WO2008131140A2 - Apparatus and method for recording and replicating mandibular movement - Google Patents

Abstract

An apparatus for use in dentistry to record and analyze mandibular movement comprises a rigid support frame for supporting a maxilla support member, a positionable mandibular member and sensing assemblies. The support member fixedly attaches to the support frame. The mandibular member is positionable proximate the maxilla member. The positional data is collected by a computing device and stored in a data storage medium as time history files. The files can then be transformed into usable information to replicate the mandibular movement in real time either virtually or mechanically. The mechanical articulator includes a base frame, an arm connected to the base frame and a suspension assembly positionable by a plurality of electro-mechanical actuators. The plurality of actuators each selectively impart movement to the sides of the suspension assembly such that the movement of the mandible obtained during a recording process can be replicated on the apparatus in real time.

Description

APPARATUS AND METHOD FOR RECORDING AND REPLICATING

MANDIBULAR MOVEMENT

CROSS-REFERENCE TO RELATED APPLICATION^) This application claims the benefit of U.S. Provisional Patent Application No.

60/912,316 entitled APPARATUS TO MEASURE, RECORD AND ANALYZE LOWER JAW MOVEMENT IN REAL TIME AND METHODS OF USING SAME, U.S. Provisional Patent Application No. 60/912,278 entitled APPARATUS FOR VIRTUALLY REPRESENTING JAW MOVEMENT AND METHODS OF USING SAME, and U.S. Provisional Patent Application No. 60/912,299 entitled APPARATUS TO REPLICATE LOWER JAW MOVEMENT IN REAL TIME AND METHODS OF USING SAME, each filed on 17 April 2007, each of which are hereby incorporated herein by reference.

TECHNICAL FIELD OF INVENTION

The present invention generally relates to dental restorative or corrective work. In particular, the present invention relates to an apparatus for measuring, recording, analyzing and replicating mandibular movement for use in dental restorative and corrective work.

BACKGROUND OF INVENTION

In restorative dentistry, it is critical that proper occlusion between the upper and lower jaws of a patient be established to maximize comfort of the patient during mastication. In corrective dentistry, especially that concerning those suffering from tempormandibular joint syndrome, a full and complete understanding of a specific patient's jaw movement is needed in order to properly diagnose and implement a treatment plan for the patient. Improper occlusion may not only lead to the discomfort of the patient while chewing, but may also contribute to other chronic debilitating affects, including improperly aligned condyles. Because such occlusion of the upper and lower teeth is so closely related to condylar movement about the tempormandibular joint ("TMJ"), a complete understanding of such movement is essential in making gnathological determination factors related to the dental restorative or corrective work.

Occlusal motion is quite complex. While a dominant factor of occlusal motion includes pivotal movement of the lower jaw about a hinge axis through the TMJ, other factors contributing to the movement include torsional and linear movement of the lower jaw. Such movement can be characterized as having factors relating to pitch, yaw and roll, as well as linear movement transverse to the condylar axis. It has therefore been quite difficult to not only record mandibular movement, but also precisely replicating such movement within precise tolerances. There exist in the art a wide variety of devices which have attempted to record mandibular movement. Perusing the prior art, incremental changes in the attempts to record such mandibular movement can be observed. Early examples include dental pantographs, such as those suggested by U.S. Patent No. 1,033,562 and U.S. Patent No. 2,794,253. These pantographs had several inherent shortcomings, including ease of use, discomfort when applied to the patient and overall accuracy of recording. Other examples of dental pantographs include: U.S. Patent No. 3,218,716; U.S. Patent. No. 3,431,649; and 4,034,475. Briefly, using such pantographic recording systems, dentists attach mechanical devices, or clutches, to the upper jaw and the lower jaw of patient. This system of clutches allowed the dentist to attach a network of connecting bars and linkages to the upper and lower jaws of the patient. Each clutch is filled with a compound material which forms a surface around the teeth of the patient, then a cement is used to temporally attach the clutch thereto. Each clutch is in turn operatively linked to a pantograph such that the dentist can guide the jaws and record the resulting movement pattern. Using a stylus and magnetic pads to record the movements of the jaw, a set of tracings in the form of trajectories were obtained.

