Patent Application
20180165818
The invention generally relates to methods and to systems for orthodontic treatment planning and, in particular, to methods and systems for registering multiple imageries of a patient's teeth.
Orthodontics is a specialty of dentistry that is concerned with improvement of the appearance of a patient's teeth, including correction of malocclusions and other defects. Orthodontic appliances, such as orthodontic brackets and other devices, are often attached to a patient's teeth. These devices apply forces to the teeth to move them into their orthodontically correct orientations according to a treatment plan. The treatment plan may be developed based on modeling of the patient's teeth.
To that end, a practitioner may initially prepare a digital model. This may include taking impressions of the patient's teeth and then capturing images of those impressions. Instead of impressions, the practitioner may capture photographic imagery or capture x-ray imagery of the patient's teeth and the surrounding skeletal structure. The information contained in the captured imagery is then used to create the digital model of one or more of the patient's teeth. Digital models may include both two-dimensional and three-dimensional models. The practitioner may then virtually manipulate the digital models in the development of the treatment plan for that patient.
By way of example, models may be developed with an intra-oral imaging system that allows a practitioner to see the inside of a patient's mouth and display the topographical characteristics of teeth on a display monitor. Certain intra-oral imagers may include an intra-oral camera with a light source. The intra-oral imager may be fabricated in the form of a slender wand that may be approximately the size of a dental mirror with the camera and light source at or near one end. The camera may be capable of magnifying captured images by 40 times or more. The wand may be inserted into the oral cavity so that the practitioner may capture images of the teeth and the gingiva. Magnifying the images allows the practitioner to visually inspect the teeth to detect defects. The information captured by the intra-oral camera may be displayed on a monitor and may be transmitted to a computational device.
As another example, the practitioner may use data collected via cone beam computed tomography (CBCT), which involves the use of a rotating CBCT scanner, to collect data regarding the teeth, surrounding bone structure, and soft tissue. The data may be transmitted to a computational device to generate CBCT imagery. The data may include three-dimensional anatomical data that can be manipulated and visualized with specialized software. The captured information may provide the practitioner with an accurate reproduction of the topographical characteristics and arrangement of the crowns of teeth in one or both of the patient's maxillary or mandible jaws. Either or both types of digital data may be used to develop the treatment plan and/or may be used to assess orthodontic treatment progress.
Plan development may also include customized appliances. Treatment may therefore include identification and design of orthodontic appliances specific to the patient's condition. The effect of the appliance may be modeled in conjunction with the digital imagery prior to placement on the patient's teeth. Software platforms allow the practitioner to digitally manipulate the model. In this way, the targeted final positions of the teeth and the treatment plan to obtain those final positions with the appliances may be refined prior to actual treatment of the patient. Refinement of treatment may include further customization of the orthodontic appliances to a particular patient. The customized appliances may then be manufactured according to the treatment plan specified.
After initiation of the treatment, treatment progress may be monitored and refined via the digital model. For example, the treatment efficacy may be monitored and adjusted as determined in conjunction with digital models of the patient's teeth. Periodic adjustments are often needed for satisfactory completion of treatment.
In view of the above, it is advantageous to capture accurate information regarding each tooth in the patient's jaws. It will be appreciated that the more accurate a model is, the more effective the orthodontic treatment is likely to be. However, there are problems with the accuracy of some types of information. The resulting imagery is then less accurate than desired. For example, there are problems with capturing accurate images of the patient's teeth, particularly data indicative of the location and orientation of the roots of each tooth. Because the roots are buried in tissue, they cannot be seen with visible light, which is typically used to capture intra-oral imagery of the teeth. This leaves locating the roots with x-rays or similar technologies.
