Umbrella-type scanning method and system for missing dentition or defective dentition

Abstract

The present invention relates to the field of intraoral scanning for implant restoration, and in particular to an umbrella-type scanning method and system for missing dentition or defective dentition. The method comprises: providing a plurality of positioning bodies, wherein each positioning body is provided with an identification body at least comprising a top feature, a cutting face geometry and curve feature, and an auxiliary rod identification body; presetting a CAD model corresponding to each identification body; acquiring the current tooth design, and acquiring point cloud data of the plurality of positioning bodies by means of an intraoral scanner; preprocessing the point cloud data to remove background noise and a non-target point cloud, and performing automatic identification and segmentation to extract the feature point cloud of each identification body; and using the feature point clouds and the CAD models for processing to output a registration result. In the present invention, during scanning, feature point clouds are accurately extracted by means of an automatic identification and segmentation technology, four coplanar key points are used to construct an initial transformation matrix, and the transformation matrix is optimized by means of an iterative least square method, thereby improving the accuracy of scanning data and the quality of model reconstruction.

Description

An umbrella scanning method and system for edentulous or dentulous TECHNICAL FIELD

[0001] The present application relates to the field of intraoral scanning for implant restoration, and in particular to an umbrella scanning method and system for edentulous or dentulous. BACKGROUND

[0002] Digital intraoral scanning is a key technology for digital impression taking in oral implant restoration. Based on the principle of optical scanning, the technology applies a laser light source for intraoral projection, completes real-time depth reconstruction, obtains local point cloud data, fuses point cloud data using a point cloud registration algorithm, and generates three-dimensional grid data using a reconstruction algorithm to scan the morphology of intraoral tissues in real time. In the digital design stage of implant restoration, the scanning rod is connected to the implant or implant abutment during scanning to obtain the three-dimensional morphology of the scanning rod, surrounding dentition, and soft tissue. The exact three-dimensional position of the implant is calculated based on these data.

[0003] In the prior art, the scanning rod is usually cylindrical and mainly positioned on the side, with a small scanning area at the top and lacking sufficient geometric features, making it impossible to quickly and accurately obtain the three-dimensional morphology of the scanning rod using this conventional strategy. The scanning strategy directly affects the accuracy of scanning. Previous studies on natural teeth have shown that the accuracy is relatively high when scanning from the occlusal surface to the palatal side and then to the buccal side.

[0004] The method further includes scanning the occlusal surface, the palatal side, and the buccal side of the teeth:

[0005] Scanning the occlusal surface: The scanning starts by capturing the occlusal surface of the teeth. This is the upper or lower surface where the teeth come into contact with each other. The scanner is moved across the teeth to capture detailed images of the occlusal surface.

[0006] Scanning the palatal (lingual) side: Next, the scanner is moved to the inner side of the teeth, which is the part closest to the roof of the mouth (lingual side). The dentist or technician carefully inserts the scanner into the mouth while capturing images of the palatal side.

[0007] Scanning the buccal side: Then, the scanner is moved to the outer side of the teeth, which is the part closest to the cheek (buccal side).

[0008] During the scanning process, the dentist or technician ensures that every corner of the teeth is scanned, including the contact points between the teeth and the junction of the teeth with the gums. After the scanning is complete, the device integrates the captured data into a complete three-dimensional model. This model can be used for diagnosis, treatment planning, or making restorations.

[0009] However, the conventional scanning rod has a small occlusal surface area and no obvious characteristic morphology, and thus cannot realize the above scanning strategy. Therefore, the present application needs a new scanning strategy for scanning a dentition defect or a dentition defect. SUMMARY

[0010] The present application aims to solve the above technical problems and provides an umbrella scanning method and system for a dentition defect or a dentition defect.

