WO2008131159A1

WO2008131159A1 - Dental restoration design using temporizations

Info

Publication number: WO2008131159A1
Application number: PCT/US2008/060725
Authority: WO
Inventors: Naimul Karim; Sumita B. Mitra; Philippe Rihon
Original assignee: 3M Innovative Properties Company
Priority date: 2007-04-20
Filing date: 2008-04-18
Publication date: 2008-10-30
Also published as: EP2142137A1

Abstract

A digital impression of an SMC-based dental temporary restoration provides a digital model for fabricating a high strength dental replacement article. An SMC temporization is used to design the fit and anatomy of a dental restoration. The SMC temporization is then scanned, providing data used as a basis designing a final dental restoration. The digital data may be used, either as such or after manipulation by a dental professional using a digital CAD/CAM process, to fabricate a high strength dental replacement article. The cured SMC temporization may be used as a temporary restoration while the final dental restoration is fabricated.

Description

DENTAL RESTORATION DESIGN USING TEMPORIZATIONS

CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of U.S. Provisional Application Serial No.

60/913037, filed April 20, 2007 and U.S. Provisional Application Serial No. 60/990665, filed November 28, 2007, which is incorporated herein by reference in its entirety.

BACKGROUND [0001] Self-supporting, Malleable, Curable ("SMC") materials have emerged as a useful substance for fabricating dental articles. While SMC materials advantageously offer a manually-workable medium that can be hardened to a sufficient strength for use as a dental article, other fabrication techniques and/or materials may be preferred for reasons such as cost, mechanical and structural properties, aesthetic properties, familiarity, or any combination of these.

[0002] There remains a need for systems and methods of fabricating dental articles that combine SMC materials and methods with other techniques.

SUMMARY [0003] A three-dimensional digital scan of an SMC-based dental temporary restoration provides a digital model for fabricating a high strength dental replacement article. An SMC temporization is used to design the fit and anatomy of a dental restoration. The SMC temporization is then scanned, providing data used as a basis for designing a final dental restoration. The digital data may be used, either as such or after manipulation by a dental professional using a digital CAD/CAM process, to fabricate a high strength dental replacement article. The cured SMC temporization may be used as a temporary restoration while the final dental restoration is fabricated.

[0004] In one aspect, a method disclosed herein includes scanning a prepared tooth surface; applying a self-supporting, malleable, curable (SMC) material to the prepared tooth surface; shaping the SMC material into a form of a final restoration; curing the SMC material; scanning the form to provide a digital three-dimensional representation; refining the digital three-dimensional representation in a computer environment to provide a final restoration form; and fabricating a final restoration from the final restoration form.

[0005] The method may include scanning a tooth prior to preparation of the tooth for a restoration to provide a pre-prep digital model; and applying the pre-prep digital model to refine the digital three-dimensional representation. The method may include scanning a dental environment including dentition surrounding the prepared tooth surface to provide an environmental digital model; and applying the environmental digital model to refine the digital three-dimensional representation. Fabricating the final restoration may include digitally machining the final restoration from the cured SMC material. Fabricating the final restoration may include digitally machining a coping for the final restoration from the cured SMC material. The method may include designing a coping from the digital three-dimensional representation in the computer environment. The method may include fabricating the coping from a second SMC material. The coping may be retained in an at least partially uncured state until the final restoration is affixed to the prepared tooth surface. The method may include designing a shell for the coping in the computer environment and fabricating the shell. The method may include assembling the shell and the coping into the final restoration. The method may include assembling the shell and the coping before curing the coping. The method may include partially curing the coping before affixing the revised final restoration form to the prepared tooth surface. [0006] The SMC material may include a resin system, a filler system, and an initiator system, wherein the SMC material exhibits sufficient malleability at a temperature of about 15⁰C to 38⁰C. The SMC material may include: a resin system comprising at least one ethylenically unsaturated component and a crystalline component; greater than 60 wt-% of a filler system; and an initiator system; wherein the SMC material exhibits sufficient malleability at a temperature of about 15⁰C to 38⁰C. The SMC material may include a polymerizable compound and an organogelator. The SMC material may include a polymerizable compound and a polymerizable organogelator.

[0007] In another aspect, a method disclosed herein includes applying a self- supporting, malleable, curable (SMC) material to a prepared tooth surface; shaping the SMC material into a form of a final restoration; scanning the final restoration form to provide a digital three-dimensional representation; and fabricating the final restoration from the digital three-dimensional representation. [0008] Fabricating may be performed by a dentist chairside. The method may include transmitting the digital three-dimensional representation to a remote dental laboratory. The method may include curing the SMC material on the prepared tooth surface to provide a temporary dental restoration. Fabricating the final restoration may include: refining the digital three-dimensional representation in a computer environment to provide a revised final restoration form; and fabricating the revised final restoration form. The method may include curing the SMC material before scanning the final restoration form. The method may include scanning the prepared tooth surface to provide a second digital three-dimensional representation; and fabricating the final restoration from a combination of the digital three-dimensional representation and the second digital three- dimensional representation. The method may include removing the SMC material from the prepared tooth surface and scanning an entire exterior surface of the final restoration form. The method may include curing the SMC material before scanning an entire exterior of the final restoration form. The SMC material may include a resin system, a filler system, and an initiator system, wherein the SMC material exhibits sufficient malleability at a temperature of about 15⁰C to 38⁰C. The SMC material may include: a resin system comprising at least one ethylenically unsaturated component and a crystalline component; greater than 60 wt-% of a filler system; and an initiator system; wherein the SMC material exhibits sufficient malleability at a temperature of about 15⁰C to 38⁰C. The SMC material may include a polymerizable compound and an organogelator. The SMC material may include a polymerizable compound and a polymerizable organogelator.

BRIEF DESCRIPTION OF DRAWINGS

[0009] The invention and the following detailed description of certain embodiments thereof may be understood by reference to the following figures.

