Apparatus for facilitating acquisition of a scanning image and oral scanning procedure

Abstract

The present invention includes an apparatus for facilitating the acquisition of scanned images during an intraoral scanning procedure using an intraoral scanner, the apparatus comprising an elongated body having an attachment portion configured to attach the elongated body to an implant in a patient's mouth, the implant having a longitudinal axis such that the elongated body is adapted to extend substantially perpendicular to the longitudinal axis of the implant when attached to the implant, the elongated body having a substantially planar upper surface and one or more side walls extending downwardly away from the upper surface, the upper surface and the one or more side walls being observable in a resulting scanned image when the intraoral scanner scans the apparatus in a direction perpendicular to the one or more upper surfaces. The present invention extends to kits including multiple items of apparatus, and to methods of performing an intraoral scanning procedure.

Description

Technical Field

[0001] Field of the Invention The present invention generally relates to an apparatus for facilitating acquisition of scanned images in a patient's mouth, and related intraoral scanning procedures.

Background Art

[0002] Background of the Invention Implant impressions are a primary criterion for the location of implants in a patient's mouth and are the basis for designing and manufacturing the frameworks of all prostheses. The accuracy of implant impressions depends on several factors. These factors include the number, depth, and angulation of the implants, the impression technique selected, and the type of impression material. The decision of the impression technique involves considering various options, including the selection of the direct or indirect method, the selection of a fixed or non-fixed solution, the selection of the design of the impression coping used, and the type of impression tray (e.g., open / closed).

[0003] Any inaccuracies during the impression acquisition stage are transferred to the resulting model. For this reason, accurate implant impressions are important for generating accurate and most reliable prosthesis models, which are the main source for fabricating precisely fitting and polished prostheses. The accurate fitting of a polished prosthesis to an implant fixed to a patient's jaw (and protruding into the patient's mouth) at the clinical stage is directly determined by the accuracy of the impression technique. Inaccurate fitting of the implant to the framework of the prosthesis can cause several problems, including inducing internal stresses in the framework, implant, prosthesis screws, and bone. The available selection options for conventional implant impressions can also result in variations in the results depending on the experience of the operator and the selection of the materials used. Furthermore, the orientation of implants within an arch can affect the accuracy of conventional implant impressions. For example, relatively angled implants can cause a decrease in accuracy in conventional impressions compared to the case of parallel implant placement.

[0004] The introduction and improvement of intraoral scanning technology have provided opportunities for the general acquisition of digital dental impressions. Digital impressions are alternatives that reduce the putative error sources associated with conventional implant impression methods. Digital impression systems can capture digital data, which can then be used to replicate the hard and soft tissues in the oral cavity, thus replacing the need for impression trays and impression materials and becoming more common.

[0005] However, the accuracy of recording multiple implant positions across an arch implanted in edentulous patients is a common problem affecting the consistency of the results. Different solutions by different intraoral scanners on the market propose different data acquisition systems and use different knitting algorithms in the compilation of complete data sets, which can cause variations in scanning information. Some of the factors affecting the accuracy of digital implant impressions are different scanning protocols, the optical settings of the scanning device, and the limitations of different technologies (such as blue light / white light, video scanners, etc.).

Summary of the Invention

Problems to be Solved by the Invention

[0006] It is desirable to provide a solution to one or more of the drawbacks generally associated with the acquisition of digital dental impressions. Alternatively, it is desirable to provide alternative means for obtaining more accurate digital data from scanned images and offer the public an alternative that is more useful than what is already on the market.

[0007] Any reference to prior art in this specification is not an admission or suggestion by a person skilled in the art that this prior art forms part of the common general knowledge in any jurisdiction or that it could reasonably be expected to be combined with any other prior art.

Means for Solving the Problems

[0008] Summary of the Invention In a first aspect, the present invention is a device for facilitating the acquisition of a scanned image during an intraoral scanning procedure using an intraoral scanner, comprising an elongate body having an attachment portion configured to attach an elongate body to an implant in a patient's mouth, the implant having a longitudinal axis, whereby the elongate body is adapted to extend substantially perpendicular to the longitudinal axis of the implant when attached to the implant, the elongate body having a substantially planar upper surface and one or more side walls extending downwardly away from the upper surface, the upper surface and the one or more side walls being observable in the resulting scanned image when the intraoral scanner scans the device in a direction perpendicular to the upper surface, the elongate body including the device.

[0009] In at least a preferred embodiment, the device of the present invention can be used to establish a very accurate three-dimensional coordinate system for use in the design of dental prostheses.

[0010] In other words, the present invention advantageously enables a user to obtain more accurate scanning information from a digital implant impression of a range of implant cases, including the case of a completely toothless patient where the implants are distributed throughout the full arch of the patient's mouth (i.e., from an intraoral scan). The user can accurately model the position and orientation of the implants inserted into the patient's mouth, thereby enabling a more accurate digital capture of the implant positions for the patient and a digital design of a prosthesis that utilizes the implant location information. These benefits are achieved due to the unique design of the surface of the elongated body of the device. When the intraoral scanner scans the device in a direction substantially perpendicular to the upper surface, by enabling the upper surface and at least one or more sidewalls to be observable in the resulting scan image, the operator only needs to move the scanner head within a limited range of motion, i.e., in the tongue-lip direction, mesial-distal direction, and superior-inferior (vertical) direction, rather than the conventional five axes of motion required in most current scanning procedures. The additional axes of motion of the scanner head (i.e., due to rotational motion) during the scanning procedure can introduce significant error sources when the scan image is used during the post-processing stage.

