Patent Description:
Prior prosthetic and orthodontic procedures typically involve preparing teeth for receiving prosthetics and for orthodontic movement. Preparation for these treatments may include material removal to shape the teeth to receive a prosthetic or material removal to provide space for orthodontic movement such as interproximal reduction. To achieve these objectives, a dental practitioner may use various tools to remove material when shaping the teeth. The dental practitioner may make an educated guess as to the appropriate tools to use, and when and how to use them.

Sometimes, these prior prosthetic and orthodontic methods and systems can result in less than ideal preparation and treatment, in at least some respects. In light of the above, improved prosthetic and orthodontic treatment planning, preparation, and treatment are needed. Ideally such prosthetic and orthodontic treatment planning, preparation, and treatment would provide more reliable and easier to follow treatment steps, more accurately prepared teeth, and greater dental practitioner confidence.

<CIT> relates to methods for evaluating the areas of contact, and near contact, between upper and lower teeth when the upper and lower arches are in a closed or occluded condition. It also provides methods of determining and displaying such occlusal contacts using a computer and three-dimensional virtual models of teeth.

The invention provides a computer program and a system for aiding in preparing a tooth of a patient as set out in the appended claims.

Other objects and features of the present invention will become apparent by a review of the specification, claims, and appended figures.

The novel features of the invention are set forth with particularity in the appended claims A better understanding of the features and advantages of the present invention will be obtained by reference to the following detailed description that sets forth illustrative embodiments, in which the principles of the invention are utilized, and the accompanying drawings of which:.

A better understanding of the features and advantages of the present disclosure will be obtained by reference to the following detailed description that sets forth illustrative embodiments, in which the principles of embodiments of the present disclosure are utilized, and the accompanying drawings.

Although the detailed description contains many specifics, these should not be construed as limiting the scope of the disclosure but merely as illustrating different examples and aspects of the present disclosure. It should be appreciated that the scope of the disclosure includes other embodiments not discussed in detail herein. Various other modifications, changes, and variations which will be apparent to those skilled in the art may be made in the arrangement, operation, and details of the methods, systems, and apparatus of the present disclosure provided herein without departing from the scope of the invention as described herein.

As used herein the term "and/or" is used as a functional word to indicate that two words or expressions are to be taken together or individually. For example, A and/or B encompasses A alone, B alone, and A and B together.

As used herein a "plurality of teeth" encompasses two or more teeth. In some embodiments, one or more posterior teeth comprises one or more of a molar, a premolar or a canine, and one or more anterior teeth comprising one or more of a central incisor, a lateral incisor, a cuspid, a first bicuspid or a second bicuspid.

The present disclosure provides systems and related methods for planning tooth preparation procedures and for carrying out tooth preparation procedures.

Turning now to the drawings, in which like numbers designate like elements in the various figures, <FIG> illustrates method <NUM> for preparing and treating teeth, in accordance with embodiments disclose herein. The method <NUM> for preparing and treating teeth includes tooth preparation and design at block <NUM>, development of a treatment plan at block <NUM>, and performance and feedback at block <NUM>. At block <NUM> a dental practitioner may make multiple records of the patient. The records may include various imaging records. For example, the dental practitioner may scan the patient's dentition with an intra-oral scanner to build a three-dimensional surface model of the patient's dentition. The dental practitioner may also compile other two-dimensional and three-dimensional images and models, such as, ultra sound, MRI, OCT, x-ray images and volumetric data from CBCT scans or transillumination scans, or volumetric models generated by the methods and systems described in <CIT>, among others. The practitioner may also select the teeth to be prepared and provide additional information, such as the type of prosthetic to be placed on the teeth. Also at block <NUM>, dental practitioner may identify tooth material that should be removed during patient treatment, such as dental caries. The dental practitioner may also indicate other treatment parameters such as the type, manufacture, and model of prosthetic to be used, and a preference for using particular types of procedures and tools.

At block <NUM> one or more treatment plans are prepared. Preparation of the treatment plans may include preparing multiple treatment suggestions showing the final preparation of the patient's teeth along with models of intermediate steps showing how the teeth are shaped from their initial shape to their final prepared shape. The dental professional may select a treatment plan from the multiple treatment suggestions.

