Systems and methods for improving accuracy of 3D representations

Abstract

The present disclosure relates to a computer-implemented method for improving the accuracy of a three-dimensional representation of a jaw, the method comprising: obtaining a first digital 3D representation of at least a portion of a first jaw; obtaining a second digital 3D representation of at least a portion of the second jaw; obtaining one or more third digital 3D representations of the first and second occlusal jaws, where the third digital 3D representations are generated by combining a plurality of 3D frames generated for a plurality of different views of the occlusal jaw, where each 3D frame comprises data representing a geometry of at least a portion of the occlusal jaw; and correcting the first digital 3D representation by adjusting the position and / or orientation of one or more surface points and / or vertices belonging to the first digital 3D representation relative to other surface points and / or vertices belonging to the first digital 3D representation based on the position of the 3D frame associated with the third digital 3D representation, thereby improving the accuracy of the first digital 3D representation. The present disclosure also relates to a 3D scanner system configured to perform the steps of the method.

Description

Technical Field

[0001] The present disclosure relates to a computer-implemented method for improving the accuracy of a three-dimensional (3D) representation. The present disclosure also relates to a 3D scanner system comprising one or more processors configured to perform the steps of the method disclosed herein. Background Art

[0002] 3D scanning technology is widely used in dentistry to create digital impressions of teeth. The technology enables dentists to obtain detailed and accurate representations of teeth in a digital format, which can then be used for a variety of applications, including the design and manufacture of dental restorations, orthodontic appliances, and other dental prostheses.

[0003] Digital impressions of teeth are usually taken in a sequence of steps that usually include first scanning the patient's lower jaw, then scanning the upper jaw, and finally scanning the jaws in occlusion. The latter step is sometimes also called a bite scan. The bite scan is usually taken on both sides of the mouth.

[0004] Improved methods and systems are needed to enable more accurate capture of digital impressions of teeth. In particular, there is a need to develop systems and methods that can generate more accurate digital 3D representations, as this will help to better treat patients, for example in orthodontics or restorations. Summary of the invention

[0005] Of course, when acquiring a 3D scan of the patient's mandibular or maxillary dentition, the patient must open his mouth. The inventors have realised that a problem associated with this is that the jaw, in particular the lower jaw, is not completely rigid; it can deform to some extent. Therefore, the width of the jaw may be different in the two situations, i.e. between the open position and the closed position (where the jaw is in a natural occlusion).

[0006] Since the patient has to open their mouth when acquiring 3D scans of the upper and lower jaws, and then close their mouth when acquiring the bite scan, there is a risk of misalignment of the upper and lower jaws due to slight deformations of the lower jaw. Misalignment may result in undesirable intersections in the final 3D model, i.e., causing teeth in the upper jaw to intersect with teeth in the lower jaw. Misalignment may also or alternatively result in undesirable gaps between the upper and lower jaws. This may result in an inaccurate restoration for the patient, for example, in which case the crown may be designed too large or too high.

[0007] In current 3D scanning systems and methods, the patient's jaws are considered rigid. Therefore, once the 3D model is generated, the upper and lower jaws are defined as static in the model, i.e., deformation is not modeled. Therefore, when acquiring an occlusal scan to determine the patient's natural bite, the two 3D scans of the jaws are forced to be put together as static objects. This may lead to the above-mentioned misalignment and / or undesired intersections, resulting in an inaccurate digital 3D model of the patient's teeth.

[0008] The systems and methods of the present disclosure address these challenges by modifying or correcting a digital 3D representation of either of the two jaws, wherein the modification or correction is based on information from an occlusal scan, i.e., from a 3D representation (or representations) of the patient's teeth in occlusion. Thus, the present disclosure relates to a computer-implemented method for improving the accuracy of a three-dimensional (3D) representation of a jaw, the method comprising the following steps:

[0009] - obtaining a first digital 3D representation of at least a portion of a first jaw (e.g. a lower jaw of a patient), wherein the first digital 3D representation comprises a plurality of surface points and / or a plurality of vertices;

[0010] - obtaining a second digital 3D representation of at least a portion of a second jaw (e.g., an upper jaw of the patient), wherein the second digital 3D representation comprises a plurality of surface points and / or one or more vertices, wherein the second jaw is located relative to the first jaw;

[0011] - obtaining one or more third digital 3D representations of the first and second jaws in occlusion, wherein the third digital 3D representation(s) are generated by combining a plurality of 3D frames generated for a plurality of different views of the jaws in occlusion, wherein each 3D frame comprises data expressing the geometry of at least a portion of the jaws in occlusion; and

[0012] - correcting the first digital 3D representation by adjusting the position and / or orientation of one or more surface points and / or vertices belonging to the first digital 3D representation relative to other surface points and / or vertices belonging to the first digital 3D representation;

[0013] Therein, the correction is performed based on the position of the 3D frame associated with the third digital 3D representation, thereby improving the accuracy of the first digital 3D representation.