[0010] Fig. 1 shows a three-dimensional scanning system.

[0011] Fig. 2 shows a dental restoration.

[0012] Fig. 3 shows a process for creating a temporization.

[0013] Fig. 4 shows a process for fabricating a crown.

DETAILED DESCRIPTION [0014] Described herein are systems and methods for fabricating a dental article using an SMC temporization and a three-dimensional scanning system. While the description emphasizes certain specific steps, materials, and types of dental articles, it will be understood that additional variations, adaptations, and combinations of the methods and systems below will be apparent to one of ordinary skill in the art, such as fabrication of dental restorations not specifically described, or use of three-dimensional scanning technologies not specifically identified, and all such variations, adaptations, and combinations are intended to fall within the scope of this disclosure. For example, while not specifically described below, it will be understood that the following techniques may be employed to fabricate components of a physical model used in the manual creation of a restoration or the like.

[0015] The following description should be read with reference to the drawings, in which like elements in different drawings are numbered in like fashion. The drawings, which are not necessarily to scale, depict selected illustrative embodiments and are not intended to limit the scope of the disclosure. Although examples of construction, dimensions, and materials are illustrated for the various elements, those skilled in the art will recognize that many of the examples provided have suitable alternatives.

[0016] Unless explicitly indicated or otherwise clear from the context, the following conventions are employed in the following disclosure, and are intended to describe the full scope of the inventive concepts herein. All numbers expressing feature sizes, amounts, and physical properties used in the specification and claims are to be understood as being modified by the term "about." Any numerical parameters set forth in this specification and attached claims are approximations that can vary depending upon the desired properties sought to be obtained by those skilled in the art utilizing the teachings disclosed herein. The recitation of numerical ranges by endpoints includes all numbers subsumed within that range (e.g. 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, and 5) and any range within that range.

[0017] As used in this specification and the appended claims, the singular forms "a", "an", and "the" encompass embodiments having plural referents, unless the content clearly dictates otherwise. As used in this specification and the appended claims, the term "or" is generally employed in its sense including "and/or" unless the content clearly dictates otherwise. In a list, the term "or" means one or all of the listed elements or a combination of any two or more of the listed elements.

[0018] When a group is present more than once in a formula described herein, each group is "independently" selected, whether specifically stated or not. For example, when more than one M group is present in a formula, each M group is independently selected.

[0019] The terms "three-dimensional surface representation", "digital surface representation", "three-dimensional surface map", and the like, as used herein, are intended to refer to any three-dimensional surface map of an object, such as a point cloud of surface data, a set of two-dimensional polygons, or any other data representing all or some of the surface of an object, as might be obtained through the capture and/or processing of three-dimensional scan data, unless a different meaning is explicitly provided or otherwise clear from the context. A "three-dimensional representation" may include any of the three-dimensional surface representations described above, as well as volumetric and other representations, unless a different meaning is explicitly provided or otherwise clear from the context.

[0020] Terms such as "digital dental model", "digital dental impression" and the like, are intended to refer to three-dimensional representations of dental objects that may be used in various aspects of acquisition, analysis, prescription, and manufacture, unless a different meaning is otherwise provided or clear from the context. Terms such as "dental model" or "dental impression" are intended to refer to a physical model, such as a cast, printed, or otherwise fabricated physical instance of a dental object. Unless specified, the term "model", when used alone, may refer to either or both of a physical model and a digital model. [0021] As used herein, the term "room temperature" refers to a temperature of

20° C to 25° C or 22° C to 25° C.

[0022] The term "comprises" and variations thereof do not have a limiting meaning where these terms appear in the description and claims.

[0023] The words "preferred" and "preferably" refer to embodiments of the invention that may afford certain benefits, under certain circumstances. However, other embodiments may also be preferred, under the same or other circumstances. Furthermore, the recitation of one or more preferred embodiments does not imply that other embodiments are not useful, and is not intended to exclude other embodiments from the scope of the invention.

[0024] The term "dental object", as used herein, is intended to refer broadly to subject matter specific to dentistry. This may include intraoral structures such as dentition, and more typically human dentition, such as individual teeth, quadrants, full arches, pairs of arches which may be separate or in occlusion of various types, soft tissue, and the like, as well as bones and any other supporting or surrounding structures. As used herein, the term "intraoral structures" refers to both natural structures within a mouth as described above and artificial structures such as any of the dental objects described below that might be present in the mouth. As used herein, the term dental article is intended to refer to a man-made dental object. Dental articles may include "restorations", which may be generally understood to include components that restore the structure or function of existing dentition, such as crowns, bridges, veneers, inlays, onlays, amalgams, composites, and various substructures such as copings and the like, as well as temporary restorations for use while a permanent restoration is being fabricated. Dental articles may also include a "prosthesis" that replaces dentition with removable or permanent structures, such as dentures, partial dentures, implants, retained dentures, and the like. Dental articles may also include "appliances" used to correct, align, or otherwise temporarily or permanently adjust dentition, such as removable orthodontic appliances, surgical stents, bruxism appliances, snore guards, indirect bracket placement appliances, and the like. Dental articles may also include "hardware" affixed to dentition for an extended period, such as implant fixtures, implant abutments, orthodontic brackets, and other orthodontic components. Dental articles may also include "interim components" of dental manufacture such as dental models (full or partial), wax-ups, investment molds, and the like, as well as trays, bases, dies, and other components employed in the fabrication of restorations, prostheses, and the like. Dental objects may also be categorized as natural dental objects such as the teeth, bone, and other intraoral structures described above or as artificial dental objects (i.e., dental articles) such as the restorations, prostheses, appliances, hardware, and interim components of dental manufacture as described above. A dental article may be fabricated intraorally, extraorally, or some combination of these.