[0011] The present application provides an umbrella scanning method for a dentition defect or a dentition defect, comprising the following steps:

[0012] A plurality of positioning bodies are provided, each positioning body comprising a scanning rod body and an auxiliary rod arranged on the side surface of the scanning rod body, and each positioning body is provided with a marking body comprising at least a top feature, a cutting surface geometry and a curve feature, and an auxiliary rod identification body;

[0013] A CAD model corresponding to each marking body is set in advance;

[0014] Obtain the design of the teeth this time: select the appropriate auxiliary rod length according to the distance between two adjacent implant composite abutments, and configure the scanning rod body to be installed on each implant composite abutment,

[0015] Obtain point cloud data of the plurality of positioning bodies by an intraoral scanner;

[0016] Preprocess the point cloud data to remove background noise and non-target point clouds, and automatically identify and segment the feature point clouds of each marking body;

[0017] The feature point clouds are processed with the CAD model, and the registration result is output; until the termination condition of registration is met, the corresponding point cloud model is output.

[0018] Further, the registration result output by processing the feature point clouds with the CAD model includes:

[0019] Select four coplanar key points through the feature point clouds, and calculate a preliminary transformation matrix based on the four coplanar key points, which is used for preliminary alignment with the CAD model of the scanning rod body;

[0020] Iteratively optimize the preliminary transformation matrix as input, and in each iteration process, update and select the translation according to the minimum distance error between the position of the feature point cloud and the CAD model.

[0021] Further, the method further comprises, in each iteration process, calculating an overlap degree of the two plurality of feature point clouds under the current transformation, the overlap degree being a ratio of a number of overlapping points to a total number of points, for quantifying the alignment accuracy; and when the overlap degree is lower than a preset threshold, adjusting parameters of the ICP algorithm, the parameters including a number of iterations, an adjustment search range, or an optimized distance metric.

[0022] Further, the termination condition includes whether a threshold of the number of iterations is reached, whether the error reaches a predetermined threshold upper limit, or a combination of the number of iterations and the error threshold.

[0023] Further, the method further comprises, in each iteration process, calculating an overlap degree of the two plurality of feature point clouds under the current transformation, the overlap degree being a ratio of a number of overlapping points to a total number of points, for quantifying the alignment accuracy; and when the overlap degree is lower than a preset threshold, adjusting parameters of the ICP algorithm, the parameters including a number of iterations, an adjustment search range, or an optimized distance metric.

[0024] Further, the method further comprises, in each iteration process, calculating an overlap degree of the two plurality of feature point clouds under the current transformation, the overlap degree being a ratio of a number of overlapping points to a total number of points, for quantifying the alignment accuracy; and when the overlap degree is lower than a preset threshold, adjusting parameters of the ICP algorithm, the parameters including a number of iterations, an adjustment search range, or an optimized distance metric.

[0025] Further, the method further comprises, in each iteration process, calculating an overlap degree of the two plurality of feature point clouds under the current transformation, the overlap degree being a ratio of a number of overlapping points to a total number of points, for quantifying the alignment accuracy; and when the overlap degree is lower than a preset threshold, adjusting parameters of the ICP algorithm, the parameters including a number of iterations, an adjustment search range, or an optimized distance metric.

[0026] Further, the method further comprises, in each iteration process, calculating an overlap degree of the two plurality of feature point clouds under the current transformation, the overlap degree being a ratio of a number of overlapping points to a total number of points, for quantifying the alignment accuracy; and when the overlap degree is lower than a preset threshold, adjusting parameters of the ICP algorithm, the parameters including a number of iterations, an adjustment search range, or an optimized distance metric.

[0027] Further, the method further comprises, in each iteration process, calculating an overlap degree of the two plurality of feature point clouds under the current transformation, the overlap degree being a ratio of a number of overlapping points to a total number of points, for quantifying the alignment accuracy; and when the overlap degree is lower than a preset threshold, adjusting parameters of the ICP algorithm, the parameters including a number of iterations, an adjustment search range, or an optimized distance metric.

[0028] Based on the same inventive concept, the present application also provides an umbrella type scanning system for missing or defective dentition, comprising a plurality of positioning bodies, a scanner scanning head, and a scanning control device.

