Patent Application
20160213442
The present disclosure relates to a reference body for intraoral scan procedures.
In order to plan prosthetic components of a patient's dentition, virtual three-dimensional models are frequently used. Such models are obtained e.g. by scanning the dentition in situ, i.e. intraorally, using optical scanners. An intraoral scan of the patient's dentition has the advantage that it is not necessary to create a physical model of the dentition based on dental imprints which in turn is scanned by a conventional dental scanner. Hence, intraoral scanning is more cost-effective and yields results faster than conventional techniques.
During an optical intraoral scan process, a rather small optical scanner is moved along a patient's dentition. Images of adjacent portions of the dentition are “stitched” together by a suitable software. The combined image of the dentition can be used to calculate a three-dimensional model of the dentition or selected parts of it. Although this approach yields reliable results in most cases, the position and/or orientation of implants which are almost completely hidden in the bone and/or the gingiva of the patient cannot be detected unambiguously. In other words, the position and/or orientation of implants cannot be determined with the required precision by intraoral scanning. This information, however, is crucial to select a suitable prosthesis to be placed on the implant.
To indicate the position and/or orientation of the implant, a reference body can be provided. Such a reference body is adapted to be releasably mountable to the dental implant during the scan procedure. During scanning, images of the reference body are acquired. From these images, the three-dimensional geometry of the reference body can be derived. Since said geometry is known, an information regarding the spatial orientation of the reference body can be determined that in turn unambiguously indicates the spatial position and/or orientation of the implant. The corresponding data can then be included in the three-dimensional data set representing the patient's dentition allowing to choose the best prosthetic component to be mounted on the implant.
Although the use of a reference body during intraoral scanning is in principle known, there is still a need for reference bodies that are simple to produce and that can be easily mounted to the implant. Moreover, the reference body should be designed such, that its geometry and/or spatial orientation can be detected reliably with minimized computational efforts.
The reference body according to the present disclosure comprises a cylindrical body portion extending along a longitudinal axis from an apical end to a coronal end, the apical end facing, in particular abutting, the dental implant in a mounted state of the reference body. Further, a coronal end surface is provided defining the coronal end of the reference body. A first radial protrusion protrudes from the body portion in a first radial direction and a second radial protrusion protrudes from the body portion in a second radial direction. The first radial protrusion and the second radial protrusion have different cross-sectional shapes in a cross-section perpendicular to the longitudinal axis of the reference body.
In other words, the cylindrical body can be positioned—directly or indirectly—on the dental implant during the intraoral scan. In particular, suitable mechanisms and/or features are provided that ensure that the reference body and the implant are positioned in an unambiguous manner relative to each other. A well-defined relative positioning can e.g. be achieved by providing the components of the reference body and of the implant that serve for coupling them with complementary geometrical features.
It should be noted in this context that the term “cylindrical” should be understood in the broad sense. A cylindrical body may e.g. have a cross-section which is elliptical or polygonal. Thus, a right circular cylinder is only one example of a cylindrical body in the sense of the present disclosure.
It should generally by noted that, in the context of this disclosure, although somewhat simplifying, anatomical directions/orientations are used as follows:
“Apical” shall mean pointing towards the jawbone or gingiva.
“Coronal” shall mean towards the free end of the teeth of the dentition, i.e. a coronal side is opposite the apical side.
“Lingual” shall mean towards the “inner side” or the “center” of the dental arch, and shall be used in connection with the lower jaw and the upper jaw.
“Buccal” shall generally mean towards the outer side of the dental arch.
The different cross-sectional shapes of the first and second radial protrusions allow to determine the spatial orientation and/or position of the reference body and to simplify the “stitching” procedure to combine images of adjacent regions of the reference body. This aspect is of special importance since the individual digital images acquired during intraoral scanning usually cover only a certain part of the reference body. Moreover, with a hand-held scanner the exact spatial orientation of the scanner during the acquisition of the individual images is per se unknown. This means that said images have to be combined to yield a picture of the reference body as a whole. The first and second radial protrusions and their differing design simplify the process of combining the images as they provide a well-define reference orientation and position with respect to each other.
In an embodiment of the reference body according to the present disclosure, a surface of the first radial protrusion and/or a surface of the second radial protrusion comprise at least two planar segments, in particular wherein transitional portions between said planar segments are rounded. Planar segments are relatively easy to manufacture and can be readily sterilized. Providing rounded transitional portions avoids edges that are difficult to clean and/or that might injure the patient's gingiva.
In a further embodiment of the reference body according to the present disclosure, the cross-sectional shape of the first radial protrusion is wedge-shaped. Alternatively or additionally, the cross-sectional shape of the second radial protrusion is trapezoidal.
In another embodiment of the reference body according to the present disclosure, the extension of the first radial protrusion and/or the second radial protrusion in a longitudinal direction is more than 50% of the extension of the body portion in said longitudinal direction, in particular more than 50% of the extension of the reference body in said direction. The extension of one of the first and second radial protrusions in a longitudinal direction may be different, in particular the extension of the first radial protrusion in the longitudinal direction may be smaller than the extension of the second radial protrusion in said longitudinal direction. Different longitudinal extensions of the protrusions further simplify the identification of the orientation and/or the spatial position of the reference body. In particular, the extension of the first radial protrusion in the longitudinal direction is smaller than the extension of the second radial protrusion in said longitudinal direction.
In an embodiment of the reference body according to the present disclosure, transitional portions between a surface of the body portion, a surface of the first radial protrusion, a surface of the second radial protrusion and/or the coronal end surface are rounded.