[0011] During the post-processing stage, the upper surface and one or more sidewalls observable in the scan image can be used as a reference that can ultimately be compared with stored information contained within a computer library, which includes a precise model and measurements of the device. From this, known measurements of the device can be assigned to the scan image, thereby enabling an accurate determination of the location and orientation of the implants relative to the soft tissue of the patient's mouth. Having this information in the digital model enables the digital design of an optimally fitting implant framework, e.g., a partial or full-arch implant bar, whereby the determined location and orientation of the implants can be used to define the preferred fixation positions of the implant framework, and the framework also conforms to the soft tissue of the arch.

[0012] In one embodiment, one or more sidewalls surround all or a substantial portion of the perimeter of the upper surface and are all visible from above the upper surface. The benefit of such an arrangement is that the device provides a plurality of reference points and reference planes around the upper surface, which can be used in the post - processing steps described above and in detail below. For example, separate scanned images of the device can be taken during an intraoral scanning procedure, and then, during the post - processing stage, the reference points and reference planes located around the perimeter of the upper surface are used together with the upper surface itself to align them with each other. This provides a more accurate alignment between the scanned images and, when accurate measurements of the location and orientation of the implant are determined, increases the reliability of the accuracy of the scanned images.

[0013] In one embodiment, the upper and lower surfaces of the elongate body define an elongate hexagon, with each of its elongate sides extending substantially parallel from a first end to a second end. The length of the pair of short sides of the hexagon at the first end of both the upper and lower surfaces can be longer than the length of the pair of short sides of the hexagon at the second end of both the upper and lower surfaces. Therefore, these surfaces can define a relatively acute angle between the pair of sides at the first end, while at the second end, they can meet at a larger, relatively obtuse angle. Therefore, these surfaces can be substantially trapezoidal.

[0014] In one embodiment, one or more sidewalls are tapered inwardly towards the upper surface of the elongate body, thus providing an inclined skirt that hangs down from the upper surface. The angle of this taper can be selected as desired for the best results. Ideally, each of the one or more sidewalls is substantially planar. Alternatively, one or more of the sidewalls can be curved. Preferably, a plurality of sidewalls defining a plurality of interconnected facets are provided, and each facet can be observed by an intraoral scanner when scanning in a direction substantially perpendicular to the upper surface.

[0015] As a specific example, the facets can be substantially planar and can be inclined by an angle of about 15° to about 40°, preferably about 25°, from a direction perpendicular to the upper surface.

[0016] In one embodiment, the elongated body includes a first end and a second end, both ends having a shape of a generally pointed end, each defined by two contacting facets. This has the advantage that when used in combination with other adjacent devices, the shadow or obscurity caused by one device on the other device can be minimized.

[0017] In one embodiment, the device includes a reference marker mounted on or integral with the upper surface. Incorporation of the reference marker can assist in alignment between separate scanned images as the marker serves as an additional reference point for accurately aligning the scanned device, particularly for vertical alignment. This is because the marker has known dimensions and is provided at a known position and orientation relative to the elongated body. The reference marker provides an additional source of three-dimensional information in the scanned data capture, which can be used for vertical correction between scanned images that may be required during a post-processing stage.

[0018] The reference marker can be of any suitable shape. In one form, the reference marker is spherical, although other shapes such as triangular, square, conical, cylindrical, oval, etc. may be used. The reference marker may be attached to the upper surface of the elongated body in any suitable manner. Alternatively, the reference marker can be integral with the upper surface either by manufacturing the reference marker and the elongated body as one integrally formed component or by permanently fixing the reference marker to the elongated body by welding or some other suitable process.

[0019] In certain embodiments, the attachment portion can be configured to receive a fastening element, such as a prosthetic screw, for fixing and attaching the elongated body to an implant in a patient's mouth (or to some other intermediate component between the implant and the elongated body). Thus, the device can be removed from the implant (e.g., following unscrewing of the prosthetic screw) once the scanning is complete.

[0020] In one embodiment, the upper surface of the elongate body includes an aperture or recess configured to receive a display element that is distinguishable in the resulting scanned image. The recess may be provided by a bore passing through the elongate body, and the bore serves to engage the elongate body with the implant. The display element may be in the form of a plug configured to be held in the recess when the device is scanned. This can be useful during post-processing because the display element can be used to identify features of the device or the scanned image. For example, when multiple devices are being scanned (e.g., as part of a full arch scan), the element is placed in the recess of the first device to be scanned, thereby indicating the starting position of the scanning path. Such information can assist in communicating information regarding the scanning path. This information can be important because generally the scan data of the device scanned first in the scanning path is more accurate than that of the device scanned last in the scanning path.

