Abstract:
Systems and methods are described for identifying a sub-gingival surface of a tooth in volumetric imagery data. Shape data is received from a surface scanner and volumetric imagery data is received from a volumetric imaging device. The shape data of the super-gingival portion of a first tooth is registered with the volumetric imagery data of the super-gingival portion of the first tooth to obtain a registration result. At least one criterion is then determined for detecting a surface of the first tooth in the volumetric imagery data of the super-gingival or the sub-gingival portion using the registration result. The surface of the sub-gingival portion of the first tooth is detected in the volumetric imagery data using the at least one criterion.

Description:
RELATED APPLICATIONS 
       [0001]    This application is a continuation of U.S. patent application Ser. No. 13/715,968, filed on Dec. 14, 2012 and entitled “INTEGRATION OF INTRA-ORAL IMAGERY AND VOLUMETRIC IMAGERY,” the entire contents of which are incorporated herein by reference. 
     
    
     FIELD 
       [0002]    The disclosure relates to a system, method, and computer readable storage medium for the integration of intra-oral imagery and volumetric imagery. 
       BACKGROUND 
       [0003]    An intra-oral imaging system is a diagnostic equipment that allows a dental practitioner to see the inside of a patient&#39;s mouth and display the topographical characteristics of teeth on a display monitor. Certain three-dimensional (3D) intra-oral imagers may be comprised of an intra-oral camera with a light source. The 3D intra-oral imager may be inserted into the oral cavity of a patient by a dental practitioner. After insertion of the intra-oral imager into the oral cavity, the dental practitioner may capture images of visible parts of the teeth and the gingivae. The 3D intra-oral imager may be fabricated in the form of a slender rod that is referred to as a wand or a handpiece. The wand may be approximately the size of a dental mirror with a handle that is used in dentistry. The wand may have a built-in light source and a video camera that may achieve an imaging magnification, ranging in scale from 1/10 to 40 times or more. This allows the dental practitioner to discover certain types of details and defects of the teeth and gums. The images captured by the intra-oral camera may be displayed on a display monitor and may be transmitted to a computational device. 
         [0004]    Cone beam computed tomography (CBCT) involves the use of a rotating CBCT scanner, combined with a digital computer, to obtain images of the teeth and surrounding bone structure, soft tissue, muscle, blood vessels, etc. CBCT may be used in a dental practitioner&#39;s office to generate cross-sectional images of teeth and the surrounding bone structure, soft tissue, muscle, blood vessels, etc. During a CBCT scan, the CBCT scanner rotates around the patient&#39;s head and may obtain hundreds of distinct CBCT images that may be referred to as CBCT imagery. The CBCT imagery may be transmitted to a computational device. The CBCT imagery may be analyzed to generate three-dimensional anatomical data. The three-dimensional anatomical data can then be manipulated and visualized with specialized software to allow for cephalometric analysis of the CBCT imagery. 
       SUMMARY 
       [0005]    Provided are a system, method, and computer readable storage medium in which shape data of a patient&#39;s crown and volumetric imagery of the patient&#39;s tooth are received. A determination is made of elements that represent one or more crowns in the shape data. A computational device is used to register the elements with corresponding voxels of the volumetric imagery. 
         [0006]    In additional embodiments, a determination is made of volumetric coordinates and radiodensities corresponding to the voxels. 
         [0007]    In further embodiments, at least one of the patient&#39;s root is determined via region growing from starting locations that include one or more of the determined volumetric coordinates and radiodensities at the voxels. 
         [0008]    In further embodiments, the region growing is performed by identifying adjacent voxels that possess correlated radiodensities along a longitudinal direction of the patient&#39;s tooth. 
         [0009]    In certain embodiments, the shape data of the patient&#39;s crown is obtained via an impression, a plaster model or an intra-oral scan. The volumetric imagery is selected from a group consisting of tomographic imagery, ultrasonic imagery, cone beam computed tomography (CBCT) imagery and magnetic resonance imagery (MRI). 
         [0010]    In further embodiments, the elements are vectors, and boundaries in the shape data correspond to the one or more crowns. The one or more crowns are represented by a plurality of limited length vectors and the volumetric imagery is represented by a plurality of voxels. Intersections of the plurality of limited length vectors and the plurality of voxels are determined subsequent to the registering. 
         [0011]    In further embodiments, the volumetric imagery is represented by a first plurality of voxels, and the one or more crowns are represented by a second plurality of voxels. The first plurality of voxels and the second plurality of voxels are registered. 
         [0012]    In further embodiments, one or more crowns are determined in the shape data via segmentation of the shape data. 
         [0013]    In yet further embodiments, the shape data is from intra-oral imagery, and the volumetric imagery is cone beam computed tomography (CBCT) imagery. The intra-oral imagery is of a higher precision than the CBCT imagery. The volumetric imagery includes both roots and crowns of teeth. The intra-oral imagery includes at least the crowns of the teeth but does not include an entirety of the roots of the teeth. 
         [0014]    In still further embodiments, a determination is made of an area of interest in the intra-oral imagery, wherein the area of interest corresponds to a location of the one or more crowns determined in the intra-oral imagery. An extraction is made within the volumetric imagery of the area of interest to reduce a size of the volumetric imagery. 
         [0015]    Provided also are a method, system, and a computer readable storage medium in which a computational device receives shape data of a patient&#39;s crown and volumetric imagery. A determination is made of elements that represent one or more crowns in the shape data. The elements are registered with corresponding voxels of the volumetric imagery. Volumetric coordinates and radiodensities are determined to determine a tooth shape. 
         [0016]    In additional embodiments, determining the tooth shape comprises filling missing or degraded data in the shape data. 
         [0017]    In yet additional embodiments, determining the tooth shape comprises filling missing or degraded data in the volumetric imagery. 