In yet another embodiment of the reference body according to the present disclosure, the reference body comprises a coronal cap position disposed on the coronal end of the body portion and the coronal end surface is disposed on the coronal cap portion. The coronal cap portion may resemble at least partially a conical or a hemispherical shape, in particular a frusto-conical or frusto-hemispherical shape. A frusto-conical shape or a frusto-hemispherical shape are in this context conical or hemispherical bodies cropped e.g. by a plane. In other words, a frusto-conical shape is to be understood as a surface, e.g. a planar surface which is disposed in particular perpendicular to the longitudinal axis, with a conical transitional surface extending from the circumference of the cylindrical body portion to said surface. A frusto-hemispherical shape is to be understood as a surface, e.g. a planar surface which is disposed in particular perpendicular to the longitudinal axis, with a transitional surface resembling a segment of a hemisphere extending from the circumference of the cylindrical body portion to said surface. Any other rounded transition between said surface and the cylindrical body portion is conceivable.
The coronal cap portion may comprise a planar coronal surface. In particular said planar surface is disposed in a plane perpendicular to the longitudinal axis of the reference body.
In an embodiment of the reference body according to the present disclosure, the reference body comprises a bore that extends from the coronal end surface into the reference body. In particular said bore extends through the reference body. The bore may in particular be coaxial with the longitudinal axis and/or centric with respect to the body portion of the reference body.
In yet another embodiment of the reference body according to the present disclosure, the body portion comprises a cavity having an opening in an apical surface of the apical end, wherein the cavity is adapted to receive a fastening component to mount the reference body to the implant. E.g. the fastening component is a protrusion projecting from the implant and having a geometry that allows to reliably mount the reference body in an unambiguous orientation to the implant. The apical interface formed by the cavity may be specific to a given implant type.
The coronal end surface may comprise a rim surrounding the bore, e.g. to indicate a specific property of the implant and/or the reference body, e.g. the implant type with which the reference body is intended to be used.
In an embodiment of the reference body according to the present disclosure, the bore comprises a step portion having an enlarged diameter at a coronal end portion of the bore. Said step portion may indicate certain properties of the implant and/or the reference body, e.g. its size.
The bore and the cavity may be connected forming a passage from the coronal end surface to the apical end of the body portion. Said passage may e.g. be provided to allow introducing a fastener, such as a screw, to mount the reference body reliably to the implant.
In an embodiment of the reference body according to the present disclosure, the body portion comprises a segment that is in a circumferential direction free of protrusions, in particular wherein said segment is formed on the apical end of the body portion. Said segment is disposed in or close to the apical end of the body portion. Especially in cases where the reference body has to be mounted to a relatively deep seating implant, such an embodiment facilitates the mounting procedure.
In particular, the first radial protrusion may be disposed on the lingual side in a mounted state of the reference body. The second radial protrusion may be disposed on the buccal side in a mounted state of the reference body.
The features and embodiments described above may be readily combined with each other.
More areas for applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples are intended for the purpose of illustration only and are not intended to limit the scope of the invention in any way. The Figures are simplified and schematic. Details not necessary for the understanding for the invention are omitted.
The present disclosure will be explained in more detail and become fully understood from the detailed description and the accompanying drawings.
Reference body 10 comprises a body portion 16 which is in essence cylindrical. Although body portion 16 has a right circular cylindrical shape, reference bodies with different cross-sectional shapes are also conceivable. The coronal end 12 of body portion 16 is provided with a coronal end surface 18 of frusto-hemispherical shape. Said frusto-hemispherical shape is obtained by cropping a hemisphere by a plane which is in the present case disposed perpendicular to a longitudinal axis 20 of reference body. Thus, coronal end surface 18 comprises a planar coronal surface 22. Planar coronal surface 22 can have other angles than 90° relative to longitudinal axis 20 in other embodiments of the reference body according to the present disclosure.
Body portion 16 is provided with a first radial protrusion 24 and a second radial protrusion 26 which both protrude from the surface of body portion 16 in a radial direction.
Second radial protrusion 26 is formed by planar surfaces 26a, 26b, 26d connected by transitional portions 26c, 26c′. Planar surfaces 26a, 26b and 26d also extend in essence parallel to longitudinal axis 20. Protrusion 26 is disposed on the opposite side of body portion 16 as protrusion 24. Exemplarily, in a mounted state of reference body 10, the second radial protrusion 26 indicates the buccal side of reference body 10 and first radial protrusion 24 indicates the lingual side.
It can be seen from
The different cross-sectional shapes of protrusions 24, 26 allow to identify unambiguously the position and/or orientation of the reference body and thus of the implant to which it is connected. Further, the geometry of the reference body 10 provides enough characteristic features to facilitate a reliable combination of overlapping partial images of reference body 10 which have to be “stitched” together it to provide an image of reference body 10 as a whole.
As it can be seen from
Contrary to reference body 10, reference body 10′ is provided with a apical segment 34 which is not provided with protrusions. In particular, protrusions 24, 26 do not extend over segment 34 which is therefore easier to insert into the gingiva of the patient.
In order to be able to distinguish between reference body 10 and reference body 10′ —especially in cases when apical segment 34 is positioned almost entirely in the gingiva of the patient—an coronal end of bore 30 is provided with a stepped portion 36 having a slightly larger diameter than bore 30 itself (cf. e.g.
An alternative feature that allows distinguishing between different reference bodies is shown in connection with embodiment 10″ of the reference body according to the present disclosure. Said embodiment 10″ is shown in
It should be understood that stepped portion 36 and/or rim 38 can also be provided on reference body 10.
The description is mainly of exemplary nature and, thus, variations that do not depart from the gist of the disclosed teachings are intended to be within the scope of the disclosure.
| Number | Date | Country | Kind |
|---|---|---|---|
| 13182321.3 | Aug 2013 | EP | regional |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2014/050476 | 1/13/2014 | WO | 00 |