[0014] The present disclosure also relates to a three-dimensional (3D) scanner system for correcting a 3D representation of a jaw, the scanner system comprising one or more processors configured to perform the steps of any of the methods disclosed herein.

[0015] The present disclosure also relates to a data processing system, such as the 3D scanner system disclosed herein, which includes one or more processors configured to perform one or more steps of the computer-implemented method disclosed herein.

[0016] The present disclosure also relates to a computer program product, which comprises instructions, which, when a computer executes the program, cause the computer to perform the steps of the method disclosed herein. The present disclosure also relates to a computer-readable data carrier, on which the computer program product is stored.

[0017] The present disclosure also relates to a computer-readable storage medium, which includes instructions, which, when executed by a computer, cause the computer to perform the steps of the method disclosed herein. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 A flow chart of an embodiment of a computer-implemented method according to the present disclosure is shown.

[0019] Figure 2 An embodiment of a 3D scanner system according to the present disclosure is shown.

[0020] Figure 3 A flow chart of an embodiment of a computer-implemented method according to the present disclosure is shown.

[0021] Figure 4 A computer system is shown in which embodiments of the present disclosure or portions thereof can be implemented as computer-readable codes. DETAILED DESCRIPTION

[0022] 3D Representation

[0023] 3D representations may be understood herein as digital representations of the external geometry and shape of a three-dimensional object. A 3D representation may represent only a portion of the geometry and shape of an object. A 3D representation may include a collection of points and / or polygons that collectively define the surface of an object. As an example, a 3D representation may be selected from the following groups: a point cloud, a signed distance field, a triangulated point cloud, a point cloud collection (optionally with additional information such as uncertainty estimates or (one or more) colors), a triangulated point cloud collection, a polygonal mesh, a volume representation (e.g., a voxel model), a parameterized surface, a surface element model, or any other suitable three-dimensional representation model. In a 3D representation, each point may be defined by its three-dimensional coordinates (x, y, z) in a Cartesian coordinate system. These points may form a portion of a surface mesh (e.g., a polygonal mesh). In some embodiments, a 3D representation is a triangular mesh, which includes a set of triangles connected by their common edges or vertices. A point collection and / or a surface mesh may be used to create a visual representation of an object, which may be rendered on a computer screen.

[0024] A 3D representation may be generated from a plurality of 3D frames. A 3D frame may be understood here as a 3D representation generated from a single field of view of an intraoral scanner. In other words, a 3D frame itself may constitute a 3D representation of a portion of the surface of the scanned object and may therefore fall within the example of a 3D representation given above. As an example, each 3D frame may constitute a point cloud having a plurality of points in a three-dimensional space. During scanning, the scanner may acquire 3D frames at a given frame rate (e.g., 20 to 35 frames per second). The 3D frames may be registered in a common reference system and stitched together to form a 3D representation that is larger than a 3D representation that may be captured in a single field of view of the scanner. Registration of 3D frames may include registering the 3D frame to one or more previously captured 3D frames of the object. Registration of 3D frames may be understood as determining the position and / or orientation of a 3D frame relative to another object and / or a collection of objects (e.g., a collection of 3D frames). Registration may also include the actual positioning of a 3D frame relative to a collection of objects and / or a collection of 3D frames. A collection of 3D frames stitched together may constitute the above-mentioned digital 3D representation. A 3D representation (eg, a 3D representation of a portion of a given jaw or dental arch) may consist of a large number of 3D frames, for example between 100 and 2500 frames. Other numbers of 3D frames are contemplated without departing from the scope of the present disclosure.

[0025] 3D Scanner System

[0026] The present disclosure also relates to a 3D scanner system for correcting and / or improving the accuracy of a three-dimensional (3D) representation of a jaw. The scanner system may include one or more processors configured to perform one or more steps of any method disclosed herein. The processor may be selected from the following group: a central processing unit (CPU), an accelerator (unloading engine), a general-purpose microprocessor, a graphics processing unit (GPU), a neural processing unit (NPU), an application-specific integrated circuit (ASIC), a field programmable gate array (FPGA), a dedicated logic circuit, a dedicated artificial intelligence processor unit, or a combination thereof. One or more processors may be operably connected to an intraoral scanner that forms part of the 3D scanner system. Some processors may be located on the intraoral scanner, and some processors may be located on a computer that forms part of the 3D scanner system. The intraoral scanner may be a handheld intraoral scanner.