         [0018]    In further embodiments, the tooth shape is determined with greater precision in comparison to the received volumetric imagery, and the tooth shape is determined with greater precision with usage of lesser radiation. At least one of the patient&#39;s root is determined via region growing from starting locations that include one or more of determined volumetric coordinates and radiodensities at the voxels. 
         [0019]    In yet further embodiments, the volumetric imagery is represented by a first plurality of voxels. The one or more crowns are represented by vectors or a second plurality of voxels. The first plurality of voxels are registered to the vectors or the second plurality of voxels. 
         [0020]    Provided also are a method, system, and a computer readable storage medium in which for improving shape data of a patient&#39;s crown, the shape data of the patient&#39;s crown is registered with volumetric data of the patient&#39;s tooth. 
         [0021]    Other aspects of the invention will become apparent by consideration of the detailed description and accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0022]    Referring now to the drawings in which like reference numbers represent corresponding parts throughout: 
           [0023]      FIG. 1  illustrates a block diagram of a computing and imaging environment that includes a computational device that integrates intra-oral imagery and volumetric imagery, such as CBCT imagery, in accordance with certain embodiments; 
           [0024]      FIG. 2  illustrates a diagram in which an exemplary intra-oral imagery and advantages and disadvantages of intra-oral imagery are shown, in accordance with certain embodiments; 
           [0025]      FIG. 3  illustrates a diagram in which an exemplary CBCT imagery and advantages and disadvantages of CBCT are shown, in accordance with certain embodiments; 
           [0026]      FIG. 4  illustrates a diagram that shows how an intra-oral imagery is segmented to determine crowns represented via limited length vectors, in accordance with certain embodiments; 
           [0027]      FIG. 5  illustrates a diagram that shows how the surface data obtained via intra-oral imagery may be represented via limited length vectors or voxels, in accordance with certain embodiments; 
           [0028]      FIG. 6  illustrates a diagram that shows how voxels represent CBCT imagery, in accordance with certain embodiments; 
           [0029]      FIG. 7  illustrates a diagram that shows how the boundary between root and crown is determined in CBCT imagery by integrating intra-oral imagery with CBCT imagery, in accordance with certain embodiments; 
           [0030]      FIG. 8  illustrates a diagram that shows how surface data and volumetric data are fitted to each other, in accordance with certain embodiments; 
           [0031]      FIG. 9  illustrates a diagram that shows how surface data of the crown is merged to volumetric data of the tooth, in accordance with certain embodiments; 
           [0032]      FIG. 10  illustrates a diagram that shows characteristics of different types of imagery, in accordance with certain embodiments; 
           [0033]      FIG. 11  illustrates a diagram that shows how surface data extracted from intra-oral imagery is fitted to model data maintained as a library dataset; 
           [0034]      FIG. 12  illustrates a flowchart for augmenting CBCT imagery with data from intra-oral imagery to determine boundary between roots and crowns, in accordance with certain embodiments; 
           [0035]      FIG. 13  illustrates a flowchart for determining a localized area in CBCT imagery to generate a reduced size CBCT imagery, by augmenting CBCT imagery with data from intra-oral imagery, in accordance with certain embodiments; 
           [0036]      FIG. 14  illustrates a diagram that shows how holes are filled in intra-oral imagery by integrating CBCT imagery with intra-oral imagery, in accordance with certain embodiments; 
           [0037]      FIG. 15  illustrates a flowchart that shows how holes are filled in intra-oral imagery by integrating CBCT imagery with intra-oral imagery, in accordance with certain embodiments; 
           [0038]      FIG. 16  illustrates a flowchart that shows how CBCT imagery is integrated with intra-oral imagery, in accordance with certain embodiments; 
           [0039]      FIG. 17  illustrates a block diagram that shows how limited length vectors of intra-oral imagery are registered to voxel data of CBCT imagery, in accordance with certain embodiments; 
           [0040]      FIG. 18  illustrates a block diagram that shows how region growing is performed to determine the entire tooth by following adjacent voxels with correlated radiodensities at each and every intersecting voxel along the direction of the centroid or any other longitudinal direction of a tooth, in accordance with certain embodiments; 
           [0041]      FIG. 19  illustrates a flowchart that shows how the root of a tooth is built from intersections of limited length vectors and voxels and region growing, in accordance with certain embodiments; and 
           [0042]      FIG. 20  illustrates a flowchart that shows how voxels of tomography imagery and limited length vectors of shape data are integrated, in accordance with certain embodiments; 
           [0043]      FIG. 21  illustrates a flowchart that shows how missing or degraded data in shape data is filled by integrating voxels of tomography imagery and limited length vectors of shape data, in accordance with certain embodiments; 
           [0044]      FIG. 22  illustrates a flowchart that shows registration of elements in shape data with corresponding voxels in tomographic imagery to determine volumetric coordinates and radiodensities at the voxels, in accordance with certain embodiments; 
           [0045]      FIG. 23  illustrates a flowchart that shows registration of elements in shape data of a patient&#39;s crown with corresponding voxels in volumetric imagery, in accordance with certain embodiments; 
           [0046]      FIG. 24  illustrates a flowchart that shows registration of elements in shape data of a patient&#39;s crown with corresponding voxels in volumetric imagery to determine tooth shape, in accordance with certain embodiments; and 
           [0047]      FIG. 25  illustrates a block diagram of a computational device that shows certain elements of the computational device shown in  FIG. 1 , in accordance with certain embodiments. 
       
    
    
     DETAILED DESCRIPTION 
       [0048]    In the following description, reference is made to the accompanying drawings which form a part hereof and which illustrate several embodiments. It is understood that other embodiments may be utilized and structural and operational changes may be made. 
         [0049]    Intra-Oral Imagery and CBCT Imagery 
         [0050]    Generally intra-oral images are of a significantly higher precision in comparison to CBCT images. Furthermore, CBCT data can be noisy. Also, the use of CBCT results in ionizing radiation to the patient and it is best to use CBCT systems with as little radiation as possible. 
