxillary metal veneers.

[0194] Six sets of double-sided metal veneers were manufactured according to the models obtained in Examples 1 and 2. Each set includes a left metal veneer and a right metal veneer. After additive manufacturing, support removal, surface finishing, and polishing, the metal veneers were 3D scanned. The left and right scanned models were registered with the corresponding design models, and the dimensional deviations of the connection surfaces were calculated. An exemplary preset deviation threshold is 0.15mm (not limited to this, it can also be 0.13mm, 0.14mm, 0.16mm, 0.17mm, etc.).

[0195] Based on the left and right deviation fields of each set of metal veneers, reverse compensation was performed on the left and right connecting surfaces of the integral resin base model. During compensation, the relative coordinate relationship and common positioning direction between the two connecting surfaces remained unchanged. The average gaps on both sides before and after compensation are shown in Table 4. Figure 13 As shown.

[0196] Table 4 Average gap on both sides before and after compensation

[0197]

[0198] Before compensation, the average gap of the twelve connecting surfaces was 0.195 mm, and after compensation, the average gap was 0.073 mm. After compensation, the average gap of the left and right connecting surfaces was lower than the 0.15 mm threshold, and the two metal cladding surfaces could be positioned and registered with the integral resin base body in the same positioning direction.

[0199] When a metal veneer on one side has an overall warping that cannot be eliminated by the connection surface, or when a positioning structure deviation on that side causes the integral resin base body to be unable to be assembled along the common positioning direction, only the metal veneer on the side with the defective deviation should be corrected and remanufactured; the metal veneer on the other side that meets the assembly accuracy requirements can continue to be used.

[0200] Example 4: Application of local resin pads on the tissue surface of bilateral maxillary metal veneers.

[0201] Based on Examples 1 to 3, in order to improve the local contact pressure in the bilateral maxillary missing areas, reference was made to... Figure 14 As shown, a left resin pad 70 is provided in the main load-bearing area where the tissue surface 65 of the left metal veneer 60 contacts the left alveolar bone, and a right resin pad 71 is provided in the main load-bearing area where the tissue surface 66 of the right metal veneer 61 contacts the right alveolar bone, for a total of two resin pads. Each resin pad is a continuous local pad, no longer separated along the mesial and distal ends, and its shape is determined according to the boundary and surface morphology of the corresponding side alveolar bone contact area.

[0202] The left and right resin pads respectively cover the main alveolar contact area of ​​the corresponding metal veneer. Each resin pad has a length of 8.0 mm to 12.0 mm along the dental arch, a buccal-palatal width of 3.0 mm to 5.0 mm, and a center thickness of 0.30 mm to 0.45 mm. The periphery of the resin pad gradually thins to no more than 0.10 mm within a transition width of 1.0 mm to 2.0 mm, creating a smooth transition between the outer surface of the resin pad and the tissue surface of the metal veneer without the resin pad. The resin pad material is a flexible dental resin suitable for contact with oral soft tissues, with an exemplary Shore A hardness of 65 to 75.

[0203] Before the resin pads are applied, the tissue surface of the metal veneer is further finished and polished using the aforementioned method to ensure it is free of through-holes and textures for mechanical interlocking. Subsequently, the designated resin pad areas on the left and right sides are cleaned, and using an adhesive suitable for bonding dental metal to resin, the independently formed left and right resin pads are bonded to the tissue surfaces of the corresponding metal veneers. The adhesive layer thickness is controlled to be 0.05mm–0.10mm; after bonding, no sharp steps should form around the perimeter of the resin pads, and the exposed tissue contact surfaces of both resin pads should remain continuously smooth.

[0204] To evaluate the exemplary effect of the resin pads, a vertical load of 120N was applied to the artificial tooth bearing areas on both the left and right sides. Contact analysis was performed on Comparative Example 2, which did not have a resin pad, and Example 4-B, which had two resin pads (one on each side). The exemplary results are shown in Table 5.

[0205] Table 5. Exemplary contact pressure results before and after application of bilateral resin pads to the maxilla.