After receiving a selection for a treatment plan, the material to be removed from the teeth is determined, and the tools for each step in the plan are selected. Finally, images including both static, two-dimensional images, manipulatable three-dimensional surface or volumetric models, and both static and manipulatable videos for each step and the treatment plan may be generated and displayed to the dental professional in order to aid the dental professional in carrying out treatment on the patient.

At block <NUM> the treatment as performed and feedback on the treatment is provided. In this process a dental professional begins removing material from the patient's teeth as indicated by the treatment plan. At any time during treatment, the dental professional may request feedback as to the progress being made. To request and receive feedback, the dental professional re-images the patient's dentition. The current physical state of the patient's dentition, as indicated by the re-imaging data, may be evaluated with reference to the treatment plan. The progress with respect to the treatment plan, and any deviations from the treatment plan, may be indicated to the dental professional. In some embodiments, the treatment plan may be revised according to the updated state of the patient's dentition and the dental professional may proceed with treatment according to the revised treatment plan. The process <NUM> is described in greater detail below.

One or more of the steps of the method <NUM> may be performed with circuitry as described herein, for example one or more of a processor or logic circuitry of a computer or a computerized system. The circuitry may be programmed to provide one or more of the steps of the method <NUM>, and the program may comprise program instructions stored on a computer readable memory or programmed steps of the logic circuitry, for example.

<FIG> illustrates a method of tooth preparation design <NUM>, in accordance with embodiments described herein. At block <NUM>, the method <NUM> includes imaging the patient's dentition, including the patient's teeth. At block <NUM>, the method <NUM> includes receiving and building of the constraints for the treatment plan. At block <NUM>, the method <NUM> identifies material to be removed from the tooth in order to prepare the tooth for, for example, receiving a prosthetic. At block <NUM> the method <NUM> finalizes the shape of the tooth. Although a single tooth is referenced above, and elsewhere herein, the treatment plan and the accompanying treatment may include the preparation and treatment of multiple teeth. For example, multiple teeth may be prepared to receive a bridge or multiple prosthetics or, for example, teeth adjacent to such teeth may be prepared in order to facilitate insertion of the prosthetic. In some embodiments, teeth are prepared to accommodate orthodontic treatment. In such an embodiment, interproximal reduction may be used to provide space in the arch for tooth movement and rotation. The interproximal reduction material removal and orthodontic movement may be considered in the method of tooth preparation design <NUM>.

A block <NUM>, multiple different imaging and model building processes may be performed. For example a volumetric three-dimensional model of the patient's dentition may be built as described in <CIT>. Two-dimensional images such as color surface images and x-ray images may be used in building the model. Color surface images may be used for color matching a prosthetic with the patient's natural teeth of for distinguishing between teeth and gingiva. Surface penetrating scans may be used to image the internal structure of the teeth. For example, X-ray images may be used to identify various internal structures of the teeth, such as the enamel and the dentin. X-ray images may also be used to identify dental caries and other defects within the teeth. Ultrasound imaging may be used to identify subsurface, internal features of the teeth. Other technologies such as infrared or near-infrared transillumination, small angle penetration imaging, or reflectance scanning may also be used to gather subsurface images of the internal features of the teeth and to aid in identifying the various internal structures within a patient's teeth.

Three-dimensional imaging or volumetric data such as from a CBCT scan or a three-dimensional surface scan of the teeth may be combined with the two-dimensional imaging data discussed above in order to build a volumetric three-dimensional, or composite, model of the patient's teeth.