         [0051]    In certain embodiments, a computational device receives shape data of a patient&#39;s crown and volumetric imagery of the patient&#39;s tooth. The shape data may be generated from intra-oral images and may correspond to the surface data of the patient&#39;s crown. The volumetric imagery may comprise CBCT imagery or other types of volumetric imagery. A determination is made of voxels that represent one or more crowns in the shape data. The voxels in the shape data are registered with corresponding voxels of the volumetric imagery. 
         [0052]    In certain embodiments, segmented crowns determined from intra-oral imagery are registered to voxels of CBCT images. This allows more accurate determination of the boundary between the crown and the root of a tooth in the CBCT data. It may be noted that without the use of the intra-oral imagery the boundary between the crown and the root of a tooth may be fuzzy (i.e., not clear or indistinct) in CBCT imagery. 
         [0053]    In certain embodiments, the surface scan data of an intra-oral imaging system is registered to the volumetric data obtained from a CBCT system. The 3-D coordinates of the crown boundaries that are found in the intra-oral imagery are mapped to the voxels of the CBCT imagery to determine the boundary between roots and crowns at a sub-voxel levels of accuracy in the CBCT imagery. As a result, the roots can be extracted, even from noisy CBCT scan data. 
         [0054]    In additional embodiments, holes in intra-oral imagery may be filled in by integrating CBCT imagery with intra-oral imagery. 
       Exemplary Embodiments 
       [0055]      FIG. 1  illustrates a block diagram of a computing and imaging environment  100  that includes a computational device  102  that integrates intra-oral imagery  104  and CBCT imagery  106 , in accordance with certain embodiments. The computational device  102  may include any suitable computational device such as a personal computer, a server computer, a mini computer, a mainframe computer, a blade computer, a tablet computer, a touchscreen computing device, a telephony device, a cell phone, a mobile computational device, a dental equipment having a processor, etc., and in certain embodiments the computational device  102  may provide web services or cloud computing services. In certain alternative embodiments, more than one computational device may be used for storing data or performing the operations performed by the computational device  102 . 
         [0056]    The intra-oral imagery  104  provides surface data of a patient&#39;s crown and the CBCT imagery  106  provides volumetric imagery of a patient&#39;s tooth, where the tooth may include both the crown and the root. In alternative embodiments, the surface data of the patient&#39;s crown may be provided by imagery that is different from intra-oral imagery, and the volumetric imagery may be provided by other types of tomographic imagery, ultrasonic imagery, magnetic resonance imagery (MRI), etc. The volumetric imagery comprises three dimensional imagery and may be represented via voxels. 
         [0057]    The computational device  102  may include an integrating application  108 , implemented in certain embodiments in software, hardware, firmware or any combination thereof. The integrating application  108  integrates the intra-oral imagery  104  and the CBCT imagery  106  to provide additional functionalities that are not found in either the intra-oral imagery  104  or the CBCT imagery  106  when they are not integrated. 
         [0058]    The computational device  102  is coupled via one or more wired or wireless connections  110  to an intra-oral imaging system  112  and a CBCT imaging system  114 , over a network  116 . In certain embodiments, the network  116  may comprise a local area network, the Internet, and intranet, a storage are network, or any other suitable network. 
         [0059]    The intra-oral imaging system  112  may include a wand  116  having an intra-oral imaging sensor  118 , where in certain embodiments the intra-oral imaging sensor  118  is an intra-oral camera that generates intra-oral imagery of the oral cavity of a patient. The CBCT imaging system  114  may include a rotating X-ray equipment  120  that generates cross-sectional CBCT imagery of the soft tissue, hard tissue, teeth, etc. of a patient. 
         [0060]    Therefore,  FIG. 1  illustrates certain embodiments in which an integrating application  108  that executes in the computational device  102  integrates intra-oral imagery  104  generated by an intra-oral imaging system  112  with CBCT imagery  106  generated by a CBCT imaging system  114 . In certain additional embodiments, the intra-oral imagery  104  and the CBCT imagery  106  may be stored in a storage medium (e.g., a disk drive, a floppy drive, a pen drive, a solid state device, an optical drive, etc.), and the storage medium may be coupled to the computational device  102  for reading and processing by the integrating application  108 . 
         [0061]      FIG. 2  illustrates a diagram  200  in which an exemplary intra-oral imagery  202  is shown, in accordance with certain embodiments. Certain exemplary advantages  204  and certain exemplary disadvantages  206  of the intra-oral imagery  202  are also shown, in accordance with certain embodiments. 
         [0062]    The intra-oral imagery  206  shows exemplary crowns (e.g., crowns  208   a ,  208   b ,  208   c ) in the upper arch of the oral cavity of a patient, where the intra-oral imagery  206  may have been acquired via the intra-oral imaging system  112 . The crown is the portion of the tooth that may be visually seen, and the root is the portion of the tooth that is hidden under the gum. 
         [0063]      FIG. 2  shows that the intra-oral imagery is typically of a high precision  210  in comparison with CBCT imagery. Additionally, no radiation that may cause harm to the patient (shown via reference numeral  212 ) is needed in acquiring the intra-oral imagery  202 . However, the intra-oral imagery  202  does not show the roots of teeth (reference numeral  214 ) and may have holes  216 , where a hole is a portion of the tooth that is not visible in intra-oral imagery. Holes may arise because of malocclusions or for other reasons. While, small and medium sized holes may be filled (i.e. the hole is substituted via a simulated surface generated programmatically via the computational device  102 ) by analyzing the intra-oral imagery  202 , larger holes (i.e. holes that exceed certain dimensions) may not be filled by just using data found in intra-oral imagery. Additionally, shiny surfaces f crowns may generate poor quality intra-oral imagery (reference numeral  218 ). 