[0029] The plurality of positioning bodies each comprises a scanning rod body and an auxiliary rod arranged on the side of the scanning body, and each positioning body is provided with a plurality of identification bodies including at least a top feature, a cutting surface geometry and curve feature, and an auxiliary rod identification body; the length of the auxiliary rod is selected according to the distance between the two adjacent implant composite abutments, and the scanning rod body is configured to be mounted on the composite abutment of each implant,

[0030] The scanner scanning head acquires point cloud data of the plurality of positioning bodies through an intraoral scanner.

[0031] The scanning control device is configured to pre-set a CAD model corresponding to each identification body.

[0032] The point cloud data is pre-processed to remove background noise and non-target point clouds, and the feature point cloud of each identification body is automatically identified and segmented.

[0033] The feature point cloud is processed with the CAD model, and a registration result is output until a termination condition of registration is met, and a corresponding point cloud model is output.

[0034] Compared with the prior art, the present application has at least one of the following technical effects:

[0035] The present application provides a digital umbrella scanning method for edentulous or dentition defect, by scanning a plurality of positioning bodies with specific geometric and curve characteristics installed on the implant, each positioning body includes a scanning rod body equipped with a side auxiliary rod, these positioning bodies correspond to a preset CAD model, allowing the length of the auxiliary rod to be adjusted according to the distance between the implants, thereby ensuring accurate installation. During the scanning process, the point cloud data collected by the intraoral scanner is preprocessed to remove background noise and non-target point clouds, and the feature point cloud is accurately extracted through automatic recognition and segmentation technology, an initial transformation matrix is constructed using four coplanar key points, preliminary alignment of the point cloud data and the CAD model is realized, and the transformation matrix is optimized through the iterative least squares method, further fine adjustment of the alignment is performed, and the error between the point cloud and the model is effectively reduced. Thus, the accuracy of the scanning data and the quality of the model reconstruction are improved, the accuracy of the oral implant restoration design and the reliability of the implementation are significantly enhanced, and the problem that the current traditional intraoral scanning technology is difficult to accurately capture complex internal details due to the simple geometric shape of the scanning rod (such as a column) and the small area of the occlusal surface area and lack of sufficient geometric features is solved. BRIEF DESCRIPTION OF DRAWINGS

[0036] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiment description:

[0037] Fig. 1 is a step flowchart of the umbrella scanning method in the embodiment of the present application;

[0038] Fig. 2 is a schematic diagram of the installation of the positioning body under the edentulous in the embodiment of the present application;

[0039] Fig. 3 is a data processing flowchart of the oral scanner scanning the positioning body in the embodiment of the present application;

[0040] Fig. 4 is a point cloud matching calculation diagram of the oral scanner scanning the positioning body in the embodiment of the present application. DETAILED DESCRIPTION

[0041] The present application will be described below with reference to specific embodiments and certain drawings, but the present application is not limited thereto. Any drawings described are only schematic and are non-limiting. In the drawings, the size of some elements can be exaggerated and not drawn to scale for the purpose of illustration. The size and relative size are not necessarily corresponding to the actual examples of implementing the present application.

[0042] Furthermore, the terms first, second, third, etc. have been used, in the description and in the claims, merely to distinguish like elements, and are not necessarily used to describe a sequential or chronological order. Unless otherwise specified, the terms are interchangeable under appropriate circumstances and embodiments of the application can operate in other sequences than described or illustrated herein.

[0043] Furthermore, the terms "top", "bottom", "upper", "lower", "side", "lateral" and the like have been used in the description and the claims merely to describe the orientation in use and are not necessarily used to describe relative positions. The terms so used are interchangeable under appropriate circumstances and embodiments of the application described herein can operate in other orientations than described or illustrated herein.