[0021] In one embodiment, one or more sidewalls adjacent to the attachment portion include at least one notch configured such that the scanner can retrieve data to assist in defining the longitudinal axis of the implant. The notch preferably extends towards the attachment portion, thereby enabling visualization of the surface of the attachment portion below the elongate body. For example, the notch enables the convex surface associated with the bore of the attachment portion to be attached to the implant to be seen when viewed by the scanner from a direction perpendicular to the upper surface. This additional information provided by the notch can be used to assist in correcting any misalignment (e.g., x-y scan data) of the scan image along the z-axis that may occur in the resulting scan image during post-processing. Further advantages result from the nature of conventional intraoral scan images and the resulting post-processing. The notch can serve the function of a smooth transition path connecting the surfaces created by the scanner by connecting the observable surface of the device and the surface of the underlying tissue as a complete scan image. This is achieved without the need to tilt the head of the scanner in a direction perpendicular to the longitudinal axis of the implant, as required by conventional scanning devices. It is this tilt or rotation of the scanner head that can introduce inaccuracies into the resulting scan image. Connecting the surfaces between the device and the underlying tissue also reduces the tendency for most post-processing software to treat separate or conflicting scan data as noise, which in some cases results in the automatic deletion of this data.

[0022] Preferably, there are at least two notches, with at least one located on the rear side of the device and at least one located on the front side of the device.

[0023] In one embodiment, one or more of the upper surface and the side walls include an identifier, thereby enabling the identification of the device in the resulting scanned image. Preferably, the identifier is provided on the upper surface. The identifier can be in any suitable form, such as one or more protrusions, one or more depressions, a scannable medium (such as a barcode), etc. The identifier can convey different types of information regarding the device, such as height, length, width, or dimensional tolerances. This is particularly important when the device is used in combination with other similar devices as part of a scanning procedure.

[0024] In a second aspect, the present invention provides a method of performing an intraoral scanning procedure, comprising inserting one or more implants into a patient's jaw, each of the one or more implants having a longitudinal axis, attaching the device as defined above to one or more implants in the patient's mouth, and scanning the device and at least a portion of the soft tissue in the patient's mouth to generate a set of scan data for use in determining the relative position and orientation of the one or more implants with respect to the soft tissue.

[0025] In one embodiment, the method can further include selecting one or more module forms of the device from a plurality of different module forms of the device to optimally conform to the space to be scanned in the patient's mouth.

[0026] In another embodiment, when a plurality of implants are inserted into the patient's jaw, the method further includes attaching each device to its respective implant such that a substantially elongate overlapping transition occurs from each device to each adjacent device across the space to be scanned.

[0027] It will be recognized that the second aspect of the present invention can include any of the features defined with respect to the first aspect of the present invention.

[0028] In a third aspect, the present invention provides a kit comprising a plurality of items of the device as defined above, the items having different dimensions, the plurality of items being selectable according to the area of the patient's mouth to be scanned and / or according to the relative positions of one or more existing implants, for a particular patient's mouth.

[0029] The different dimensions may include different lengths and / or heights. The different heights may be provided to adapt to the depth of a given implant relative to the surrounding tissue. For example, excessive pressure applied by the tissue to the lower surface of one item may be avoided by using an item with a greater height. Further, an item of a suitable height may be used such that the depth of field of the scanner head gets closer to the tissue without touching the tissue, thereby increasing the accuracy of the scan and thus enabling better stitching between scan data. In a similar way, different lengths may be provided to adapt to different distances between implants.

[0030] In one embodiment, each particular item within the kit is measured and the measurements are stored in a digital library for post - processing of the resulting scan images.

[0031] It will be appreciated that the third aspect of the present invention may include any of the features defined in relation to the first or second aspect of the present invention.

[0032] In a fourth aspect, the present invention is a method of performing an intraoral scanning procedure to determine the position and orientation of one or more implants in a patient's mouth, each implant having a longitudinal axis, the method comprising using one or more scanable bodies and providing a scanable body to each of the one or more implants, the scanable body extending substantially perpendicular to the longitudinal axis of each respective implant, the scanable body having a substantially planar first surface facing away from the soft tissue of the patient's mouth and one or more additional surfaces extending from the first surface, the one or more additional surfaces being viewable from a direction perpendicular to the first surface, scanning the one or more scanable bodies, thereby generating a set of scan data associated with the intraoral scanning procedure, and assigning information from a set of stored data to the scan data, and determining the position and orientation of the one or more implants from the scan data and the assigned information.

[0033] It will be appreciated that the fourth aspect of the present invention may include any of the features defined with respect to the first, second, and third aspects of the present invention.

[0034] As used herein, unless the context requires otherwise, the term "comprise" and variations of that term, such as "comprising," "comprises," and "comprised," are not intended to exclude further additions, components, integers, or steps.

[0035] Further aspects of the present invention and further embodiments of the aspects described above will become apparent from the following description given by way of example and with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] BRIEF DESCRIPTION OF THE DRAWINGS

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Mode for Carrying Out the Invention

[0037] Detailed Description of Embodiments It will be understood that the invention disclosed and defined herein extends to all alternative combinations of two or more of the individual features described or apparent from the text or drawings. All of these different combinations constitute various alternative aspects of the invention.