The resulting tracings have the appearance of a regular strip charge recorder with no interface to any data storage device for future analysis. Despite the accuracy of the aforementioned pantographic systems, the overall time required to prepare the system with the patient and the overall difficulty in using the pantographic system has hindered its wide-spread growth. Subsequently, less accurate but more workable systems are have become more popular. More recently, there have been other attempts to record mandibular movement. One such attempt includes supplementing the recording surface of the aformentioned dental pantographs with pressure sensitive elements capable of transmitting an electric signal. Such devices, however, still did not accurately and precisely depict three-dimensional motion of the jaw.

Another example includes the use of corresponding arrays of ultrasonic transmitters and receivers in order to record jaw movement with at least six degrees of the freedom. This attempt again required the patient to wear the entire device in order to record movement of the lower jaw. Also, this attempt has inherent accuracy and precision issues as the contact points for the arrays within each jaw are secluded to a single area which, for example, can compound errors when determining roll characteristics of mandibular movement.

An even further example includes the use of video cameras to optically capture a target image attached to a tooth on the upper jaw and a target image attached to a tooth on the lower jaw of the patient. This attempt also has inherent accuracy and precision issues as the contact points within each jaw are secluded to movement of the lower jaw about a single tooth, which may not accurately or precisely record roll or uneven pivoting about the condyles.

Regarding replicating mandibular movement, there exist in the art a wide variety of devices which have attempted to replicate, using dental casts, the occlusal relationship between the upper and lower jaw. In the prior art, incremental changes in the attempts to replicate the occlusal relationship can be observed. Early examples include those suggested by U.S. Patent No. 1,848,267, U.S. Patent No. 1,989,367 and U.S. Patent No. 2,043,394. These devices, known as dental articulators, had several inherent shortcomings, primarily the ease of use and overall accuracy. None of these examples permitted pivotal movement of one cast relative to the other. Eventually, semi-adjustable and adjustable articulators appeared, including those as suggested by U.S. Patent No. 3,218,716; U.S. Patent. No. 3,431,649; and 4,034,475. These examples, however, had inherent shortcomings in that only simple pivotal motion of either jaw relative to the other could be observed. A precise means of replicating mandibular movement was still needed in the area of dentistry, especially to replicate mandibular movement in real time. The prior art also includes examples of devices which attempted to mimic mandibular movement. These examples, however, have been found to be unreliable in producing successful results, so there still remains a need to precisely and accurately replicate mandibular movement.

BRIEF SUMMARY OF INVENTION

A first embodiment of the present invention includes an apparatus for recording and analyzing in real time mandibular movement, or the movement of the mandible (lower jaw) of a patient relative to the maxilla (upper jaw) of the patient. The apparatus includes a recording device which is suspended by a wrist mechanism and revolute arm such that the recording device is freely positionable proximate the patient. The recording device includes three electro-mechanical sensors positioned substantially orthogonal to one another. Each sensor is designed to be positionable about three degrees of freedom to collect pitch, yaw and translational movement proximately along its respective axis. A freely moveable recording bar connects to each sensor. The maxilla of the patient is fixedly securable to the recording device, whereupon securing the mandible to the recording bar, mandibular movement in the form of positional data is obtained from each of the three sensors and stored into a computer as time history files. Dental casts of the lower and upper jaws of the patient are digitally scanned in such a manner to preserve their occlusal relationship based upon a hinge axis reference. The time history files and the digital scans of the dental casts can then be processed by the computer to replicate the mandibular movement of the patient in either a virtual environment or on an electro-mechanical articulator.

