WO2012090211A1

WO2012090211A1 - Augmented reality computer model facebow system for use in dentistry

Info

Publication number: WO2012090211A1
Application number: PCT/IN2010/000865
Authority: WO
Inventors: Jeevan Kumar SANTIAGO
Original assignee: Santiago Jeevan Kumar
Priority date: 2010-12-29
Filing date: 2010-12-29
Publication date: 2012-07-05

Abstract

An Augmented Reality computer model for use in dentistry is implemented using an alpha blending and optic flow analysis software. Recorded patient images or videos are superimposed over the teeth or casts during and/or after the treatment procedure. Improved real time feedback is generated by the system in the presence and absence of the patient. The face bow system enables determination of the hinge axis of the jaw of the patient, precise mounting and transfer of dental models to the articulator, tracing jaw movements, communication of aesthetic parameters of the patient to the dental laboratory and real time design, planning or modeling of restorations or prostheses to fit the patient's smile.

Description

AUGMENTED REALITY COMPUTER MODEL FACEBOW SYSTEM FOR USE IN DENTISTRY

DESCRIPTION OF THE INVENTION

BACKGROUND ART

In Dentistry, there is an ever growing need for reliability and precision. After the patient leaves the dental office, the patient data stored is used for a diverse range of purposes. The clinician or the dentist would send the patient data or info to a dental laboratory technician. After mounting the dental models or casts in a device popularly known as the dental articulator, dental restorations are manufactured to fit the patient well.

The dental articulator serves to hold the dental models or casts in a precise relationship like how the upper and lower arches of teeth relate to each other in the patient's mouth. They must also be held in a precise relation to the hinge axis of the articulator in such a way that the opening and closing of the patient's jaw can be precisely reproduced in the casts or models mounted on the articulator. Failure to record and reproduce upper and lower arch relationships in the articulator may reflect in a defective or incorrect restoration or prosthesis. While being fitted in the mouth, the clinician would have to spend valuable chair time correcting the discrepancies or redo the dentures or crowns. While manufacturing a restoration or prostheses that would be visible while the patient smiles, the dental laboratory technician must be able to correlate the work done over the bench with the actual smile of the patient.

PRIOR ART

References from both scientific and patent literature can stated that aim at solving the existing challenges mentioned above and can be broadly classified into two groups for the sake of convenience. Group I involves knowledge, methods and devices used to primarily record and transfer information of the functional aspects of the patients bite or occlusion. U.S. Pat: Nos. 4,836,779; 4,330,277; 3,307,262; and 3,866,323 describe mechanical face bows. US Pat. No. 4,261,696 ,US Pat .No. 3,431,649 U.S. Pat No US 2005/0075585 Al U.S. Pat No US 2009/0305185 Al ,U S Pat No US 2003/0204150A1. The above patents describe methods, devices and techniques that are used to record the hinge axis of the jaw through mechanical and complex software based means. The complexity, cost and reliability are factors that determine the successful implementation of the above devices and methods in the dental clinical setting. Group II involves knowledge, methods and devices used to primarily record and visualize the aesthetic aspects of the patient's bite or occlusion

U.S. Pat No US 2007/0009855A1, U.S. Pat No US 2007/0196782, U.S.Pat : 2009/0291 08A1 discuss methods for enhanced visualization and communication of the aesthetic form of the patient's teeth for chair side diagnostic evaluation and communication.

The methods and devices mentioned in the patent literature above have certain advantages and disadvantage either in the cost or complexity factor. This has led to the wide spread use of "try- in" dentures or wax-ups that are the cost effective and reliable ways to record and convey esthetic information to the dental laboratory. But the wax-iips take considerable amount of fabrication time. It would be advantageous if the clinician or dental laboratory technician would be able to correlate the work done over the casts or dental models mounted in the dental articulator in the absence of the patient. There are also chair side procedures that require correlation with the actual patient's smile. This is when the patient would be administered an anesthetic for aesthetic procedures like crowns and veneers wherein the clinician would be working over a retracted view of patient's teeth requiring correlation with the smile. The AR (Augmented Reality) dental face bow records functional and esthetic parameters of the patient and reproduces the recorded patient graphic data over the articulator.