[0038] Refer to FIGS. 1 - 5 showing various views of an embodiment of the device of the present invention. A scan abutment (or scan gauge) 10 is configured to be attached directly or indirectly to an implant in a patient's mouth, for example, an implant pin (i.e., a dental implant) surgically implanted in the patient's mandible or maxilla. In some examples, the scan abutment 10 can be attached to an intermediate adapter (not shown), such as a multi - unit adapter (as known in the art), which is attached to the implant. Note that reference to the implant may, where the context permits, include reference to the intermediate adapter.

[0039] In this specification, references to vertical directions refer to the vertical directions as generally understood in an anatomical position (i.e., where the patient is standing upright). In this specification, references to upper and lower should be understood in relation to the scan abutment as shown in the accompanying drawings. However, as will be understood, depending on whether the scan abutment is used on the upper arch or the lower arch in the patient's mouth (i.e., where there are implants in the upper jaw or the lower jaw, respectively), the terms upper and lower may be reversed. In the illustrated embodiment, since the scan abutment is used on the lower arch of the patient's mouth (i.e., attached to the implants in the lower jaw), the terms "upper" and "lower" are used from that perspective.

[0040] The scan abutment 10 includes an elongate prism 11 having a first end 12 and a second end 14. The prism 11 is preferably solid, but alternatively, it may be a hollow body. The prism 11 further includes a planar upper surface 16, a planar lower surface 17, and a plurality of side walls 18 extending between the peripheral edge of the upper surface 16 and the peripheral edge of the lower surface 17. As shown in the figure, the upper and lower surfaces 16, 17 are in the form of an elongate hexagon having a similar shape, and respectively, their elongate sides extend parallel from the first end 12 to the second end 14. The length of the pair of short sides of the hexagon at the first end 12 of both the upper surface 16 and the lower surface 17 is longer than the length of the pair of short sides of the hexagon at the second end 14 of both the upper surface 16 and the lower surface 17. Therefore, these surfaces define a relatively sharp acute angle between the pair of sides at the first end 12, while contacting at a larger obtuse angle at the second end 14. This difference in form is due to the need to minimize lateral overlap (and related shadow formation) that can adversely affect the accuracy of the scan.

[0041] Therefore, the prism 11 has the form of an elongated frustum of a hexagonal pyramid, with a single plane of symmetry extending along the longitudinal centerline.

[0042] Those skilled in the art will recognize that the top surface 16 and the bottom surface 17 do not necessarily have to have the same shape as shown in this embodiment, but can take on any other suitable shape, such as rectangular, oval, triangular, polygonal, etc. However, as will become apparent from the following description, a series of straight edges and the faceted sidewalls of the associated planes are preferred. Further, the overall shape of the prism 11 does not necessarily have to have the top surface 16 and the bottom surface 17 having the same shape, and overall shape changes from those shown in this embodiment are also possible.

[0043] The sidewall 18 includes several separate facets, six facets 18a - 18f in the illustrated example, which extend between the respective edges that circumscribe the entire periphery of the top surface 16 and the bottom surface 17. The peripheral edge of the bottom surface 17 includes a chamfered transition lip 19, from which the facets 18a - f extend upwardly towards the top surface 16. As shown in the drawing, the facets 18a - f are generally tapered inwards from the chamfered transition lip 19 to the top surface 16, thereby defining a series of interconnected planar inclined walls. The inclination of the sidewalls 18a - f can be selected as desired. Ideally, this inclination is between 15° and 40° with respect to the vertical line (i.e., the direction perpendicular to the top surface 16), and preferably about 25° with respect to the vertical line. In other embodiments, the sidewall may be curved, or a single curved sidewall may extend from and surround the entire top surface 16. However, preferably, for ease of surface identification and data manipulation, planar facets are preferred.

[0044] Interestingly, when the scan abutment 10 is viewed in a direction that is substantially upward and perpendicular to the upper surface 16 by the scanning head of the intraoral scanner (with the scan abutment 10 mounted on the proximal end of the implant in the patient's mouth), the six facets 18a - 18f and the upper surface 16 can all be directly observed in the scan image (as shown in the plan view of FIG. 3). In this way, when aligning the separate scan images of the scan abutment 10 in the patient's mouth, all seven facets can serve the function of a reference plane. This provides complete 3D reference information regarding the relative position and orientation of the scan abutment, and thus the position and orientation of the implant relative to the soft tissue within that region of the patient's mouth.

[0045] This is quite useful because it only requires the scanning operator to manipulate the scanning head within a limited range of motion in the patient's mouth, i.e., in the tongue - lip direction, mesial - distal direction, and - if necessary - the vertical direction. By manipulating the scanning head in these directions, the upper surface 16 and the side walls 18 can be captured without the need to manipulate the scanning head in any rotational direction. This is important because it has been found that rotational movements of the scan introduce the largest source of error estimated when capturing internal scan data. This generally relates to internal interpolation algorithms that work to fill in any gaps that may exist in the image data and cause significant distortion, and thus inaccuracy, across the entire scan image. Of course, it is almost impossible to eliminate some instances of the scanner software that are required to remove a certain degree of rotational movement that occurs during the scanning procedure and to join multiple gaps in the scan image. However, by eliminating the need for substantial rotation of the scanning head during the scanning procedure, the operator can mostly keep the movement of the scanning head within the limited range of motion described above and significantly limit the amount of data interpolation required.