A second embodiment of the present invention includes an apparatus to replicate in real time mandibular movement using dental casts of an upper jaw portion and a lower jaw portion obtained from a patient. The apparatus includes a base frame for supporting an arm to hold the dental cast of the upper jaw, a positionable suspension assembly supporting a platform to hold the dental cast of the lower jaw, and a plurality of actuators for imparting movement to the suspension assembly. The suspension assembly includes first and second opposing struts which connect to the platform in such a manner so as to represent a hinge axis along a tempormandibular joint of the patient. Each actuator connects to the struts through a series of linkages. A computer, using data obtained during the recording process, selectively activates each actuator to synchronously impart movement to each strut. First and second actuators selectively impart elevation to a lower portion of each strut. Third and fourth actuators selectively impart translational movement to a middle portion of each strut. A fifth actuator selectively imparts lateral movement to an upper portion of one of the struts. Each of the aforementioned actuators represent five active degrees of freedom in displacement mode. A sixth passive degree is of freedom is selectively imparted by a sixth actuator which applies force to a rearward portion of the platform. The passive degree of freedom represents an approach motion between the upper and lower jaw about the tempormandibular joint. The dental cast of the lower jaw is thereby positionable within six degrees of freedom in a reference or coordinate system.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is an overall view of a first embodiment of the present invention showing a general arrangement of components.

Figure 2 is a perspective view of a recording device of the first embodiment of the present invention positioned proximate a patient.

Figure 3 is a perspective view of the recording device of the first embodiment of the present invention with protective shields removed.

Figure 4 is a perspective view of a sensor assembly of the first embodiment of the present invention.

Figure 5 is a perspective view of the recording device of the first embodiment of the present invention illustrating a recording bar decoupled from a locking bar. Figure 6 is a perspective view of the recording device and clutch assemblies of the first embodiment of the present invention illustrating the recording bar coupled to the locking bar.

Figure 7 is a perspective view of the recording device of the first embodiment of the present invention illustrating the recording bar decoupled from the locking bar. Figure 8 is a perspective view of dental casts of the upper and lower jaw for use in accordance with the first embodiment of the present invention. Figure 9 is a perspective view of an alignment device for forming the dental casts of Figure 8 in accordance with the first embodiment of the present invention.

Figure 10 is a perspective view of a calibrating bar for use in accordance with the present invention. Figure 11 is a perspective view of an alignment device having the calibrating bar Figure 10 disposed therein in accordance with the present invention.

Figure 12 is a perspective view of a fixture and dental cast for use in accordance with the present invention.

Figure 13 is a right-hand perspective view of a replicating apparatus of a second embodiment of the present invention.

Figure 14 is a left-hand perspective view of the replication apparatus of the second embodiment of the present invention.

Figure 15 is an exploded perspective view of a suspension assembly of the second embodiment of the present invention. Figure 16 is a perspective view of a calibrating frame as used in accordance with the second embodiment of the present invention.

Figure 17 is a perspective view of an adjusting device as used in accordance with the second embodiment of the present invention.

Figure 18 is a diagram of the second embodiment of the present invention showing a general arrangement of components.

DETAILED DESCRIPTION

A dental recording system of the present invention for recording and analyzing mandibular movement in real time is generally indicated at 100 in Figure 1. Generally, the system includes a recording apparatus 102, connected to a user interface 104 and computing means 106, and supported by a wrist device 108 and revolute arm 110. Both the wrist device 108 and revolute arm 110 allow the recording apparatus 102 to be positionable proximate a patient, as illustrated in Figure 2, and suspend the recording apparatus 102 at any desired position. The wrist device 108 is positionable within three degrees of freedom, providing for pitch, roll and yaw orientation of the recording apparatus 102 when attached thereto. The wrist device 108 includes a rod 114 having a distal end pivotally attached to the recording apparatus 102 by means of a rotational joint 116 allowing the recording apparatus 102 to be positioned with roll orientation. An opposing proximal end of the rod 114 disposes upon a set of bearings 117 contained within a housing 118, allowing pitch positioning of the recording apparatus 102. The wrist device 108 further includes a connecting arm 120 having a proximal end 122 fixedly attached to an outer surface of the housing 118 and a distal end 124 rotatably attached to the revolute arm 110, also by means of a rotational joint 112, allowing yaw positioning of the recording apparatus 102. Preferably, each rotational joint used in construction of the wrist 108 includes low friction bearings to reduce the effort of angularly positioning the recording apparatus 102 during both the initial setup with the patient and throughout the recording process.