<FIG> depict a two-dimensional cross-section <NUM> of a three-dimensional volumetric model of a patient's tooth <NUM>. As shown in <FIG>, an integrated volumetric model of the teeth may be formed from the combination of two-dimensional imaging data, such as X-rays and surface penetrating infrared imaging, with three-dimensional images allows for the presentation in display of both interior and exterior structures of the tooth. The innermost structures, for example the pulp <NUM> may be determined based on x-ray imaging. The location and volume of other interior structures of the tooth <NUM> may be determined based on a combination of x-ray imaging and surface penetrating infrared imaging. Such interior structures depict the extent and location of the enamel <NUM> and the dentin <NUM>. In addition to modeling the interior structures of the teeth, two-dimensional and three-dimensional imaging may be used to model other structures of the patient's mouth such as the gingiva to <NUM> and the bone <NUM>.

Surface penetrating infrared imaging and x-ray imaging produce two-dimensional images of the interior structure of the tooth, however, at block <NUM> the method <NUM> may combine the two-dimensional images of the interior of the tooth with generic or other, non-patient specific, models of the interior structure of a teeth to generate a three-dimensional volumetric model of the patient's tooth.

<FIG> shows a detailed portion of the enamel <NUM> of the tooth <NUM>, including a carie <NUM>. As discussed above, <FIG> depict a portion of a volumetric model <NUM> of the tooth <NUM>. A volume metric model, such as volumetric model <NUM>, is comprised of many voxels, such as voxels <NUM>, <NUM>. Each voxel <NUM>, <NUM> represents a discrete volume of the tooth <NUM>. Each voxel <NUM>, <NUM> may be assigned qualities such as density, dental structure type, and other properties such as whether or not a portion of the voxel includes a structural defect, such as a portion of a carie. As shown in <FIG>, voxel <NUM> is a portion of the enamel <NUM> of the tooth <NUM>. Accordingly, voxel <NUM> may be assigned properties such as a dental structure type of enamel and a density determined based on surface penetrating infrared imaging and x-rays at the location of the voxel <NUM>.

Voxel <NUM> represents a volume of the tooth <NUM> that is part of the enamel <NUM> and includes a portion of a structural defect, such as the carie <NUM>. Accordingly, voxel <NUM> may be assigned properties such as a dental structure type of enamel, a defect type of carie, and a density determined based on a surface penetrating infrared image and x-ray image at the location of voxel <NUM>. Defects may include structural defects, such as a carie, fracture, chip, lesions, or other structure defects, or non-structural defects, such as nerve decay or death, dental fillings and others.

At block <NUM>, the method <NUM> includes receiving and building constraints for treatment and preparation of the tooth. The constraints may be received from the dental professional, such as their preferred tools to use, their preferred dental structures and shapes for prepared teeth, whether teeth adjacent to the prepared to may be modified to aid in treatment, and other doctor preferences.

Other constraints may be dictated by the type of prosthetic being used, its wall thickness and margin shape. For example, manufacturers of particular prosthetics may recommend certain shapes for the prepared tooth, certain minimum thicknesses, and tolerances or spacing with respect to adjacent teeth, the level of retention of the prosthetic, the margin shape, the marginal seal between the tooth in the prosthetic, and other constraints. These constraints and others may be used in determining in identifying material for removal and the final prepared shape of the tooth. In some embodiments, multiple suggested preparations are determined based on the constraints. These multiple suggested preparations may be displayed to the dental professional and a selected preparation may be you received from the dental professional.

In some embodiments, the multiple suggested preparations may be determined based on different priorities for each of the constraints. For example, in some embodiments, some constraints are mutually exclusive, for example, the dental professional may have a preference for a sub gingiva margin line and had also selected a particular prosthetic, however the prosthetic manufacture of the selected prosthetic recommends a super gingival margin preparation. Accordingly, one suggested preparation may include a sub gingival margin line and an alternative prosthetic, while a second suggested preparation may include a super gingival margin line with the selected prosthetic. Similarly, optimization of one constraint may lead to less than optimal preparation with respect to a second constraint. In such embodiments multiple suggested preparations may also be suggested. The suggested preparations may include a first suggested preparation that optimizes for the first constraint, a second suggested preparation that optimizes for the second constraint, and a third suggested preparation that balances the two constraints.