BRIEF DESCRIPTION OF THE INVENTION

The Augmented Reality dental model is based upon AR (Augmented Reality) implementation using a computer, camera bearing devices described as face bows and software. The basic function of the software is to superimpose recorded video over live video footage of the patient within a frame of reference on the computer screen. There are two embodiments of a method and device that are used to capture the functional and esthetic parameters of the patient. The first embodiment comprises of a jaw clutch that engage the jaw of the patient bearing an adjustable frame. Cameras and pointer are mounted on a frame that focuses on the front and sides of the patient's face as the patient makes jaw movements. Transparent graphs and fiduciary markers are placed over the live video footages on screen obtained from the cameras for jaw motion analysis and hinge axis determination. The cameras freely move along with the jaw attached to the bite fork maintaining a specific distance from the patient without any mechanical contact or restrictions. The transparent graphs and fiduciary markers enable the clinician to analyze and quantify jaw movement in a particular plane and determine the axis of rotation of the jaw. The recorded patient video obtained from the cameras mounted on the frames is used to orient dental models in an articulator in relation with the hinge axis using live video transparency features.

In the second embodiment of the invention, a right angled frame or rod is used with a camera that focuses on the patient's face to capture smile data from a stable point of reference or location. The video and image data captured by the camera is stored in a computer and used as virtual information that is superimposed on the patient's real time video footage for aiding chair side smile design procedures or superimposed over the patient's dental models or casts mounted in the articulator for improving the level of communication with a dental laboratory. The camera has a perforated plate on top which is used for performing a bite registration. The bite registration is performed using a bite fork which has a perforated plate on one end and a bite plate on the other. A quick setting, rigid bite registration material is introduced between the perforated plates of the camera and bite fork to attach or seal them together in the position at which the camera acquired smile data. The bite fork along with the camera is sent to the dental laboratory technician for mounting the camera before the dental articulator at the same position at which the camera captured smile data of the patient.

The smile data of the patient is superimposed or alpha blended over the live cast footage for enhancing correlation between the work done on the dental technician's bench and the patient who is not present.

BRIEF SUMMARY OF DRAWINGS Fig 1 shows the face bow system assembly and parts and how it relates to the computer and the patient for determining the jaw hinge axis and studying mandibular movements.

Fig 2 shows the face bow system assembly and parts and how it relates to the computer, the patient and articulator for determining the jaw hinge axis and studying mandibular movements.

Fig 3 shows the face bow assembly and parts and how it relates to the computer, patient and the articulator for recording aesthetic parameters of the patient and transferring the information to the articulator.

Fig 4 shows the face bow assembly and system and how it relates to the patient for aesthetic correlation- during chair side procedures.

Fig 5 shows how a camera can be attached to an existing commercially available pantograph for studying and recording mandibular or jaw movement using software.

DETAILED DESCRIPTION OF THE INVENTION

In the field of dentistry it is conventional for a dentist to obtain impressions of the patient's dental structure in order to diagnose the patient's needs. Normally, these impressions are made by the use of a tray filled with impression material which the dentist places of the patient's teeth. The dentist then subsequently makes a model or cast of the dental patient's teeth from the impression mold and sends it to the dental laboratory technician. A dentist may also use a CAD CAM route to acquire three dimensional data of patient's teeth. -

The dental laboratory technician would manufacture these higlily esthetic and biocompatible restorations or prostheses for the patient. There are . a few cases or instances where the clinician may prefer to complete the treatment chair side right in the patient's mouth. Placement of composite or CAD CAM veneers to improve the overall smile or appearance of the patient is one such exemplary procedure of treatment done chair side. Conventionally, the clinician has to prepare or shape teeth through a high speed dental drill, take a measurement of the prepared tooth or teeth and send it to the dental laboratory for the required work to be done outside the patient's mouth. The dental laboratory technician receives the dental models and other important records from the clinician and starts fabricating the required denture or restoration for the patient.

The grinding down of natural dentition or teeth for creating abutment or support teeth for a given fixed dental bridge is being eliminated by the placement of implants. The stability of a conventional denture is being improved by the availability of implants and precision milled framework that connect these implants together. The lower denture in many patients can easily be supported by implants for added stability while mastication or chewing. All these modern procedures are planned using computer tomography techniques such as CBCT where a 3D virtual model of the patient is used , to plan the result even before the surgical procedure. There are also vast advancements being made in material science, research and development where very strong biocompatible all ceramic restorations are being developed that won't corrode in the patient's mouth and would resemble natural teeth. These materials along with the procedures such as CBCT and other treatment planning software and the ubiquitous CAD CAM revolution are transforming Dentistry. These modern protocols and techniques available have created , a scenario where implants directly fix artificial teeth to the bone without the periodontal mechanisms of support found in natural teeth. This means necessitating a more carefully planned occlusal scheme for the patient. The jaw joints that make chewing or occlusion possible should not be compromised in any manner due to ill fitting restorations or dentures that don't match the patient's occlusal scheme^" or bite.