[0044] The term "comprising", used in the claims, should not be interpreted as being restricted to the means listed thereafter; it does not exclude other elements or steps. It needs to be interpreted as specifying the presence of the stated features, integers, steps or components as referred to, but does not preclude the presence or addition of one or more other features, integers, steps or components, or groups thereof. Thus, the scope of the expression "a device comprising means A and B" should not be limited to devices consisting only of components A and B. It means that with respect to the present application, the only relevant components of the device are A and B.

[0045] In the context of the present application, a marker is understood to comprise any 2D or 3D geometric object capable of defining a predetermined reference point, the coordinates of which can be determined. The kind of suitable markers is basically not limited. Preferred markers have a regular geometric shape, as the predetermined reference point of the marker can easily be defined, or even be intuitive. Suitable markers can be, for example, equilateral triangles, squares, rectangles, circles or regular polygons, wherein, for example, the center point can be considered the predetermined reference point. Suitable markers can also be line segments, wherein a point can be considered the predetermined reference point. Suitable 3D markers can be, for example, spheres, hemispheres or cubes, wherein the center point can then be considered the predetermined reference point. The applicant has found that the size and shape of the markers can vary within a very wide range and that markers of different shapes and or or sizes can be used as part of the same pattern. The applicant has found that the contrast of the marker to its surroundings can be further enhanced by adding a strongly contrasting edge around the marker.

[0046] In the context of the present application, pre-calibration is understood to mean a recognition process, including the results thereof, to which recognition techniques are applied in a clinical situation in connection with a given type of implant or various species to be connected in order to obtain from the pattern formed by the markers as part of the scan positioning all the information required to retrieve the implant position and orientation. The information thus collected forms reference information in the process of correlating the visualized pattern to the implant type or equivalent in the clinical situation presented inter- orally.

[0047] In the context of the present invention, the "vector" of a dental implant or implant root is defined as spatial information that first defines an orientation axis of the dental implant root. The carrier also includes the position of the top of the dental implant root along the orientation axis. Thus, the top is defined as the face corresponding to the height of the implant root.

[0048] The creation process of the present invention is described.

[0049] The present inventors have found in clinical research that current intraoral scanning technology faces the problem of insufficient accuracy in the application of edentulous jaw scanning. Due to the lack of obvious geometric features of soft tissue caused by tooth loss in edentulous patients, the availability of necessary geometric features in the scanning process is limited. Secondly, the mucosal soft tissue on the buccal side and the lingual side in the mouth may introduce data noise in the scanning process. With the increase of scanning data, the cumulative error will gradually increase, further reducing the accuracy of scanning. Although some studies have tried to increase the geometric features of the soft tissue transition stage by adding auxiliary devices to the scanning rod, this method has achieved certain results in improving the accuracy of edentulous implant scanning, but it still has not reached the accuracy level comparable to single tooth or multiple tooth implant restoration. In addition, the conventional implant scanning strategy is usually to scan the jaw surface of the dentition first, and then scan the buccal side or lingual side of the dentition. This method has been proven to provide higher scanning accuracy in single tooth or multiple tooth implantation. In natural teeth and crown restorations, the soft tissue transition area is part of the crown contour. For edentulous implant restorations, this transition area is mainly soft tissue.

[0050] In modern oral implantation and restoration, obtaining accurate intraoral three-dimensional images is crucial for the successful implementation of edentulous implant restoration. Currently, most intraoral scanners rely on optical technology, scanning the oral cavity with lasers or other light sources to obtain detailed images of the implant and its surrounding soft tissue. However, for edentulous patients, since the implant is usually buried under the bone and there is a lack of reliable geometric feature points in the mouth, the traditional cylindrical scanning rod often cannot provide sufficient accuracy to guide the precise positioning of the implant. This is mainly because the shape and size of the traditional scanning rod limit its scanning range and feature point capture ability in the mouth.