[0206]

[0207] Under these exemplary analytical conditions, after the resin pads were installed, the peak contact pressure on the left side decreased by approximately 33.3%, and the peak contact pressure on the right side decreased by approximately 34.1%; the average contact pressure on both sides decreased accordingly. The left and right resin pads continuously buffer the main contact areas between the corresponding metal veneers and the gums, without requiring separate mesial and distal resin pads on any one side of the metal veneer, and without altering the positioning structure, connection structure, or overall assembly relationship of the non-tissue surfaces of the metal veneers.

[0208] After the two resin pads are bonded together, the composite denture base is trial-fitted along the common placement direction. Once it is confirmed that the left resin pad fits snugly against the left jawbone contact area, and the right resin pad fits snugly against the right jawbone contact area, and that neither resin pad has obvious warping, sharp edges, or localized thickening that hinders placement, the final assembly is completed. The outer surface of the resin pads can be further finely polished to create a continuous, smooth surface suitable for contact with soft tissue.

[0209] Through the implementation of the above embodiments, the problems existing in the manufacturing technology of denture bases, such as easy detachment of resin and metal bonding, insufficient rigidity of pure resin bases, and resin oxidation affecting adsorption effect and mucosal damage, are solved. By using a composite denture base manufacturing method, a composite denture base manufacturing system, and a computer-readable medium, the manufactured composite denture base can improve the tissue surface adsorption and fit stability and reduce local stress concentration, thus achieving the purpose of the present invention.

[0210] The above embodiments are only for illustrating the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be construed as limiting the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A method for manufacturing a composite denture base, characterized in that, The method for manufacturing the composite denture base includes: Acquire an intraoral 3D model and CBCT images, wherein the intraoral 3D model includes the crown surface and the outer gingival surface, and the CBCT images include alveolar bone images of the area to be repaired; Rigid registration is performed based on the common hard tissue features of the teeth in the intraoral 3D model and CBCT images, so that the two are in the same coordinate system; Identify the area to be repaired, the adjacent teeth at both ends of the area to be repaired, and the crown-gingival boundary of the adjacent teeth, and obtain the alveolar bone surface of the area to be repaired from CBCT images; Calculate the distance from the alveolar bone surface to the outer surface of the gingiva to form a soft tissue thickness distribution map; A metal veneer model is generated based on the alveolar bone surface, soft tissue thickness distribution map, and boundary of the area to be repaired. The metal veneer model is a non-uniform thickness structure, and its local thickness is determined according to the soft tissue thickness at the corresponding location. Based on the area to be repaired and the adjacent teeth, a resin base model is generated to determine the denture placement direction and the undercut area of ​​the adjacent teeth. Under the constraint of the crown-gingival boundary, a clasp model that matches the undercut area of ​​the adjacent teeth is generated. A positioning structure and a connection structure that cooperate with each other are set on the non-organic surface of the metal veneer and the connection surface of the resin base body; The metal veneer and resin base body are manufactured using additive manufacturing technology. The metal veneer and resin base body, which meet the assembly accuracy requirements, are aligned using the positioning structure and connected using at least one of adhesive connection and mechanical interlocking connection to obtain a composite denture base.

2. The method for manufacturing a composite denture base according to claim 1, characterized in that, In the steps of identifying the area to be repaired, the adjacent teeth located at both ends of the area to be repaired, and the crown-gingival boundary of the adjacent teeth, identifying the area to be repaired and the adjacent teeth includes: The crown surfaces in the intraoral 3D model are segmented, and the tooth position sequence is determined according to the arrangement of each crown along the dental arch. The consecutive missing tooth intervals are determined based on the tooth position sequence and the spatial interval between adjacent crowns, and the gingival region corresponding to the consecutive missing tooth intervals is determined as the area to be repaired; The teeth located at both ends of the consecutive missing tooth interval and directly adjacent to it are identified as the adjacent teeth.