However, in order to clinically diagnose a patient's dental needs and proceed with the right treatment, a dentist must be able to ascertain the location of the patient's teeth in relation to his jaw and jaw hinge axis. ' The clinician must also be able to deliver the patient an improved appearance or smile that would satisfy and fulfill the patient's expectations or desires. Sometimes during treatment, the VDO (Vertical dimension of occlusion) or simply called the height of the bite has to be raised to compensate for all the wear and tear that would have taken place on teeth. Particularly when the VDO is raised, the clinician or dental laboratory technician working on the case would need information regarding the precise jaw opening and closing path also known as the arc of closure and along with information on other mandibular or jaw movements that occur sideways or laterally. This information is required to visualize how the upper and lower teeth occlude or functions in a patient. With this information at hand the clinician or dental laboratory technician is able to plan or foresee ways through which restorations or prostheses could be devised without causing occlusal interferences in the patient's mouth.

There are many procedures, techniques and devices in the scientific literature used to record mandibular movement occurring three dimensionally in all the three facial planes and a mention of all of them is beyond the scope of the current disclosure. It is known for those skilled in the art that mandibular movements are extremely complex movements occurring in all the three planes of the face. This has led to the use of many devices that aim at capturing jaw movement and the jaw hinge axis center about which the jaw is able to purely rotate without any excursion or translation in its path. There are other movements like translation combined with a rotation the jaw can make while the patient opens and closes his or her mouth. Jaw shifts occurring laterally during the movements are known as the Bennett shift or the working side shift of the jaw (the side the mandible moves while chewing). These extremely complex three dimensional movements of the jaw must first be properly analyzed or studied in a prospective patient about to undergo rehabilitative treatment. After studying and isolating all the anomalies or abnormalities of jaw movement in a patient, they have to be accurately replicated in an articulator for applying the information recorded while fabricating restorations or prostheses. In-order to capture the exact location of the patient's teeth relative to the jaw joint, it has been conventional to mount the impression tray and bite-fork on a face bow. There are a few easy to record and replicate positions of the jaw of a healthy individual of patient for instance the centric relation position. Centric relation ( CR ) is that position of the jaw where the jaw purely rotates on a central axis. Any ordinary articulator would also be able to make the simple hinge movement reliably and most accurately. After the CR point of contact of posterior teeth in the patient's mouth, the jaw translates forward into the place where maximum contact of teeth is observed is also known as the MI (Maximum Interception) position. The MI position has not been chosen as the ideal position to take a bite index or a record. Instead, the CR position which is the most retruded position of the jaw when the patient bites repeatedly using the back teeth has been used to record the bite. The condoles or jaw joints are at the limiting walls of the joint fossae and the teeth occlude at a single reproducible position that the clinician tries to record with a centric check bite record without any sideward deviation or translation of the jaw. Therefore it is clear that the CR record can be taken with a degree of jaw opening where the jaw is able to trace the pure arc of closure. Forceful manipulation of the jaw into this retruded CR contact position has in many instances distorted the record. There have been no accurate guides so far for the clinician ^'to tell when the patient consistently is biting on the position where the CR bite record can be taken. At this juncture it must be known that an important scope of the disclosure or invention is to provide a real time guide to record, visualize and correlate all mandibular movements occurring in the patient. Once the CR record is obtained , there must also be a method to relate the CR record obtained to the hinge axis of the patient .The dentist then ascertains the location of the patient's teeth by measuring and recording the relative distances between the bite-fork and the patient's jaw hinge axis, as defined by the hinge pointers in the face bow. The face bow record obtained is used to mount dental models or casts in the dental articulator at exactly the same anatomic relationships found to exist between the teeth and the jaw joint axis in the patient. The aesthetic restoration or prosthesis is then planned and fabricated to fit the patient's individual smile.

Failure in reproducing anatomical relationships, orientation or features of the patient's arches in the dental articulator would result in restorations and/or prostheses that would not fit the bite or occlusion of the patient well because of the wrong arc of closure of the dental casts or models in the articulator. Failure in creating aesthetic restorations or dentures that don't fit the smile of the patient well would result in a very unsatisfied patient.