[0051] In view of these limitations of the prior art, the present application proposes an umbrella scanning method and system for edentulous or dentition defect, which is composed of multiple positioning bodies, each including a scanning rod body and an auxiliary rod arranged on the side of the scanning rod body. The positioning body not only includes top features, cutting surface geometry, and auxiliary rods on the side of the scanning rod body, but also enhances the geometric feature recognition of the soft tissue transition stage, cooperates with automatic feature point cloud matching and iterative optimization of ICP algorithm, improves the alignment accuracy between point cloud data and model, constructs a transformation matrix by selecting four coplanar key points and performs continuous iteration, considers the overlap and minimum distance error of the point cloud in the optimization process, further fine adjusts the alignment, and ensures that the final output model meets the high precision standard. The umbrella scanning method is not only suitable for conventional edentulous restoration, but also particularly suitable for complex implant restoration of edentulous jaw.

[0052] First embodiment

[0053] In this embodiment, for the case of edentulous or severe defect, the conventional scanning method often fails to capture accurate three-dimensional data due to the lack of stable reference points. This embodiment introduces multiple positioning rods including at least top features, cutting surface geometry, and curve features, auxiliary rod recognition bodies, improves the feature recognition capability in the intraoral scanning process, ensures the accuracy of the data, and at the same time adopts automatic feature point cloud registration and alignment algorithm to improve the automation degree of data processing and the accuracy of the final result. The specific implementation scheme is as follows:

[0054] As shown in FIGS. 1-4, the present application provides an umbrella scanning method for edentulous or dentition defect, which uses multiple positioning bodies, each including a scanning rod body and an auxiliary rod arranged on the side of the scanning rod body, and each positioning body includes at least top features, cutting surface geometry, and curve features, auxiliary rod recognition bodies. Each recognition body is relative to a pre-set CAD model to ensure the accuracy and reproducibility of the scanning. During the scanning process, first, the length of the auxiliary rod is selected according to the distance between two adjacent implant composite abutments, the scanning rod body is configured and installed on each implant composite abutment, the point cloud data of the positioning body is collected using an intraoral scanner, then the point cloud data is preprocessed to remove background noise and non-target point cloud, the feature point cloud of each recognition body is automatically recognized and segmented by edge detection and curve fitting; the feature point cloud is processed with the CAD model, and the registration result is output; until the termination condition of registration is met, the corresponding point cloud model is output.

[0055] The registration result output by processing the feature point cloud and the CAD model includes: first, four coplanar key points are selected from the feature point cloud, and a preliminary transformation matrix is calculated based on the four coplanar key points, which is used for preliminary alignment with the CAD model of the scanning rod body; then, the preliminary transformation matrix is input for iterative optimization, and in each iteration process, the corresponding update selection and translation are performed according to the minimum distance error between the positions of the feature point cloud and the CAD model. In each iteration process, the overlap degree of the two feature point clouds under the current transformation is calculated, and the overlap degree is the ratio of the number of overlapping points to the total number of points, which is used to quantify the alignment accuracy; when the overlap degree is lower than a preset threshold, the ICP algorithm parameters are adjusted, including the number of iterations, the adjustment search range or the optimization distance metric standard. The termination conditions include whether the threshold of the number of iterations is reached, whether the error reaches the upper limit of the predetermined threshold, or the combination of the number of iterations and the error threshold.

[0056] The specific registration process is shown in FIG. 4. Four coplanar key points are determined, first, vector ac and vector ab are calculated, and the vector cross product formula is used The corresponding normal vector is calculated The vector is removed is perpendicular to the plane formed by points a, b, and c. Whether the fourth point d is coplanar is verified by the normal vector, and the dot product of vector ad and the normal vector is calculated. Considering the accuracy of the numerical value, if the point set is close to zero, then the point d is also on the plane. Then, the preliminary transformation matrix is estimated by the four coplanar points, which specifically includes finding the geometric center e of the four points and the center e' of the corresponding points in the target point cloud. The positions of the four points in the original and target clouds are used to calculate the optimal rotation matrix R and translation vector t. Specifically, the least squares method is used to determine the rotation matrix R and translation vector t in point cloud registration to minimize the total registration error, that is, by minimizing i || (R * p i +t)-p' 2 | i and p' i are the corresponding points in the original and target point clouds.