         [0064]    Therefore,  FIG. 2  illustrates certain embodiments in which intra-oral imagery may have holes and do not show the entirety of the roots of teeth. 
         [0065]      FIG. 3  illustrates a diagram  300  in which an exemplary CBCT imagery  302 , and certain advantages  304  and certain disadvantages  306  of CBCT imagery are shown, in accordance with certain embodiments. 
         [0066]    In the CBCT imagery the entire tooth (i.e., the root and the crown) is imaged (reference number  310 ) and there are few holes (reference number  312 ). The few holes that exist may be caused by artifacts as a result of amalgam fillings on tooth (reference numeral  320 ). However, the CBCT images may be of a lower precision and may be more noisy in comparison to intra-oral imagery (reference numeral  314 ). There is a potential for ionizing radiation to the patient in the acquisition of CBCT imagery (reference numeral  316 ) unlike in intra-oral imagery in which there is no ionizing radiation in the acquisition process. Furthermore, while the complete tooth is imaged in CBCT imagery, the boundary between the root and the crown may not be clear (reference numeral  318 ) as may be seen (reference numeral  320 ) in the exemplary CBCT imagery  302 . The fuzzy and indistinct boundary  320  between the crown  322  and the root  324  may be caused by varying radiodensities during the process of acquiring CBCT images. In certain embodiments, motion of the patient may generate inferior quality CBCT imagery. 
         [0067]    Therefore,  FIG. 3  illustrates certain embodiments in which CBCT images may have low precision and have noisy data with the boundary between the root and crown not being clearly demarcated. 
         [0068]      FIG. 4  illustrates a diagram  400  that shows how an intra-oral imagery  202  is segmented to determine crowns  402  represented via limited length vectors  404 , in accordance with certain embodiments. The segmentation of the intra-oral imagery  202  to determine crowns  402  may be performed via the integrating application  108  that executes in the computational device  102 . Exemplary segmented crowns are shown via reference numerals  406   a ,  406   b ,  406   c . The segmented crowns are of a high resolution and show clearly defined edges and are represented via limited length vectors  404 . A vector has a direction and magnitude in three-dimensional space. A limited length vector is a vector whose length is limited. In other embodiments, the segmented crowns may be represented via data structures or mathematical representations that are different from limited length vectors  404 . 
         [0069]    Therefore,  FIG. 4  illustrates certain embodiments in which intra-oral imagery is segmented to determine crowns represented via limited length vectors. 
         [0070]      FIG. 5  illustrates a diagram that shows how an intra-oral imaging system  410  scans the inside of a patient&#39;s mouth and generates surface samples of the crowns of a patient&#39;s teeth, where the aggregated surface samples may be referred to as a point cloud  412 . 
         [0071]    The point cloud  412  may processed by the integrating application  108  executing the computational device  102  to represent the surface of the crowns. The crown of the tooth is a solid object, and the surfaces of the crown correspond to the boundaries of the solid object. The crown surface may be represented by a surface mesh of node points connected by triangles, quadrilaterals or via different types of polygon meshes. In alternative embodiments, a solid mesh may also be used to represent the crown surface. The process of creating the mesh is referred to as tessellation. 
         [0072]    In certain embodiments, the surface corresponding to the crown is represented in three dimensional space via limited length vectors  414  or via voxels  416  or via other data structures  418 . The voxels  416  correspond to three-dimensional points on the surface of a crown. In certain embodiments, the limited length vectors  414  may be converted to vowel representation via appropriate three dimensional coordinate transformations  420 . The limited length vectors  414  may correspond to the sides of the different types of polygon meshes (e.g., triangles, quadrilaterals, etc.) in the surface representation of the crown. 
         [0073]    Therefore,  FIG. 5  illustrates certain embodiments in which intra-oral imagery is processed to determine crowns represented via limited length vectors or via voxels. The limited length vectors or voxels correspond to a surface data representation  422  of the crown. Surface data may also be referred to as shape data. 
         [0074]      FIG. 6  illustrates a diagram  500  that shows how voxels  502  represent CBCT imagery  302 , in accordance with certain embodiments. A voxel (e.g., voxel  504 ) is a volumetric pixel that is a digital representation of radiodensity in a volumetric framework corresponding to the CBCT imagery  302 . The radiodensity may be measured in the Hounsfield scale. In  FIG. 6  an exemplary voxel representation  502  of part of the CBCT imagery  302  is shown, 
         [0075]    The voxel representation  502  has a local origin  504 , with X, Y, Z coordinates representing width, depth, and height respectively (shown via reference numerals  506 ,  508 ,  510 ). The coordinate of the voxel where the X, Y, Z values are maximum are shown via the reference numeral  512 . An exemplary voxel  504  and an illustrative column of voxels  514  are also shown. Each voxel has a volume defined by the dimensions shown via reference numerals  516 ,  518 ,  520 . 
         [0076]    In certain embodiments, limited length vectors of intra-oral imagery are registered to the voxel representation of the CBCT imagery, to determine where the limited length vectors intersect the voxels of the CBCT imagery. In an exemplary embodiments, an intersecting limited length vector  522  is shown to intersect the voxels of the CBCT imagery at various voxels, wherein at least one voxel  524  at which the intersection takes place has a volumetric coordinate of (X,Y,Z) with an associated radiodensity. 
         [0077]    Therefore,  FIG. 6  illustrates certain embodiments in which CBCT imagery is represented via voxels. The limited length vectors of the intra-oral imagery intersects the voxels of the CBCT imagery when both are placed in the same coordinate system, wherein each intersection has a X,Y,Z coordinate and a radiodensity. In certain embodiments, the limited length vectors may be one or more of the sides of triangulated tessellations used to represent shape data. The limited length vectors may be chained in shape representations. 