The Augmented Reality dental model is based upon AR (Augmented Reality) a new technology involved with the viewing of real time events along with superimposed graphic data. This has been envisioned in order for the user of the system to benefit by having virtual information exactly wherever and whenever necessary. An example for AR implementation in Dentistry is where live video footage and recorded video virtual information or data of the patient are superimposed one on top of the other. Though AR application development in general involves higher costs, a novel AR application system and model can be easily implemented for use in Dentistry by using simple and commonly available techniques such as real time alpha blending that is common to all modern computers and operating systems. The AR dental computer model system about to be disclosed would also implement object tracking features that are synonymous with Computer Vision applications. Open Computer Vision ( OpenCV) is a well known library of code that has been designed and maintained by Intel Corporation for research and future, application development related to computer vision and object recognition. A specific tracking algorithm known as the Lucas Kanade algorithm would be implemented for tracking jaw movements of the patient in the AR implementation. The cameras used to capture the videos or images of the patient are preferably of high resolution mounted on frames that are used to capture the functional and aesthetic parameters of the patient. . While one frame comprises of a mandibular clutch that engages the jaw of the patient, there is another one employed to capture the patient's aesthetic parameters by resting securely on a frame suspended from the patient' s head and nasal bridge or nasion . Cameras are fixed on the frames to focus on the patient as the patient makes jaw movements or smiles. The cameras are interfaced to a computer through wired or wireless means. Transparent graphs and markers are placed over the videos obtained for jaw motion analysis and hinge axis determination. Since the cameras freely move along with the jaw without any mechanical contact or restrictions like impingement of ear inserts, they are able to capture mandibular movement more precisely and with the least amount of discomfort to the patient. The recorded video information is then used to orient dental models in an articulator using video transparency. The transparent graphs and markers enable the clinician to analyze and quantify jaw movement in a particular plane and determine the rotation axis of the jaw.

In one such embodiment of the invention, the face bow system employed for studying jaw movements, locating and transferring the hinge axis of the jaw is seen fig 1. The face bow in fig 1 is exemplarily used for studying or quantifying mandibular or jaw movements in various facial planes. A computer 1 that has a USB connection or blue tooth connectivity feature 12 & 13 is used to receive inputs from cameras 3, 7 & 8. These cameras are located in an assembly frame which is attached to a bite fork clutch 6 through screw mechanisms 5 and 10. Camera 7 that is located at side arm of the frame is located at a distance represented by 11 in fig 1 and focuses on a pointer or camera 8 in the other arm. The cameras can be attached or detached to the bite fork clutch 6 or can be attached to the conventional face ^'bows through mechanism 4. The purpose of fixing cameras to existing kinematic face bows as in fig 5 is to' eliminate the need for using micro adjustable side arms and other mechanical devices for recording jaw movement .

The kinematic face bow locates the true hinge axis point of the jaw using a micro adjustable side ann, a stylus and a marking stage or platform where a small sheet of graph paper is stuck. There are numerous references to this device in the patent and scientific literature and a detailed description of them all is out of scope for the current disclosure. The micro adjustable side arms are connected to a bite fork clutch that is inserted into the mouth of the patient. The stage or the platform where the stylus must mark is fixed to the patient's head. The patient is asked to make various jaw movements and the movement of the stylus over the marking platform is observed closely. The stylus is repeatedly adjusted so that while the patient bites in centric relation the stylus would no longer arc. The point where the stylus no longer arcs is determined to be the hinge axis point of the patient. Due to the elaborate nature and complexity of kinematic face bow and pantograph, many clinicians have resorted to the use of an arbitrary face bow for recording the jaw hinge axis. The arbitrary face bow apart from using an approximation as guide for determining the hinge axis would use a mechanical clamp to record and transfer the arbitrary hinge axis position. There are studies that indicate that due to tissue impingement or settling of the ear piece of the face bow into the ear canal and issues like over tightening of the clamp that connects the bite fork to the frame, a distortion of the true recorded position of the maxillary arch occurs. Therefore it is clear from the above discussion that there is not yet a system available in Dentistry to cost effectively, accurately and easily perforin a face bow transfer.

hi fig 5, 45 is the specially designed lightweight camera that is attached to a red 46 that is bent at right angles and attaches to a clamp mechanism 47. The full view of the pantographic of the face bow 48 and how the Panadent pantograph is applied to the patient along with the camera. The clamp 47 in fig 5 allows the camera to be adjusted in two different directions to make it focus on the most probably hinge axis area.

