Intraoral scanner system with corrected feedback signal

Abstract

An intraoral scanner system (100) configured to display a corrective feedback signal during a scanning session is disclosed. An intraoral scanner system (100) comprises a handheld intraoral scanner (101) configured to acquire light information reflected from a dental subject (108) within an oral cavity through a field of view (105) of the handheld intraoral scanner (101); one or more processors configured to process the light information and generate a digital 3D model (103) of the dental object (108) based on the processed light information; and a graphical user interface (102) configured to display the digital 3D model (103). The one or more processors are configured to display a field-of-view frame (104) representing a position of a field of view (105) of the handheld intraoral scanner (101) in real time on the graphical user interface (102) and to generate a correction feedback signal corresponding to the field-of-view frame (104), and wherein the correction feedback signal comprises a suggested correction of the position of the field of view (105) of the handheld intraoral scanner (101).

Description

Technical Field

[0001] The present disclosure relates to an intraoral scanner system having a correction feedback signal to guide a user toward a suggested scanning area in the oral cavity. Specifically, the present disclosure relates to an intraoral scanner system including one or more processors configured to display a field of view box on a graphical user interface (the field of view box displays the actual field of view of the scanning tip of the handheld intraoral scanner) and further configured to display the correction feedback signal. Background Art

[0002] When scanning the oral cavity of a patient using a handheld intraoral scanner, the user (e.g., a dentist) may adopt a non-optimal scanning method. It may therefore happen that the user performing the scan misses certain areas of the oral cavity, resulting in a lack of optical information received by the handheld intraoral scanner from the certain areas. For example, this may occur due to a lack of experience in intraoral scanning. As a result, the generation of a digital 3D model may be interrupted, or an incomplete digital 3D model of the oral cavity may be created. The user may not follow the optimal scanning path that allows the minimum amount of optical information sufficient to generate a digital 3D model of the oral cavity of the desired quality to be received. In addition, during the scanning process, the intraoral scanner system may lose the registration of the obtained optical information, resulting in the user needing to navigate the handheld intraoral system to the location where the registration is lost and continue scanning from that location. Overall, the scanning process may be severely slowed down and obstructed. Therefore, it is clear that user guidance is needed during the scanning process to improve efficiency and generate a digital 3D model of the desired quality. Summary of the invention

[0003] One aspect of the present disclosure is to provide an intraoral scanner system that can provide assistance to its users by generating and displaying corrective feedback signals during a scanning session.

[0004] According to an embodiment, the intraoral scanner system may be configured to display a correction feedback signal during a scanning session, wherein the intraoral scanner system may include:

[0005] - a handheld intraoral scanner configured to obtain light information reflected from a dental object in the oral cavity through a field of view of the handheld intraoral scanner;

[0006] - one or more processors configured to process the light information and generate a digital 3D model of the dental object based on the processed light information; and

[0007] - a graphical user interface configured to display the digital 3D model,

[0008] The one or more processors may be configured to:

[0009] -displaying in real time on the graphical user interface a field of view box representing the position of the field of view of the handheld intraoral scanner; and

[0010] - generating a correction feedback signal which may correspond to the field of view frame, and wherein the correction feedback signal may include a suggested correction to the position of the field of view of the handheld intraoral scanner.

[0011] A dental object may relate to any object within the oral cavity of a patient, such as a tooth, a portion of a tooth, multiple teeth, an upper or lower jaw or portions thereof, a gum or a portion of a gum, a tongue, a jaw, a restoration and / or a preparation. Optical information may relate to information received by a handheld intraoral scanner during a scanning session. In the present disclosure, a handheld intraoral scanner is also referred to as a scanner.

[0012] During a scanning session, a digital 3D model representing a dental object can be generated and updated by processing light information received through the field of view of the handheld intraoral scanner. The digital 3D model can be displayed on a graphical user interface included in the intraoral scanner system. The field of view of the scanner can be understood as the maximum area that the scanner can image.

[0013] By observing the graphical user interface, a user of the intraoral scanner system (e.g., a dentist) can see in real time a displayed field of view box corresponding to the position of the handheld intraoral scanner, more specifically its field of view relative to the patient's oral cavity. Thus, the position of the field of view box relative to the digital 3D model can correspond to the position of the field of view of the handheld intraoral scanner relative to the dental object in the patient's oral cavity. In this way, the user can obtain a reference of the position of the scanner relative to the dental object in the oral cavity by viewing the graphical user interface.

[0014] During a scanning session, the user may move the scanner away from the dental object that will be the target of the scan. As a result, the generation of the digital 3D model may be interrupted, or the digital 3D model may be generated in a suboptimal manner based on less scan data than is available. In some cases, an incomplete digital 3D model may be generated with missing information.

[0015] Once the scanner is moved in such a way that the amount of scan data collected is reduced, a correction feedback signal can be generated. An interruption in optimal generation (or construction) may occur when the scanner is moved so that a portion of the digital 3D model that is presented and therefore visible through the field of view box moves away from the edge of the field of view box. This may correspond to the fact that the scanner is moved so that the scanned surface is reduced. The generated correction feedback signal can be associated with the displayed field of view box and can be used as guidance to the user on how to move the scanner to return to a position in the oral cavity from which scanning can be resumed in an optimal manner, for example by exposing a larger surface area of ​​the teeth to the scanner and thereby collecting more scan data. The correction feedback signal can be displayed so that it suggests a correction to the position of the field of view of the handheld intraoral scanner. For example, a user operating the scanner can see the movement trajectory of a guiding element (e.g., a rectangle) moving in the signal direction by observing the field of view box.

[0016] The correction feedback signal may be characterized by signal direction and / or signal strength (these will be discussed in detail later).

[0017] The signal direction may indicate the direction in which the user should move the scanner in order to resume acquisition of scan data. The signal strength may indicate the amount by which the user should move the scanner in the direction of the signal. The signal direction and / or signal strength may provide guidance to the user for efficient scanning and optimal generation of a digital 3D model.

[0018] According to an embodiment, the intraoral scanner system may be configured to display a correction feedback signal during a scanning session, wherein the intraoral scanner system may include:

[0019] - a handheld intraoral scanner configured to obtain light information reflected from a dental object through a field of view of the handheld intraoral scanner;

[0020] - one or more processors configured to process the light information and generate a digital 3D model of the dental object based on the processed light information; and

[0021] - a graphical user interface configured to display the digital 3D model,

[0022] The one or more processors may be configured to:

[0023] -displaying in real time on the graphical user interface a field of view box representing the position of the field of view of the handheld intraoral scanner; and

[0024] - if the handheld intraoral scanner deviates from the recommended scanning path, generating a corrective feedback signal, wherein the corrective feedback signal may be configured to guide the user to steer the handheld intraoral scanner to the recommended scanning path.