To suspend and maneuver the wrist 108 and recording device 102 proximate to the patient, Figure 1 illustrates the revolute arm 110 being secured to the ground by a base 125. A horizontal segment 126 rotationally connects to a vertical member 128 secured to the base 125 by means of a rotational joint 130. An upright segment 132 in turn connects to the horizontal segment 126 by means of a second rotational joint 134, providing rotational positioning of the upright segment 132 along a vertical axis. However, the upright segment 132 also includes a pivotal joint 136 positioned proximate the rotational joint 134, allowing the upright segment 132 to be pivoted past the vertical. Springs (not shown) positioned inside the upright segment provide balance and allow the upright segment 132 to maintain its positioning, as is known in the art. Pivotally attached to an opposing end of upright segment 132 is the segment 138. Segment 138 connects to the upright segment 132 by means of pivotal joint 140, which allows segment 138 to be pivoted relative to the upright segment 132. Finally, connection segment 141 pivotally attaches segment 138 by means of join pivotal joint 143 and joins the wrist 108 to the revolute arm by connecting to pivotal joint 112. Segments 132 and 138 each contains springs (not shown) positioned inside to maintain positioning thereof. It should be noted that although only three degrees of freedom are needed to position the arm, the revolute arm 110 has four degrees of freedom, which not only allows the wrist 108, and subsequently the recording apparatus 102, to be infinitely positionable within three-dimensional space, but the added degree of freedom provides flexibility in orientation around the vertical axis, enhancing the ease at which the wrist 108 can initially position the recording apparatus 102 relative to the patient.