[0027] The 3D scanner system may also include a computer memory for storing instructions that, when executed, cause the processor(s) to perform, in whole or in part, any of the computer-implemented methods disclosed herein, e.g., such that, when executed, some processors perform some method steps and other processors perform other method steps. In some embodiments, the 3D scanner system includes a computer memory for storing instructions that, when executed, cause the processor(s) to perform steps of correcting the first and / or second digital 3D representations, wherein the correction steps are performed by changing the position and / or orientation of one or more 3D frames associated with the first and / or second digital 3D representations and / or by adjusting the position and / or orientation of one or more vertices belonging to the first and / or second digital 3D representations.

[0028] In some embodiments, the intraoral scanner is based on mechanical confocal scanning, where an optical element (e.g., a lens) is configured to mechanically move back and forth during scanning to scan a volume while the projected light is spatially filtered in a detector plane. In some embodiments, the intraoral scanner is based on chromatic confocal scanning, where a volume is scanned by shining light through a highly chromatic material and varying the scanning wavelength while the projected light is spatially filtered in a detector plane.

[0029] In some embodiments, the intraoral scanner is based on a focus scanning principle, such as depth-from-focus. In such an embodiment, the scanner includes an optical element, such as a focusing lens, which is configured to move back and forth during scanning to change the focus of the scanner, so that the depth can be estimated based on the focus metric. The same applicant further describes a focus scanner in EP2442720B1, which is incorporated herein by reference. In some embodiments, the intraoral scanner is based on a depth-from-defocus scanning principle, in which an optical property, such as an aperture, is changed between acquiring two images, so that the depth can be estimated by determining the degree of defocus between the two images.

[0030] In some embodiments, the intraoral scanner is based on triangulation, wherein at least one camera and a projector unit are positioned so that they form a triangle relative to a point on the scanned surface. As an example, the projector and the camera can be used to determine a point in 3D space based on triangulation. Alternatively, the intraoral scanner may include two or more cameras that observe a scene or a scanned object from two different directions, wherein the cameras are configured to acquire a set of images, wherein a correspondence problem is solved based on triangulation. The correspondence problem generally refers to the problem of determining which parts of one image correspond to which parts of another image. In particular, the projector unit may be configured to project a plurality of projector rays that are projected onto the surface of the dental object. In particular, solving the correspondence problem may include the steps of determining image features in an image in a set of images, and further associating the image features with a specific projector ray. Subsequently, the depth of each projector ray may be calculated, so that a 3D representation of the scanned object may be generated.

[0031] Method Overview

[0032] The first step of the method may be obtaining a first digital 3D representation of at least a portion of a first jaw, such as the lower jaw or the upper jaw of a patient. The digital 3D representation may be obtained using an intraoral scanner. Alternatively, it may be obtained from a database, such as a database forming part of the disclosed 3D scanner system or from an external database. Typically, when obtaining a digital impression of a patient's dentition, the lower jaw is scanned first; however, in other cases, the upper jaw is scanned first. The systems and methods of the present disclosure may work regardless of the order in which the two jaws are scanned, i.e. regardless of whether the first 3D representation belongs to the lower jaw or the upper jaw. The digital 3D representation of the first jaw may be obtained in a number of steps in succession.

[0033] Any of the first or second jaws may include the patient's dentition, gums, edentulous ridges, retromolar triangles, hard palate, soft palate, and floor of mouth, etc. Other parts or dental objects may be represented in the first digital 3D representation of the first or second jaw, such as dental fillings, restorations, preparation sites, implants, etc. Any of the first or second 3D representations may fall within any definition and example of 3D representations provided herein. Therefore, any of the first, second, and / or third digital 3D representations may include multiple 3D frames as described herein. 3D frames may be registered in a common coordinate system. Any of the first, second, and / or third digital 3D representations may be generated by registration and / or stitching together multiple 3D frames, wherein the 3D frames are acquired or generated for multiple different views of the jaw. The method may include a step of subsequently (i.e., after registration) translating and / or rotating one or more 3D frames in a post-processing step to improve the accuracy of the 3D representation.