[0046] As described above, the chamfered transition lip 19 extends from the lower surface 17. The transition lip 19 causes the scan abutment 10 to have a relatively sharp lower edge detail with respect to the side wall 18. This helps to reduce the risk of tissue in the lower part of the side wall 18 overlapping. The lower edge detail also helps to more precisely define the implant / tissue boundary. This can improve scanning accuracy by minimizing interpolation errors that can occur, for example, when tissue is mistaken for the implant.

[0047] It is advantageous but not essential for the scan abutment 10 to include side walls that are visible throughout the periphery surrounding the upper surface 16. For example, having side walls that are visible only at a portion of the periphery of the upper surface 16 can still provide a suitable data set and sufficient reference planes for use in comparing and aligning separate scanned images of the scan abutment 10. However, it will be apparent to those skilled in the art that the more visible reference points and reference facets there are, the higher the accuracy of the scan and the usefulness of the scanned images.

[0048] As can be seen from the overall shape and form of the scan abutment 10, the first end 12 and the second end 14 of the scan abutment 10 terminate in pointed ends, provided that the planes 18a, 18f and 18c, 18d are in contact respectively. The benefits resulting from using such a scan abutment with pointed ends are most highly appreciated in scenarios where multiple scanning bodies are placed in a patient's mouth (e.g., when scanning a full arch or a partial arch). In a preferred scanning procedure, the scan abutments 10 are arranged adjacent to each other to obtain the most accurate scan images of the desired scanning area. Placing the scan abutments very close to each other means that some of the sidewall surfaces may be obscured by the adjacent scan abutment if the ends of the scan abutment are, for example, curved, thus limiting the details available in the post - processing stage. Having relatively pointed ends reduces such a possibility of overlap when the scan abutments are very close to each other.

[0049] The elongate body 11 includes a bore 22 that extends between the upper surface 16 and the lower surface 17 adjacent to the first end 12. The bore 22 is configured to receive the proximal end of an implant (or an intermediate adapter) and to accept a prosthetic screw for fixing the scan abutment 10 to the implant. When the scan abutment 10 is attached to the implant, a cylindrical mounting portion 26 configured to cover and rest on the upper side of the implant extends vertically from the lower surface 17. In some embodiments, the implant or a suitably attached intermediate adapter may provide a male connection portion shaped to fit within the bore 22 such that the lower end of the mounting portion 26 rests on the lower surface of the plane of the implant or adapter. The male connection portion may be in the form of a cylindrical cap that allows a slip fit between the bore and the male connection portion.

[0050] The illustrated embodiment provides a screw connection between the scan abutment 10 and the implant, although other connection means between the implant and the scan abutment 10 are possible. For example, the scan abutment may include a female screw that can mate with a corresponding male screw of the implant bearing, or the bore 22 may connect to the proximal head of the implant in a snap - fit arrangement configuration.

[0051] The bore 22 can serve an additional function of receiving a display element that can convey additional information in the scanned image. In one embodiment, the display element is in the form of a plug (not shown) that fits within and covers the upper end of the bore 22. The display element can be used, for example, to indicate the direction in which the scanned image was taken. For example, when the scanned image is taken with a plurality of scan abutments from left to right, the display element can be placed on the left - most scan abutment and provide a display of the scan data indicating that the left - most scan abutment was scanned first.

[0052] Remembering the direction of the scan in this way can be particularly useful because, typically, when the scan head moves from the beginning to the end of the scan path, the information provided at the beginning of the path may be more accurate than that provided later in the path. This difference in accuracy results from errors that accumulate as the scan head moves from the beginning to the end of the scan path. The errors are minimized by using the vertical lengths of some markers and overlaying scans from left - to - right and right - to - left. This results in a combination of several scanned images that can be suitably collected and used to assist in weighting the acquired image data. However, as will be understood, the display element can be used in any other way that can convey suitable information to the end - user in the resulting scanned image.

[0053] In one embodiment, the scan abutment 10 includes a reference marker (not shown) that is attached to or integral with the elongate body 11. The reference marker is preferably in the form of a three-dimensional shape, such as a sphere, a prism, or the like. Since the reference marker has well-known dimensions and is in a well-known position / orientation with respect to the scan abutment 10, it provides additional 3D reference information that can be used in a post-processing step of aligning separate scan images, particularly for vertical alignment.