[0025] The recommended scan path may be provided by the scanner manufacturer.The corrective feedback signal may be configured to guide the user to maneuver the handheld intraoral scanner to a point on the recommended scan path where a deviation occurs.

[0026] According to an embodiment, the intraoral scanner system may be configured to display a correction feedback signal during a scanning session, wherein the intraoral scanner system may include:

[0027] - a handheld intraoral scanner configured to obtain light information reflected from a dental object through a field of view of the handheld intraoral scanner;

[0028] - one or more processors configured to process the light information and generate a digital 3D model of the dental object based on the processed light information; and

[0029] - a graphical user interface configured to display the digital 3D model,

[0030] The one or more processors may be configured to:

[0031] -displaying in real time on the graphical user interface a field of view box representing the position of the field of view of the handheld intraoral scanner; and

[0032] - generating a correction feedback signal based on a relative position of a portion of the digital 3D model rendered in the field of view frame with respect to the field of view frame.

[0033] The corrective feedback signal may be configured to guide the user to steer the handheld intraoral scanner in a direction towards a position in the oral cavity from which further scanning should be continued in order to recover an optimal construction of the digital 3D model.

[0034] The signal direction and / or signal strength may be determined based on the relative position of the portion of the digital 3D model presented in the field of view frame relative to the field of view frame. For example, the signal direction and / or signal strength may be determined based on the relative position of the centroid of the portion of the digital 3D model presented in the field of view frame relative to the center of the field of view frame.

[0035] The signal direction may be a direction from the center of the field of view box towards the centroid of the portion of the digital 3D model presented in the field of view box.

[0036] The signal strength may be a function of the distance between the center of the field of view box and the centroid of the portion of the digital 3D model presented in the field of view box.

[0037] The correction feedback signal may include a shape and / or dynamic pattern indicating a suggested correction for the position of the handheld intraoral scanner's field of view.

[0038] The shape included in the correction feedback signal may be a geometric shape, such as a rectangle or multiple rectangles. Similarly, the shape may be an arrow. A dynamic pattern may refer to a moving pattern of a shape (e.g., a rectangle or an arrow) that moves in a direction toward a position in the oral cavity from which further scanning should be continued in order to recover the construction of the digital 3D model. The shape and / or dynamic pattern may include any geometric shape.

[0039] In an embodiment, a suggested correction to the position of the handheld intraoral scanner's field of view may be displayed in the form of a shape (eg, a rectangle) and / or a dynamic pattern.

[0040] Suggested corrections to the position of the handheld intraoral scanner's field of view may include an orientation or rotation of the handheld intraoral scanner's field of view.

[0041] The suggested correction to the position of the field of view of the handheld intraoral scanner can be an instruction to the user to manipulate the scanner toward a position in the oral cavity where more scan data can be captured and the construction of the digital 3D model on the graphical user interface can be restored in an optimal manner with the additional scan data. The instruction may include translation and / or rotation instructions for movement of the handheld intraoral scanner. Thus, the user may be instructed to manipulate the scanner in a particular direction according to the translation instructions and / or rotate the scanner according to the rotation instructions. For example, the user may be prompted to move the scanner in the occlusal plane or any plane substantially parallel to the occlusal plane. Additionally or alternatively, the user may be prompted to move the scanner closer to or farther away from the dental object substantially along an axis that may be orthogonal to the occlusal plane.

[0042] In an embodiment, the shape and / or dynamic pattern may include the indication, which includes a translation indication and / or a rotation indication, for moving the handheld intraoral scanner towards a position in the oral cavity from which further scanning should be continued in order to recover an optimal construction of the digital 3D model.

[0043] The one or more processors may also be configured to display a field of view frame. The field of view frame may be configured to display in real time the area of ​​the digital 3D model within the field of view of the handheld intraoral scanner. Thus, the user may be able to see through the field of view frame the portion of the digital 3D model corresponding to the oral cavity area within the field of view of the handheld intraoral scanner.

[0044] The portion of the displayed digital 3D model that is visible within the field of view frame may correspond to an area of ​​the oral cavity that is within the field of view frame of the handheld intraoral scanner. The term "rendered" may be used instead of the term "visible" because the portion of the digital 3D model may be rendered within the field of view frame. The portion may be observable by the user.

[0045] In an embodiment, the recommended correction may be determined by a trained neural network trained on training data comprising an optimal scanning path for intraoral scanning and / or comprising optimal corrections for different scanning situations, and wherein the trained neural network may be configured to determine the recommended correction based on the training data.

[0046] Thus, in an embodiment, the trained neural network may be configured to generate a suggested correction to the position of the field of view of the handheld intraoral scanner if the user moves the scanner away from the scan target. One of the effects of the trained neural network may be to generate an improved scan path based on the training data. The improved scan path may refer to a predefined scan path or a scan path generated dynamically during the scanning process.

[0047] In an example, portions of a digital 3D model presented on a graphical user interface and visible through a field of view box may be segmented during the scanning process. In this way, individual teeth and gums may be identified as separate three-dimensional objects. A trained neural network may predict a specific location in three-dimensional space on the scanning path based on the segmented objects in the field of view box, to which the user should move the scanner. A trained neural network may predict where adjacent teeth should be located by obtaining information about the teeth in the field of view box, and output a suggested correction for the prediction. The information about the teeth may be information about the type of teeth (e.g., incisors, molars, premolars, canines), information about the location of the centroid of the teeth, and / or information about the orientation of the teeth in the jaw.

[0048] In an example, the suggested correction may be based on a prediction of the position of a neighboring dental object to the dental object being scanned.

[0049] In an example, a portion of the digital 3D model presented on a graphical user interface and visible through a field of view box can be segmented to identify teeth. In addition, the center of mass of the teeth can be identified. Next, the position of the adjacent teeth can be predicted based on the identified teeth. In particular, the position of the center of mass of the adjacent teeth can be predicted. A feedback correction signal can be generated that points from the center of mass of the tooth to the center of mass of the adjacent teeth.

[0050] Information such as recommended scan paths, for example provided by a scanner manufacturer, can be used as training data for designing a trained neural network configured to provide suggested corrections. Information about the surface geometry of various teeth (various 3D scans) can comprise part of the training data. Optimal corrections for different scanning situations can be derived from the training data.

[0051] The proposed correction may be based on a scan path. The scan path may define a path of the handheld intraoral scanner's field of view along the dentition within the oral cavity.