The mechanism that attaches and detaches the cameras seen in figs 1 & 2 are for reducing transportation costs. The computer 1 in figs 1 &2 runs software that is able to make live videos and images transparent on screen. Commercially available software that can do this is called Actual Title Buttons by Actual Tools. Custom software can also be used to superimpose or alpha blend graphical elements like videos and images. The frame boundaries of the graphic elements such as videos and images act as two dimensional orienting aides on the screen. The computer screens in fig 1 show how the video input of the camera is displayed. Lines that are drawn from the four corners of the video window intersect at point 2 which represents the center of the boundary box. This line can be drawn on a transparent overlay using common programs such as MS Paint after making the paint program transparent of custom software can be used. The central point of the video window is used as a real time orienting aide along with the boundary box of the video window to make sure that that the optical axis of the camera 7 coincides with a reference hinge axis line 9 that connects the cameras or pointers. A transparent graph 14 shown in fig 2 is uperimposed over the live video feed of camera 7 in figs 1 &2, the bite fork clutch 6 in fig 1 is inserted in the patient's mouth and the patient is asked to make jaw movements. Camera 3 in fig 1 which captures jaw movement in the frontal plane is also activated. The patient is asked to open and close his or her mouth and the cameras 3& 7 record the movement of the jaw and present them as live video footages in the computer screen 15 shown in fig 2. Since camera 7 is attached to the jaw clutch^' through the frame and is away from the side of the patient's face indicated by distance 11, the camera would display the live footage of patient's ear and the most probable hinge axis point location in front of the ear. Jaw and camera movement in the video is observed as pure rotation or translation depending on the way the patient bites. The pure rotation of the jaw on its hinge axis is easily observed while the patient bites using the back teeth. A rotation and translation of the jaw is observed when the patient opens and closes his or her mouth. The transparent graph 14 in fig 2 placed over the live video footage would be able to indicate the type and degree of movement of any fiduciary point marked on the live video or placed on the patient. A non arcing fiduciary point 16 (fig2) observed in the live video indicates the jaw hinge axis. The degree of movement in the frontal plane is recorded using camera 3. Fiduciary points are either placed on the video or on the patient's skin. The sagittal and frontal plane movements are then studied. The fiduciary points are placed over the video using an optic-flow algorithm that can track the movement of pixels using the open Computer Vision library developed by Intel Corporation. The video footage that was used to determine the hinge axis is stored in the computer. The face bow frame is adjusted by loosening the screw mechanisms 5 &10 in both fig 1 & 2 and the face bow adjusted in such a way that the hinge axis point 16 determined in the patient would merge with the center of the window 2 in fig 2. The screws 5 & 10 are tightened again to lock the face bow in place before removing the face bow from the patient's mouth. The face bow is then positioned along with the dental models or casts in the articulator as shown in fig 2. The marker 8 in fig 2 is used for placing one arm of the face bow over the articulator hinge and adjust, or align the casts in such a way that the articulator hinge axis 17 aligns with the center of the video window.

During the mounting of casts in the articulator, the camera 7 is turned on and the live video feed displayed on screen of the articulator hinge axis 17 is used to align the dental models by making sure that physical marker 8, the center of the video window 2 in fig 2, the patient's recorded hinge axis 16 in fig2 and the articulator hinge axis 17 in fig 2 are all visualized in a straight line in the computer screen. The accuracy of three dimensional alignment of the hinge axis can be checked by looking at the transparent three dimensional overlap of the points displayed real time on the computer screen. Dental wax or suitable substance may be used for this purpose for holding the models and face bow in the articulator while the hinge axis of the patient is transferred to the articulator 17a in fig 2 through conventional mounting procedures using stone plaster. In fig 2, the patient's hinge axis and the articulator hinge axis is represented by line 9. The mounting dental models in an articulator in proper relationship to the hinge axis line 9 are a very significant and important ste in the prosthetic rehabilitation of the patient. The groups of patients who require a change or increase in the vertical dimension of occlusion for the satisfactory treatment of their condition require the true hinge axis to be recorded and transferred to the articulator. There are also challenges purely aesthetic in nature that needs to be met while treating a patient needing extensive or even minimal prosthetic rehabilitation. Due to the introduction of highly biocompatible tooth like alternatives for the replacement of missing teeth, there is a great, spurt of growth witnesses in the field of Cosmetic and Esthetic Dentistry. There are porcelain veneers that are so strong that they require only minimal reduction of the upper anterior teeth. Many patients in a contemporary dental practice may ask the clinician ways to improve their smile without extensively grinding teeth or without the use of orthodontic appliances. The clinician has several options or possibilities through which the smile of the patient can be corrected to make it look naturally pleasing or attractive. Given the number of highly esthetic materials available and also the number of patients who are interested in improving their smile, the clinician must be doubly sure whether each and every step taken starting from the aesthetic treatment planning is really going to benefit and satisfy the patient. The clinician must also be able to communicate effectively with the patient and the dental laboratory technician who would tailor makes the required restoration or prostheses for the patient. Effective and accurate communication between the various parties involved regarding the preferred shape, size and position of teeth in relation with the actual smile line of the patient is the only sure way to a happy, satisfied and content customer for both the clinician as well as the dental laboratory technician.