[0057] When the preliminary transformation matrix is obtained, optimization is performed by iteration. In each iteration, the nearest corresponding point is found for the point after the current transformation, and the transformation matrix is recalculated based on the newly found corresponding point pair to further reduce the average distance between the points. When the update amount of the transformation matrix is less than a certain threshold, or the preset number of iterations is reached, or the error between the point clouds is small enough, the algorithm is terminated.

[0058] As shown in FIG. 2 and FIG. 4, the plurality of scanning rod bodies design an umbrella-shaped scanning portion and its corresponding connecting portion, the top of the umbrella-shaped scanning portion is equipped with a first top surface, and the first and second cutting surfaces with unique geometric shapes are symmetrically arranged on both sides of the first top surface. These cutting surfaces extend outward from the first top surface, forming distinct junction lines with each other and with the first top surface. This constitutes a top with multi-directional anisotropy, greatly enhancing the recognition and positioning ability of the scanning rod in the intraoral scanning device, especially from the top perspective of the rod body. In addition, the auxiliary rod in this design has a unique function, which is used to eliminate noise and unnecessary data generated during scanning. Through its specially designed structure and materials, the auxiliary rod can reduce reflection and scattering in the scanning data, optimizing the quality of the data. In the data processing stage, the configuration of the auxiliary rod allows the algorithm to more effectively separate and eliminate non-target point clouds, improving the clarity and usability of the final image. This integrated elimination function not only simplifies the subsequent data processing steps, but also provides more accurate and reliable scanning results.

[0059] Therefore, by integrating the registration algorithm, the complex geometric features at the top of the umbrella-shaped scanning portion are optimized for quick and accurate recognition and positioning, effectively handling the unique data points generated by the umbrella-shaped structure. This not only enhances the automation level of the scanning process, but also ensures the high reproducibility and precise alignment of the data, greatly supporting complex dental restoration and implant operations.

[0060] At the same time, obtaining point cloud data of the plurality of positioning bodies through the intraoral scanner includes: as shown in FIG. 2, using the intraoral scanner to preferentially scan the implant from the top, obtaining three-dimensional position data of the plurality of positioning bodies, providing accurate reference points for subsequent scanning; then, starting from the occlusal surface of the mouth, scanning the top of the scanning rod installed on the implant, and locking the scanning based on the top features of the scanning rod; that is, through the top features of the scanning rod for accurate positioning, and through the locking scanning to ensure that the scanning rod is horizontally aligned with the bottom of the mouth, then turning to the buccal and lingual sides of the mouth to scan the scanning rod, identifying the cutting geometry and curve features of the scanning rod, and obtaining point cloud data of the scanning rod in contact with adjacent teeth, scanning rods or soft tissue, improving the overall scanning accuracy, and finally including scanning the gum soft tissue which has less impact on accuracy, perfecting the scanning of soft tissue, and ensuring the comprehensiveness of the data.

[0061] Second embodiment

[0062] An umbrella-shaped scanning system for missing or defective dentition, comprising a plurality of positioning bodies, a scanner scanning head and a scanning control device:

[0063] A plurality of positioning bodies, each positioning body comprising a scanning rod body and an auxiliary rod arranged on the side of the scanning body, each positioning body being provided with at least a top feature, a cutting surface geometry and a curve feature, an identification body including an auxiliary rod identification body; the scanning rod body is configured to be mounted to the composite base of each implant,

[0064] A scanner scanning head acquires point cloud data of the plurality of positioning bodies through an intraoral scanner;

[0065] A scanning control device is configured to pre-set a CAD model corresponding to each identification body;

[0066] The point cloud data is pre-processed to remove background noise and non-target point clouds, and the feature point clouds of each identification body are automatically recognized and segmented and extracted;

[0067] The feature point clouds are processed with the CAD model, and a registration result is output; until the termination condition of registration is met, the corresponding point cloud model is output.