[0052] The scan path can be one of the following:

[0053] -Default scan paths predefined by the system manufacturer or user;

[0054] - Customized scan paths determined for a single scan session;

[0055] - an optional scanning path selected among a plurality of optional scanning paths for different dentitions; or

[0056] - A dynamic scan path configured to be modified by the one or more processors during a scanning session to adjust relative to a current position of a field of view of the handheld intraoral scanner.

[0057] In an embodiment, the proposed correction may be directed to a scan path of a field of view of a handheld intraoral scanner, wherein the scan path is one of:

[0058] -Default scan paths predefined by the system manufacturer or user;

[0059] - Customized scan paths determined for a single scan session;

[0060] - an optional scanning path selected among a plurality of optional scanning paths for different dentitions; or

[0061] - A dynamic scan path configured to be modified by the one or more processors during a scanning session to adjust relative to a current position of a field of view of the handheld intraoral scanner.

[0062] The customized scan path may be a scan path based on at least one earlier scan of the same patient.The customized scan path may be based on the needs and / or desires of a user (eg, a dentist).

[0063] Optional scanning paths can be selected based on the specific needs of the patient. For example, an optional scanning path can be selected for an edentulous patient. Scanning an edentulous patient may require a specific scanning strategy in order to achieve the desired scanning accuracy, for example, including a slow and steady scan of the jaw. Depending on the purpose of the scanning process, optional scanning paths can be provided. For example, an optional scanning path can be provided for a preparation scan. When scanning a preparation, it may be critical to acquire detailed information about the preparation line so that an accurate digital 3D model of the preparation and restoration can be generated.

[0064] A dynamic scan path may be a scan path that changes and adjusts during the scanning process. Portions of the digital 3D model that require additional scanning may be determined, and suggested corrections may be generated for the determined portions of the digital 3D model. In the event that generation of the digital 3D model is interrupted, for example due to a lack of scan data from a specific location required to continue presenting the digital 3D model, a correction feedback signal may be generated, wherein the signal direction is toward the specific location. In this way, the user may overcome the problem of missing scan data by moving the scanner to a specific location by following the correction feedback signal.

[0065] The one or more processors may be configured to determine a deviation of the position of the field of view of the handheld intraoral scanner from the scan path. The one or more processors may also be configured to determine a suggested correction to the position of the field of view of the handheld intraoral scanner based on the determined deviation and a current position of the field of view of the handheld intraoral scanner. The current position of the field of view of the handheld intraoral scanner may correspond to a position of the field of view box relative to a portion of the digital 3D model.

[0066] In an example, the one or more processors may be configured to determine a suggested correction to the position of the field of view of the handheld intraoral scanner based on the determined deviation.

[0067] In an example, the deviation of the position of the field of view of the handheld intraoral scanner from the scanning path may be understood as the shortest distance of the position of the field of view of the handheld intraoral scanner from the scanning path.

[0068] The user may deviate from the scan path while holding the scanner. Depending on the degree of deviation, a suggested correction may be generated so that the user can return to the scan path.

[0069] One or more processors may be configured to determine a customized scan path for a separate scanning session by receiving separate dentition information, which may include surface information of the dental object and the arrangement of the dentition. In addition, one or more processors may be configured to determine a customized scan path based on the separate dentition information. A customized scan path may be advantageous if the user has a tendency to deviate from the recommended (default) scan path in a particular way. For example, such behavior may be detected by a trained neural network, and a customized scan path may be generated to correct the undesirable behavior.

[0070] The one or more processors may also be configured to determine an area of ​​the digital 3D model of the dental object or a portion thereof within the field of view frame, determine a direction and / or orientation of the field of view of the handheld intraoral scanner to center the area within the field of view frame, and generate a suggested correction based on the determined direction and / or orientation of the field of view of the handheld intraoral scanner. Typically, it may be desirable to center the portion of the digital 3D model observable through the field of view at the center of the field of view frame. The generated correction feedback signal may be configured to indicate on a graphical user interface the movement of the scanner required to center the portion of the digital 3D model observable through the field of view frame around the center of the field of view frame. In effect, a larger surface area is exposed to the field of view of the scanner and more scan data is captured so that the digital 3D model can be constructed in an optimal manner.

[0071] The one or more processors may also be configured to determine an area of ​​the digital 3D model that includes missing information, determine a direction and / or orientation of the field of view of the handheld intraoral scanner toward the area of ​​the digital 3D model, and generate a suggested correction based on the determined direction and / or orientation. The area of ​​the digital 3D model that includes missing information may be a portion of the digital 3D model that includes empty space (hole) due to missing scan data required to generate a complete digital 3D model.

[0072] Generating a digital 3D model including areas with missing information may be a result of incomplete light information captured by the scanner. Therefore, an insufficient amount of light information received by the scanner may result in generating an incomplete digital 3D model, for example, including blank areas also referred to as "holes". A suggested correction in this case may be reflected in a field of view frame arranged in a direction toward the area of ​​the digital 3D model with missing information, so that the user can react according to the suggested correction and move the scanner to a corresponding position in the oral cavity.

[0073] The one or more processors may be configured to determine a first position of a reference dental object of a reference digital 3D model, and wherein the reference digital 3D model may include an expected position of the reference dental object, determine a second position on the generated digital 3D model that may correspond to the first position on the reference digital 3D model, and wherein the generated digital 3D model may not include the dental object at the second position as may be indicated by the first position, and generate a suggested correction based on the second position on the generated digital 3D model. The reference digital 3D model may be a previously generated digital 3D model of the same patient. The reference digital 3D model may be segmented into separate reference dental objects, such as reference teeth and gums. During the scanning process, the one or more processors may use information about the reference dental objects and / or the reference digital 3D model to generate a suggested correction for a correction feedback signal.

[0074] The one or more processors may utilize a trained neural network configured to determine the first position and the second position. The trained neural network may be trained based on a plurality of digital 3D models of different dentitions. The plurality of digital 3D models may include different arrangements and surfaces of teeth of different dentitions.

[0075] The indication of the suggested correction of the position of the field of view of the handheld intraoral scanner may include one or more of a geometric object, an arrow, or a lightning effect. In this way, the user may be guided to the optimal scanning path by following the suggested correction.

[0076] The dynamic pattern may include a moving object that may be configured to move along the direction of the signal.

[0077] In an example, the dynamic pattern may include a moving object configured to move in the direction of the signal toward or away from the field of view frame. In this way, the user may be assisted in steering the scanner toward a location where scanning may have been interrupted.

[0078] If the distance between the scanning tip of the handheld intraoral scanner and the dental object being scanned exceeds a predetermined distance limit, the moving object may be configured to increase in size during movement toward or away from the field of view frame.