There are a plurality of methods devices and techniques that were tried and still that are in use to communicate with the dental laboratory. Describing all of them would be out of bounds for this disclosure. Prestige Dental Corporation sells a device known as the Behrend Hanau Clinometer. The Behrend Hanau Clinometer is a device that is used to mark lip lines, smile line and patient's face and dental midline in a plastic plate and transfer the plate to articulator so that the dental laboratory technician would be able to see where the teeth have to be placed in accordance with the various smile parameters marked. The smile information is so vital that in the total absence of it, the dental laboratory technician is literally blind folded while working on a particular case.

It is also known for them that are skilled in the art that even with the presence of such guides to properly communicate with the dental laboratory, there could be certain errors introduced due to the errors of parallax that are introduced while drawing over transparent plates or due to facial asymmetries that are difficult to record or communicate. Cosmetic and Aesthetic Dentistry has therefore fallen into the realm of a skilled art more than a science, performed by many painstaking trial and error mock -ups in the patient's mouth and many more consultation appointments held with the patient. There are many patients who may need a change in their appearance but can't express what they really want or wish their teeth to look like. These patients are considered to be very challenging patients to treat and satisfy. If the patient's aesthetic desires are not met the patient is turned to an unsatisfied patient. For this reason it is customary for the clinician to use a wax-up of teeth that is initially tried on the patient as a temporary alternative that would give the dental team a fairly good idea on how the final veneers, crowns or dentures for teeth have to be designed or fabricated. A dental imaging system which has a camera for acquiring smile images can also be used to show the patient a pre and post operative perspectives of the result. The patient Okays the result shown in the screen and the dental laboratory is given a prescription of the design characteristics to be incorporated into the restorations or new set of teeth.

The wax-up of teeth is done by the clinician or a dental laboratory technician and tried in the patient .The patient tells the clinician whether the changes she or he observes in the overall smile are satisfactory or quite pleasing. In this way the trial wax-up is carried out till the patient and the clinician arrive at a common consensus about the exact final shape of the restorations, dentures or crowns the dental laboratory would manufacture.

Though the wax-up procedure may seem easy it is plagued with difficulties like a lot of chair time spent on a particular patient, the dental laboratory needing to work in tandem with the clinician, and the patient sometimes being unable to decide immediately and give consent for the proposed treatment plan. The computerized dental imaging system which even the dental staff can be trained to handle consists of a computer and a software program that is able to digitally manipulate pixels using a software clone tool or transfer pixels in the screen from one point of the visible image of teeth to the other. Any program like Adobe Photoshop or UleadPhotoImpact can easily accomplish this within. A smile can be imported from a smile gallery and placed on the existing smile of the patient for the patient to give her input or feedback. Dental cosmetic imaging is a viable alternative provided the results are not unrealistic. The digital pixel cloning in a single smile image of the patient is a viable alternative and so is the creation of composite images or videos of the smile, cast and /or retracted patient's teeth. This creates unique modes for enhanced visualization of both the smile of the patient as well as the work done on the cast for the particular patient. Digital compositing or alpha blending which was originally invented by Microsoft researcher Dr. Alvy Ray Smith involves using an additional channel known as the alpha channel along with the color information (RGB) of an image. The alpha channel was introduced as an additional channel that would carry opacity/ transparency information of any given pixel of the image. The reason behind introducing the alpha channel was primarily to composite, merge or combine images and pack more conveyable information into a collage of images that can be placed on a website .Pixar Graphics was renowned in creating breathtaking special effects in their movies using alpha blending effects. The workspace or desktop of a computer was then not just limited to a flat single display but had infinite and unlimited workspace hidden behind the visible desktop of the computer giving the user the sense of total immersion. The user can combine different images or even videos depending on the capability of the system and software and assemble them in the screen as a collage and combine them all together with a click of the mouse. Digital compositing brought about by the alpha channel not only made web pages more attractive by the anti aliasing of text and graphics, but also made them more functional due to the additional information that can be visualized as transparencies. Computers have now become more sophisticated with enormous CPU processing speeds , dual core processing and system RAM ( Random Access Memory) enhancements conveniently packed into a single tablet pc or laptop. Computers with dual core processors and with a lot of RAM are ubiquitous these days and are becoming an industry norm. Miniaturization bf microcircuits has led to the improvement of the computer in general where they are becoming more robust and versatile for multitasking. A modem operating system for instance Windows Vista from Microsoft has video transparency enabled which can make live video footages transparent. The Mac OS X has the alpha blending functionality built into its very kernel and therefore is better enabled to perform transparency effects and device custom applications involving transparency effects. There are also available a myriad of standalone software that can be installed in any computer running a Windows XP operating system. The software installed can then be used to make any program window transparent, remember the transparency setting for each window and also apply transparency within a range between 0 till 100. A window with a transparency value of 100 % would almost be invisible. A window with a transparency value of 0% would be fully visible in the desktop. A partly transparent window with a transparency level of 20 % would display not only its own content but also the content that exists in the underlying window. The windows can contain a live video footage from a camera and a window placed on top of it can contain even an image. The user would see both the image as well as the video footage depending upon the transparency factor set for the image window on top. The boundary boxes of the window can be used as a reference for aligning one window on top of the other and act as a software aide for checking the accuracy of face bow alignments or mounting of casts in the dental articulator. Changes made to the real object namely the dental casts can be viewed in part with the virtual smile information displayed and a correlation can be ^easily made. Therefore this form of interactive visualization through the use of AR has got enormous potential in the field of Dentistry. The comparison of mock-ups or build-ups of teeth over the cast with the actual smile of the patient has enormous amount of application potential particularly in the field of Cosmetic and Aesthetic Dentistry.