[0068] Although the present application has been disclosed with the above preferred embodiments, it is not intended to limit the present application, and any person skilled in the art can make possible changes and modifications to the technical solutions of the present application by using the above disclosed methods and technical contents without departing from the spirit and scope of the present application. Therefore, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present application, which does not deviate from the technical solutions of the present application, belongs to the protection scope of the technical solutions of the present application.

Claims

1. An umbrella scanning method for edentulous or dentulous arches, characterized in that, The method comprises the following steps: providing a plurality of positioning bodies, each of which comprises a scanning rod body and an auxiliary rod arranged on the side of the scanning rod body, and each of which is provided with an identification body comprising at least a top feature, a cutting surface geometry and a curve feature, an auxiliary rod identification body; pre-setting a CAD model corresponding to each of the identification bodies; obtaining the design of the teeth this time: selecting an auxiliary rod length suitable for the distance between two adjacent implant complex abutments, and the scanning rod body is configured to be mounted on each of the implant complex abutments, obtaining point cloud data of a plurality of the positioning bodies by an intraoral scanner; preprocessing the point cloud data to remove background noise and non-target point clouds, and automatically identifying and segmenting feature point clouds of each of the identification bodies; processing the feature point clouds and the CAD model to output a registration result; until a termination condition of registration is met, output a corresponding point cloud model, wherein processing the feature point clouds and the CAD model to output a registration result further comprises: selecting four coplanar key points from the feature point clouds, and calculating a preliminary transformation matrix based on the four coplanar key points, which is used for preliminary alignment with the CAD model of the scanning rod body; inputting the preliminary transformation matrix for iterative optimization, and in each iteration process, updating and selecting translation according to the minimum distance error between the positions of the feature point clouds and the CAD model.

2. The umbrella scanning method of claim 1, wherein, Further comprising, in each iteration process, calculating the overlap degree of two major feature point clouds under the current transformation, the overlap degree being the ratio of the number of overlapping points to the total number of points, which is used for quantifying the alignment accuracy; when the overlap degree is lower than a preset threshold, adjusting the ICP algorithm parameters, the parameters including the number of iterations, the adjustment search range or the optimization distance metric standard.

3. The umbrella scanning method of claim 2, wherein, The termination condition includes whether the threshold of the number of iterations is reached, whether the error reaches a predetermined threshold upper limit, or a combination of the number of iterations and the error threshold.

4. The umbrella scanning method of claim 1, wherein, Obtaining point cloud data of a plurality of the positioning bodies by an intraoral scanner comprises: using the intraoral scanner to preferentially scan the implant from the top, obtaining three-dimensional position data of a plurality of the positioning bodies, and providing accurate reference points for subsequent scanning; starting scanning the top of the scanning rod installed on the implant from the occlusal surface of the mouth, and locking scanning based on the top feature of the scanning rod; scanning the scanning rod from the buccal side and the lingual side of the mouth, identifying the cutting surface geometry and the curve feature, and obtaining the point cloud data of the contact between the scanning rod and adjacent teeth, the scanning rod or soft tissue; scanning the gum soft tissue which has less influence on accuracy, and perfecting the scanning of soft tissue.

5. An umbrella scanning system for missing or defective dentition, comprising a plurality of positioning bodies, a scanner scanning head and a scanning control device: A plurality of positioning bodies, each of the positioning bodies comprising a scanning rod body and an auxiliary rod arranged on the side of the scanning body, each of the positioning bodies being provided with identification bodies including at least top features, cutting surface geometry and curve features, auxiliary rod identification bodies; the scanning rod body is configured to be mounted on the composite base platform of each implant, A scanner scanning head acquires point cloud data of the plurality of positioning bodies through an intraoral scanner; A scanning control device is configured to pre-set a CAD model corresponding to each identification body; The point cloud data is pre-processed to remove background noise and non-target point clouds, and feature point clouds of each identification body are automatically identified and segmented and extracted; The feature point clouds are processed with the CAD model, and a registration result is output; until a termination condition of registration is met, a corresponding point cloud model is output.

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