[0025] The following description emphasizes the use of self-supporting, malleable, curable (SMC) materials, also referred to herein as "hardenable compositions." In general, an SMC material is self-supporting in the sense that the material has sufficient internal strength before curing to be formed into a desired shape that can be maintained for a period of time, such as to allow for transportation and storage. An SMC material is malleable in the sense that it is capable of being custom shaped and fitted under moderate force, such as a force that ranges from light finger pressure to that applied with manual operation of a small hand tool, such as a dental composite instrument. An SMC material is curable in the sense that it can be cured using light, heat, pressure or the like. For dental applications, the material may be both partially curable to improve rigidity during certain handling steps, and fully curable to a hardness suitable for use as a dental article. The forgoing characteristics are now discussed in greater detail.

[0026] The term "self-supporting" as used herein means that an article is dimensionally stable and will maintain its preformed shape without significant deformation at room temperature (i.e., about 2O⁰C to about 25⁰C) for at least two weeks when free-standing (i.e., without the support of packaging or a container). In many embodiments, the temporizations are dimensionally stable at room temperature for at least one month, or for at least six months. In some embodiments, the temporizations are dimensionally stable at temperatures above room temperature, or up to 4O⁰C, or up to 5O⁰C, or up to 6O⁰C. This definition applies in the absence of conditions that activate any initiator system and in the absence of an external force other than gravity. [0027] The terms "malleable" or having "sufficient malleability" as used herein in reference to SMC materials indicates that the material is capable of being custom- shaped and fitted onto a prepared tooth, or shaped into a suitable temporization, under a moderate manual force (i.e., a force that ranges from light finger pressure to that applied with manual operation of a small hand tool, such as a dental composite instrument). In many embodiments, the SMC materials may exhibit the desired sufficient malleability at temperatures of, e.g., 40 degrees Celsius or less. In other instances, the SMC materials may exhibit "sufficient malleability" in a temperature range of, e.g., 15⁰C to 38⁰C.

[0028] The terms "curable" or "hardenable" are used interchangeably herein to refer to materials that can be cured to lose their sufficient malleability. The hardenable (i.e., curable) materials may be irreversibly hardenable, which, as used herein, means that after hardening such that the composition loses its malleability it cannot be converted back into a malleable form without destroying the external shape of the resulting product. Examples of some potentially suitable hardenable compositions that may be used to construct the temporizations described herein with sufficient malleability may include, e.g., hardenable organic compositions (filled or unfilled), polymerizable dental waxes, hardenable dental compositions having a wax-like or clay-like consistency in the unhardened state, etc. In some embodiments, the temporizations are constructed of hardenable compositions that consist essentially of non-metallic materials.

[0029] Numerous SMC materials are described, for example in the following references, each of which is incorporated herein by reference: United States Patent Application No. 10/921,648 to Karim et al. entitled Hardenable Dental Article and Method of Manufacturing the Same, filed on August 19, 2004 and published on May 12, 2005 as U.S. Pub. No. 2005/0100868; United States Patent Application No. 10/749,306 to Karim et al. entitled Curable Dental Mill Blanks and Related Methods, filed on December 31, 2003 and published on July 7, 2005 as U.S. Pub. No. 2005/0147944; United States Patent Application No. 10/643,771 to Kvitrud et al. entitled Dental Crown Forms and Methods, filed on August 19, 2003 and published on February 24, 2005 as U.S. Pub. No. 2005/0042577; United States Patent Application No. 10/643,748 to Oxman et al. entitled Dental Article Forms and Methods, filed on August 19, 2003 and published on February 24, 2005 as U.S. Pub. No. 2005/0042576; United States Patent Application No. 10/219,398 to Karim et al. entitled Hardenable Self-Supporting Structures and Methods, filed on August 15, 2002 and published on June 19, 2003 as U.S. Pub. No. 2003/0114553; and International Patent Application No. US06/016197 to Karim et al. entitled Malleable Symmetric Dental Crowns. In addition, 3M™, of St. Paul, Minnesota, markets a shell temporization made of SMC material under the trade name PROTEMP™ Crown. More generally, any material having self-supporting, malleable, curable characteristics suitable for use in the temporizations described herein may be suitably employed.

[0030] The SMC materials as used herein may be provided to a dentist as a preformed shell-type temporization, or as a variety of shapes and sizes to fit various types and sizes of teeth. The SMC materials may also, or instead, be provided in a bulk form (not as a shell or other preformed article) the can be modeled by a dental professional into any desired shape and size of temporization. As used herein, the term "SMC temporizations" refers to a temporization made of an SMC material. It will be understood that, while the SMC materials described herein may usefully be employed in SMC temporizations, that one skilled in the art will appreciate how the methods and systems described herein may be adapted to other materials having similar properties. A number of potentially suitable SMC materials are now described in greater detail.

[0031] With respect to certain of the hardenable compositions described above, the unique combination of highly malleable properties (preferably without heating above room temperature or body temperature) before hardening (e.g., cure) and high strength (preferably, e.g., a flexural strength of at least about 25 MPa) after hardening may provide preformed temporizations with numerous potential advantages. For example, a preformed temporization that is sufficiently malleable can facilitate forming of a temporization shape before curing, or facilitate fitting of the temporization onto a prepared tooth surface during a fitting process. Because the compositions are hardenable, the adjusted external shape can also be retained permanently as desired. As described above, useful hardenable compositions for the SMC materials described herein may include e.g., polymerizable waxes, hardenable organic materials (filled or unfilled), etc. Some potentially suitable hardenable compositions may include those described in U.S. Pat. No. 5,403,188 to

Oxman et al.; U.S. Pat. No. 6,057,383 to Volkel et al.; and U.S. Pat. No. 6,799,969 to Sun et al. The entire content of these references in incorporated by reference herein.