[0034] The second step of the computer-implemented method may be to obtain a second digital 3D representation of at least a portion of a second jaw (e.g., a lower jaw or upper jaw of a patient). The second jaw should be understood as a jaw located in the patient's mouth opposite to the first jaw. As an example, if the first jaw is the lower jaw, the second jaw should be the upper jaw, and vice versa. The digital 3D representation of the second jaw can be acquired continuously in multiple steps. As an example, during a given scanning session, the intraoral scanner can be stopped or paused multiple times, wherein the first or second digital 3D representation is acquired or generated by the 3D scanner system. The first and second digital 3D representations can be generated using the same intraoral scanner or using two different intraoral scanners, and they can be acquired or generated continuously, for example, one after another during a patient visit. Alternatively, the first and / or second 3D representations can be obtained from a database. Depending on the type of workflow, the first and / or second digital 3D representations may include one or more dental objects, such as the patient's dentition, but also dental fillings, restorations, preparation sites, implants or other dental-related objects. Typically, the workflow is outlined in a scanner software application running on a computer system that forms part of the 3D scanner system. The typical workflow for creating a digital impression of the dentition is to first scan the mandible, then the maxilla, and finally the jaws in occlusion, the latter step sometimes also referred to as an occlusal scan. However, as previously mentioned, the specific order may vary, and the disclosed systems and methods are invariant to the order of steps.

[0035] The third step of the method may be to obtain one or more third digital 3D representations of the first and second jaws in occlusion, wherein the (one or more) third digital 3D representations are generated by combining a plurality of 3D frames generated for a plurality of different views of the jaws in occlusion. In this case, each 3D frame of the third digital 3D representation preferably comprises data expressing the geometry of at least a portion of the jaws in occlusion. Acquiring 3D data of the jaws in occlusion is sometimes also referred to as an occlusion scan. One or more occlusion scans may be acquired, for example, one or more occlusion scans on each side of the oral cavity. This step is very important for determining how the generated digital 3D representation of the jaws fits in occlusion according to the patient's natural occlusion. An accurate occlusion scan will typically improve the accuracy of the combined first and second 3D representations (sometimes also referred to as a digital 3D model), such that, for example, the restoration will fit better in the patient's mouth when the jaws are occluded.

[0036] The inventors have realized that, although today's 3D scanners are quite precise and accurate, none of the existing 3D scanner systems take into account deformities of (one or more) jaws, in particular deformities of the mandible. This is a problem because the geometry of the jaw may change slightly between the open and closed positions of the jaw. As an example, the width of the mandible may be narrower in the open position than when the jaw is in occlusion. The width of the jaw may be understood in this context as the intermolar width, which may be understood as the distance between the mesiobuccal cusp tips of the left and right maxillary and mandibular first molars. This distance may vary from person to person, but typical values ​​range from 45 mm to 55 mm. Since the 3D representation of the mandible is acquired when the patient opens his mouth, the representation may not accurately depict the mandible in occlusion with the maxilla. The above differences (e.g. in terms of width) may have a negative impact on the accuracy of the combined digital 3D model (i.e., the two 3D representations in their common reference system). For example, the difference in intermolar width between the open and closed positions may be between 0.1 mm and 1 mm, such as approximately 0.5 mm, which is sufficient to negatively impact the accuracy of the 3D model.

[0037] Therefore, the systems and methods of the present disclosure preferably include the following steps: correcting the first and / or second digital 3D representations by changing the position and / or orientation of one or more 3D frames associated with the first digital 3D representation based on the position of the 3D frame associated with the third digital 3D representation, thereby improving the accuracy of the first digital 3D representation. Therefore, multiple 3D frames (e.g., all 3D frames) associated with the first digital 3D representation can be corrected based on the position of the 3D frame associated with (one or more) third digital 3D representations. In an alternative to modifying the position and / or orientation of one or more 3D frames, the method may include the following steps: changing the position of one or more 3D surface points that form part of the first and / or second digital 3D representation. In some embodiments, the 3D representation is a surface model, such as a mesh model. In this case, the correction may include distorting the surface model, for example, distorting the mesh by changing the position of one or more 3D surface points and / or vertices that form part of the 3D representation. In other cases, the surface of the first or second 3D representation is completely reconstructed from the corrected 3D frame.

[0038] Since the (one or more) third digital 3D representations (i.e. the (one or more) bite scans) are acquired and generated during jaw occlusion, the (one or more) third digital 3D representations can be used to correct any of the first and / or second digital 3D representations; in particular the representation representing the mandible. Therefore, the method may include an optimization step, wherein the position and / or orientation of the 3D frames of the first or second digital 3D representation are adjusted based on information belonging to the 3D frames of the (one or more) bite scans (i.e. the (one or more) third digital 3D representations). Alternatively, the first or second digital 3D representation may be adjusted directly, for example by adjusting or distorting the surface of the 3D representation, for example by adjusting the position and / or orientation of one or more vertices of the 3D representation, which is for example embodied as a surface mesh model.