3. The method for manufacturing a composite denture base according to claim 2, characterized in that, In the steps of identifying the area to be repaired, the adjacent teeth located at both ends of the area to be repaired, and the crown-gingival boundary of the adjacent teeth, identifying the crown-gingival boundary includes: Input the point cloud or mesh of the adjacent tooth region into the pre-trained semantic segmentation model to obtain crown labels and gingival labels; The junction between the crown tag and the gingival tag is extracted, and a continuous curve is fitted to the junction to obtain the crown-gingival boundary line.

4. The method for manufacturing a composite denture base according to claim 1, characterized in that, In the step of rigid registration based on common hard tooth tissue features in the intraoral 3D model and CBCT images, the rigid registration includes: Initial registration was performed based on the common hard dental tissue features in the intraoral 3D model and CBCT images; The iterative nearest point algorithm is used for fine registration to obtain the rigid transformation relationship; Applying the rigid transformation relationship entirely to the alveolar bone surface extracted from the CBCT image, and keeping the anatomical distance between the alveolar bone surface and the outer gingival surface from undergoing non-rigid changes.

5. The method for manufacturing a composite denture base according to claim 4, characterized in that, the step of forming the soft tissue thickness distribution map comprises: The alveolar bone surface is triangularly meshed to obtain a set of triangular mesh elements {T}. i }, determine each triangular mesh element T i Center of gravity C i and the normal vector N towards the outer surface of the gum i ; With C i Starting from N i The direction intersects with the outer surface of the gingiva to obtain the distance C along the direction. i The nearest valid intersection point P i ; The soft tissue thickness h at the corresponding location is calculated using the following formula. i : h i =‖P i -C i ‖; Based on the soft tissue thickness h of each effective triangular mesh element i The soft tissue thickness distribution map H is formed.

6. The method for manufacturing a composite denture base according to claim 1, characterized in that, in the step of generating the metal veneer model according to the alveolar bone surface, the soft tissue thickness distribution map and the boundary of the region to be restored, generating the metal veneer model comprises: determining the alveolar ridge crest line and the soft tissue bearing region according to the morphology of the alveolar bone surface; projecting the boundary of the soft tissue bearing region onto the outer gingival surface to obtain the outer boundary of the metal veneer; smoothing the outer boundary, and making the edge of the metal veneer transition with the tissue surface in a circular arc; determining the local thickness of each position of the metal veneer according to the soft tissue thickness distribution map, to obtain the metal veneer model with non-uniform thickness.

7. The method for manufacturing a composite denture base according to claim 6, characterized in that, the local thickness t of the metal veneer is 0.30mm to 1.00mm, and is determined according to the soft tissue thickness h at the corresponding position within the following range: when h≤1.00mm, t is 0.30mm to 0.45mm; when 1.00mm<h≤2.00mm, t is 0.45mm to 0.70mm; when h>2.00mm, t is 0.70mm to 1.00mm.

8. The method for manufacturing a composite denture base according to claim 6, characterized in that, the local thickness t is determined according to the following piecewise relationship, wherein the units of h and t are both millimeters: when 0≤h≤1.00, t=0.30+0.15h; when 1.00<h≤2.00, t=0.45+0.25(h-1.00); when h>2.00, t=min{0.70+0.15(h-2.00), 1.00}, this formula means that t takes the smaller value of 0.70+0.15(h-2.00) and 1.

00.

9. The method for manufacturing a composite denture base according to claim 1, characterized in that, in the step of generating the metal veneer model according to the alveolar bone surface, the soft tissue thickness distribution map and the boundary of the region to be restored, generating the metal veneer model further comprises performing finite element analysis on the metal veneer, determining the high-load region of the metal veneer according to the finite element analysis result, and increasing the local thickness of the metal veneer by 0.05mm to 0.30mm in the high-load region; the thickened local thickness does not exceed 1.00mm, and a smooth transition is formed between the high-load region and the adjacent region.

10. The method for manufacturing a composite denture base according to claim 1, characterized in that, the tissue surface of the metal veneer is finished and polished to form a continuous smooth curved surface, and the positioning structure and the connecting structure are both arranged on the non-tissue surface of the metal veneer and do not penetrate through the tissue surface.