         [0078]      FIG. 7  illustrates a diagram  600  that shows how the boundary between root and crown is determined in CBCT imagery by integrating intra-oral imagery with CBCT imagery, in accordance with certain embodiments. In certain embodiments, the voxel representation  606  of CBCT imagery is integrated (via the integrating application  108 ) with the limited length vector representation or voxel representation  607  of the intra-oral imagery to overlay the high resolution clearly segmented crowns of the intra-oral imagery on the low resolution fuzzy crowns of the CBCT imagery (as shown via reference numeral  608 ), to clearly demarcate the boundary between roots and crowns in the CBCT imagery  602 . In certain embodiments the integration of CBCT imagery and intra-oral imagery results in a type of filtration operation that sharpens the CBCT imagery to determine the boundary between roots and crowns. 
         [0079]    Therefore,  FIG. 7  illustrates certain embodiments in which CBCT imagery is augmented with data from intra-oral imagery to determine the boundary between roots and crowns with a greater degree of accuracy in comparison to using the CBCT imagery alone. As a result of the augmentation, high precision crowns and low precision roots are obtained. 
         [0080]      FIG. 8  illustrates a diagram  609  that shows how surface data and volumetric data are fitted to each other, in accordance with certain embodiments. In certain embodiments, the surface data (i.e., the crown surface data) may be represented with reference to a first coordinate system (shown via reference numeral  610 ) The volumetric data that represents the tooth may be represented in a second coordinate system (shown via reference numeral  612 ). 
         [0081]    In certain embodiments one or both of the crown surface data and the tooth volumetric data may have to be rotated  614 , translated  616 , morphed  618 , scaled  620 , or made to undergo other transformations  622  to appropriately overlap the crown surface data and the tooth volumetric data in a single unified coordinate system. For example, in certain embodiments the tooth volumetric data is fitted to the crown surface data in the coordinate system of the tooth surface data by appropriate rotations, translations, morphing, scaling, etc., of the tooth volumetric data (as shown via reference numeral  624 ). In other embodiments, crown surface data is fitted to the tooth volumetric data in the coordinate system of the tooth volumetric data by appropriate rotations, translations, morphing, scaling, etc., of the crown surface data (as shown via reference numeral  626 ). In other embodiments, both the crown surface data and the tooth volumetric data may undergo rotations, translations, morphing, scaling, etc. to fit the crown surface data and tooth volumetric data in a new coordinate system (as shown via reference numeral  628 ). 
         [0082]      FIG. 9  illustrates a diagram  650  that shows how surface data of the crown is merged to volumetric data of the tooth, in accordance with certain embodiments. An empty cube of voxels in the three dimensional space is populated with the shape data of a crown. As a result, the surface data of the crown is represented via voxels of a three dimensional space  652 . 
         [0083]    The three dimensional space  652  with surface data is overlaid on the three dimensional space  654  that has the volumetric representation of the tooth, to generate the overlay of the surface data on the volumetric data shown in the three dimensional space  656 . The fitting of the surface data to the volumetric data may be performed via an iterative closest point (ICP) registration. ICP may fit points in surface data to the points in volumetric data. In certain embodiment, the fitting may minimize the sum of square errors with the closest volumetric data points and surface data points. In certain embodiments, the limited length vectors of the surface data are represented as voxels prior to performing the ICP registration. 
         [0084]    The anatomy of brackets, wires, filling or other features on the tooth may often assist in properly registering the surface data to the volumetric data. The registration may in various embodiments be performed via optimization techniques, such as simulated annealing, correlation techniques, dynamic programming, linear programming etc. 
         [0085]    In certain embodiments a multiplicity of representations of the same object obtained by CBCT, magnetic resonance imagery (MRI), ultrasound imagery, intra-oral imagery based surface data, etc., may be registered to generate a better representation of a crown in comparison to embodiments that do not use data from the multiplicity of representations. 
         [0086]      FIG. 10  illustrates a diagram  670  that shows characteristics of different types of imagery, in accordance with certain embodiments. The intra-oral imagery  672  may provide not only the surface data  676  but may also be processed to provide information on reflectivity  678  and translucency  680  of the surface of the objects that are imaged. For example, the reflectivity and the translucency of the crown may be different from that the gingiva, and the intra-oral imagery  672  may be processed to distinguish the crown from the gingiva based on the reflectivity and the translucency differences and the segmentation of the crown may be improved by incorporating such additional information. In certain embodiments where interferometry fringe patterns are used for capturing the intra-oral imagery the reflectivity and translucency information may be generated with greater precision in comparison to embodiments where such fringe patterns are not used. 
         [0087]    In certain embodiments, the volumetric data  682  and the radiodensity information  684  corresponding to the CBCT imagery  674  may be used in association with the surface data  676 , reflectivity information  678  and translucency information  680  of the intra-oral imagery  672  to provide additional cues for performing the registration of the surface data  676  and the volumetric data  682 . Ray tracing mechanisms may also be used for simulating a wide variety of optical effects, such as reflection and refraction, scattering, and dispersion phenomena (such as chromatic aberration) for improving the quality of the different types of images and for registration. 
         [0088]      FIG. 11  illustrates a diagram  688  that shows how surface data  690  extracted from intra-oral imagery is fitted to one or more of model data  694   a ,  694   b , . . .  694   n  maintained as a library dataset  692 . The library dataset  692  may include model data for various types of teeth (e.g., incisors, canines, molars, etc.) and also model data for various patient parameters, such as those based on age, gender, ethnicity, etc. In certain embodiments where the CBCT imagery is unavailable, the surface data  690  may be registered (reference numeral  696 ) to an appropriately selected model data  694   a  . . .  694   n  to provide better quality information to a dental practitioner. When the roots of a tooth are well formed and the crowns are relatively regular, then such fusion with model data is often adequate for treatment purposes. However, with as little as two to three degrees of error in alignment, such embodiments may have to be substituted with embodiments in which surface data from intra-oral imagery is registered with CBCT imagery to provide better quality information to the dental practitioner. In certain additional embodiments, the surface data is registered with the CBCT imagery with additional cues obtained from the model data. 