As is known, x-rays are capable of differentiating soft tissue from bone and so can provide information as to the location and orientation of the roots of each of the patient's teeth. There are, however, some problems with x-rays. For one, x-rays are capable of damaging human tissue. Thus, when x-rays are used, the patient is only exposed to the lowest dosage necessary to obtain the information for treatment. While being safer for the patient, as the dosage decreases, the information obtained from the x-rays becomes less accurate. There is therefore a trade-off between dosage and model accuracy. As a consequence, because patient safety is paramount, low dosage is used such that the location and orientation of the roots are not generally accurately known. More often than not, images formed from x-ray data are fuzzy and unclear at low dose x-ray levels. The presence of metal fillings and such in or near a patient's teeth only serves to obscure and distort imagery that may already be fuzzy. While there are methods to overcome image distortion due to metal fillings, these methods most often require significant data pre-processing. This type of pre-processing requires significant operator involvement and/or very sophisticated algorithms and for that reason, pre-processing is avoided in all but the most severe cases, which may justify the added time and expense.
Thus, while creation of dental models has been generally successful, orthodontists, software and device manufacturers continually strive to improve the accuracy of models, particularly those that are based on x-ray data, to afford the most efficient and cost effective treatment possible while using only the lowest x-ray dosage and avoiding problems associated with metal fillings and such. In this regard, there exists a need for methods and systems for registration of imagery from multiple sources to form accurate digital models.
The present invention addresses the foregoing and other shortcomings and drawbacks of dental model accuracy heretofore known for use in orthodontic treatment. While the invention will be described in connection with certain embodiments, it will be understood that the invention is not limited to these embodiments. On the contrary, the invention includes all alternatives, modifications, and equivalents as may be included within the spirit and scope of the present invention.
In accordance with the principles of the present invention, a method for registering imageries of a patient's tooth, such as a first imagery of a patient's tooth and a second imagery of the patient's tooth, comprises integrating the first imagery of a tooth and the second imagery of the tooth so that the first imagery is roughly registered with the second imagery. The method includes cross-sectioning the first imagery and the second imagery through the tooth, and moving the second imagery relative to the first imagery to align the cross section of the second imagery with the cross section of the first imagery.
In one embodiment, moving includes at least one of rotating and translating the second imagery relative to the first imagery. Rotating and translating may be relative to a characteristic feature of the tooth in the first imagery.
In one embodiment, the tooth is an anterior tooth, such as an incisor.
In one embodiment, the method further includes selecting a characteristic feature on the tooth and wherein cross-sectioning includes cross-sectioning the first imagery at the characteristic feature.
In one embodiment, selecting a characteristic feature of the tooth includes selecting a characteristic feature of an incisor.
In one embodiment, cross-sectioning includes cross-sectioning along at least one of a sagittal plane, a transverse plane, and a coronal plane.
In one embodiment, moving includes at least one of rotating and translating the second imagery on a plane-by-plane basis in each of the sagittal plane, the transverse plane, and the coronal plane.
In one embodiment, after moving the second imagery, the method further includes evaluating an error in the position of the second imagery relative to the first imagery.
In one embodiment, the method further includes repeating moving the second imagery relative to the first imagery to further align the cross section of the second imagery with the cross section of first imagery.
In one embodiment, after moving the second imagery, the method further includes moving the first imagery relative to the second imagery.
In one embodiment, the first imagery is a surface imagery and the second imagery is a volumetric imagery.
According to one aspect of the invention, there is a method for registering a first imagery of a patient's tooth and a second imagery of the patient's tooth. The method comprises integrating the first imagery of a tooth and the second imagery of the tooth so that the first imagery is roughly registered with the second imagery. The method further includes selecting a characteristic feature of the tooth in the first imagery and moving the second imagery relative to the first imagery about the characteristic feature so as to align the second imagery with the first imagery.
In one embodiment, selecting the characteristic feature includes selecting a feature on an anterior tooth. Selecting the characteristic feature may include selecting a feature on an incisor.
In one embodiment, the method further includes cross-sectioning the first imagery through at least the characteristic feature.
In one embodiment, cross-sectioning includes cross-sectioning along at least one of a sagittal plane, a transverse plane, and a coronal plane.
In one embodiment, cross-sectioning includes cross-sectioning the second imagery.
In one embodiment, the first imagery is a surface imagery of the tooth and the second imagery is a volumetric imagery of the tooth.
In one embodiment, moving includes at least one of rotating and translating the second imagery.
In one embodiment, after moving the second imagery, the method further includes evaluating an error in a position of the second imagery relative to the first imagery.
In one embodiment, the method further includes repeating moving the second imagery relative to the first imagery.