[0079] In an example, the dynamic pattern may include a plurality of shapes, such as rectangles or arrows. When the distance between the position of the handheld intraoral scanner's field of view and the suggested position increases, the distance between each shape may increase. When the distance between the position of the handheld intraoral scanner's field of view and the suggested position decreases, the distance between each shape may decrease.

[0080] The distance between each shape in the correction feedback signal may also be referred to as signal strength.

[0081] One or more processors may be configured to generate a second field of view frame within the field of view frame if the distance between the scanning tip of the handheld intraoral scanner and the dental object being scanned exceeds a distance limit that can be predetermined. In this case, the predetermined distance limit means a distance limit substantially along an axis orthogonal to the occlusal plane. In this case, the distance may be referred to as a height distance. In an example, the predetermined distance limit may be a specific depth of field of the scanner. In an example, the depth of field of the scanner may be in the range of 10-20 mm, preferably in the range of 15-18 mm. Depending on the technology used in the scanner, the depth of field may be greater than 18 mm. Typically, the predetermined distance limit may be related to the distance between the scanner and the dental object (scanning target) at which the maximum amount of scan data can be collected from the dental object.

[0082] The size of the second field of view frame may vary as the height distance varies relative to the predetermined distance limit.

[0083] The one or more processors may be configured to increase the frequency of the dynamic pattern as the field of view of the handheld intraoral scanner moves closer to the suggested location. The frequency may refer to the frequency of movement of the shapes within the dynamic pattern.

[0084] The one or more processors may be configured to change the shape of the correction feedback signal to include a curved object when the suggested correction includes rotation of the field of view of the handheld intraoral scanner.

[0085] The one or more processors may be configured to change the dynamic pattern of the correction feedback signal to include an object moving along a curved path when the suggested correction includes rotation of the field of view of the handheld intraoral scanner.

[0086] One or more processors may be configured to generate tactile and / or visual signals in the handheld intraoral scanner that, when generated, may correspond to the corrective feedback signals, and / or generate audio signals in the handheld intraoral scanner and / or a device displaying a graphical user interface that, when generated, may correspond to the corrective feedback signals.

[0087] The one or more processors may be configured to perform registration of the obtained optical information to generate a digital 3D model. The registration may correspond to a registration region of the digital 3D model. The one or more processors may perform partial registration of the obtained optical information to generate a digital 3D model. The partial registration may correspond to a partial registration region of the digital 3D model. The one or more processors may be configured to detect a loss of registration of the obtained optical information. The one or more processors may be configured to generate a suggested correction including a location of the partial registration region when a loss of registration is detected.

[0088] One or more processors may generate an incomplete digital 3D model due to missing scan data from a portion of the oral cavity. For example, this may occur if the user missed scanning that portion of the oral cavity and did not receive light information from that portion of the oral cavity or the light information is incomplete. The generated incomplete digital 3D model may include blank spaces (holes) corresponding to portions of the oral cavity that have not been scanned or have been partially scanned. One or more processors can detect the loss of light information and can generate a corrective feedback signal based on the detected loss. The corrective feedback signal can be configured to dynamically guide the user toward the portion of the oral cavity from which no light information is received or an insufficient amount of light information is received. The corrective feedback signal can be displayed in a graphical user interface.

[0089] The one or more processors may be configured to display a field of view box including a shape simulating the shape of a field of view of a handheld intraoral scanner.

[0090] The one or more processors may be configured to display a field of view box including a shape simulating a shape of a window of a handheld intraoral scanner, wherein the window may be configured to facilitate passage of light information reflected from a dental object.

[0091] In an embodiment, a method for generating a correction feedback signal during a scanning session is disclosed, wherein the method comprises:

[0092] - Obtaining light information reflected from dental objects inside the oral cavity through the field of view of a handheld intraoral scanner,

[0093] - processing the light information and generating a digital 3D model of the dental object based on the processed light information,

[0094] - displaying in real time on the graphical user interface a field of view frame representing the position of the field of view of the handheld intraoral scanner,

[0095] - generating a correction feedback signal corresponding to the field of view frame, wherein the correction feedback signal includes a suggested correction of the position of the field of view of the handheld intraoral scanner.

[0096] The correction feedback signal can be characterized by a signal direction, wherein the signal direction can be a direction from the center of the field of view frame toward the center of mass of a portion of the digital 3D model presented in the field of view frame, or a direction parallel to a direction from the center of the field of view frame toward the center of mass of a portion of the digital 3D model presented in the field of view frame.

[0097] Generating the correction feedback signal may include displaying the correction feedback signal on a graphical user interface, for example, in association with the field of view box. The correction feedback signal may be displayed together with the signal direction and / or signal strength. Thus, the correction feedback signal may provide a user with clear guidance on how to move the scanner to achieve an efficient and fast scanning process and result in the generation of an accurate digital 3D model.

[0098] The present invention discloses a non-transitory computer-readable medium, which includes instructions. When the instructions are executed by a computer, the computer performs the method according to any one or more of the disclosed embodiments.

[0099] The present invention discloses a computer program product, which includes instructions. When a computer executes the program, the instructions enable the computer to execute any one or more of the methods described in the disclosed embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0100] Figure 1 schematically illustrates scanning of the oral cavity with a handheld intraoral scanner and the corresponding digital 3D model displayed on a graphical user interface;

[0101] Figure 2 The scan path is shown;

[0102] Figure 3A , 3B A correction feedback signal with signal direction and signal strength is shown;

[0103] Figure 3C , 3D An example of a digital 3D model, a field of view box representing the position of the field of view of a handheld intraoral scanner, and a correction feedback signal are shown;

[0104] Figure 4A , 4B shows additional examples of a digital 3D model, a field of view box representing the position of the field of view of a handheld intraoral scanner, and a correction feedback signal;

[0105] Figure 5A , 5B shows additional examples of a digital 3D model, a field of view box representing the position of the field of view of a handheld intraoral scanner, and a correction feedback signal;

[0106] Figure 6 A method for generating a correction feedback signal during a scanning session is shown;

[0107] Figure 7 An intraoral scanner system is shown. DETAILED DESCRIPTION

[0108] In the following description, reference is made to the accompanying drawings, which show by way of illustration how the invention may be practiced.

[0109] Figure 1 A portion of an intraoral scanner system 100 is shown, namely a handheld intraoral scanner 101 and a graphical user interface 102, which may be part of a computer device (e.g., a laptop computer 110). The handheld intraoral scanner 101 (also referred to as a scanner) may be configured to scan an oral cavity of a patient. Figure 1 As shown, the teeth of the lower jaw 109 of the patient's mouth may be scanned.