[0039] The optimization step may be performed as a post-processing step, i.e. after the generation of the first, second and third 3D representations. The upper jaw can be considered as a good approximation to be static, i.e. without the ability to deform between open and closed positions of the mouth. Therefore, in the optimization step, the digital 3D representation of the upper jaw is preferably fixed, such that the 3D frames associated with the representation remain in their original positions. Therefore, the second digital 3D representation may be static, such that the 3D frames associated with the second digital 3D representation are fixed in space. In contrast, the 3D frames belonging to the digital 3D representation of the lower jaw may be free to move, e.g. the position and / or orientation may be changed according to a Euclidean transformation. In other embodiments, one or more 3D frames forming part of the representation of the lower jaw are tilted or scaled according to one or more predefined transformations.

[0040] In some embodiments, when performing correction of the first digital 3D representation, the positions and / or orientations of 3D frames from different 3D representations have different weights. As an example, the weight of the position of a 3D frame associated with the third digital 3D representation (i.e., a 3D frame belonging to an occlusal scan) may be higher than the position of a 3D frame associated with the first or second digital 3D representation. In some embodiments, each 3D frame includes a plurality of points in 3D space, wherein one or more points of a given 3D frame have different weights relative to other points of the 3D frame. In some embodiments, the points and / or surfaces of a given 3D frame are classified as teeth and non-teeth, wherein teeth have a higher weight than non-teeth. In some embodiments, the weight of each point and / or vertex in (one or more) 3D frames is different. In some embodiments, the weights of 3D frames are based on how far the 3D frames are moved from each other. Other examples include giving different weights to the correction of 3D frames based on (one or more) differences in orientation, color, or other attributes (e.g., classification of points / surfaces within (one or more) 3D frames).

[0041] In some embodiments, before performing correction of the first and / or second digital 3D representation, the first or second digital 3D representation is modified. The modification may comprise distorting the representation so that the first or second jaw is distorted inwardly or outwardly, whereby the arch of the jaw becomes narrower or wider. As an example, the first jaw, e.g. the lower jaw, may be distorted outwardly to provide a better starting point for optimization. Thus, the method may comprise a step of distorting the first digital 3D representation prior to the correction step, wherein the distorted representation is used as input for the correction. Prior to the step of distorting the digital 3D representation, the method may comprise a step of determining a rough estimate of the error (e.g. in terms of the width of the jaw), which may be used as input for the modification. Distortion may be understood as distorting or deforming a given 3D representation, e.g. by applying one or more geometric transformations.

[0042] In some embodiments, the method further comprises the step of selecting a subset of 3D frames, wherein the subset is selected among the 3D frames associated with the first digital 3D representation (e.g., the digital representation of the jaw). The one or more 3D frames corrected in the correction step may include the selected subset of 3D frames, and the remaining 3D frames associated with the first digital 3D representation may be corrected based on the correction performed on the selected subset of 3D frames.

[0043] Therefore, the system and method of the present disclosure provide a framework for improving the accuracy of 3D representations by performing global optimization, wherein multiple 3D frames of a first 3D representation are moved and / or re-aligned based on the positions of 3D frames belonging to other 3D representations. As previously described, the weights of 3D frames in the optimization may be different, for example, the weights of 3D frames belonging to a third 3D representation may be higher than 3D frames belonging to other 3D representations. Global optimization may take into account all 3D frames of all 3D representations, and as previously described, 3D frames belonging to the first or second 3D representation may be static so that they remain in their positions during the optimization step. In summary, the method may include the steps of acquiring or generating at least three digital 3D representations as previously described, and then determining whether any 3D representation of (one or more) jaws has inaccurate dimensions, such as in terms of intermolar width. Then, the method may include the steps of correcting 3D representations with inaccurate dimensions according to the description provided herein. Thus, a more accurate 3D representation is achieved, and therefore a more accurate restoration can be designed for the patient.

[0044] Detailed description of the drawings

[0045] Figure 1A flowchart 100 of an embodiment of a computer-implemented method disclosed herein is shown. In step 102, a first digital 3D representation of at least a portion of a first jaw is obtained. The first 3D representation may digitally represent a first jaw of a patient, such as a lower jaw of the patient. The first digital 3D representation may include a plurality of surface points. In step 104, a second digital 3D representation of at least a portion of a second jaw (e.g., an upper jaw of the patient) is obtained. The second digital 3D representation may similarly include a plurality of surface points, and the position of the second jaw may be relative to the first jaw. In step 106, one or more third digital 3D representations of the first and second jaws in occlusion are obtained. These third digital 3D representations may also be referred to herein as "occlusion scans". The (one or more) third digital 3D representations may be generated by combining a plurality of 3D frames generated for a plurality of different views of the jaws in occlusion, wherein each 3D frame includes data expressing the geometry of at least a portion of the jaws in occlusion. In step 108, the first and / or second digital 3D representations are corrected based on the position of the 3D frame associated with the third digital 3D representation. The correction is preferably performed based on the position of the 3D frame associated with the third digital 3D representation.