Figs 3& 4 show the face bow assembly that is used to record and transfer the aesthetic parameters of the patient to the articulator for enhanced real time correlation using video transparency. The real time video transparency is also used for improved visualization of the smile during certain procedures performed chair side seen in fig 4. In fig 3 the side views of the face bow assembly is seen being applied to the patient and articulator. 18 in fig 3 is the elastic head frame that can be adjusted to fit the individual or patient. The head frame has a nasion or nose bridge that is used to hold and suspend a camera frame 20 before the patient. The camera bearing frame 20 is seen as an inverted "L"' shaped rod that can be adjusted with a screw mechanism 19 fixed to the nasion or nose bridge. The camera 22 is adjusted so that it would display and acquire a full smile of the patient as shown in the monitor screen 24. The camera is connected to the computer through an USB or Bluetooth wireless connection as indicated in 13 of fig 3. The camera has a screw mechanism 23 that can be used to position the camera depending on the patient's face to capture a full smile as seen in 24 .The camera has a perforated plate 21 which is fixed above it which is used to register the position of the camera 22 after it capture the smile of the patient. There is also seen in fig 3 a bite fork 25 which has a bite fork plate. A short rod that has been bent at the center in right angles and a perforated plate at the end of the rod is also seen in 26. The bite fork 25 along with the perforated plate 21 on top of the camera is used for registering the camera position. After the smile information of the patient is captured by the camera and stored in the computer, the bite fork which has bite tabs is placed in the patient's mouth and adjusted so that the perforated plates 26 and 21 would be over each other as seen in fig 3. The camera would then capture the smile with the bite fork as seen in the monitor screen as seen in 29 of fig 3. A suitable bite registration material that would set fast is introduced between the perforated plates 26 and 21 as seen in fig 3. Once the material sets the camera and the bite fork that are joined together as one are removed from the rest of the assembly as seen in 28 of fig 3. The captured smile could be in the form of high resolution videos and images. The images and/ or videos are sent to the dental laboratory along with the camera and bite record seen in 28 of fig 3. The dental laboratory technician receives the digital smile infonnation in the form of videos and images and mounts the camera 22 before dental casts at exactly the same orientation at which it took smile images of the patient. The articulator 35 shown at the bottom of fig 3 is first placed on a metallic platform 37 and is held firmly in the platform 37 with the aide of a powerful magnet 36 stuck to the base of the articulator 35. The standard incisal table pin of the articulator is replaced by a rod 31 that would keep the articulator open and at the same time would not block the camera view of the casts. The upper model 30 is articulated or fixed to the articulator using the hinge axis information formerly obtained with the aide of the face bow assembly to capture jaw movements using camera 7 and 3 in fig 2. The upper model or cast is mounted on a magnetic mount which holds the cast in place and can also facilitate easy fixing and removal of the cast in and out of the articulator. The upper model or cast 30 is then removed from the articulator and the bite fork and camera 28 attached to it. Another rod and magnet 34 is used sequentially or in steps to align the camera 22. A cast support 32 is used to hold he bite fork, camera and the model in place. A magnetic mounted receptacle 34 that can hold the camera 22 in place is placed on the metallic plate. The position of the receptacle 34 is adjusted so that a rod can be inserted into the receptacle 34 after it passed through the screw hole of the camera 22. After the rod is inserted the camera screw is tightened and a quick setting dental stone plaster is used to cement the camera rod with the receptacle. Once the plaster sets, a high speed drill is used to cut the bite fork of remove the bite registration material that holds the camera along with the bite fork. After removing the bite fork, the camera is turned on and live footage video of the cast is viewed in the computer screen 38 of fig 3. The smile video and image records previously obtained while the patient was present are superimposed or alpha blended over the live cast footage. Any restoration or prostheses placed over the cast can be visualized or checked how it fits the patient's smile. This can be done in the total absence of the patient improving the level of correlation between the work done over the dental technician's bench and the actual smile of the patient.