[0110] The scanner 101 may be configured to acquire light information reflected from a dental object 108 in the oral cavity through a field of view 105 of the scanner 101. The dental object 108 may be any tooth or part thereof, multiple teeth, gums, preparations, palates, restorations, or any other object in the oral cavity. The intraoral scanner system 100 may include one or more processors 106 configured to process the light information and generate a digital 3D model 103 of the dental object 108 based on the processed light information. The one or more processors 106 may be located in the scanner 101 (e.g., Figure 1 ), in a computer device displaying the graphical user interface 102 and / or may be part of a remote computer resource.

[0111] The area (surface) of the oral cavity captured momentarily by the scanner 101 can be defined by the field of view 105 of the scanner 101, such as Figure 1 . The scanner 101 may receive light information from a dental object 108 within a field of view 105 of the scanner 101. Based on the received light information, one or more processors 106 may generate a digital 3D model 103. The generated digital 3D model 103 may represent the surface of the dental object 108. When a user (e.g., a dentist) moves the scanner 101 within the oral cavity, the field of view of the scanner may cover the rest of the oral cavity, and the digital 3D model 103 may be updated accordingly.

[0112] The scanner 101 may be based on any known scanning principle, such as focus scanning, triangulation, confocal scanning, stereo vision, structure from motion.

[0113] For example, the scanner 101 can be based on a focus scanning principle, wherein the scanner 101 may include 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 101, so that depth information can be estimated based on focus measurement. Focus scanners are further described in EP2442720B1, which is incorporated herein by reference. In some examples, the scanner 101 can be based on a depth-from-defocus scanning principle, wherein optical properties, such as an aperture, are changed between the acquisition of two images, so that the depth can be estimated by determining the degree of defocus between the two images. Focus scanners are characterized by a relatively narrow depth of field characteristic, which can limit the volume in which the dental object can be located so that it is in focus when scanned. The depth of field of a focus scanner can be understood as a depth interval from 0 to a maximum depth of field. In an example, the interval can be 0 to 20 mm, where 20 mm is the maximum depth of field.

[0114] In some examples, the scanner 101 can be 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, a point in a 3D space can be determined based on triangulation using a projector and a camera. Alternatively, the scanner 101 can include two or more cameras that observe a scene or a scanned object from two different directions, wherein the cameras are configured to collect 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. Specifically, the projector unit can be configured to project a plurality of projector rays that are projected onto the surface of a dental object. Specifically, solving the correspondence problem can include the step 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 can be calculated, so that a 3D representation of the scanned object can be generated. Compared to a focusing scanner, a triangulation scanner is characterized by a deeper depth of field characteristic.

[0115] The scanner 101 can generate multiple two-dimensional (2D) images of the dental object 108, which can then be stitched together to create the digital 3D model 103. This process of combining 2D images together can be called "stitching" or registration. Registration of 2D images can include stitching together 2D images that have overlapping portions.

[0116] The movement of the scanner 101 within the oral cavity may include a set of complex motions in three-dimensional space. Some simplified examples of possible movements of the scanner 101 are mentioned below. The movement of the scanner 101 within the oral cavity can be observed by a coordinate system defined by three orthogonal axes x, y and z, such as Figure 1 As shown, as disposed in the mandible 109. The movement may include translational movement along the axis and / or rotational movement about the axis. The scanner 101 may be moved in a plane substantially parallel to an XY plane defined by the x-axis and the y-axis to scan the occlusal surface and the incisal surface of the tooth, also referred to as the biting surface of the tooth. The scanner 101 may be moved approximately along the z-axis toward or away from the scan target, for example Figure 1 The dental object 108 in the scanner. To scan the facial (cheek) or tongue surfaces, the scanner can be rotated so that these surfaces are within the field of view 105 of the scanner.

[0117] The one or more processors 106 may be configured to display a field of view frame 104 on the graphical user interface 102, which may indicate the position of the field of view 105 of the scanner 101. In this way, the user may know exactly which area of ​​the oral cavity is within the field of view 105 of the scanner by observing the field of view frame 104. Therefore, the movement of the scanner 101 may result in a corresponding movement of the field of view frame 104 on the graphical user interface 102.

[0118] The field of view frame 104 may be displayed superimposed on the digital 3D model 103 being rendered, such as Figure 1 Additionally or alternatively, a field of view box 104 may be displayed separately from the digital 3D model 103 being presented on the graphical user interface 102. Such a separately displayed field of view box 104 may indicate the position of the field of view 105 of the scanner 101 by displaying the 2D image or multiple 2D images or 2D image streams as they are captured by the scanner 101. In general, the field of view box 104 may be displayed on the graphical user interface 102 and may indicate the position of the scanner relative to the dental object 108 being scanned.

[0119] Figure 2 An example of a scan path is shown, in this example for the patient's jaw 109 . Figure 2 The scan path 200 shown in the figure may be referred to as a recommended scan path and may be recommended by the scanner manufacturer to mitigate the inherent accuracy deficiencies of the scanner 101 and to help the user learn best practices for fast and accurate scanning. The scan path 200 includes a curved portion above the front teeth (incisors), which are particularly difficult to scan because of their small cut surface area. The user may move the scanner 101 according to the scan path 200 to complete the scan of the mandible 109. The recommended scan path for the upper jaw may be similar or identical to the scan path 200 for the mandible 109.

[0120] An experienced user may operate the scanner 101 by following the scan path 200 so that all relevant information about the surface geometry of the oral cavity is captured, and thus a complete digital 3D model 103 may be generated. However, in some cases, the generation of the digital 3D model 103 may be based on insufficient scan data, or even interrupted, for various reasons. For example, an inexperienced user may move the scanner 101 completely away from the teeth, so that the teeth are completely outside the field of view 105 of the scanner. This may be seen as a lack of information in the field of view box 104 on the graphical user interface 102. For example, no data may be visible through the field of view box 104. Therefore, the generation of the digital 3D model 103 may be interrupted.

[0121] When the user begins to move the scanner 101 away from the teeth, less data will be collected, which may result in the generation of the digital 3D model 103 with a suboptimal amount of scan data. The user may need to obtain guidance on how to move the scanner 101 back to a certain position in the mouth so that a larger tooth surface can be scanned and the generation of the digital 3D model 103 can be resumed based on more captured data. Such guidance may be desirable once the user begins to move the scanner 101 away from the teeth. Embodiments of the present disclosure provide a solution in the form of a corrective feedback signal.

[0122] The location in the oral cavity to which the scanner 101 may be directed would be a location where a larger surface area of ​​the dental object 108 is to be scanned than the current location of the scanner 101 .