[0046] Figure 2 An embodiment of a 3D scanner system 200 according to the present disclosure is shown. The 3D scanner system can be configured to generate a three-dimensional (3D) representation of an object 202 (e.g., a dental object). As an example, the object 202 can be at least a portion of an oral cavity, including any of the dentition, gums, retromolar triangle, hard palate, soft palate, and floor of mouth, etc. In this embodiment, the 3D scanner system includes an intraoral scanner 204 for acquiring a set of images of the scanned object, such as in a person's oral cavity. The 3D scanner system also includes one or more processors for generating a three-dimensional (3D) representation of the scanned object based on the acquired images. Typically, the 3D representation can represent only a portion of the surface of the object, such as captured by the field of view of the intraoral scanner 204. Such a 3D representation may also be referred to herein as a sub-scan or 3D surface. The (one or more) processors can be part of the 3D scanner 204, or they can be located outside the intraoral scanner, or a combination of both, that is, certain processing is performed on the 3D scanner and other processing is performed on the computer system 206. The intraoral scanner can be configured to continuously (e.g., in real time) acquire a set of images and generate one or more 3D surfaces and / or sub-scans based on the images. It can also be configured to continuously (wired or wirelessly) transmit the sub-scans to the computer system 206. The sub-scans can be registered and stitched together to form a digital 3D model of the scanned object. The 3D model can be displayed on a display, such as a display connected to the computer system.

[0047] Figure 3A flowchart 300 of an embodiment of a computer-implemented method disclosed herein is shown. In step 302, a first digital 3D representation of at least a portion of a first jaw is obtained. The first 3D representation may digitally represent a first jaw of a patient, such as a lower jaw of the patient. The first digital 3D representation may include a plurality of surface points. In step 304, a second digital 3D representation of at least a portion of a second jaw (e.g., an upper jaw of the patient) is obtained. The second digital 3D representation may similarly include a plurality of surface points, and the position of the second jaw may be relative to the first jaw. In step 306, one or more third digital 3D representations of the first and second jaws in occlusion are obtained. These third digital 3D representations may also be referred to herein as "occlusion scans". The (one or more) third digital 3D representations may be generated by combining a plurality of 3D frames generated for a plurality of different views of the jaws in occlusion, wherein each 3D frame includes data expressing the geometry of at least a portion of the jaws in occlusion. In a next step, the first and / or second digital 3D representations are corrected based on the position of the 3D frame associated with the third digital 3D representation. The step of correcting the first and / or second digital 3D representations may be accomplished by at least two alternatives. In a first alternative (step 308), the correction is performed by changing the position and / or orientation of one or more 3D frames associated with the first and / or second digital 3D representation. In a second alternative (step 310), the correction is performed by adjusting the position and / or orientation of one or more vertices belonging to the first and / or second digital 3D representation. In a third alternative (not shown), the step of correcting the first and / or second digital 3D representation comprises changing the position of one or more 3D surface points forming part of the first and / or second digital 3D representation. In any case, the result of the correction is an improved accuracy of the first and / or second digital 3D representation.

[0048] Figure 4A computer system 400 is shown, in which embodiments of the present disclosure or parts thereof can be implemented as computer-readable code. The computer system can include multiple components for implementing data processing, storage, communication and user interaction. The computer system described herein can include one or more processors 404, a communication interface 424, a hard disk drive 412, a removable storage drive 414, an interface 420, a main memory 408, a display interface 402 and a display 430. One or more processors 404 can be configured to perform one or more steps of the computer implementation method disclosed herein. The communication interface 424 can be configured to allow the computer system to communicate with external devices and networks. It can support various communication protocols, such as Ethernet, Wi-Fi or Bluetooth, so as to achieve data exchange and promote connectivity with other devices. The hard disk drive 412 can be configured to provide non-volatile storage for the computer system. It can store software programs, operating system files, user data and other files in a medium (e.g., a magnetic medium). The hard disk drive 412 can ensure persistent storage, and data can be retained even when the system is shut down. Removable storage drive 414 (e.g., a CD / DVD drive or a USB port) can be configured to provide the computer system with the ability to read from and / or write to removable storage unit 418. This allows a user to access an external storage device (e.g., an optical disk or USB flash drive) and transfer data to and from the computer system. Interface 420 can be configured to connect various external devices (e.g., a keyboard, mouse, printer, scanner, or audio device) to the computer system.