In one embodiment, after moving the second imagery, the method further includes moving the first imagery relative to the second imagery about the characteristic feature.
In one embodiment, the first imagery is a surface imagery and the second imagery is a volumetric imagery.
According to one aspect of the invention, there is a dental registration system that comprises a first imaging system that is capable of capturing information that is usable to prepare a first imagery of a patient's tooth. The dental registration system further includes a second imaging system that is capable of capturing information that is usable to prepare a second imagery of the patient's tooth. The second imagery is different than the first imagery. The dental registration system further includes at least one computer that is operatively coupled to the first imaging system and the second imaging system and includes an integrating application that is capable of manipulating the first imagery and the second imagery. The integrating application is capable of cross-sectioning the first imagery and the second imagery along at least one of a sagittal plane, a transverse plane, and a coronal plane and is capable of moving the second imagery relative to the first imagery.
The accompanying drawings, that are incorporated in and constitute a part of this specification, illustrate various embodiments of the invention and, together with the detailed description of the embodiments given below, serve to explain the embodiments of the invention.
To these and other ends, embodiments of the present invention include systems, methods, and computer readable storage mediums that are capable of forming an accurate model of a patient's teeth through registration of multiple independent imageries. In general, highly accurate surface data and/or shape data of the crowns of a patient's teeth, such as from intra-oral scanning or other scanned data, may be registered with less accurate, though more comprehensive data, such as volumetric data acquired from cone beam computed tomography (CBCT). This integration may ultimately provide a more accurate model of the patient's teeth even when low x-ray dosage x-rays are used and/or when the patient has one or more fillings that tend to distort x-rays. Thus, registration according to embodiments of the invention may produce data from a combination of data from one type of imagery that includes portions of one or more teeth together with data from another type of imagery in which the portions of the patient's teeth are not visible. Imagery may include any information related to the patient's teeth, including, but not limited to, data indicative of any single one or a combination of the surface, shape, relative location, and orientation of one or more of the patient's teeth. Imagery may be displayed for the clinician's visual assessment and manipulation.
Following registration, the model of the patient's teeth may be a compilation of identifiable features found in the separate imageries. For example, all or a portion of the crowns depicted in the model may be from one imagery and all or a portion of the roots depicted in the model may be from a separate imagery. Registration may include independent alignment of the imageries in separate predetermined cross-sectional planes. The predetermined planes may be taken through an overlay of the separate imageries at a common tooth feature. The common feature may include one or more landmarks characteristic to a specific tooth. The imageries may be manipulated or moved relative to one another about the common feature to bring about their registration.
Manipulation may include translating and rotating of one imagery relative to another imagery on a plane-by-plane basis. In each selected plane, a practitioner may manipulate the imageries to pattern match cross sections of a tooth in each of the imageries. Pattern matching may be based on human perception or an automatic algorithm and may be focused around anterior incisors. Embodiments of the invention therefore minimize the effect of distortion associated with fillings typically found in the crowns of posterior teeth. By embodiments of the invention, the accuracy of a digital model of the patient's teeth, particularly the roots of the patient's teeth, is improved. Registration according to embodiments of the invention improves the overall accuracy and detail of the constructed, final 3-D model of the patient's teeth. Advantageously, embodiments of the invention may not require best-fit calculations or threshold calculations and so lack the complication and error associated with those calculations. Nevertheless, embodiments of the invention produce accurate 3-D models of a patient's teeth because the methods and systems according to the present invention are less influenced by noisy data, distortion in the data, and/or incomplete data.