[0123] It may happen that the user moves the scanner 101 away from the tooth to such an extent that the generation of the digital 3D model 103 is interrupted. In this case, the user may need to obtain guidance on how to move the scanner 101 back into the oral cavity so that the generation of the digital 3D model 103 can continue. As a solution, a corrective feedback signal may be generated based on the last known position of the scanner 101 to guide the user to move the scanner 101, thereby causing the generation of the digital 3D model 103 to resume.

[0124] The user may also hold the scanner 101 at a distance (generally along the z-axis 107) that is too far away from the dental object 108 that may be the target of the scan. In this case, the user may need to receive guidance on how to move the scanner 101 closer to the dental object 108 along the z-axis 107. This may be particularly useful for scanners with a narrow depth of field, where slight movement of the scanner 101 along the z-axis 107 may cause the dental object 108 to appear out of focus. For example, this may occur if the distance from the scanner tip to the dental object 108 is greater than the depth of field of the scanner 101. Such instructions may be particularly beneficial when scanning uneven surfaces or when the scanner 101 is angled to capture the buccal and / or lingual surfaces of the teeth. In some cases, the user may wish to receive instructions to move the scanner 101 further away from the dental object 108 so that more data can be collected.

[0125] The one or more processors 106 may be configured to generate a correction feedback signal 301 (eg, such as Figure 3A , 3B ). The correction feedback signal 301 may include a suggested correction of the position of the field of view 105 of the scanner 101. Therefore, the correction feedback signal 301 may be displayed in relation to the field of view frame 104, for example, on the field of view frame 104, at one or more points on the boundary of the field of view frame 104, or at one or more points inside the field of view frame 104 (e.g., at the center of the field of view frame 104).

[0126] In an example, the corrective feedback signal 301 may be associated with the field of view frame 104 and may occur depending on the position of the scanner 101 relative to the dental object 108 which may be the target of the scan.

[0127] The position of the scanner 101 relative to the dental object 108 may be observed by viewing the field of view box 104 on the graphical user interface 102 .

[0128] The correction feedback signal 301 may be characterized by a signal direction 302 and a signal strength. The correction feedback signal may appear on the graphical user interface 102 as a visually identifiable signal associated with the field of view box 104. For example, the correction feedback signal 301 may be in the form of a plurality of rectangles attached to the field of view box 104. The signal direction 302 may determine the orientation of the correction feedback signal 301. The signal strength may indicate different levels of movement required by the user of the scanner 101 in order to return the scanner 101 to a position in the oral cavity from which the digital 3D model 103 may continue to be generated (e.g., in the case of an increase in the amount of scan data).

[0129] The correction feedback signal 301 may be a dynamic signal, for example, its shape may move along the signal direction 302 .

[0130] Figure 3A A plurality of correction feedback signals 301 in the form of rectangles attached to the field of view box 104 are shown. The correction feedback signals are oriented along a signal direction 302.

[0131] In an example, the signal direction 302 may be determined from the relative position of the portion of the digital 3D model 103 visible in the field of view frame 104 and the field of view frame 104 itself. Figure 3A In the example shown, the signal direction 302 is determined by a line connecting the center (o) of the field of view box 104 and the center of mass (m) of the portion of the digital 3D model 103 presented in the field of view box 104 .

[0132] Therefore, in order to determine the signal direction 302, the centroid (m) of the portion of the digital 3D model 103 presented in the field of view frame 104 may first be determined. Then, the signal direction 302 may be determined by connecting the center (o) of the field of view frame 104 and the centroid (m) of the portion of the digital 3D model 103 presented in the field of view frame 104. The signal direction 302 may be a direction from the center (o) to the centroid (m).

[0133] The portion of the digital 3D model 103 presented in the field of view frame 104 may refer to the portion of the digital 3D model that is in focus in the field of view frame 104 .

[0134] Figure 3BAn example of determining the signal strength of the correction feedback signal 301 is shown. The signal strength may be understood as the distance (d) between each of the plurality of shapes (e.g., rectangles) included in the correction feedback signal 301. In one example, the signal strength may depend on the portion ( Figure 3B The portion of the digital 3D model 103 not shown in the figure, but only the position of the center of mass (m) of the center of mass m) thereof is shown. The surface area of ​​the field of view frame 104 can be divided into a plurality of zones, which can have the same shape as the field of view frame 104 and can have the same center (o) as the field of view frame 104 (concentric zones). If the center of mass (m) is located in zone 1, the signal strength can have a first value. The first value can be zero, and in this case the correction feedback signal 301 can not appear. If the center of mass (m) is located in zone 2, the signal strength can have a second value higher than the first value. If the center of mass (m) is located in zone 3, the signal strength can have a third value higher than the second value. It can be defined with Figure 3B The three zones shown in FIG. 1 have different numbers of zones.

[0135] In another example, the signal strength may be a function of the distance (o, m) between the center (o) of the field of view frame 104 and the centroid (m) of the portion of the digital 3D model 103 presented in the field of view frame 104:

[0136]

[0137] Wherein, the maximum intensity is the maximum value of the signal intensity. The maximum intensity may be the value of the maximum distance (d) between each of the plurality of rectangles contained in the correction feedback signal 301, in millimeters. It may be predefined or may be set by a user. The correction feedback signal 301 may have the maximum intensity when the distance between the center (o) of the field of view frame 104 and the center of mass (m) of the portion of the digital 3D model 103 presented in the field of view frame 104 is the largest. This occurs when the center of mass (m) of the portion of the digital 3D model 103 presented in the field of view frame 104a is located at the point on the field of view frame 104 that is farthest from the center (o).

[0138] Figure 3C The digital 3D model 103, the field of view box 104a in a first position, and the field of view box 104b in a second position are shown. These two positions may represent two correct positions of the field of view 105 of the scanner 101 located on the scanning path 200. The portions of the digital 3D model 103 visible through the field of view boxes 104a, 104b are centered within their respective fields of view. In these cases, no correction feedback signal 301 is generated.

[0139] Figure 3DThe digital 3D model 103, the field of view box 104c in a third position, and the field of view box 104d in a fourth position are shown. These two positions may represent two non-optimal positions of the field of view 105 of the scanner 101 (e.g., relative to the scan path 200) because the scanner 101 collects less data than the position indicated by the scan path 200. It can be seen that the portions of the digital 3D model 103 visible through the field of view box 104c and the field of view box 104d are not centered around the center points of their respective field of view boxes. In both positions of the field of view boxes 104c, 104d, a corrective feedback signal 301 may be generated. The corrective feedback signal 301 may be directed along a signal direction 302, which may be determined as previously described. The corrective feedback signal may indicate that the scanner 101 should be moved in the XY plane to return the field of view 105 of the scanner 101 to the position in the oral cavity from which further scanning should be continued, thereby restoring the direction of the optimal construction of the digital 3D model 103.