[0049] Further details of the invention

[0050] 1. A computer-implemented method for improving the accuracy of a three-dimensional (3D) representation of a jaw, the method comprising the steps of:

[0051] - obtaining a first digital 3D representation of at least a portion of a first jaw (e.g. a lower jaw of a patient), wherein the first digital 3D representation comprises a plurality of surface points and / or a plurality of vertices;

[0052] - obtaining a second digital 3D representation of at least a portion of a second jaw (e.g., an upper jaw of the patient), wherein the second digital 3D representation comprises a plurality of surface points and / or one or more vertices, wherein the second jaw is located relative to the first jaw;

[0053] - obtaining one or more third digital 3D representations of the first and second jaws in occlusion, wherein the third digital 3D representation(s) are generated by combining a plurality of 3D frames generated for a plurality of different views of the jaws in occlusion, wherein each 3D frame comprises data expressing the geometry of at least a portion of the jaws in occlusion; and

[0054] - correcting the first digital 3D representation by adjusting the position and / or orientation of one or more surface points and / or vertices belonging to the first digital 3D representation relative to other surface points and / or vertices belonging to the first digital 3D representation;

[0055] Wherein the correction is performed based on the position of the 3D frame associated with the third digital 3D representation, thereby improving the accuracy of the first digital 3D representation.

[0056] 2. The method according to item 1, wherein the second digital 3D representation is static such that the 3D frame associated with the second digital 3D representation is fixed in space.

[0057] 3. The method according to any of the preceding items, wherein a plurality of 3D frames associated with the first digital 3D representation are corrected based on the position of the 3D frames associated with the third digital 3D representation.

[0058] 4. The method according to any of the preceding items, wherein all 3D frames associated with the first digital 3D representation are corrected based on the position of the 3D frames associated with the third digital 3D representation.

[0059] 5. The method according to any of the preceding items, wherein all 3D frames associated with the first digital 3D representation are considered for correction.

[0060] 6. A method according to any preceding claim, wherein the position and / or orientation of one or more 3D frames is changed according to a Euclidean transformation.

[0061] 7. A method according to any preceding item, wherein the position and / or orientation of one or more vertices is adjusted according to a Euclidean transformation.

[0062] 8. A method according to any preceding claim, wherein, when performing the correction of the first digital 3D representation, positions and / or orientations of 3D frames from different 3D representations have different weights.

[0063] 9. A method according to any preceding claim, wherein each 3D frame comprises a plurality of points in 3D space.

[0064] 10. The method according to any of the preceding items, wherein the step of correcting the first and / or second digital 3D representation comprises changing the position of one or more 3D surface points forming part of the first and / or second digital 3D representation.

[0065] 11. A method according to items 9-10, wherein one or more points of a given 3D frame have different weights relative to other points of the 3D frame.

[0066] 12. A method according to any of items 9-11, wherein points and / or surfaces of a given 3D frame are classified into rigid materials (e.g. teeth and / or implants) and soft tissue (e.g. gums).

[0067] 13. The method of item 12, wherein rigid material is weighted higher than soft tissue in the correction.

[0068] 14. A method according to any of items 9-13, wherein points and / or surfaces of a given 3D frame are classified as teeth and non-teeth.

[0069] 15. The method according to item 14, wherein teeth are weighted higher than non-teeth in the correction.

[0070] 16. Method according to any of the preceding items, wherein the first or second digital 3D representation is modified before performing a correction of the first and / or second digital 3D representation.

[0071] 17. A method according to item 16, wherein the modification comprises distorting the representation so that the first or second jaw is distorted inwardly or outwardly so that the arch of the jaw becomes narrower or wider.

[0072] 18. A method according to any preceding claim, wherein the weighting of the positions of 3D frames associated with the third digital 3D representation is higher than the weighting of the positions of 3D frames associated with the first digital 3D representation.

[0073] 19. The method according to any of the preceding items, wherein the method further comprises the step of warping the first digital 3D representation before the correction step, wherein the warped representation is used as input for the correction.

[0074] 20. The method according to any of the preceding items, wherein the method further comprises the step of selecting a subset of 3D frames, wherein the subset is selected among the 3D frames associated with the first digital 3D representation.

[0075] 21. The method according to item 20, wherein the one or more 3D frames corrected in the correction step include a selected subset of 3D frames.

[0076] 22. The method according to item 21, wherein the remaining 3D frames associated with the first digital 3D representation are corrected based on the correction performed on the selected subset of 3D frames.

[0077] 23. A method according to any of the preceding items, wherein the first jaw is the patient's lower jaw and the second jaw is the patient's upper jaw.

[0078] 24. A method according to any preceding item, wherein the first digital 3D representation of the first jaw is inaccurate, for example, wherein a width of the first jaw of the digital representation is narrower than the first jaw of the patient.