         [0089]      FIG. 12  illustrates a flowchart  700  for augmenting CBCT imagery with data from intra-oral imagery to determine the boundary between roots and crowns, in accordance with certain embodiments. The operations shown in flowchart  700  may be performed via the integrating application  108  that executes in the computational device  102 . 
         [0090]    Control starts at block  702  in which the computational device  102  receives intra-oral imagery  104  and CBCT imagery  106 . The integrating application  108  determines (at block  704 ) one or more crowns in the intra-oral imagery, wherein the one or more crowns of the intra-oral imagery are represented by limited length vectors or voxels, and the CBCT imagery is represented by voxels. Control proceeds to block  706 , in which the integrating application  108  integrates the one or more crowns determined in the intra-oral imagery into the CBCT imagery by registering the limited length vectors pr voxels that represent the one or more crowns in the intra-oral imagery with the voxels of the CBCT imagery, to determine a boundary between at least one crown and at least one root in the CBCT imagery. 
         [0091]      FIG. 13  illustrates a flowchart  800  for determining a localized area in CBCT imagery to generate a reduced size CBCT imagery, by augmenting CBCT imagery with data from intra-oral imagery, in accordance with certain embodiments. The operations shown in flowchart  800  may be performed via the integrating application  108  that executes in the computational device  102 . 
         [0092]    Control starts at blocks  802  and  804  in which CBCT imagery and intra-oral imagery are provided to the integrating application  108 . The integrating application  108  determines (at block  806 ) an area of interest in the intra-oral imagery, wherein the area of interest corresponds to a location of the one or more crowns determined in the intra-oral imagery via segmentation. 
         [0093]    Control proceeds to block  808  in which the integrating application  108  extracts from the CBCT imagery the area of interest to reduce the size of the CBCT imagery, and the reduced size CBCT imagery is stored (at block  810 ) in the computational device  102   
         [0094]    Therefore  FIG. 8  illustrates certain embodiments in which the size of CBCT imagery is reduced by incorporating an area of interest determined from intra-oral imagery. 
         [0095]      FIG. 14  illustrates a diagram  900  that shows how holes are filled in intra-oral imagery by integrating CBCT imagery with intra-oral imagery, accordance with certain embodiments. 
         [0096]    In  FIG. 9  an exemplary intra-oral imagery  104  has holes  902  (i.e., areas of the crown of teeth that are not imaged by the intra-oral imaging system  112 ). The integrating application  108  uses the CBCT imagery  106  to fill the holes via the low precision crowns without holes that are found in the CBCT imagery  106 , to generate augmented intra-oral imaging data  904  in which all holes are filled. In certain embodiments, a range of radiodensities are determined in voxels of a determined boundary between roots and crowns, and based on the range of radiodensities and the determined boundary, the holes in the intra-oral imagery are filled from selected voxels of the CBCT imagery. 
         [0097]      FIG. 15  illustrates a flowchart  1000  that shows how holes are filled in intra-oral imagery by integrating CBCT imagery with intra-oral imagery, accordance with certain embodiments. The operations shown in flowchart  1000  may be performed via the integrating application  108  that executes in the computational device  102 . 
         [0098]    Control starts at block  1002  in which the computational device  102  receives intra-oral imagery  104  and volumetric imagery, such as, cone beam computed tomography (CBCT) imagery  106 . Control proceeds to block  1004 , in which the integrating application  108  determines one or more crowns in the intra-oral imagery  104  and the CBCT imagery  106 , where the one or more crowns determined by the intra-oral imagery  104  has one or more holes, and where a hole is a part of a tooth that is not visible in the intra-oral imagery. The one or more crowns determined in the CBCT imagery are integrated (at block  1006 ) into the intra-oral imagery  104 , to fill the one or more holes in the intra-oral imagery. 
         [0099]    Therefore  FIGS. 14 and 15  illustrate how holes are filled in intra-oral imagery by integrating information from CBCT imagery. Conversely, if missing or degraded data is found in volumetric imagery, such missing or degraded data may be filled from surface data found in the intra-oral imagery. 
         [0100]      FIG. 16  illustrates a flowchart  1100  that shows how CBCT imagery  106  is integrated with intra-oral imagery  104 , in accordance with certain embodiments. The operations shown in flowchart  1100  may be performed via the integrating application  108  that executes in the computational device  102 . 
         [0101]    Control starts at block  1102  in which a computational device  102  receives intra-oral imagery  104  and CBCT imagery  106 . The intra-oral imagery  104  and the CBCT imagery  106  are integrated (at block  1104 ), to determine a boundary between at least one crown and at least one root in the CBCT imagery  106 , and to fill one or more holes in the intra-oral imagery  104 . 
         [0102]      FIG. 17  illustrates a block diagram  1200  that shows how limited length vectors of intra-oral imagery are registered to voxel data of CBCT or other volumetric imagery, in accordance with certain embodiments. 
         [0103]    In  FIG. 17  the hatched area indicated via reference numeral  1202  indicates an uncertainty region of the CBCT imagery in which the actual tooth boundary of the patient is likely to found. The limited length vectors (or voxels) of the intra-oral imagery are registered to the voxels of the CBCT imagery to determine the intersections  1204 . At each of the intersections  1204  there is an X,Y,Z coordinate and an associated radiodensity (shown via reference numeral  1206 ), where adjacent voxels may have similar radiodensities or correlated radiodensities in the uncertainty region  1202  (as shown via reference numeral  1208 ). 