[0140] In an embodiment, Figure 3A , 3B , 3D, the correction feedback signal 301 may include a geometric shape, such as a rectangle. A plurality of shapes (e.g., rectangles) may be arranged in a pattern to include the correction feedback signal 301. The shapes in the pattern may have different opacities. In addition, the shapes in the pattern may move toward or away from the field of view frame 104, thereby forming a dynamic pattern. The shapes in the pattern may be arranged along a signal direction 302, which may be associated with a suggested correction of the position of the field of view 105 of the scanner 101. Thus, if the field of view 105 of the scanner 101 moves so that the portion of the digital 3D model visible through the field of view frame 104 becomes moved away from the center of the field of view frame 104, the shape may be generated. In this case, the movement of the scanner 101 may be in a plane substantially parallel to the XY plane defined by the x-axis and the y-axis.

[0141] The distance between the shapes (e.g., rectangles) in the correction feedback signal 301 can be understood as the signal strength of the correction feedback signal 301. Depending on the position of the portion of the digital 3D model 103 visible through the field of view frame 104 relative to the field of view frame 104, the signal strength can be higher or lower. Figure 3D As shown, the field of view box 104c indicates the position of the scanner 101, more precisely the position of the scanner tip, which deviates from the optimal position where the scanner tip should be, for example, to collect data from a larger scanning surface. The correct position of the scanner tip, for example, when it is located on the scanning path 200, can be used Figure 3AThe deviation may be understood as a deviation in a plane substantially parallel to the XY plane. The arrangement of the shapes in the correction feedback signal 301 associated with the field of view frame 104c and their movement in the signal direction 302 may indicate to the user that the scanner 101 should be moved substantially in a direction corresponding to the signal direction 302.

[0142] exist Figure 3D It can also be seen that the field of view box 104d indicates the position of the scanner 101, more precisely the position of the scanner tip, which deviates from the optimal position that the scanner tip should be in. The optimal position of the scanner tip can be Figure 3C 302. The position corresponding to the field of view frame 104b in the correction feedback signal 301 is shown in FIG. 304. In this case, the deviation can be understood as the deviation of the scanner tip in a plane substantially parallel to the XY plane. The arrangement of the shapes in the correction feedback signal 301 associated with the field of view frame 104d and their movement in the signal direction 302 can indicate to the user that the scanner 101 should be moved substantially along the direction corresponding to the signal direction 302. The distance between the shapes (rectangles in this example) in the correction feedback signal 301 associated with the field of view frame 104d is smaller than the distance between the shapes displayed as rectangles in the correction feedback signal 301 associated with the field of view frame 104c. Therefore, the deviation between the scanner tip position indicated by the position of the field of view frame 104c and the optimal position indicated by the position of the field of view frame 104a is greater than the deviation between the scanner tip position indicated by the position of the field of view frame 104d and the correct position indicated by the position of the field of view frame 104b. Thus, observing the correction feedback signal 301, the user can react to the movement at a greater distance when the scanner 101 is held in a position corresponding to the field of view frame 104c than in a position corresponding to the field of view frame 104d. In both cases, the user can be prompted to move the scanner 101 in a plane parallel to the XY plane in a direction corresponding to the signal direction 302.

[0143] Figure 4A and Figure 3A Similarly, the digital 3D model 103 and the field of view box 104e associated with the optimal position of the field of view 105 of the scanner 101 are shown. The portion of the digital 3D model 103 visible through the field of view box 104e is centered around the center of the field of view box 104e. This position of the scanner 101 can also be located on the scan path 200. In this case, no correction feedback signal 301 is generated.

[0144] Figure 4BThe digital 3D model 103 and the field of view box 104f associated with the position of the field of view 105 of the scanner 101 are shown, which may be an optimal position relative to the scan path 200 in a plane substantially parallel to the XY plane. However, this position of the scanner 101 may not be optimal along the z-axis 107, for example because less scan data is collected by moving the scanner 101 further away from the dental object 108 along the z-axis 107. Therefore, the scanner 101 is positioned such that the optimal scanning height along the z-axis 107 is not achieved. This situation may be indicated to the user by a correction feedback signal 301, which may include a scanning frame gap between the field of view box 104f and a second box 401 that may be concentric with the field of view box 104f.

[0145] Throughout the disclosure, the second frame 401 may also be referred to as a second field of view frame 401 .

[0146] If the distance between the scanner 101 (or more precisely the scanner tip) and the scan target is such that less scan data is used to generate the digital 3D model 103 than is optimal, a second box 401 may be generated. The shape of the second box 401 may correspond to the shape of the field of view box 104f. The second box 401 may be scaled relative to the field of view box 104f to indicate a suggested correction of the position of the field of view 105 of the scanner 101 along the z-axis 107. For example, Figure 4B As shown, the second frame 401 is reduced together with the digital 3D model 103 to indicate that the scanner height is not optimal. In this case, the scanner 101 may be held too high relative to the dental object 108. Therefore, the scan frame gap that may appear may indicate the distance between the height at which the scanner 101 is located and the position where the scanner 101 should be held in order to achieve the optimal scan height. This provides a clear guide for the user to adjust the scan height.

[0147] Thus, the correction feedback signal 301 may include a scan frame gap to indicate a correction to the position of the field of view 105 of the scanner 101 so that when the user applies the correction, an optimal scan height is achieved. It will be appreciated that in addition to the scan frame gap, the correction feedback signal 301 may also include a plurality of shapes arranged along the signal direction 302. This component of the correction feedback signal 301 may appear to suggest that the scanner 101 move in a plane substantially parallel to the XY plane.

[0148] The correction feedback signal 301 may include a scanning frame gap between the field of view frame 104f and the second frame 401 to indicate a correction of the position of the field of view 105 of the handheld intraoral scanner 101 so that when the user applies the correction, the distance between the scanning tip of the handheld intraoral scanner 101 and the scanned dental object 108 is less than a predetermined distance limit.

[0149] Figure 5A A correction feedback signal 301 associated with the field of view box 104g is shown, comprising a plurality of shapes (in this case rectangles) arranged along a signal direction 302, thereby indicating the direction in which the user should move the scanner 101 to return to a position in the oral cavity from which further construction of the digital 3D model 103 can optimally continue. The rectangles may have different opacities and / or may be arranged to move toward or away from the field of view box 104g. Figure 5A In this case, the correction feedback signal 301 can indicate to the user that the scanner 101 should be moved in a plane substantially parallel to the XY plane in the direction of the shape coinciding with the signal direction 302. No adjustment of the scan height is required because the correction feedback signal 301 does not include the frame gap.