[0032] The SMC materials described above may include a resin system that includes a crystalline component, greater than 60 percent by weight (wt-%) of a filler system (preferably, greater than 70 wt-% of a filler system), and an initiator system, wherein the hardenable composition exhibits sufficient malleability to be formed onto a prepared tooth, preferably at a temperature of about 15⁰C to 38⁰C (more preferably, about 2O⁰C to 38⁰C, which encompasses typical room temperatures and body temperatures). In some embodiments, the hardenable compositions do not need to be heated above body temperature (or even above room temperature) to become malleable as discussed herein. [0033] At least a portion of the filler system of a hardenable composition may include particulate filler. In this and various other embodiments, if the filler system includes fibers, the fibers may be present in an amount of less than 20 wt-%, based on the total weight of the composition. [0034] The crystalline component may provide a morphology that assists in maintaining the self-supporting first shape. This morphology includes a noncovalent structure, which may be a three-dimensional network (continuous or discontinuous) structure. If desired, the crystalline component can include one or more reactive groups to provide sites for polymerizing or crosslinking. If such crystalline components are not present or do not include reactive groups, or optionally where crystalline components are present and do include reactive groups, such reactive sites may be provided by another resin component, such as an ethylenically unsaturated component.

[0035] Thus, for certain embodiments, the resin system includes at least one ethylenically unsaturated component. Ethylenically unsaturated components can be selected from the group consisting of mono-, di-, or poly-acrylates and methacrylates, unsaturated amides, vinyl compounds (including vinyl oxy compounds), and combinations thereof. This ethylenically unsaturated component can be the crystalline component or noncrystalline.

[0036] The crystalline component can include polyesters, polyethers, polyolefms, polythioethers, polyarylalkylenes, polysilanes, polyamides, polyurethanes, or combinations thereof. The crystalline component can include saturated, linear, aliphatic polyester polyols containing primary hydroxyl end groups. The crystalline component can optionally have a dendritic, hyperbranched, or star-shaped structure, for example.

[0037] The crystalline component can optionally be a polymeric material (i.e., a material having two or more repeat units, thereby including oligomeric materials) having crystallizable pendant moieties and the following general formula:

-( CH₂ — CR )- [0038] X-(CH₂^_n-CH₃

[0039] wherein R is hydrogen or a (Ci-C₄) alkyl group, X is -CH₂-, -C(O)O-, -O-C(O)-, -C(O)-NH-, -HN-C(O)-, -O-, -NH-, -0-C(O)-NH-, -HN-C(O)-O-, - HN-C(O)-NH-, or -Si(CHs)₂-, m is the number of repeating units in the polymer (preferably, 2 or more), and n is great enough to provide sufficient side chain length and conformation to form polymers containing crystalline domains or regions.

[0040] Alternative to, or in combination with, the crystalline component, the hardenable composition can include a filler that is capable of providing a morphology to the composition that includes a noncovalent structure, which may be a three-dimensional network (continuous or discontinuous) structure, that assists in the maintenance of the first shape. In some embodiments, such a filler has nanoscopic particles, or the filler is an inorganic material having nanoscopic particles. To enhance the formation of the noncovalent structure, the inorganic material can include surface hydroxyl groups. In some embodiments, the inorganic material includes fumed silica.

[0041] In some embodiments, the composition includes, in addition to a resin system and an initiator system, either a crystalline component or a filler system that includes a particulate filler (e.g., a micron-size particulate filler, a nanoscopic particulate filler, a colloidal or fumed filler, a prepolymerized organic filler, or any combination of these), or both a crystalline component and a filler system. Furthermore, the use of one or more surfactants may also enhance the formation of such a noncovalent structure, and a surfactant system may optionally be employed. As used herein, a filler system includes one or more fillers and a surfactant system includes one or more surfactants.

[0042] Another potential embodiment may include a hardenable composition that includes a resin system, a filler system at least a portion of which is an inorganic material having nanoscopic particles with an average primary particle size of no greater than about 50 nanometers (nm), a surfactant system, and an initiator system. The hardenable composition can exhibit sufficient malleability to be formed onto a prepared tooth at a temperature of about 15⁰C to 38⁰C. In embodiments with a surfactant system and nanoscopic particles, the resin system can include at least one ethylenically unsaturated component, and the filler system is present in an amount of greater than 50 wt- %. [0043] In other embodiments, hardenable compositions may include a resin system that includes: a noncrystalline component selected from the group consisting of mono-, di-, or poly- acrylates and methacrylates, unsaturated amides, vinyl compounds, and combinations thereof; and a crystalline component selected from the group consisting of polyesters, polyethers, polyolefms, polythioethers, polyarylalkylenes, polysilanes, polyamides, polyurethanes, polymeric materials (including oligomeric materials) having crystallizable pendant moieties and the following general formula:

-( CH₂ — CR)-

[0044] X-(CH₂I_n-CH₃

[0045] wherein R is hydrogen or a (C₁-C₄) alkyl group, X is -CH₂-, -C(O)O-, -O-C(O)-, -C(O)-NH-, -HN-C(O)-, -O-, -NH-, or -0-C(O)-NH-, -HN-C(O)-O-, -HN-C(O)-NH-, or -Si(CHs)₂-, m is the number of repeating units in the polymer

(preferably, 2 or more), and n is great enough to provide sufficient side chain length and conformation to form polymers containing crystalline domains or regions, and combinations thereof. The hardenable composition may further include greater than about 60 wt-% of a filler system and an initiator system. The hardenable composition can exhibit sufficient malleability to be formed onto a prepared tooth at a temperature of about 15⁰C to 38⁰C. If the filler system includes fibers, the fibers may be present in an amount of less than 20 wt-%, based on the total weight of the hardenable composition.

[0046] In yet another embodiment, the hardenable compositions includes a resin system with a crystalline compound of the formula:

[0048] wherein each Q independently comprises polyester segments, polyamide segments, polyurethane segments, polyether segments, or combinations thereof; a filler system; and an initiator system.