In an exemplary embodiment and with reference to
With continued reference to
With regard to an intra-oral imaging system, imaging system 14 may include a wand 22 having an imaging sensor 24 and a light source 26. The imaging sensor 24 may be an intra-oral camera that captures information regarding the oral cavity of the patient when exposed to light, for example from the light source 26. As is known, the practitioner may insert at least a portion of the wand 22 into the patient's mouth. Using the light source 26 and the imaging sensor 24, the practitioner may capture data of all or selected crowns of the patient's teeth. A crown of a tooth is a solid object, and the surfaces of the crown are boundaries of that object. The data collected may include surface data and/or shape data of the crown that may be represented by a surface mesh of node points connected by triangles, quadrilaterals, or another polygon mesh. The process of creating a mesh may be referred to as tessellation. The data collected may be used to construct imagery of one or more of the patient's teeth. The surface data may also include or be processed to extract information regarding the reflectivity and translucency of each of the patient's teeth. This information with regard to each crown is different from the reflectivity and translucency of the patient's gingiva. The imaging system 14 and/or the computer 12 may process the surface data in a manner so that the patient's crowns may be distinguished from the surrounding gingiva based on the reflectivity and the translucency differences. This may facilitate segmentation of the crown, when necessary. It will be appreciated that the imaging system 14 is not limited to an intra-oral imagining system.
As an alternative, the light source 26 may be incorporated into a scanner (not shown) that emits laser light. In this exemplary embodiment, the imaging sensor 24 may capture laser light reflected from an impression (e.g., a PVS impression) of the patient's teeth external to the patient. In this way, surface data for at least the crowns of the patient's teeth may be captured though the light source 26 and imaging sensor 24 may not be a part of an intra-oral camera.
The imaging system 14 may ultimately construct surface imagery 30 (e.g., shown in
The imaging system 14 may also include another imaging system that is capable of producing imagery based on information that is different from the reflected light information used to construct surface imagery 30. To ease description only, in one embodiment, the computer 12 may also be operatively coupled via the wireless connection 16 to a cone beam computed tomography (CBCT) imaging system 40. While being described separately, the intra-oral imaging system 14 and the CBCT imaging system 40 may form a single system. The CBCT imaging system 40 may utilize the x-ray spectrum (i.e., wavelengths in the range of 0.01 nm to 10 nm) to produce images of the patient's teeth that are not readily observed with light in the spectrum of the intra-oral imaging system 14. Because x-rays pass through human tissue, x-rays may be utilized to develop imagery of the position and orientation of the roots of one or more of the patient's teeth. It will be appreciated that the methods and systems described herein are not limited to using visible light or x-rays. In fact, imagery produced from light at different wavelengths may be useful according to embodiments of the invention.
The exemplary CBCT imaging system 40 may include a rotating gantry 42. An x-ray generator 44 and an x-ray detector 46 may be affixed to and rotate with the gantry 42. The x-ray generator 44 may deliver a divergent pyramidal or cone-shaped source of ionizing radiation toward a patient positioned between the generator 44 and the x-ray detector 46. The x-rays detected by the detector 46 thus contain information specific to the skeletal and other tissues of the patient. Exemplary CBCT imaging systems include iCat from Imaging Sciences International, Carestream from Carestream Health, Planmeca from Planmeca USA, Inc., and Sirona from Dentsply Sirona.
As is known, x-rays pass through human tissue but are absorbed at different rates by different tissue. Because of the relatively high energy associated with x-rays, the practitioner may operate the CBCT imaging system 40 to deliver the lowest dose of radiation possible to the patient while the detector 46 captures sufficient volumetric data to develop a volumetric image by which embodiments of the invention are utilized to prepare a 3-D model of the patient's teeth. By way of example and not limitation, low radiation dosage means from about 1 μSv to about 30 μSv per scan. Low radiation dosages, while safer for the patient, have a downside. As the radiation dosage is reduced, the images of the patient's tissues are not as clean, that is, the detector 46 may be incapable of clearly differentiating the desired information from useless noise. In many instances, the level of noise relative to the useful data makes evaluation and treatment of the patient more difficult. Advantageously, embodiments of the invention may allow a lower dosage of x-rays in the above range to be used while maintaining or improving the accuracy of the 3-D model of the patient's teeth.