[0054] The scan abutment 10 can be provided to the operator as a kit 1000 (shown in FIG. 11) that combines elements of different dimensions that can be selected by the operator to fit the size and shape of the patient's mouth in order to provide the coverage amount required for the scanning procedure. In most cases, multiple scan abutments 10 are used to span the space between multiple implants inserted into the patient's mouth, and each scan abutment 10 is attached to a separate implant. As can be understood, flexibility is increased by having scan abutments of different dimensions. For example, suitable dimensions for the scan abutment 10 can include an overall length ranging from about 10 mm to about 30 mm and an overall height (i.e., as viewed in an elevation drawing) ranging from about 3 mm to about 10 mm. However, since the scan abutment can be manufactured in any suitable size, these dimensions are merely exemplary.

[0055] The scan abutment 10 is generally fabricated from titanium grade 5. However, other suitable materials, such as alternative suitable metals or plastic materials, may be used.

[0056] The scan abutment 10 is generally designed with CAD / CAM software and then manufactured on a suitable 5-axis CNC machine. The precision of the manufactured scan abutment is important for the post-manufacture scanning procedure of each scan abutment, and a coordinate measuring machine (CMM) is used to precisely measure all of the relevant dimensions of the scan abutment. This information is stored in a database so that it can be called during the assignment step in the method, as will be described in detail below. Therefore, each individual kit may also include its own unique digital library, in which the precise measurements of each scan abutment 10 of the kit are stored. Therefore, the digital library for each kit of scan abutments is unique to that kit. A kit identifier (e.g., kit number) can be assigned to each kit and thus to each scan abutment within the kit. This ensures that the assignment step of the method described below accurately represents the scanned body and thus the precise position of the implant (as well as other scanned data points) in the patient's mouth.

[0057] An exemplary method of using the scan abutment 10 will now be described, particularly as part of a scanning procedure for a full arch of an edentulous patient. However, those skilled in the art will recognize that a similar method may be used when scanning a portion of a full arch. The exemplary method includes providing a plurality of implants in the patient's mouth that are screwed and fixed to the maxillary or mandibular bone in a conventional surgical procedure. The suitable number and positioning of the implants depend on the particular situation and the prosthesis required. Generally, it is considered that four implants are sufficient to support a finished prosthesis fixed within the maxilla with a high degree of predictability, but clinicians often implant six implants. In many cases, it may be desirable to implant the implants parallel to each other, but this is not often achieved due to surgical or structural limitations.

[0058] Subsequently, a plurality of scan abutments are provided and each is attached to the proximal head of the implant. This attachment is achieved by engaging the bore 22 of the scan abutment 10 to cover the upper side of the head of the implant, and attachment thereto by a prosthetic screw is accessed from the upper end of the bore. The scan abutment 10 is selected and positioned to substantially cover the entire area of the arch, and an exemplary implementation of this is shown in FIG. 6. The scan abutments need to be positioned in proximity to each other, but they do not need to be in contact, and it is considered preferable to have an overlapping transition from the midpoint of one abutment to the midpoint of the next abutment (when viewed in elevation - see FIG. 6). This minimizes and simplifies the stitching of the scanned data (and thus reduces the likelihood of errors occurring in the post - processing of the data), and ensures that two or more well - known surfaces (facets) belonging to adjacent scan abutments 10 are clearly visible in the scanner's field of view when moving between scan abutments.

[0059] As will be appreciated, the implementation shown in FIG. 6 is only an example of the positioning of the scan abutments. Care must be taken when positioning the scan abutments so that most and preferably all of the upper surfaces and side walls of the scan abutments are visible from above (and thus to the scanner head). Also, care must be taken to avoid significant gaps between adjacent scan abutments as these gaps can cause errors. Furthermore, a head - to - tail arrangement configuration of the scan abutments as shown in FIG. 6 is considered preferable in order to obtain maximum information and minimize error sources.

[0060] Once the scan abutment is placed in position, the operator begins the intraoral scanning procedure using a conventional intraoral scanner. The operator may first place a display element within the bore 22 of the selected scan abutment to provide an indication of which scan abutment was scanned first during the scanning procedure. The operator then begins scanning from one end of the arch to the other, preferably operating the scanner in an overall zigzag path as shown in FIG. 6. As will be appreciated, the operator only needs to operate the scanning head within a limited range of motion (as described above) and avoids any need for rotational movement of the scanning head. Preferably, the operator then scans the scan abutment along a direction opposite to the initial scan (i.e., from right to left) to generate a second data set. For improved accuracy, additional scans may be performed in both directions by the operator, so that multiple scan images may be used in the post-processing stage. Further, the operator takes a scan image of the same part of the patient's mouth with the implant in place but without a scan abutment to obtain all impression information regarding the soft tissue. This may be done before or after the scan abutment is placed in position. Further, scan images may be taken before the implant is placed in the mouth, although this is not considered essential due to the slight differences that may be created by the implant placement surgical procedure. Each set of scan data takes the form of an STL file containing raw point cloud data.

[0061] Thereafter, this scan data is transferred to post - processing. As part of the post - processing stage, the received STL file, which includes separate scan images of the arches together with the scan abutments, is compared to each other and aligned. An example of this process is shown in Figure 7, where computer software is used to align sets of scan data of various scan images to each other and to highlight the discrepancies between the respective scan images. For example, during this alignment stage, the discrepancy between each scan image exceeds 50 μm, and inaccurate scan images can be excluded from the alignment process. The alignment process provides means regarding how well each of the scan abutments aligns between separate scan images.