[0049] The SMC material may include organogelators and polymerizable components that can be used in a variety of dental applications. [0050] In one embodiment, the SMC material includes a polymerizable component, an organogelator, and a crystalline material. In another embodiment, the SMC material includes a hardenable dental composition that includes a polymerizable component, an organogelator, and 60% or more filler material. In another embodiment, the SMC material includes a hardenable dental composition that includes a polymerizable component, an organogelator, and filler material comprising nanoscopic particles. In another embodiment, the SMC material includes a hardenable dental composition that includes a polymerizable component and a polymerizable organogelator.

[0051] In certain embodiments, the hardenable composition can be in the form of a hardenable, self-supporting (i.e., free-standing) structure having a first shape. The self- supporting structure has sufficient malleability to be reformed into a second shape, thereby providing for simplified customization of a device, e.g., simplified customized fitting of a dental prosthetic device. Once reformed into a second shape, the composition can be hardened using, for example, a free radical curing mechanism under standard photopolymerization conditions to form a hardened composition with improved mechanical properties. Significantly, for certain embodiments of the compositions described herein, the hardened structure does not need an additional veneering material.

[0052] In certain embodiments, the hardenable composition includes an organogelator of the general formula (Formula I):

[0054] I

[0055] wherein each M is independently hydrogen or a polymerizable group; each X is independently an alkylene group, cycloalkylene group, arylene group, arenylene group, or a combination thereof, and n is 1 to 3. Such organogelators are also provided by the present invention.

[0056] Herein, an "organogelator" is a generally low molecular weight organic compound (generally no greater than 3000 g/mol) that forms a three-dimensional network structure when dissolved in an organic fluid, thereby immobilizing the organic fluid and forming a non-flowable gel that exhibits a thermally reversible transition between the liquid state and the gel state when the temperature is varied above or below the gel point of the mixture.

[0057] Herein, the "polymerizable component" can include one or more resins, each of which can include one or more monomers, oligomers, or polymerizable polymers. [0058] Fig. 1 shows a three-dimensional scanning system that may be used with the systems and methods described herein. In general, the system 100 may include a scanner 102 that captures images from a surface 106 of a subject 104, such as a dental patient, and forwards the images to a computer 108, which may include a display 110 and one or more user input devices such as a mouse 112 or a keyboard 114. The scanner 102 may also include an input or output device 116 such as a control input (e.g., button, touchpad, thumbwheel, etc.) or a display (e.g., LCD or LED display) to provide status information.

[0059] The scanner 102 may include any camera or camera system suitable for capturing images from which a three-dimensional point cloud may be recovered. For example, the scanner 102 may employ a multi-aperture system as disclosed, for example, in United States Patent App. No. 11/530,420 to Rohaly et al. entitled Three-Channel Camera systems with CoHinear Apertures, filed on September 8, 2006 and published on August 16, 2007 as U.S. Pub. No. 2007/0188769, the entire content of which is incorporated herein by reference. While Rohaly discloses certain multi-aperture systems, it will be appreciated that any multi-aperture system suitable for reconstructing a three- dimensional point cloud from a number of two-dimensional images may similarly be employed. In one multi-aperture embodiment, the scanner 102 may include a plurality of apertures including a center aperture positioned along a center optical axis of a lens, along with any associated imaging hardware. The scanner 102 may also, or instead, include a stereoscopic, triscopic or other multi-camera or other configuration in which a number of cameras or optical paths are maintained in fixed relation to one another to obtain two- dimensional images of an object from a number of slightly different perspectives. The scanner 102 may include suitable processing for deriving a three-dimensional point cloud from an image set or a number of image sets, or each two-dimensional image set may be transmitted to an external processor such as contained in the computer 108 described below. In other embodiments, the scanner 102 may employ structured light, laser scanning, direct ranging, or any other technology suitable for acquiring three-dimensional data, or two-dimensional data that can be resolved into three-dimensional data.

[0060] In one embodiment, the scanner 102 is a handheld, freely positionable probe having at least one user input device 116, such as a button, lever, dial, thumb wheel, switch, or the like, for user control of the image capture system 100 such as starting and stopping scans. In an embodiment, the scanner 102 may be shaped and sized for dental scanning. More particularly, the scanner may be shaped and sized for intraoral scanning and data capture, such as by insertion into a mouth of an imaging subject and passing over an intraoral surface 106 at a suitable distance to acquire surface data from teeth, gums, and so forth. The scanner 102 may, through such a continuous acquisition process, capture a point cloud of surface data having sufficient spatial resolution and accuracy to prepare dental objects such as prosthetics, hardware, appliances, and the like therefrom, either directly or through a variety of intermediate processing steps. In other embodiments, surface data may be acquired from a dental model such as a dental prosthetic, to ensure proper fitting using a previous scan of corresponding dentition, such as a tooth surface prepared for the prosthetic. [0061] Although not shown in Fig. 1 , it will be appreciated that a number of supplemental lighting systems may be usefully employed during image capture. For example, environmental illumination may be enhanced with one or more spotlights illuminating the subject 104 to speed image acquisition and improve depth of field (or spatial resolution depth). The scanner 102 may also, or instead, include a strobe, flash, or other light source to supplement illumination of the subject 104 during image acquisition.