Next, at block <NUM>, method <NUM> proceeds to identify the material for removal for each of the suggested preparation designs. Some of the material identified for removal may include caries within the teeth. For example, a dental professional may identify voxels that comprise a portion of a carie or other defect within the tooth from the volumetric model discussed above and shown and described , for example, with respect to <FIG>. In such an embodiment, at block <NUM>, the method marks each voxel that comprises at least a portion of the caries for removal. In other embodiments, other portions of the tooth may be identified for removal based on other constraints mentioned above, such as, the marginal seal recommended by the manufacturer of the prosthetic, the level of retention desired by the dental professional, and the material strength of the prosthetic.

Identifying the material for removal may also take into consideration the location and shape of nearby teeth. For example, proper installation of a prosthetic may dictate a particular insertion path for the prosthetic. In some embodiments the insertion path may interfere with adjacent teeth or a standard abutment shape. Accordingly, material may be removed from adjacent teeth or the tooth receiving the prosthetic in order to provide a clear and unobstructed insertion path for the prosthetic.

In some embodiments, material removal may include modeling of the interproximal and occlusion contacts to ensure that when the prosthetic is placed on the prepared tooth, the prosthetic interact properly with adjacent teeth and teeth of the opposing jaw during natural occlusion.

In some embodiments, material removal may include interproximal reduction of one or more teeth. For example, if an arch of the patient is crowded, then treatment may include determining the amount and location an interproximal reduction of the one or more teeth of the arch. In determining the amount of interproximal reduction, the method may evaluate the thickness of the enamel depicted in the biometric three-dimensional and volumetric models or other two-dimensional and three-dimensional imagery to select candidates for interproximal reduction such that the remaining enamel in each tooth of the arch is clinically acceptable.

Next, at block <NUM>, one or more suggested preparation designs are presented to the dental professional and a selected finalized shape is received. As shown in <FIG>, a model of the current state of the dentition <NUM> may be displayed along with a model <NUM> of the dentition with the prepared tooth <NUM>. The model <NUM> shows the prepared tooth <NUM> including both the location and shape the margin line <NUM> and the prepared abutment shape <NUM> of the tooth <NUM>. Some embodiments, in addition to showing the suggested preparation <NUM>, the intermediate steps that lead to the suggested preparation <NUM> are also displayed for review by the dental professional into aid in determining the selected final preparation design from the one or more suggested final preparation designs. After the final preparation design is selected, the tooth shape is finalized and the process <NUM> proceeds to block <NUM>.

Moving to <FIG>, a method of treatment planning <NUM> is depicted in accordance with embodiments described herein. Preparation of the treatment plans may include preparing multiple treatment suggestions showing the final preparation of the patient's teeth and models of intermediate steps showing how the teeth are shaped from their initial shape to their final prepared shape for each treatment suggestion. The treatment suggestions may also depict the material removal processes using different tools or different material removal steps. The dental professional may select a treatment plan from the multiple treatment suggestions.

After selection of a treatment plan, images including both static two-dimensional images, three-dimensional models, and videos for each step of the treatment plan may be generated and displayed to the dental professional in order to aid the dental professional in carrying out treatment on the patient.

The method of treatment planning <NUM> may include Block <NUM>, where the intermediate material removal steps are determined for each of the individual material removal steps. At block <NUM> the material to be removed for each step is identified for example by highlighting or showing in a contrasting color, as depicted in <FIG>.

<FIG> depicts three models <NUM>, <NUM>, <NUM> of the teeth of a patient during a stage of treatment. Each of the models <NUM>, <NUM>, <NUM> indicate the same total amount of interproximal reductions <NUM> between each of the teeth depicted in the respective models. However each model displays different options for treatment with interproximal reduction. A model, such as model <NUM>, may be shown to an experienced dental practitioner who does not desire to have each of the individual interproximal reductions highlighted, instead only using the amount of interproximal reduction indicated in the model.