According to the CBCT imaging system 40, x-rays pass through the patient and into the detector 46 as the gantry 42 rotates around the patient. In a single rotation of the gantry 42, the CBCT imaging system 40 may generate volumetric data sufficient to form a plurality of planar projection images (from 100 to more than 600 image slices) of the patient's jaws and maxillofacial structures including soft tissue, hard tissue, teeth, etc. The individual planar projection images may be stacked to obtain volumetric imagery 50 of at least the patient's jaws. Stacking or reconstruction of the planar projection imagery by the CBCT imaging system 40 or another computer system (e.g., the computer 12) produces the volumetric imagery 50 that may have a voxel resolution ranging from about 0.4 mm to about 0.0076 mm. The volumetric imagery 50 may thus include volumetric data of both the crown and the root of one or more teeth in each of the patient's jaws as well as information regarding the surrounding tissues and contain data in three-dimensions of the patient's jaw. In one embodiment, the volumetric imagery 50 includes data regarding the location and orientation of each tooth in the patient's jaws in three dimensions. The volumetric imagery 50 obtained via x-rays may include radio density information. This information may be processed in combination with the surface data and/or shape data when registering the surface imagery 30 and the volumetric imagery 50, as is described below. Other light sources or other types of energy may be utilized to provide volumetric data regarding one or more of the patient's teeth. By way of example only, tomographic imagery, ultrasonic imagery, magnetic resonance imagery (MRI), etc., may be utilized to acquire volumetric data useful according to embodiments of the present invention.
Further in this regard, the exemplary embodiment shown in
In general, integrating application 52 may include program code that typically includes computer readable instructions. These are resident at various times in various memory and storage devices in the computer 12 and that, when read and executed by one or more processors in the computer 12, cause that computer 12 to execute operations and/or elements embodying the various aspects of the embodiments of the invention. Computer readable program instructions for carrying out operations of the embodiments of the invention may be, for example, assembly language or either source code or object code written in any combination of one or more programming languages. Any particular program nomenclature herein is used merely for convenience, and thus embodiments of the invention are not limited to use solely in any specific application identified and/or implied by such nomenclature. Furthermore, given the generally endless number of manners in which computer programs may be organized into routines, procedures, methods, modules, objects, and the like, as well as the various manners in which program functionality may be allocated among various software layers that are resident within a typical computer (e.g., operating systems, libraries, API's, applications, applets, etc.), the embodiments of the invention are not limited to the specific organization and allocation of program functionality that may be described herein.
In one or more additional embodiments, the surface imagery 30 and the volumetric imagery 50 (or the corresponding data) 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 computer 12 for reading and processing by the integrating application 52. Computer readable storage media, which is inherently non-transitory, may include volatile and non-volatile and removable and non-removable tangible media implemented in any method or technology for storage of information, such as computer-readable instructions, data structures, program modules, or other data. Computer readable storage media may further include RAM, ROM, erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other solid state memory technology, portable compact disc read-only memory (CD-ROM), or other optical storage, magnetic cassettes, magnetic tape, magnetic disk storage or other magnetic storage devices, or any other medium that can be used to store the desired information and which can be read by a computer. A computer readable storage medium should not be construed as transitory signals per se (e.g., radio waves or other propagating electromagnetic waves, electromagnetic waves propagating through a transmission media such as a waveguide, or electrical signals transmitted through a wire).
With reference to
Also shown in
In that regard, the volumetric imagery 50 differs from the surface imagery 30 in at least the information about the same teeth of the patient. For example, as described above, the system 10 may include a CBCT imaging system 40 that produces volumetric imagery 50 with regard to the patient's teeth. In the exemplary embodiment of the volumetric imagery 50, specific cross sections of the imagery corresponding to the volumetric data are shown in
Referring to
In
In addition to the streaks 96, the data associated with the tooth 66 adjacent the tooth 68 with the filling 94 may be distorted. So, distortion in the data caused by fillings is not localized to a single tooth, i.e., the tooth with the filling, but can extend to one or more unfilled teeth adjacent the filling. Ultimately, in regions proximate (within one or two teeth) the filling 94, there may be no data or insufficiently accurate data with which to construct an accurate enough 3-D model on which to plan the patient's treatment. In this regard, the orientation of a tooth (particularly a crown) with a filling may remain unknown in the volumetric imagery 50 and thus present a problem for the practitioner for establishing a prognosis and for planning treatment based solely on the volumetric imagery 50.