[0062] The subject 104 may be any object, collection of objects, portion of an object, or other subject matter. More particularly with respect to the dental fabrication techniques discussed herein, the object 104 may include human dentition captured intraorally from a dental patient's mouth. A scan may capture a three-dimensional representation of some or all of the dentition according to a particular purpose of the scan. Thus the scan may capture a digital model of a tooth, a quadrant of teeth, or a full collection of teeth including two opposing arches, as well as soft tissue or any other relevant intraoral structures. In other embodiments where, for example, a completed fabrication is being virtually test fit to a surface preparation, the scan may include a dental prosthesis such as an inlay, a crown, or any other dental prosthesis, dental hardware, dental appliance, or the like. The subject 104 may also, or instead, include a dental model, such as a plaster cast, wax-up, impression, or negative impression of a tooth, teeth, soft tissue, or some combination of these. [0063] The computer 108 may be, for example, a personal computer or other processing device. In one embodiment, the computer 108 includes a personal computer with a dual 2.8GHz Opteron central processing unit, 2 gigabytes of random access memory, a TYAN Thunder K8WE motherboard, and a 250 gigabyte, 10,000 rpm hard drive. This system may be operated to capture approximately 1,500 points per image set in real time using the techniques described herein, and store an aggregated point cloud of over one million points. As used herein, the term "real time" means generally with no observable latency between processing and display. In a video-based scanning system, real time more specifically refers to processing within the time between frames of video data, which may vary according to specific video technologies between about fifteen frames per second and about thirty frames per second. More generally, processing capabilities of the computer 108 may vary according to the size of the subject 104, the speed of image acquisition, and the desired spatial resolution of three-dimensional points. The computer 108 may also include peripheral devices such as a keyboard 114, display 110, and mouse 112 for user interaction with the camera system 100. The display 110 may be a touch screen display capable of receiving user input through direct, physical interaction with the display 110. [0064] Communications between the computer 108 and the scanner 102 may use any suitable communications link including, for example, a wired connection or a wireless connection based upon, for example, IEEE 802.11 (also known as wireless Ethernet), BlueTooth, or any other suitable wireless standard using, e.g., a radio frequency, infrared, or other wireless communication medium. In medical imaging or other sensitive applications, wireless image transmission from the scanner 102 to the computer 108 may be secured. The computer 108 may generate control signals to the scanner 102 which, in addition to image acquisition commands, may include conventional camera controls such as focus or zoom.

[0065] In an example of general operation of a three-dimensional image capture system 100, the scanner 102 may acquire two-dimensional image sets at a video rate while the scanner 102 is passed over a surface of the subject. The two-dimensional image sets may be forwarded to the computer 108 for derivation of three-dimensional point clouds. The three-dimensional data for each newly acquired two-dimensional image set may be derived and fitted or "stitched" to existing three-dimensional data using a number of different techniques. Such a system employs camera motion estimation to avoid the need for independent tracking of the position of the scanner 102. One useful example of such a technique is described in commonly-owned United States Patent App. No. 11/270,135 to Zhang et al. entitled Determining Camera Motion filed on November 8, 2005 and published on May 10, 2007 as U.S. Pub. No. 2007/0103460, the entire content of which is incorporated herein by reference. However, it will be appreciated that this example is not limiting, and that the principles described herein may be applied to a wide range of three- dimensional image capture systems.

[0066] The display 110 may include any display suitable for video or other rate rendering at a level of detail corresponding to the acquired data. Suitable displays include cathode ray tube displays, liquid crystal displays, light emitting diode displays and the like. In some embodiments, the display may include a touch screen interface using, for example capacitive, resistive, or surface acoustic wave (also referred to as dispersive signal) touch screen technologies, or any other suitable technology for sensing physical interaction with the display 110.

[0067] Fig. 2 shows a dental restoration that may be fabricated with the methods and systems described herein. In general, a restoration 200 includes a veneer 202 coupled to a coping 204 that is affixed by a cement layer 206 to a tooth stump 208. The coping

204 may be formed, for example, from zirconium or alumina. In practice, a dentist shapes the tooth stump 208 to receive the coping 204 using dental tools. The dental restoration 200 may form a partial tooth, a full tooth, or multiple teeth. More generally, the dental restoration 200 may include any of the dental articles described above. The exterior line where the tooth stump 208 meets the coping 204 is generally referred to as the margin 210. In the dental restoration 200, a first surface 212 is formed by an exterior surface of the veneer 202. The first surface 212 provides an exterior surface to the dental restoration 200 generally, and may be formed of a material having functional or aesthetic properties selected to substantially match the dentition that is being replaced by the dental restoration 200. A second surface 214 is formed where the veneer 202 meets the coping 204. A third surface 216 is formed where the coping 204 meets the cement 206. And a fourth surface 218 is formed by an exterior surface of the tooth stump 208.

[0068] Fig. 3 shows a process for creating a temporization, also referred to herein as a temporary restoration. [0069] The process 300 may begin with a dentist preparing a tooth stump as shown in step 302. This step may involve any suitable techniques including use of conventional grinding tools and relatively standard target shapes for the tooth stump. [0070] As shown in step 304, once the tooth stump has been prepared for a temporization, a three-dimensional scan of the prepared tooth surface may be captured using, for example, the scanning system described above with reference to Fig. 1.

[0071] As shown in step 306, a temporization may be provided. This may include, for example, selecting and applying a pre-formed temporization shell or combination of shells to the tooth stump. Or this may include providing an unformed mass of SMC material or the like, and manually fashioning the unformed mass into a temporization, either before or after applying the material to the tooth stump, or some combination of these. [0072] As shown in step 308, the temporization may then be customized using any suitable techniques. This may include, for example adjusting the size of the temporization, shaping the temporization using a finger or tools, or cutting away or otherwise removing material from the temporization. This step may proceed in multiple sub-steps. For example, a gross customization may be performed by a dentist before seating the temporization on a prepared tooth stump. After a gross customization, the dentist may proceed with fine customization including shaping the temporization to conform to adjacent teeth and/or adjusting occlusal fit and the like to more closely conform the temporization to a patient's natural (or improved) dental context. Other adjustments may include trimming the temporization to follow a gingival contour in situ, or adjusting the outer shape of the buccal or lingual surfaces. It will be understood that customization may be performed inside a dental patient's mouth with the temporization seated, or outside the dental patient's mouth, or some combination of these.