Models <NUM>, <NUM> may be shown to dental practitioners who desire guidance with respect to interproximal reduction or when multiple clinically acceptable types of interproximal reduction are available. The model <NUM>, for example, shows an option for interproximal reduction where both upper central incisors <NUM>, <NUM> have equal amounts of the indicated <NUM> of interproximal reduction <NUM>, <NUM> applied to each tooth. The contrasting or highlighting of the interproximal reductions <NUM>, <NUM> provides a visual guide to the dental professional when carrying out interproximal reduction on the patient and show both the location and extent of the interproximal reduction on the model. Model <NUM> shows an alternative interproximal reduction where material is removed from only the right upper central incisor <NUM>. As shown in model <NUM>, the entirety of the <NUM> of interproximal reduction is removed from the right central incisor <NUM>. The models <NUM>, <NUM>, <NUM> may be presented to the dental practitioner and a selection of a desired model may be received. In some embodiments, a preferred model may be presented that is based in part on volumetric data of the teeth where interproximal reduction is desired. For example, if the volumetric data or other surface penetrating image data (e.g., x-ray, CBCT, etc.) suggests that both teeth have equal amounts of enamel, then the interproximal reduction may be equally distributed between the teeth. In other examples, if the volumetric data or other surface penetrating image data suggest that one tooth has more enamel compared to the adjacent tooth, then the interproximal reduction may be distributed more toward the tooth with more enamel (e.g., weighted or proportioned depending on the differences in enamel thickness between the teeth).

Moving to block <NUM>, constraints for tool selection are received or otherwise determined. Constraints may include physical constraints such as the size or dimensions of the patient's mouth and entry into the oral cavity. For example, children have a relatively small opening that may dictate that only certain smaller tools may be used during the procedure. In some embodiments, a patient may have physical restrictions on the degree to which they can open their mouth that may also dictate that smaller tools are used. In addition, other constraints may include a doctor's preference for a certain type of tool and burr heads. In another example, in patients with large oral cavities, tools having additional reach or length or a particular minimum reach or length may be used as a constraint, while shorter tools are not considered.

After the constraints are received and analyzed at block <NUM>, the method <NUM> continues to block <NUM> where the tools are determined for each step of the treatment. The tools, including both hand tools and tool heads are determined based on the location of the material to be removed, the amount of material to be removed, and any other constraints, such as, for example, those discussed above. After identifying the tool for use in each step of the treatment plan, the tool's path, position, and orientation are determined for each of the material removal steps at block <NUM>. In some embodiments, determination of each tool and the determination of the tool's path, position, and orientation are determined together rather than at separate blocks. In some embodiments, the tool position and tool path information may be used to generate instructions for a robotic or a computer controlled material removal process, such as a CNC process.

After determination of the tool position and tool path at block <NUM>, the process <NUM> continues to block <NUM> where the visualizations for each of the treatment steps are generated. <FIG> depict visualizations of two steps of the material removal process of a treatment plan. <FIG> depicts the proximal preparation of a tooth <NUM>. In <FIG>, the buccal surface of the tooth <NUM> has already been prepared in a previous step of the preparation process. The visualization shows the position and orientation of the tool <NUM> and the tool head <NUM> with respect to the tooth <NUM> being prepared. The orientation of the tool <NUM> and tool head <NUM> may be shown with respect to, for example, a central axis <NUM> of the tooth that extends from the center of the root of the tooth through the center of the occlusal surface of the tooth. The visualization may also include a depiction or indication of the tool type <NUM> and the tool head type <NUM>. Finally, the visualization also includes an indication of the direction354 in which the tool head <NUM> should be moved, including both translation and rotation, in order to remove the appropriate material from the tooth <NUM> for this particular step of the treatment plan.

Although depicted as a two-dimensional image, the visualization shown in <FIG> may be a manipulatable three-dimensional model that allows a practitioner to rotate, zoom, and otherwise manipulate the model such that the practitioner may view the material removal step from several perspectives. Moreover, in some embodiments, the visual depiction may show the procedure in two-dimensional or three-dimensional video or motion forms. In such an embodiment, in addition to indicating the direction of tool movement, the video may depict a simulation of the material removal process including a depiction of the movement of the tool, showing both the directional translation and rotation of the tool's movement and the appropriate speed at which the tool should be moved during the material removal process.