By contrast, in
With reference to
To that end, and with reference to
With reference to
In one embodiment, the modified volumetric imagery 98 may include volumetric data from the minimum slice 100 to the maximum slice 104. Any volumetric data external to the minimum slice 100 and the maximum slice 104 is discarded. In this respect, volumetric data not pertinent to the patient's orthodontic treatment is removed. While containing less data than the volumetric imagery 50, the modified volumetric imagery 98 facilitates more efficient manipulation of the volumetric data pertinent to the patient's teeth.
In one embodiment, and with reference to
The surface imagery 30 may include holes. These are areas of the crown that are not imaged by the imaging system 14. Surface and/or shape data is not available in the holes. The volumetric imagery 50 may be used, such as by the integrating application 52, to fill in at least some data with regard to the crowns at these areas according to commonly owned U.S. Pat. No. 9,135,498, which is incorporated herein in its entirety. It will be appreciated that embodiments of the invention are not limited to any hole filling procedure.
In one embodiment, and with reference to
Once the imageries 30 and 98 are in the same coordinate system, the practitioner may roughly register them by manipulating the modified volumetric imagery 98. Rough registration may include positioning the surface imagery 30 and the modified volumetric imagery 98 reasonably close to one another so that the central incisors in each image overlap to a degree. By way of example, the images of the central incisor in each imagery 30, 98 may touch one another. Rough registration generally does not produce exact alignment. Further, while the central incisors may touch, alignment between the two imageries may decrease at locations away from the incisors so that the molars, for example, in each imagery do not touch or are visually out of alignment as is shown best in
While each of the imageries 30 and 98 may include its own coordinate system, in one exemplary embodiment, in the overlapping imageries, the surface imagery 30 establishes a master coordinate system and the modified volumetric imagery 98 is manipulated within that master coordinate system. By way of example only, the coordinate system of the surface imagery 30 may be designated as Ci={Bi|(Xi, Yi, Zi)}, where Bi is a characteristic feature on a selected tooth at the coordinate Xi along an X axis, Yi along a Y axis, and Zi along a Z axis of the coordinate system Ci of the surface imagery 30. The coordinate system of the modified volumetric imagery 98 (or volumetric imagery 50) may be designated as Cv={Bv|(Xv, Yv, Zv)}, where Bv is a characteristic feature on a selected tooth at the coordinate Xv along an X axis, Yv along a Y axis, and Zv along a Z axis of the coordinate system of the modified volumetric imagery 98. Each of the coordinate systems Ci and Cv may be utilized during registration of the surface imagery 30 and the modified volumetric imagery 98. In one embodiment, Ci is the master coordinate system during initial registration and Cv is the slave coordinate system. During later stages of registration, Cv may be the master coordinate system and Ci may be the slave coordinate system.
Alternatively, and according to one embodiment of the invention, the modified volumetric imagery 98 may establish the master coordinate system initially and so the surface imagery 30 may be rotated and translated relative to the fixed orientation of the coordinate system of the modified volumetric imagery 98. The surface imagery 30 may then establish the master coordinate system during later stages of registration.
With reference to
Referring to
By alignment, the peripheral outline of the cross sections may be matched so as to be congruent if the cross sections are exactly the same size and shape. Otherwise during alignment there may be deviations between the peripheral outlines of the two cross sections. In this case, the two cross sections may be pattern matched so that they appear to visually align. That is, the outlines of the cross sections may be brought into visual alignment. This type of pattern matching may include moving the slave coordinate system relative to the master coordinate system.
With reference to
In accordance with the description above, Ci may be the master coordinate system (Cmaster) during an initial stage of registration and Cv may be the slave coordinate system (Cslave) that is moved relative to Ci according to M (Ci, Cv): {Cv->Ci}. As described above, Ci and Cv may alternate as the master coordinate system. For example, Ci may be the master coordinate system when imagery of the maxillary jaw 80 is registered and Cv may be the master coordinate system when the imagery of the mandibular jaw 60 is registered.