[0073] Once a satisfactory fit has been achieved for the temporization, the process 300 may proceed to step 310 where the temporization is cured. This may include, for example, an application of heat, pressure, electromagnetic radiation (e.g., ultraviolet light or visible light) or any other curing techniques suitable for the temporization materials. This may also include various cycles of any of the above, or combinations thereof, as appropriate to the particular SMC materials or other materials used. It will be understood that multiple curing and shaping steps may also be employed to take advantage of increasing degrees of hardness that result for various states of cure. Thus for example, interim curing and shaping steps may be employed to preserve gross shape while making fine adjustments with greater application of pressure, or with a grinding tool or the like. [0074] As shown in step 312, the temporization may then be finished and polished in advance of final fitting. In certain embodiments, finishing may include seating the temporization to obtain an accurate fit with the tooth stump and adjacent teeth, and then curing the temporization to a final hardness. Finishing may also include milling or otherwise customizing the shape of the temporization before seating for use by the patient. [0075] As shown in step 314, the temporization may be scanned. This may include scanning while the temporization is seated in a patient's mouth, or scanning with the temporization removed from the patient's mouth, or some combination of these. The acquired data may be employed to fabricate a final restoration as discussed below in greater detail with reference to Fig. 4.

[0076] As shown in step 316, the temporization may then be seated on a tooth stump in a patient's mouth. Seating and final fitting of the temporization may involve, for example, adding cement to the temporization (in the void that will receive the tooth stump) and placing the temporization into the dental infrastructure of the patient. Once the cement has cured, either through passage of time or application of any of the curing agents described above, the patient may enjoy the esthetic and functional benefits of a temporary tooth while a more durable replacement is being made. [0077] In various embodiments, the temporization may be used in fabricating a final restoration. For example, with certain SMC materials, the temporization may itself be cured to a hardness suitable for use as a permanent restoration, and this permanent restoration may be digitally milled or otherwise shaped using the techniques for fabricating a final restoration as described above. In other embodiments, the temporization may be milled to provide a coping for a final restoration or a mold for a coping, which can advantageously use the tooth stump shape directly impressioned from the tooth stump by the temporization material.

[0078] It will be understood that a number of variations are possible to the method described above. For example, for design of the final restoration, interior and exterior surfaces may be obtained from a full scan of the temporization after it has been fully customized and finished, or the interior and exterior surfaces may be obtained from the prepared tooth stump and the temporization respectively. As a significant advantage, this latter approach permits scanning of primarily convex surfaces, and avoids the need for a three-dimensional scanning system capable of accurately capturing surface data from within deep concavities. As another example, the method may include a scan of dentition before a tooth stump has been prepared for a restoration - the so-called pre-prep surface. This surface data of the original dental anatomy may assist a designer in refining the shape of a final restoration created from the scan data. All such variations as would be apparent to one of ordinary skill in the art may be used with the systems and methods described herein.

[0079] Fig. 4 shows a process for fabricating a crown according to the methods and systems disclosed herein. [0080] The process may begin by receiving surface data for a crown as shown in step 402. This may include, for example, scans of a prepared tooth surface and/or a temporization as generally described above with reference to Fig. 3. This may also include environmental data such as surface data for surrounding dentition including neighboring teeth, opposing teeth, and more generally full arch data for a patient's dentition.

[0081] However acquired, the surface data may be manipulated within a computer environment to design a coping and veneer for a crown as shown in step 404. This design step may include accounting for a cementation void between a coping and a tooth stump to provide space for cement when the crown is seated in a patient's mouth. The coping and veneer may be designed using any suitable design software. This may include any number of steps typically performed with a physical dental model, such as determining bite registration and checking occlusal surfaces of the crown. This may also include selecting color, shade, and the like for the veneer that is to be added to the coping, and determining an appropriate thickness for the veneer. In general, a digital model for fabricating a crown may be created that provides spatial information and the like for the coping and veneer.

[0082] The design step may include providing surface data or the like to a digital design program. The digital design program may start with the surface defined by the tooth stump and the exterior of the temporization. The exterior of the temporization may be presumptively assigned to the veneer exterior of the crown, identified as the first surface 212 in Fig. 2. The program may then determine a suitable thickness for the veneer and thus establish an exterior surface of a coping, identified as the second surface 214 in Fig. 2. The program may also automatically determine a suitable cementation void (or this may be provided by a program operator) and use this thickness to determine the interior surface of the coping, identified as the third surface 216. This last step may include adding the cementation void to the surface of the tooth stump, or the fourth surface 218 of Fig. 2. In one aspect, the digital design program may display these surfaces and presumptive assignments in a three dimensional format to a user. The user may then manipulate surfaces of the various layers of the dental restoration as appropriate, and make any other spatial adjustments to finalize the digital coping and veneer models. [0083] Once the design is finalized, data sets that define the outer and inner surfaces of the veneer and the outer and inner surfaces of the coping may be used to manufacture the veneer and coping as shown in step 406. Manufacture of the veneer and coping may be done "chairside," or in close proximity to the dental professional using on- site milling technologies. Alternatively, the finalized data set may be sent to a remote location such as a dental laboratory for manufacturing.

[0084] As shown in step 408, once the coping and veneer are complete, they may be assembled into a crown. While a conventional veneer may be employed, it will be understood that other exterior materials may be suitably employed with the systems and methods described herein. For example, a shell of SMC material or the like may be designed or fabricated using the techniques described herein and provided for assembly with the coping. This technique may advantageously provide an exterior layer with a degree of malleability to permit adjustments to manufacturing defects in the physical interface with the coping, as well as adjustments to the final shape before curing, which adjustments may be made by the dentist either before or after a restoration is seated.

[0085] As shown in step 410, the dentist may receive the crown and seat the crown on a tooth stump in the patient's mouth, removing the temporization if still present. This final step may include testing of the fit, any final shaping or other finishing, and cementing the crown to the tooth stump. [0086] It will be understood that the above process 400 is merely exemplary.