<FIG> shows further preparation of the left central upper incisor <NUM>. The visualization shows the position and orientation of the tool <NUM> and the tool head <NUM> with respect to the tooth <NUM> being prepared. The tool <NUM> and the tool head <NUM> may be different than the tool <NUM> and the tool head <NUM> depicted it in <FIG>. As with the treatment step shown in <FIG>, the orientation of the tool <NUM> and tool head <NUM> may be shown with respect to, for example, a central axis of the tooth <NUM> that extends from the center of the root of the tooth through the center of the occlusal surface of the tooth. The visualization in <FIG> may also include a depiction or indication <NUM> of the tool type and tool head type. Finally, the visualization may also include an indication of the direction <NUM> in which the tool head <NUM> should be moved in order to remove the appropriate material from the tooth <NUM>.

In some embodiments, at block <NUM> or block <NUM>, the dental professional may perform simulated material removal in a computer simulated environment with virtual tools, for example tools that resemble actual tools or through the use of digital volume removal tools, that simulate the removal of material, but do not show and simulate the presence of a tool. Such simulated material removal by be shown with a model of a patient's mouth, teeth, and/or gingiva, for example, a volumetric model or a surface model. In such a simulation, as the dental professional moves the virtual tool or the digital volume removal tools model is modified to show the simulated changes to the tooth, for example, the volumetric model may be updated by removing volume from the model or the surface model may be updated to reflect an updated surface profile that reflects the material removed by the dental professional's use of the tool.

<FIG> illustrates a method <NUM> of evaluating treatment and providing feedback during treatment, in accordance with embodiments described herein. The method <NUM> may include material removal, reimaging of the dentition, and updating the treatment plan. At block <NUM>, a dental professional may attempt to remove material from a tooth, as depicted in one or more steps of a treatment plan that was generated in accordance with methods described above. After having removed some material from a patient's tooth, at block <NUM> the dental professional may rescan the patient's dentition including for example the tooth being prepared. Reimaging of the patient's dentition or tooth may include one or more of the processes discussed above with respect to the imaging conducted at block <NUM> of method <NUM>, shown and described with respect to <FIG>. After reimaging and rebuilding an updated model of the patient's dentition, the model may be marked to indicate the remaining material to be removed from the teeth. For example, updated models, such as the models shown in <FIG>, may be generated and shown to potential practitioner. The models may indicate an amount of material to be removed both numerically and also by highlighting the material that remains to be removed on the model (e.g., using a heat map or the like).

In some embodiments, the material may be removed though robotic assisted methods, such as robotic-assisted surgery, wherein a dental professional controls movement of a robot and attached dental tools via a telemanipulator or through computer control. The material removal may also be performed by computer numerical control (CNC) wherein the automation of one or more machine tool is controlled by means of one or more computer executing pre-programmed sequences of machine control commands.

In some embodiments, method <NUM> for generating visualizations may be repeated based on the updated model. In such an embodiment, updated tool information including tool type, tool position, and tool path may be used to generate updated visualizations of the treatment. In some embodiments the updated visualization made simply depict an updated to a particular step in the treatment plan, such as the current step for removing the remaining tooth material.

However, in some embodiments, a dental practitioner may have removed material that was not indicated for removal according to the treatment plan. In such embodiments, the treatment planning process may be revised using the updated scans. New finalized tooth shapes may be generated according to method <NUM> shown and described with respect to <FIG> and new visualizations may be generated according to method <NUM> shown and described with respect to <FIG>. After generating the updated visualizations, the dental practitioner may continue with treatment. The dentition may be rescanned at block <NUM> and an updated treatment plan may be generated at block <NUM> as many times as a dental professional performing the preparation desires and until preparation is complete.

<FIG> illustrates a system for carrying out the methods of visual prosthetic and orthodontic treatment planning, in accordance with embodiments. <FIG> is a simplified block diagram of a data processing system <NUM> that may be used in executing methods and processes described herein. The data processing system <NUM> typically includes at least one processor <NUM> that communicates with one or more peripheral devices via bus subsystem <NUM>. These peripheral devices typically include a storage subsystem <NUM> (memory subsystem <NUM> and file storage subsystem <NUM>), a set of user interface input and output devices <NUM>, and an interface to outside networks <NUM>. This interface is shown schematically as "Network Interface" block <NUM>, and is coupled to corresponding interface devices in other data processing systems via communication network interface <NUM>. Data processing system <NUM> can include, for example, one or more computers, such as a personal computer, workstation, mainframe, laptop, and the like.