         [0104]      FIG. 18  illustrates a block diagram  1300  that shows how region growing is performed to determine the entire tooth by following adjacent voxels with correlated radiodensities at each and every intersecting voxel along the direction of the centroid  1302  of a tooth, in accordance with certain embodiments. The centroid is located along a longitudinal direction of the tooth. The correlated radiodensities may be determined via correlation windows of different sizes. For example, a cube of voxels with length, breadth, and height of three voxels each may be used as a correlation window to determine which adjacent voxel is most correlated to a previously determined voxel in terms of radiodensities. 
         [0105]    Reference numeral  1306  shows the entire tooth outlined via region growing with seed values starting from the voxels and limited length vector (or surface voxel) intersections  1204  and the associated radiodensities. Other mechanisms may also be adopted for region growing to determine the entire tooth. 
         [0106]      FIG. 19  illustrates a flowchart  1400  that shows how the root of a tooth is built from intersections of limited length vectors (or surface voxel) and voxels and region growing, in accordance with certain embodiments. Control starts at block  1402  where the voxel information at each voxel of a CBCT image is given by a volumetric coordinate X,Y,Z and the radiodensity. Control proceeds to block  1404  in which a determination is made as to which voxels of CBCT image and limited length vectors (or voxel) of the boundary of the crown of intra-oral image intersect. The root of the tooth is built (at block  1406 ) from the determined intersections via region growing techniques based on following adjacent radiodensities that are correlated (i.e., similar in magnitude) to each other. 
         [0107]      FIG. 20  illustrates a flowchart  1500  that shows how voxels of tomography (i.e. volumetric) imagery and limited length vectors of shape data are integrated, in accordance with certain embodiments. A computational device receives (at block  1502 ) shape data of a patient&#39;s dentition and tomography imagery. Vectors that represent one or more crowns in the shape data are determined (at block  1504 ). The vectors are registered with corresponding voxels of the tomography imagery, and volumetric coordinates and radiodensities at the voxels are determined (at block  1506 ). At least one of the patient&#39;s teeth is determined via region growing from starting locations that include one or more of the determined volumetric coordinates and the radiodensities at the voxels, and the region growing is performed by following adjacent voxels with closest radiodensities along a direction of a centroid of a tooth (at block  1508 ). In alternative embodiments voxels (referred to as surface voxel) corresponding to the limited length vectors of the surface data may be used instead of the limited length vectors for registration. 
         [0108]      FIG. 21  illustrates a flowchart  1600  that shows how missing or degraded data in shape data is filled by integrating voxels of tomography imagery and limited length vectors of shape data, in accordance with certain embodiments. A computational device receives (at block  1602 ) shape data of a patient&#39;s dentition and tomography imagery. Vectors that represent one or more crowns in the shape data are determined, wherein the one or more crowns has degraded data or missing data (at block  1604 ). The vectors are registered with corresponding voxels of the tomography imagery, and volumetric coordinates and radiodensities at the voxels are determined (at block  1606 ). At least one of the patient&#39;s teeth is determined via region growing from starting locations that include one or more of the determined volumetric coordinates and the radiodensities at the voxels to fill the degraded or the missing data in the one or more crowns of the shape data (at block  1606 ). 
         [0109]    In certain alternative embodiments vectors are registered with corresponding voxels of the tomography imagery to determine volumetric coordinates and radiodensities at the voxels, to determine a tooth with greater precision and to fill missing or degraded data in the shape data. In certain embodiments, by determining the tooth with greater precision the received tomography imagery is obtained with usage of lesser radiation. 
         [0110]      FIG. 22  illustrates a flowchart  1700  that shows registration of elements (e.g., vectors) in shape data with corresponding voxels in tomographic imagery to determine volumetric coordinates and radiodensities at the voxels, in accordance with certain embodiments. A computational device receives (at block  1702 ) shape data of a patient&#39;s dentition and tomography imagery. Elements (e.g. vectors or voxels) that represent one or more boundaries in the shape data are determined (at block  1704 ). The elements are registered with corresponding voxels of the tomography imagery, and volumetric coordinates and radiodensities at the voxels are determined (at block  1706 ). In certain embodiments, the boundaries in the shape data delineate one or more crowns of teeth. 
         [0111]      FIG. 23  illustrates a flowchart  2300  that shows registration of elements in shape data of a patient&#39;s crown with corresponding voxels in volumetric imagery, in accordance with certain embodiments. 
         [0112]    Control starts at block  2302  in which shape data of a patient&#39;s crown and volumetric imagery of the patient&#39;s tooth is received. A determination is made (at block  2304 ) of elements that represent one or more crowns in the shape data. A computational device is used to register (at block  2306 ) the elements with corresponding voxels of the volumetric imagery. 
         [0113]      FIG. 24  illustrates a flowchart  2400  that shows registration of elements in shape data of a patient&#39;s crown with corresponding voxels in volumetric imagery to determine tooth shape, in accordance with certain embodiments. 
         [0114]    Control starts at block  2402  in which shape data of a patient&#39;s crown and volumetric imagery are received. A determination is made (at block  2404 ) of elements that represent one or more crowns in the shape data. The elements are registered (at block  2406 ) with corresponding voxels of the volumetric imagery by using a computational device, and volumetric coordinates and radiodensities are determined to determine a tooth shape. 
         [0115]    Therefore,  FIGS. 1-24  illustrate certain embodiments in which the tooth of a patient is determined more accurately by integrating information extracted from intra-oral imagery and CBCT imagery. Also, degraded or missing data in the crowns of intra-oral imagery are filled by integrating information extracted from CBCT imagery. By integrating intra-oral imagery with CBCT imagery, both intra-oral imagery and CBCT imagery are enhanced to have greater functionalities and CBCT imagery may be obtained with usage of a lower amount of radiation. 