When multiple planes are considered in reference to
where, in one embodiment, the error is measured by a difference in running averages of the magnitudes of M in each plane. In other words, as the iteration of M (Cmaster, Cslave) progresses, the amount of M in each plane may be reduced. In this way, the cross section in the slave coordinate system converges on the cross section in the master coordinate system. When the iteration of M (Cmaster, Cslave) reaches a point where the correction produced by a consecutive iteration is insignificant, the cross section in the slave coordinate system is considered to be registered onto the master coordinate system, and the process is stopped. If both the mandibular arch 60 and the maxillary arch 80 are registered, the general representation may include M (Ci, Cv): {Cv->Ci}| first arch and M (Cv, Ci): {Ci->Cv}| second arch, where the first arch includes one of the arches 60 and 80 and the second arch includes the other of the arches 60 and 80. In one embodiment, the first arch and the second arch are registered separately.
Specifically as the general representations described above apply to an exemplary embodiment and with regard to
According to Ms (Ci, Cv): {Cv->Ci}| first arch, in which Ci defines the master coordinate system and the first arch is the maxillary arch 80, the modified volumetric imagery 98 is moved to orient the cross section of the crown of the incisor 82 into alignment with the crown of the incisor 82 (shown as a black profile in
In that regard, the practitioner may utilize pattern recognition techniques to bring about alignment of the surface imagery 30 and the modified volumetric imagery 98 in the sagittal plane of the maxillary arch 80. Pattern recognition techniques mimic human perception. In that regard, in embodiments of the invention in which the practitioner is able to discern the teeth in the modified volumetric imagery 98, pattern recognition algorithms may be used to accurately align the imageries 30, 98. By finding the precise location and orientation of the cross section of the tooth in the modified volumetric imagery 98 relative to the cross section of the tooth in the surface imagery 30, it is possible to obtain deterministic information on how to correct the misalignment between surface imagery 30 and modified volumetric imagery 98.
As a result of rotation R and/or translation T, the modified volumetric imagery 98 is moved relative to the surface imagery 30 so as to align the cross section of the incisor 82 in the modified volumetric imagery 98 with the corresponding cross section of the incisor 82 in the surface imagery 30. This is shown in
Further, other characteristic features on the selected tooth may define Bi and Bv. For example, points determined by measuring one or more dimensions on the selected tooth may be used. By way of specific examples, a centroid of the selected tooth crown, a midpoint, or a most prominent point on the exterior surface of the tooth may be used. The midpoint may be located by identifying a facial axis of the clinical crown (FACC line) for the selected tooth and measuring one half the height of the crown (generally defined from the gingival margin to the incisal edge) on the FACC line. In one embodiment, and with reference to
There may remain a slight misalignment between the surface imagery 30 and the modified volumetric imagery 98 following an initial movement Ms. This may be addressed by additional movements Mt and/or Mc. In that regard and with reference to
As is described below, once the cross sections are aligned in the sagittal plane, the practitioner may proceed to the next plane, such as coronal plane 126 or transverse plane 128 (
By way of further example, and with reference to
Each of Ms, Mt, and Mc may be completed in a series and the error calculated and checked against the termination threshold for that series. If the error is greater than the termination threshold, each of Ms, Mt, and Mc may be repeated. So, the registration process may be repeated until the calculated error is less than the termination threshold. In this way, any misalignment between the cross sections of the tooth in the surface imagery 30 and in the modified volumetric imagery 98 is corrected in each plane independently for the maxillary arch. Advantageously, this greatly reduces complexity of alignment of the coordinate systems, because embodiments of the invention eliminate the necessity of evaluating simultaneous movement across multiple planes. The order of operations Ms, Mt, and Mc described above is not limiting. The order of each of the movements Ms, Mt, and Mc may be different from that shown and may vary even between the first iteration and last iteration of the overall operation M (Cmaster, Cslave)|maxillary arch. When the error in alignment is reduced to less than the termination threshold, the registration of the modified volumetric imagery 98 to the surface imagery 30 for the patient's maxillary arch 80 may be terminated. This leaves the imageries 30 and 98 of the mandibular arch 60 to be registered, if necessary.
In that regard, according to
In one embodiment, each of Ms, Mt, and Mc is completed in the sagittal, transverse, and coronal planes of the mandibular arch 60, respectively, in a manner similar to that described above with regard to the maxillary arch 80. In particular, registration of the mandibular arch 60 according to M (Cv, Ci): {Ci->Cv}| mandibular arch may include:
Ms (Cmaster, Cslave)|mandibular arch;
Mt (Cmaster, Cslave)|mandibular arch; and
Mc (Cmaster, Cslave)|mandibular arch, in which Ms describes movements in a sagittal plane, Mt describes movements in a transverse plane, and Mc describes movements in a coronal plane similar to Ms, Mt, and Mc described above with regard to the maxillary arch 80.