11. The method for manufacturing a composite denture base according to claim 1, characterized in that, The step of generating the resin base body model includes: The shape of the resin base body is established with the area to be repaired and the outer boundary of the metal veneer as constraints. A connecting surface that matches the non-organic surface of the metal veneer is formed on the side facing the metal veneer, and a positioning structure and a connecting structure are formed on the connecting surface; An artificial tooth bearing area is formed on the side facing the artificial tooth to support the artificial tooth.

12. The method for manufacturing a composite denture base according to claim 1, characterized in that, The step of generating the circlip model includes: Determine the denture placement direction and undercut area of ​​adjacent teeth based on the surface morphology of adjacent teeth; A retention point is selected in the undercut area of ​​the adjacent tooth, and a clasp is generated to connect the resin base body and the retention point; The clasp body should not cross the crown-gingival boundary. The starting position of the clasp should be 0.2mm to 1.0mm from the crown side of the crown-gingival boundary, and the end of the clasp should be 0.2mm to 2.0mm from the crown-gingival boundary.

13. The method for manufacturing a composite denture base according to claim 1, characterized in that, This also includes performing 3D scanning and dimensional deviation detection on the manufactured metal veneer, and compensating for or remanufacturing the metal veneer on the connecting surface of the resin base body based on the detection results. Specifically, this includes: The scanned model of the metal veneer is registered with the design model of the metal veneer, and the dimensional deviation of the metal veneer connection surface is calculated. When the dimensional deviation exceeds a preset deviation threshold and can be compensated by the connection surface to meet the assembly requirements, the connection surface of the resin base body is compensated according to the dimensional deviation. When the dimensional deviation cannot meet the assembly requirements through the connection surface compensation, the metal veneer model is modified and the metal veneer is remanufactured.

14. The method for manufacturing a composite denture base according to claim 1, characterized in that, The tissue surface of the metal veneer has a resin pad in the predetermined contact area. The resin pad has a length of 8.0 mm to 12.0 mm along the dental arch direction, a buccal-palatal width of 3.0 mm to 5.0 mm, a central thickness of 0.30 mm to 0.45 mm, and a periphery that gradually thins to no more than 0.10 mm within a transition width of 1.0 mm to 2.0 mm, so that the outer surface of the resin pad forms a smooth transition with the tissue surface of the metal veneer where no resin pad is provided. The resin pad is made of flexible dental resin material with a Shore A hardness of 65 to 75, and is bonded to the tissue surface of the metal veneer by an adhesive material with an adhesive layer thickness of 0.05 mm to 0.10 mm. The resin pad does not alter the positioning structure, connection structure, or overall assembly relationship of the non-organic surface of the metal cladding.

15. A composite denture base manufacturing system, said composite denture base manufacturing system being applied to the composite denture base manufacturing method as described in any one of claims 1 to 14, characterized in that, The composite denture base manufacturing system includes: The data acquisition module is used to acquire intraoral 3D models and CBCT images; The registration and analysis module is used to rigidly register the intraoral 3D model with CBCT images, identify the area to be repaired, adjacent teeth and crown-gingival boundary, obtain alveolar bone surface and form a soft tissue thickness distribution map. The model generation module is used to generate a non-uniform thickness metal veneer model with a continuous and smooth tissue surface, no through holes and no uneven texture structure, as well as to generate a resin base body model and a retaining ring model. Manufacturing equipment for manufacturing the metal veneer and the resin base body according to the metal veneer model and the resin base body model, respectively; The scanning and inspection module is used to acquire a scanned model of the manufactured metal veneer and to detect dimensional deviations. The assembly module is used to align and connect the metal veneer, which meets the assembly accuracy requirements, to the resin base body through a positioning structure.

16. The composite denture base manufacturing system according to claim 15, characterized in that, The registration and analysis module and the model generation module are implemented by the processor executing program instructions in a computer-readable medium; the manufacturing equipment includes metal additive manufacturing equipment and resin additive manufacturing equipment; and the scanning and detection module includes a three-dimensional scanning device.

17. A computer-readable medium, characterized in that: The computer-readable medium stores a control program that, when executed by a processor, causes the processor to perform the steps of the composite denture base manufacturing method as described in any one of claims 1 to 14.

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