Any number of adaptations may be made, and steps may be added, removed, or varied consistent with the scope of this disclosure. By way of example and not limitation, surface data for the crown may be obtained using physical impressioning with a material such as wax or a polyvinyl siloxane or polyether impressioning material. As another example, certain dental fabrication techniques involve milling or otherwise forming a dental article from a monolithic material. The design steps described above may be suitably adapted to such materials. As another example, a coping may be fabricated from an SMC material, and the surface mating to the tooth stump may be left uncured or partially uncured so that the coping can be physically fitted to the tooth stump with an application of force and then cured to final shape and hardness. It will also be clear that while fabrication of a crown is shown in Fig. 4, other restorations and dental articles may be fabricated using the techniques disclosed herein. [0001] It will be appreciated that various aspects of the methods described above may be realized in hardware, software, or any combination of these suitable for the data acquisition and fabrication technologies described herein. This includes realization in one or more microprocessors, microcontrollers, embedded microcontrollers, programmable digital signal processors or other programmable devices, along with internal and/or external memory. The realization may also, or instead, include one or more application specific integrated circuits, programmable gate arrays, programmable array logic components, or any other device or devices that may be configured to process electronic signals. It will further be appreciated that a realization may include computer executable code created using a structured programming language such as C, an object oriented programming language such as C++, or any other high-level or low-level programming language (including assembly languages, hardware description languages, and database programming languages and technologies) that may be stored, compiled or interpreted to run on one of the above devices, as well as heterogeneous combinations of processors, processor architectures, or combinations of different hardware and software. At the same time, processing may be distributed across devices such as the scanning device, computerized design environment, and so forth in a number of ways or all of the functionality may be integrated into a dedicated, standalone device. All such permutations and combinations are intended to fall within the scope of the present disclosure. [0087] While the invention has been disclosed in connection with certain preferred embodiments, other embodiments will be recognized by those of ordinary skill in the art, and all such variations, modifications, and substitutions are intended to fall within the scope of this disclosure. Thus, the invention is to be understood with reference to the following claims, which are to be interpreted in the broadest sense allowable by law.

Claims

1. A method comprising: scanning a prepared tooth surface; applying a self-supporting, malleable, curable (SMC) material to the prepared tooth surface; shaping the SMC material into a form of a final restoration; curing the SMC material; scanning the form to provide a digital three-dimensional representation; refining the digital three-dimensional representation in a computer environment to provide a final restoration form; and fabricating a final restoration from the final restoration form.

2. The method of claim 1 further comprising: scanning a tooth prior to preparation of the tooth for a restoration to provide a pre- prep digital model; and applying the pre-prep digital model to refine the digital three-dimensional representation.

3. The method of claim 1 further comprising: scanning a dental environment including dentition surrounding the prepared tooth surface to provide an environmental digital model; and applying the environmental digital model to refine the digital three-dimensional representation.

4. The method of claim 1 wherein fabricating the final restoration includes digitally machining the final restoration from the cured SMC material.

5. The method of claim 1 wherein fabricating the final restoration includes digitally machining a coping for the final restoration from the cured SMC material.

6. The method of claim 1 further comprising designing a coping from the digital three-dimensional representation in the computer environment.

7. The method of claim 6 further comprising fabricating the coping from a second SMC material.

8. The method of claim 7 wherein the coping is retained in an at least partially uncured state until the final restoration is affixed to the prepared tooth surface.

9. The method of claim 6 further comprising designing a shell for the coping in the computer environment and fabricating the shell.

10. The method of claim 9 further comprising assembling the shell and the coping into the final restoration.

11. The method of claim 10 further comprising assembling the shell and the coping before curing the coping.

12. The method of claim 10 further comprising partially curing the coping before affixing the revised final restoration form to the prepared tooth surface.

13. The method of claim 1 wherein the SMC material includes a resin system, a filler system, and an initiator system, wherein the SMC material exhibits sufficient malleability at a temperature of about 15⁰C to 38⁰C.

14. The method of claim 13 wherein the SMC material includes: a resin system comprising at least one ethylenically unsaturated component and a crystalline component; greater than 60 wt-% of a filler system; and an initiator system; wherein the SMC material exhibits sufficient malleability at a temperature of about 15⁰C to 38⁰C.

15. The method of claim 1 wherein the SMC material includes a polymerizable compound and an organogelator.

16. The method of claim 15 wherein the SMC material includes a polymerizable compound and a polymerizable organogelator.

17. A method comprising : applying a self-supporting, malleable, curable (SMC) material to a prepared tooth surface; shaping the SMC material into a form of a final restoration; scanning the final restoration form to provide a digital three-dimensional representation; and fabricating the final restoration from the digital three-dimensional representation.

18. The method of claim 17 wherein fabricating the final restoration is performed by a dentist chairside.

19. The method of claim 17 further comprising transmitting the digital three- dimensional representation to a remote dental laboratory.

20. The method of claim 17 further comprising curing the SMC material on the prepared tooth surface to provide a temporary dental restoration.

21. The method of claim 17 wherein fabricating the final restoration includes : refining the digital three-dimensional representation in a computer environment to provide a revised final restoration form; and fabricating the revised final restoration form.

22. The method of claim 21 further comprising curing the SMC material before scanning the final restoration form.

23. The method of claim 17 further comprising: scanning the prepared tooth surface to provide a second digital three-dimensional representation; and fabricating the final restoration from a combination of the digital three-dimensional representation and the second digital three-dimensional representation.

24. The method of claim 17 further comprising removing the SMC material from the prepared tooth surface and scanning an entire exterior surface of the final restoration form.

25. The method of claim 24 further comprising curing the SMC material before scanning an entire exterior of the final restoration form.

26. The method of claim 17 wherein the SMC material includes a resin system, a filler system, and an initiator system, wherein the SMC material exhibits sufficient malleability at a temperature of about 15⁰C to 38⁰C.

27. The method of claim 26 wherein the SMC material includes: a resin system comprising at least one ethylenically unsaturated component and a crystalline component; greater than 60 wt-% of a filler system; and an initiator system; wherein the SMC material exhibits sufficient malleability at a temperature of about 15⁰C to 38⁰C.

28. The method of claim 17 wherein the SMC material includes a polymerizable compound and an organogelator.

29. The method of claim 28 wherein the SMC material includes a polymerizable compound and a polymerizable organogelator.