In one embodiment, Cslave as a result of M (Cmaster, Cslave):{Cslave->Cmaster}| first arch, when the calculated error is less than the termination threshold, becomes Cmaster for the second arch in M (Cmaster, Cslave):{Cslave->Cmaster}| second arch. In an exemplary embodiment described above with reference to
Switching the master coordinate systems to the modified volumetric imagery 98 when proceeding with M (Cmaster, Cslave)| mandibular arch assumes that the occlusion or bite conditions of the patient during the CBCT scan is a good model to follow and that the occlusion of the intra-oral imagery (i.e., surface imagery 30) should be slightly modified to match the modified volumetric imagery 98. It will be appreciated that the imageries of the mandibular arch and maxillary arch in the surface imagery 30 may be taken separately because the patient's mouth is open or the impressions are of separate arches. Further in that regard, the two imageries 30 and 98 should be taken within a short time of one another, such as in a single office visit. This timing ensures that the teeth 62, 64, 66, and 68 in the mandibular arch 60 or the teeth 82, 84, 86, 88 in the maxillary arch 80 have not moved relative to one another within the gingiva 70 between development of surface imagery 30 and volumetric imagery 50. At 216 in
The registration process of M (Ci, Cv): {Cv->Ci}| maxillary arch and then M (Cv, Ci): {Ci->Cv}| mandibular arch may be repeated either with respect to one arch and then the other arch or M may be repeated within a single arch multiple times. Alternatively, a combination of the above may be completed. By way of example, registration may include 3 or 4 complete rounds of M (Ci, Cv)| first arch followed by 3 or 4 complete rounds of M (Cv, Ci)| second arch. Advantageously, embodiments of the invention do not rely on fitting or thresholding schemes. The resulting alignment of the cross sections of the selected tooth on each of the surface imagery 30 and the modified volumetric imagery 98 is not an approximation and is not sensitive to poor density distribution across the modified volumetric imagery 98 due to low x-ray dosage or for other reasons. It will be appreciated that the volumetric imagery 50 (i.e., the unmodified volumetric imagery) may be utilized instead of the modified volumetric imagery 98. While registration is described with regard to the practitioner visually manipulating the surface imagery 30 and the modified volumetric imagery 98 via the integrating application 52, for example, manipulation may also be performed automatically via an algorithm on the computer 12.
Advantageously, movement M in one plane, such as movement in one of the sagittal, transverse, or coronal planes, may reduce error between imageries 30 and 98 in one or both of the other two planes. This is shown by way of example with reference to
By way of additional example and with reference to
In one embodiment and with reference to
With regard to M (Cmaster, Cslave)| maxillary arch, above, registration of the imagery 140 to the imagery 150 in the sagittal plane according to Ms may include translation and rotation due to the alignment of two fixed length vectors: (1) vector Rv between BC points on two adjacent central incisors 130, 132 in the imagery 140 and (2) vector Ri between BC points on two adjacent central incisors 130, 132 in the imagery 150. In particular, Ms may include translation T and compound rotations W with respect to a midpoint Pv of vector Rv relative to a midpoint Pi of vector Ri. Translation T (represented as a vector in
While the invention has been illustrated by a description of various embodiments and while these embodiments have been described in considerable detail, it is not the intention of the Applicant to restrict or in any way limit the scope of the appended claims to such detail. Additional advantages and modifications will readily appear to those skilled in the art. The invention in its broader aspects is therefore not limited to the specific details, representative apparatus and method, and illustrative examples shown and described. Accordingly, departures may be made from such details without departing from the spirit or scope of the Applicant's general inventive concept.
This application claims the benefit of U.S. Provisional Patent Application Ser. No. 62/433,441 filed on Dec. 13, 2016, the disclosure of which is expressly incorporated by reference herein in its entirety.
| Number | Date | Country | |
|---|---|---|---|
| 62433441 | Dec 2016 | US |