[0062] Each scan abutment can be properly aligned in each scan image using well - known major surfaces (top surface and side walls). Ideally, all seven facets of the scan abutment are used. However, if one or more of the major surfaces are determined to be inaccurate, they can be excluded from further processing. This can be due to something being unclear in the scan image in some way or inaccuracies that occurred in the scan image that prevented that surface from being aligned with the corresponding surface of another scan image. This becomes apparent when the surface of the scan abutment has a discrepancy (e.g., a deviation of the facet between scan images exceeding 10 microns) greater than an acceptable threshold with respect to other scan images. In such a situation, this surface or these surfaces can be excluded from consideration in the alignment stage, and in the averaging process between (non - rejected) information from different scan images, only the more accurately aligned surfaces are considered. In data processing, if there is a scaling error between one scan image and another, the actual marker measurements can be used to scale up or down again in order to be able to accurately compare the data sets.

[0063] Once the alignment process is completed to a satisfactory level, the scan abutment can be separated in software from the remaining part of the scanned element (soft tissue information), and the file of the averaged scan image here is saved for use in subsequent steps. The stored digital file of each scan abutment can here be accessed and used to assign the precise measurements of each scan abutment to the averaged scan image. The exact dimensions of each facet of the scanned body are assigned to the averaged scan image, and from this, the precise positioning and orientation of each implant relative to the precise shape of the soft tissue are determined. This information, in combination with a scan image taken without using the scanned body (showing all of the underlying soft tissue), enables the end user to digitally construct an implant framework for attachment to the implant by using the position and orientation of the implant as the corresponding attachment points of the implant framework. Further, the captured peripheral soft tissue data within the scanned body can be matched with the underlying soft tissue scan image to identify structures common to the two scan images. These identified common structures can then be used in operations such as aligning multiple scan images.

[0064] It will be appreciated that other information may be required to ultimately construct a dental prosthesis for a patient who previously had no dental prosthesis. The reader is directed to the applicant's previous application PCT / AU2020 / 050215 (the content of which is incorporated herein by reference) regarding information on obtaining an impression of the patient's mouth.

[0065] It will also be appreciated that a similar method can be used in situations where a new prosthesis is to be manufactured for a patient who has a pre-existing prosthesis and thus an implant is already inserted into the patient's mouth. It is relatively common for pre-existing prostheses to wear or become damaged over time, and there can be significant challenges in manufacturing a suitable replacement prosthesis for the patient. However, this process can be substantially simplified by the present invention.

[0066] In such a situation, several additional steps can be used with respect to the above-described methodology. In a first step, an in-situ scanning image of an existing prosthesis (e.g., the upper arch) is obtained. This is then followed by obtaining a scanning image of the opposing arch. Thus, a full occlusal scanning image can be obtained, which provides information regarding both the upper and lower arches. In the next step, any pre-existing prosthesis is removed. Once removed, the implant (or intermediate adapter) becomes visible here. Depending on the space between the existing implants, a scan abutment 10 of a suitable dimension (for the purposes described above) is selected and fixed to the implant. In a manner similar to that described above, the scan abutment 10 is scanned and, with the scan abutment 10 removed, a further scanning image of the underlying tissue is taken.

[0067] In this example, considering that a pre-existing prosthesis is already present, the information provided by the existing prosthesis can simplify the post-processing and tooth design stages. Therefore, the method includes obtaining a 360° scanning image of the existing prosthesis outside the mouth. To assist in aligning the scanning images during post-processing, a cylindrical cap 50 of a well-known dimension (included in the kit, as shown in FIG. 11) can be attached to a fixing construct on the existing prosthesis before taking the scanning image. These caps 50 effectively simulate the precise location of the implant (or intermediate adapter) and thus provide a geometric shape of a well-known dimension that is fully visible in the scanning image. This scanning image can be used together with the obtained scanning image of the scan abutment to generate an accurate model of the location of the implant in the patient's mouth. In combination with the scanning image of the patient's tissue, an accurate representation of the entire patient's mouth is provided to enable the design of a new dental prosthesis, such as the prosthesis described in the applicant's previous application PCT / AU2019 / 051222, the content of which is incorporated herein by reference.

[0068] As described above, the cap 50 can be provided as part of the kit 1000 together with the scan abutment 10.

[0069] Referring now to FIGS. 8 - 10, which show a slightly modified form of the scan abutment 100. Since the scan abutment 100 includes some features common to the scan abutment 10, these features will not be described in detail again. The common features between the scan abutment 10 and the scan abutment 100 are provided with reference numerals in the 100 series when referring to the scan abutment 100.