Many chair side procedures that the clinician would perform without involving or collaborating with the dental laboratory technician also need a method or system for improved correlation. Many chair side cosmetic procedures such as teeth contouring, veneering, gum surgeries and others require that the patient be able to smile well even during the procedure for the clinician to have an idea or feedback on how the work done would influence the actual smile of the patient. Almost all of these works are done over a retracted view of the patient's teeth as seen in fig 4. The cheeks are retracted using a commonly known device known as the cheek retractor 39 as seen in fig 4. Once the cheek retractor 39 is in place, the patient would not be able to smile without the clinician removing it from the mouth for evaluating the smile during the procedure. Apart from this the patient is also administered an anesthetic for numbing the teeth or the associated structures where a certain procedure needs to be done. After the administration of anesthetic, the patient would not be able to smile well due to the nerves that supply the facial muscles the lips getting anesthetized. Fig 4 shows the camera assembly that captures smile information of the patient before the treatment procedure. Once the smile information is acquired, the cheek retractor is applied or the anesthetic administered. The camera assembly that is lightweight and which comfortably fits the patient is left at the same position to capture live video footage of the retracted view of teeth as seen in 40 of fig 4. The smile videos or images previously acquired before the start of the procedure at the same orientation is then superimposed or alpha blended over the live video footage of the same patient as seen in fig 41. Alpha blending software is then used to make transparent any portion of the screen with the aide of the cursor 42 as seen in fig 4. Whole screen images or videos can be made transparent or selective portions or areas of the smile images can be made transparent revealing the live video information of the retracted teeth at the same orientation. The clinician would therefore be able to work on the actual patient's teeth and at the same time visualize and correlate changes using a number of cosmetic imaging techniques with the actual smile of the patient. In fig 3 the live retracted view footage of patient's teeth is represented by 43 in the screen. 44 is the portion of the lower lip of the patient superimposed selectively over the patient. Patient's smile image can be acquired into a standard cosmetic imaging program for the post treatment view. The patient's consent is obtained with the post treatment view which can further be used as a template for building actual restorations or prostheses that would fit the patient.

Though there are a number of possibilities, aspects and scopes that are not expressly and explicitly written in the body of the description it should be understood for those concerned that they all fall within the scope of this invention. Any alteration or modification can be done to the described art without deviating from the spirit and scope of the invention.

Claims

CLAIMS:

1. A system comprising of means to digitally record patient video or image from a reproducible point of reference before the patient, analyze the patient data tlirough software and utilize the data while working with a dental articulator.

2. A system as mentioned in claim 1 where the acquiring of patient's graphic data is through the use of mobile and stationary video cameras to record the functional and aesthetic aspects of the patient's upper and lower dental arches.

3. A system and method based on claim 2 where the cameras are attached to already existing commercial face bows.

4. The cameras in claim 3 are mounted on frame assemblies to record jaw movement and the esthetics of the patient's smile.

5. The assembly that records jaw movement comprises of cameras situated on a frame to the side and front of the patient that move along with the jaw of the patient maintaining only jaw clutch contact .

6. The assembly mentioned in claim 4 comprising of a camera that records patient's smile and that which registers the camera position relative to the patient.

7. A method employing face bows and Augmented Reality software to acquire, visualize and / or study patient data recorded with cameras mentioned in claims 5&6 for implementation in diverse procedures ranging from jaw hinge axis determination to smile design.

8. A method for implementing augmented reality to visualize, record and transfer jaw hinge axis by moving cameras attached to the assembly mentioned in claim 5 , analyze jaw movements in various planes and record aesthetic parameters of the patient using a stationary camera mentioned in claim 6, for improved accuracy of communication between the clinician, dental laboratory technician and patient and also for enhancing real time feedback during chair side and dental laboratory oriented procedures .

9. Method and software mentioned in claim 7 comprising algorithms for the study of jaw movement with cameras wherein the cameras are attached to the jaw for studying jaw movement, identification and quantification of jaw movement and jaw movement anomalies or disorders in various planes, augmenting live patient video with virtual information through real time alpha blending , augmenting live cast video footage with virtual patient data, aligning the dental models/ casts accurately with the hinge axis of the articulator, correlating work done over the cast in the patient's absence and for accurately documenting clinical and laboratory procedures performed.

10. Method employed to articulate dental models in a dental articulator using the face bow devices and augmented reality software.