[0150] It is to be understood that the correction feedback signal 301 may include any geometric shape or multiple shapes, such as a line, an arrow, a triangle, a circle, etc.

[0151] and Figure 5A different, Figure 5B A correction feedback signal 301 is shown indicating to the user that further correction of the scan height may be required in addition to corrections in a plane substantially parallel to the XY plane. Correction of the scan height may be indicated by a frame gap appearing between the field of view frame 104h and the second frame 401. The second frame 401 may be reduced in size relative to the field of view frame 104h. Optionally, the digital 3D model 103 may be scaled down to the second frame 401. Figure 5B In the case of , the correction feedback signal 301 may include multiple shapes, such as rectangles, whose size decreases along the signal direction 302. This may indicate to the user that two types of movements are required for position correction. Figure 5B Based on the correction feedback signal 301, the user can move the scanner 101 in a plane substantially parallel to the XY plane in the direction indicated by the plurality of rectangles to bring the scanner 101 into the correct position so that the portion of the digital 3D model 103 is centered around the center of the field of view box 104h. In addition, observing the displayed scan gap, the user can reduce the scan height along the z-axis 107, for example by moving the scanner 101 closer to the dental object 108, so that the scan gap disappears. By moving the scanner 101 closer to the dental object 108 (scan target), a maximum amount of scan data from the scan target can be captured. In this way, the user can be provided with suggestions for moving the scanner 101 to the correct position, at which the digital 3D model 103 can continue to be optimally constructed, for example by scanning a larger surface and collecting a larger amount of scan data than a suboptimal position.

[0152] exist Figure 6, steps of a method 600 for generating a correction feedback signal 301 during a scanning session are shown. The method 600 comprises obtaining 601 light information reflected from a dental object 108 in an oral cavity through a field of view 105 of a handheld intraoral scanner 101. Furthermore, the method shows processing 602 the light information and generating a digital 3D model 103 of the dental object 108 based on the processed light information. Furthermore, the method shows displaying 603 a field of view box 104 representing the position of the field of view 105 of the handheld intraoral scanner 101 in real time on a graphical user interface 102. Also shown is the step of generating 604 a correction feedback signal 301 corresponding to the field of view box 104, wherein the correction feedback 301 signal comprises a suggested correction of the position of the field of view 105 of the handheld intraoral scanner 101.

[0153] Figure 7 An intraoral scanner system 100 is shown, which may include a computer 710 capable of performing any of the methods of the present disclosure. The computer 710 may include a wired or wireless interface to a server 715, a cloud server 720, and a wired or wireless handheld intraoral scanner 101. The handheld intraoral scanner 101 may be capable of obtaining light information reflected from the patient's oral cavity. The handheld intraoral scanner 101 may be equipped with various modules, such as a fluorescent module, a natural color module, and / or an infrared module, so as to be able to capture information related to diagnosing a dental condition (e.g., caries, tooth cracks, gingivitis, tooth atrophy, and / or dental plaque).

[0154] The intraoral scanner system 100 may include a data processing device configured to execute the method according to one or more embodiments of the present disclosure. The data processing device may be a part of a computer 710, a server 715, a cloud server 720, or a handheld device not shown in the figure.

[0155] A non-transitory computer-readable storage medium may be included in the intraoral scanner system 100. The non-transitory computer-readable medium may carry instructions that, when executed by a computer, cause the computer to perform the method described in accordance with one or more embodiments of the present disclosure.

[0156] The computer program product may be embodied in a non-transitory computer-readable storage medium. The computer program product may include instructions, which, when executed by a computer, cause the computer to perform the method according to any embodiment presented herein.

Claims

1. An intraoral scanner system configured to display a correction feedback signal during a scanning session, wherein: The intraoral scanner system comprises: - a handheld intraoral scanner configured to obtain light information reflected from a dental object within the oral cavity through a field of view of the handheld intraoral scanner; - one or more processors configured to process the light information and generate a digital 3D model of the dental object based on the processed light information; and - a graphical user interface configured to display the digital 3D model, Wherein, the one or more processors are configured to: -displaying in real time on the graphical user interface a field of view box representing the position of the field of view of the handheld intraoral scanner; and - generating a correction feedback signal corresponding to the field of view frame, and wherein the correction feedback signal includes a suggested correction of the position of the field of view of the handheld intraoral scanner, wherein the correction feedback signal is characterized by a signal direction, wherein the signal direction is a direction from the center of the field of view frame towards the center of mass of a portion of the digital 3D model presented in the field of view frame.

2. The system according to claim 1, wherein: Further, the correction feedback signal is characterized by signal strength.

3. The system according to claim 2, wherein: The signal strength is determined as a function of a distance between a center of the field of view frame and a centroid of the portion of the digital 3D model presented in the field of view frame.

4. A system according to any one of the preceding claims, wherein: The one or more processors are further configured to generate a second field of view frame within the field of view frame if a distance between a scanning tip of the handheld intraoral scanner and the scanned dental object exceeds a predetermined distance limit.

5. The system according to claim 4, wherein: The predetermined distance limit is the depth of field of the handheld intraoral scanner.

6. A system according to any one of the preceding claims, wherein: The one or more processors are configured to: - determining a deviation of the position of the field of view of the handheld intraoral scanner from a scan path; and - Determining a proposed correction to the position of the field of view of the handheld intraoral scanner based on the determined deviation and the current position of the field of view of the handheld intraoral scanner.

7. A system according to claim 6, wherein: The scan path is one of the following: - a selectable scanning path, which is selected among a plurality of selectable scanning paths for different dentitions; or - a dynamic scan path configured to be modified by the one or more processors during a scanning session to adjust relative to a current position of a field of view of the handheld intraoral scanner.

8. A method for generating a correction feedback signal during a scanning session, wherein: The method comprises: - Obtaining light information reflected from dental objects inside the oral cavity through the field of view of a handheld intraoral scanner, - processing the light information and generating a digital 3D model of the dental object based on the processed light information, - displaying a field of view frame indicating the position of the field of view of the handheld intraoral scanner on a graphical user interface in real time, -Generate a correction feedback signal corresponding to the field of view box, wherein the correction feedback signal includes a suggested correction of the position of the field of view of the handheld intraoral scanner, wherein the correction feedback signal is characterized by a signal direction, and wherein the signal direction is a direction from the center of the field of view box towards the center of mass of a portion of the digital 3D model presented in the field of view box.

9. A computer-readable medium comprising instructions which, when executed by a computer, cause the computer to perform the method according to claim 8.

10. A computer program product comprising instructions which, when a computer executes the program, cause the computer to perform the method according to claim 8.

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