[0079] 25. The method according to any of the preceding items, wherein the width of the first digital 3D representation of the first jaw is corrected based on a third digital 3D representation of the first and second jaws in occlusion.

[0080] 26. A computer program product comprising instructions which, when a computer executes the program, cause the computer to perform the steps of the method according to any one of items 1 to 25.

[0081] 27. A computer-readable storage medium comprising instructions which, when executed by a computer, cause the computer to perform the steps of the method according to any one of items 1-25.

[0082] 28. A computer-readable data carrier having stored thereon the computer program product of item 26.

[0083] 29. A three-dimensional (3D) scanner system for correcting a three-dimensional (3D) representation of a jaw, the scanner system comprising one or more processors configured to perform the steps of the method according to any one of items 1-25.

[0084] 30. A 3D scanner system according to item 29, wherein the scanner system also includes an intraoral scanner.

[0085] Although some embodiments have been described and shown in detail, the present disclosure is not limited to these details, but may also be embodied in other ways within the scope of the subject matter defined in the appended claims. In particular, it should be understood that other embodiments may be utilized and structural and functional modifications may be made without departing from the scope of the present disclosure. In addition, those skilled in the art will find that unless an embodiment is specifically presented only as an alternative, different disclosed embodiments may be combined to achieve a specific implementation, and such a specific implementation is within the scope of the present disclosure.

[0086] Any one or more of the first, second and / or third digital 3D representations may be obtained during a scanning session using an intraoral scanner, or they may be obtained from a database. Thus, according to some embodiments, all steps of the computer-implemented method may be performed by a disclosed 3D scanner system or a computer system comprising one or more processors. Thus, in some cases, the 3D scanner system does not have to include an intraoral scanner for obtaining the 3D representation, as the scanner system may retrieve or obtain the representation from an internal or external database.

Claims

1. A computer-implemented method for improving the accuracy of a three-dimensional (3D) representation of a jaw, the method comprising the steps of: - obtaining a first digital 3D representation of at least a portion of a first jaw, such as a lower jaw of the patient, wherein the first digital 3D representation comprises a plurality of surface points and / or a plurality of vertices; - obtaining a second digital 3D representation of at least a portion of a second jaw, such as the upper jaw of the patient, wherein the second digital 3D representation comprises a plurality of surface points and / or one or more vertices, wherein the second jaw is located relative to the first jaw; - obtaining one or more third digital 3D representations of the first and second jaws in occlusion, wherein the third digital 3D representations have been generated by combining a plurality of 3D frames generated for a plurality of different views of the jaws in occlusion, wherein each 3D frame comprises data expressing the geometry of at least a portion of the jaws in occlusion; and - correcting the first digital 3D representation by adjusting the position and / or orientation of one or more surface points and / or vertices belonging to the first digital 3D representation relative to other surface points and / or vertices belonging to the first digital 3D representation; Therein, the correction is performed based on the position of a 3D frame associated with the third digital 3D representation, thereby improving the accuracy of the first digital 3D representation.

2. The method according to claim 1, wherein: The second digital 3D representation is static such that a 3D frame associated with the second digital 3D representation is fixed in space.

3. A method according to any one of the preceding claims, wherein: A plurality of 3D frames associated with the first digital 3D representation are corrected based on the positions of the 3D frames associated with the third digital 3D representation.

4. A method according to any one of the preceding claims, wherein: When performing correction of the first digital 3D representation, positions and / or orientations of 3D frames from different 3D representations have different weights.

5. A method according to any one of the preceding claims, wherein: The positions of 3D frames associated with the third digital 3D representation are weighted higher than the positions of 3D frames associated with the second digital 3D representation.

6. A method according to any one of the preceding claims, wherein: The step of correcting the first digital 3D representation comprises changing the position of one or more 3D surface points forming part of the first digital 3D representation.

7. A method according to any one of the preceding claims, wherein: Each 3D frame includes a plurality of points in 3D space, and wherein one or more points of a given 3D frame have different weights relative to other points of the 3D frame.

8. A method according to any one of the preceding claims, wherein: Points and / or surfaces of a given 3D frame are classified into rigid material and soft tissue, and wherein rigid material is weighted higher than soft tissue in the correction.

9. A method according to any one of the preceding claims, wherein: The first digital 3D representation is modified before performing the correction, wherein the modification comprises distorting the first representation such that the first jaw is digitally distorted outwards such that an arch of the jaw becomes wider.

10. A three-dimensional (3D) scanner system for correcting a 3D representation of a jaw, the 3D scanner system comprising one or more processors configured to perform the steps of the method according to any one of the preceding claims.

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