The user interface input devices <NUM> are not limited to any particular device, and can typically include, for example, a keyboard, pointing device, mouse, scanner, interactive displays, touchpad, joysticks, etc. Similarly, various user interface output devices can be employed in a system of the invention, and can include, for example, one or more of a printer, display (e.g., visual, non-visual) system/subsystem, controller, projection device, audio output, and the like.

Storage subsystem <NUM> maintains the basic required programming, including computer readable media having instructions (e.g., operating instructions, etc.), and data constructs. The program modules discussed herein are typically stored in storage subsystem <NUM>. Storage subsystem <NUM> typically includes memory subsystem <NUM> and file storage subsystem <NUM>. Memory subsystem <NUM> typically includes a number of memories (e.g., RAM <NUM>, ROM <NUM>, etc.) including computer readable memory for storage of fixed instructions, instructions and data during program execution, basic input/output system, etc. File storage subsystem <NUM> provides persistent (non-volatile) storage for program and data files, and can include one or more removable or fixed drives or media, hard disk, floppy disk, CD-ROM, DVD, optical drives, and the like. One or more of the storage systems, drives, etc may be located at a remote location, such coupled via a server on a network or via the internet/World Wide Web. In this context, the term "bus subsystem" is used generically so as to include any mechanism for letting the various components and subsystems communicate with each other as intended and can include a variety of suitable components/systems that would be known or recognized as suitable for use therein. It will be recognized that various components of the system can be, but need not necessarily be at the same physical location, but could be connected via various local-area or wide-area network media, transmission systems, etc..

Scanner <NUM> includes any means for obtaining a digital representation (e.g., images, surface topography data, etc.) of a patient's teeth (e.g., by scanning physical models of the teeth such as casts <NUM>, by scanning impressions taken of the teeth, or by directly scanning the intraoral cavity), which can be obtained either from the patient or from treating professional, such as an orthodontist, and includes means of providing the digital representation to data processing system <NUM> for further processing. Scanner <NUM> may be located at a location remote with respect to other components of the system and can communicate image data and/or information to data processing system <NUM>, for example, via a network interface <NUM>. Fabrication system <NUM> fabricates appliances <NUM> based on a treatment plan, including data set information received from data processing system <NUM>. Fabrication machine <NUM> can, for example, be located at a remote location and receive data set information from data processing system <NUM> via network interface <NUM>.

Claim 1:
A computer program comprising instructions which, when the program is executed by a computer, cause the computer to carry out a method comprising:
receiving a model (<NUM>) of a dentition of a patient comprising a model of an initial shape of a tooth (<NUM>) of the patient;
generating a treatment plan comprising a plurality of steps to modify the initial shape of the tooth to a final shape of the tooth;
rendering visualizations for the plurality of steps of the treatment plan, the visualizations depicting removal of tooth material to modify the initial shape of the tooth to the final shape of the tooth corresponding to each of the plurality of steps;
receiving an updated model of the dentition including an updated model of the patient's tooth based on an updated image of the patient's dentition after a portion of material has been removed according to a step of the treatment plan;
comparing the updated model of the dentition with a model of the dentition for the step of the treatment plan; and
indicating remaining material that should be removed according to at least one of the plurality of steps of the treatment plan
wherein the model of the dentition of the patient is a three-dimensional composite model comprising a plurality of voxels (<NUM>, <NUM>),
the three-dimensional composite model is based on a three-dimensional surface model from a three-dimensional surface scan of the patient's dentition and a volumetric model from a scan of an internal structure of the patient's dentition, and
the plurality of voxels (<NUM>, <NUM>) comprise a location within the composite model, a dental structure type of the internal structure, a density, and/or a defect type.