[0070] In addition to the features described with reference to the scan abutment 10, the scan abutment 100 includes a partially cylindrical cutout portion 130 provided in opposing side walls adjacent to the bore 122. In the illustrated example, as shown in FIG. 9, two cutout portions 130 are provided, one in side wall 118e and one in side wall 118b. As best seen in the drawings, the cutout portion 130 allows the outer surface 132 of the attachment portion 126 around the concentric bore 122 to be directly visualized when viewed from above. Since the attachment portion 126 is seated on the implant when the scan abutment 100 can be attached to the implant (aligned with the longitudinal centerline of the implant), visual access to the surface 132 allows the scanner to acquire additional data along the longitudinal axis of the implant. This additional information can assist in correcting any vertical misalignment that might otherwise occur in the scanned image during post - processing, and can also provide further information about the location of the implant relative to the underlying tissue.

[0071] In this regard, the outer surface 132 of the attachment portion 126 serves the function of a smooth transition path between the observable surface of the scan abutment 100 and the scanned data representing the surface features of the underlying tissue. This can be achieved without the need to tilt the scanner head in a direction perpendicular to the longitudinal axis of the implant in order to view the surface of the attachment portion 126. The risk associated with conventional post - processing software, where adjacent scan information at the transition from the scan abutment 100 to the underlying tissue is either physically separated or, if not, mutually conflicting scan data is treated as noise and automatically deleted from the data set, can be significantly reduced.

[0072] The notch portion 130 can be formed by a milling step initiated during the manufacture of the scan abutment 100. Alternatively, the notch portion 130 can be formed by other manufacturing methods such as being provided as a recessed portion in the casting of the scan abutment.

[0073] The scan abutment 100 further includes identifier markings shown as a pair of circular depressions 140 formed on opposite sides of the bore 122 of the upper surface 116. The identifier markings are intended to be visible in the resulting scan image and provide dimensional and tolerance information regarding a given scan abutment 100. These markings are useful during the assignment step of the method described above to indicate which scan abutment(s) (from a plurality of scan abutments) were used.

[0074] It will be understood that the invention, as disclosed and defined herein, extends to all alternative combinations of two or more of the individual features described or apparent from the text or drawings. All of these different combinations constitute various alternative aspects of the invention.

Claims

**Claim 1** An apparatus for facilitating the acquisition of a scanned image during an intraoral scanning procedure using an intraoral scanner, comprising: a long body having a first end and a second end, and having an attachment portion configured to attach the long body to an implant or an intermediate component in a patient's mouth, the implant having a longitudinal axis, whereby the long body, when attached to the implant or the intermediate component, extends along a longitudinal centerline that extends substantially perpendicular to the longitudinal axis of the implant or the intermediate component; the long body defining a long polygon having a substantially planar upper surface and a substantially planar lower surface, each of the upper surface and the lower surface having two long sides that extend substantially parallel to each other, and a plurality of side walls that extend downward from the upper surface and are tapered inwardly from the lower surface toward the upper surface; at least one of the first end and the second end of the long body having a generally pointed end shape defined by a pair of contacting side walls, the pair of side walls forming an acute angle therebetween; the plurality of side walls being inclined at an angle of about 15° to about 40° from a direction perpendicular to the upper surface; the upper surface and all of the plurality of side walls being such that, when the intraoral scanner scans the apparatus in a direction substantially perpendicular to the upper surface to provide complete 3D reference information, the long body, including the upper surface, can be observed from above in the resulting scanned image. **Claim 2** The apparatus according to claim 1, wherein the plurality of side walls surround all of the periphery of the upper surface. **Claim 3** The apparatus according to claim 1 or 2, wherein each of the plurality of side walls is substantially planar. **Claim 4** The apparatus according to any one of claims 1 to 3, further comprising the plurality of side walls defining a plurality of interconnected facets, each facet being observable by the intraoral scanner when scanning in a direction substantially perpendicular to and upward from the upper surface. **Claim 5** The apparatus according to any one of claims 1 to 4, further comprising a reference marker mounted on or integral with the upper surface. **Claim 6** The apparatus according to any one of claims 1 to 5, wherein the attachment portion is configured to receive a fastening element for fixedly attaching the long body to the implant. **Claim 7** The apparatus according to any one of claims 1 to 6, wherein the upper surface of the elongated body includes an aperture or a recess configured to receive a display element that is distinguishable in the resulting scanned image.

8. The apparatus according to any one of claims 1 to 7, wherein one or more side walls adjacent to the attachment portion include at least one notch configured such that the intraoral scanner can retrieve data to assist in defining the longitudinal axis of the implant.

9. The apparatus according to claim 8, wherein the notch extends towards the attachment portion, thereby enabling visualization of the surface of the attachment portion below the elongated body.

10. The apparatus according to any one of claims 1 to 9, wherein one or more of the upper surface and the side walls include an identifier, thereby enabling identification of the apparatus in the resulting scanned image.

11. The apparatus according to claim 10, wherein the identifier indicates one or more of the height, length, width or dimensional tolerances of the apparatus.

12. A kit comprising a plurality of the apparatuses according to any one of claims 1 to 11, the plurality of apparatuses including apparatuses of different dimensions, the plurality of apparatuses being selectable for use in a particular patient's mouth according to the area of the patient's mouth to be scanned and / or according to the relative positions of one or more existing implants and / or one or more intermediate components.

13. The kit according to claim 12, wherein the different dimensions include different lengths, widths and / or different heights.

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