       Further Details of Embodiments 
       [0116]    In a volumetric data representation there may be areas of high contrast and low contrast. When segmenting via thresholding (e.g., by thresholding radiodensities) it may be easier to threshold crowns than roots. This is because crowns appear with high density against soft tissue. It may be noted that roots appear with low contrast against the bone. High contrast junctions may be easier to segment this manner. In certain embodiments, the crowns may be thresholded and the borders may be used to seed the segmentation to isolate the roots. Thus the volumetric data set may be used to segment itself. This may automatically register the crown root object. This may even be used to register the crown surface data. 
         [0117]    In certain embodiments, instead of segmenting roots, certain embodiments may extract only the centroid of the root. 
         [0118]    Certain embodiments may link the shape and tomography imagery data together in a file system. For example, information may be added to the headers of the image files of both the CBCT and intra-oral scan data to enable viewing software to easily reference one from the other. Alternatively, the viewing software may keep track of which intra-oral scan image and CBCT image files have been registered with one another and store the information in a separate file. In certain embodiments correlation or optimization techniques may be used to find the intersection points in the image data. 
         [0119]    In certain embodiments, the output of the processes is a data structure that is an advanced representation of the surface or a volumetric data enhanced by the fusion process of registration of multiple sources of imagery. Multidimensional data representation and visualization techniques may be used to display such enhanced surfaces or volumes. In certain embodiments, the collected image data may after processing and registration be rendered and displayed as three dimensional objects via volumetric rendering and segmentation. 
       Additional Details of Embodiments 
       [0120]    The operations described in the figures may be implemented as a method, apparatus or computer program product using techniques to produce software, firmware, hardware, or any combination thereof. Additionally, certain embodiments may take the form of a computer program product embodied in one or more computer readable storage medium(s) having computer readable program code embodied therein. 
         [0121]    A computer readable storage medium may include an electronic, magnetic, optical, electromagnetic, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing. The computer readable storage medium may also comprise an electrical connection having one or more wires, a portable computer diskette or disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or Flash memory), a portable compact disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, etc. A computer readable storage medium may be any tangible medium that can contain, or store a program for use by or in connection with an instruction execution system, apparatus, or device. 
         [0122]    Computer program code for carrying out operations for aspects of the present invention may be written in any combination of one or more programming languages. 
         [0123]    Aspects of the present invention are described below with reference to flowchart illustrations and/or block diagrams of methods, system and computer program products according to certain embodiments. At least certain operations that may have been illustrated in the figures show certain events occurring in a certain order. In alternative embodiments, certain operations may be performed in a different order, modified or removed. Additionally, operations may be added to the above described logic and still conform to the described embodiments. Further, operations described herein may occur sequentially or certain operations may be processed in parallel. Yet further, operations may be performed by a single processing unit or by distributed processing units. Computer program instructions can implement the blocks of the flowchart. These computer program instructions may be provided to a processor of a computer for execution. 
         [0124]      FIG. 25  illustrates a block diagram that shows certain elements that may be included in the computational device  102 , in accordance with certain embodiments. The system  2500  may comprise the computational device  102  and may include a circuitry  2502  that may in certain embodiments include at least a processor  2504 . The system  2500  may also include a memory  2506  (e.g., a volatile memory device), and storage  2508 . The storage  2508  may include a non-volatile memory device (e.g., EEPROM, ROM, PROM, RAM, DRAM, SRAM, flash, firmware, programmable logic, etc.), magnetic disk drive, optical disk drive, tape drive, etc. The storage  2508  may comprise an internal storage device, an attached storage device and/or a network accessible storage device. The system  2500  may include a program logic  2510  including code  2512  that may be loaded into the memory  2506  and executed by the processor  2504  or circuitry  2502 . In certain embodiments, the program logic  2510  including code  2512  may be stored in the storage  2508 . In certain other embodiments, the program logic  2510  may be implemented in the circuitry  2502 . Therefore, while  FIG. 25  shows the program logic  2510  separately from the other elements, the program logic  2510  may be implemented in the memory  2506  and/or the circuitry  2502 . 
         [0125]    The terms “an embodiment”, “embodiment”, “embodiments”, “the embodiment”, “the embodiments”, “one or more embodiments”, “some embodiments”, and “one embodiment” mean “one or more (but not all) embodiments of the present invention(s)” unless expressly specified otherwise. 
         [0126]    The terms “including”, “comprising”, “having” and variations thereof mean “including but not limited to”, unless expressly specified otherwise. 
         [0127]    The enumerated listing of items does not imply that any or all of the items are mutually exclusive, unless expressly specified otherwise. 
         [0128]    The terms “a”, “an” and “the” mean “one or more”, unless expressly specified otherwise. 
         [0129]    Devices that are in communication with each other need not be in continuous communication with each other, unless expressly specified otherwise. In addition, devices that are in communication with each other may communicate directly or indirectly through one or more intermediaries. 
         [0130]    A description of an embodiment with several components in communication with each other does not imply that all such components are required. On the contrary a variety of optional components are described to illustrate the wide variety of possible embodiments. 
         [0131]    When a single device or article is described herein, it will be readily apparent that more than one device/article (whether or not they cooperate) may be used in place of a single device/article. Similarly, where more than one device or article is described herein (whether or not they cooperate), it will be readily apparent that a single device/article may be used in place of the more than one device or article or a different number of devices/articles may be used instead of the shown number of devices or programs. The functionality and/or the features of a device may be alternatively embodied by one or more other devices which are not explicitly described as having such functionality/features. 
         [0132]    The foregoing description of various embodiments of the invention has been presented for the purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed. Many modifications and variations are possible in light of the above teaching. It is intended that the scope of the invention be limited not by this detailed description, but rather by the claims appended hereto. The above specification, examples and data provide a complete description of the manufacture and use of the composition of the invention. Since many embodiments of the invention can be made without departing from the spirit and scope of the invention, the invention resides in the claims hereinafter appended.