It should be noted that the base 125 of the revolute arm 110 should be secured to the ground in such a manner that the recording apparatus 102 and wrist 108 can be suspended therefrom without toppling over. This may be accomplished by providing flat platform with an appropriate amount of surface area, or providing the base 125 with an appropriate amount of mass, such as by securing weights to the base 125. Alternatively, the base member 125 can be permanently affixed to the ground by bolting or otherwise cementing the base 125 to the floor. It should be noted, though, that any means necessary to secure the base 125 to the ground is well within the scope of the present invention. Upon properly securing the base 125 to the ground, both the wrist device 108 and revolute arm 110 allow the recording apparatus 102 to be both easily positionable proximate a patient and hold the recording apparatus at any desired position. Referring again to Figure 3, the recording device 102 is illustrated with protective shields 142 removed therefrom. The recording device 102 includes a frame 144 built as a spatial three-dimensional structure to achieve light-weight characteristics coupled with high rigidity. The frame 144 includes four longitudinal bars 146 positioned in rectangular formation and connected at each end with connecting bars 148. Centrally positioned cross bars 150 provide rigidity to the frame 144 and assist in attaching the wrist device 108 thereto by means of the rotational joint 116, as previously discussed. The frame further includes a "L"-shaped substructure 152 extending downwardly therefrom for attaching mounting plates 154. A first mounting plate 154a attaches to a first leg 156 of the sub-structure 152 proximate a lower forward corner 158 of the frame 144. A second mounting plate 154b attaches to a second leg 160 of the sub-structure 152 proximate a lower central rearward portion of the frame 162. A third mounting plate 154c attaches to an upper forward corner 166 of the frame 144. The mounting plates 154 are for attaching sensor assemblies 168 frame 144. As illustrated in Figure 4, each sensor assembly 168 includes first and second rotational joints, 170 and 171 respectively, and a linear translational joint 172. The first and second rotational joints, 170, 171 are disposed upon a housing member 174, and act like cooperating gimbals wherein the first joint 170 is pivotal relative the housing member 174 and the second joint 171 is pivotal orthogonal to the first joint 170. The housing member is attached to a base plate 175 which is attachable to the respective mounting plate 154. A crossbar 176 connects the linear translational joint 172 to the second angular joint 171. The linear joint 172 includes a sensor rod 178 disposed within a tube 180 for detecting the positioning of the tube 180 relative to the rod 178. Angular joint information is monitored by a pair of linear optical encoders, 182 and 183 respectively, mounted to the housing member 174. Each of the aforementioned sensors 182, 183 is commercially available by Heidenhain Corporation of Schaumburg, Illinois. After the sensor assemblies 168a, 168b, 168c are mounted onto the frame 144, a set of calibrating fixtures (not shown) are used to verify and adjust their positioning. Proper alignment of the sensor assemblies 168a, 168b, 168c ensures squareness of the recording system 102, establishes a proper home position and zeros all sensor assemblies at this home position. Referring back Figure 3, the first sensor assembly 168a is positioned on the frame such that the linear translational joint is positioned substantially along an x- axis. The second sensor assembly 168b is positioned on the frame such that the linear translational joint is positioned substantially along a y-axis. The third sensor assembly 168c is positioned on the frame such that the linear translational joint is positioned substantially along a z-axis. Each sensor assembly 168a, 168b, 168c provides coordinate information along three axes relative to its respective axis positioning. The coordinate information relates to a point A[I] at the end of the translational joint where I = X, Y or Z on a three-dimensional coordinate plane. The sensor assembly also includes a fourth degree of rotational freedom of the tube about the rod. However, this fourth degree of freedom does not influence the A[I] information of the interface and is used as an passive degree of freedom. To avoid any additional load on the jaw of the patient during the recording process, it is preferable that each sensor assembly is capable of being positioned with low friction and low resistance. As illustrated in Figures 5 through 7, each sensor assembly 168a, 168b, 168c connects to an interface point on a positionable recording bar 184 by means of a universal joint 186. The recording bar 184 is suspended by springs 188 connected to the frame 144, which also provide balance to the recording bar 184 to offset the weight of the bar and allow for free movement thereof when connected to the lower jaw of the patient. When not in use, or to calculate a home position, the recording bar 184 is fixedly secured to the frame 144 by connecting pins 190 insertable into mateable apertures 192 contained within the recording bar 184. The connecting pins 190 are positioned on a locking bar 194 which fixedly connects to the frame 144 via a post 196. Also fixedly attached to the post 196 is an upper bar 198 for holding the upper jaw or maxilla of the patient in a fixed position relative to the recording device 102. The recording bar 184 is essential to the recording system because the lower jaw or mandible of the patient attaches to the recording bar 184 through a clutch device 200. The clutch device 200, which is securable to either the upper jaw or lower jaw, includes a metal, plastic or ceramic tray 202 similarly shaped to the contour of the jaws. The tray 202 is attachable to a transfer bar 204. The transfer bar 204 is in turn attachable to the respective upper bar 198, or the recording bar 184, aligned by connecting pins, 205 and 207 respectively. Each transfer bar is then frictionally secured to the respective bar 198 or 184 by threaded screws 209. Proper positioning is further ensured by detents (not shown) positioned on each transfer bar 204 mateable with indents 211 contained with the upper bar 198 and the recording bar 184. Using a clutch device 200 for each jaw, the lower jaw of the patient is securable to the recording bar 184, and the upper jaw of the patient is securable to the upper bar 198. It should be noted, though, that when the jaws of the patient are connected to the recording device 102, the recording device 102 itself is still permitted to move in three-dimensional space as it is suspended by the revolute arm 110 and wrist 108. Thus, the patient is still permitted to slightly move their head or body during the recording process without interfering with the recording itself. This provides an extra degree of comfort to the patient who does not have to support the recording device, as was typically required in the prior art, and further allows the patient to move their head and jaws in a natural state during the entire recording process. To monitor the movement of the jaw, the initial location and orientation of the recording bar 184 must be recorded to obtain the real time position of each jaw. The recording bar 184 connects to each sensor assembly 168a, 168b, 168c through the universal joint 186 with interface point A[I] at the center of each universal joint 186. The universal joint 186 provides two angular degrees of freedom between each respective sensor assembly and the respective attachment point on the bar. A third degree of freedom, in the form of the rotation of the tube 180 about the sensor rod 178, is a passive degree of freedom and is not recorded.

To sustain a repeatable and accurate recording in real time, the computer utilizes a system of high speed data acquisition channels 206 to condition, read-in and store the information simultaneously from each sensor assembly. Such hardware is made commercially available through National Instruments of Austin, Texas. Two digital I/O channels are used to allow the dentist to control the process of recording in hands-free mode through two foot operated switches. A first switch 208 signals the computer when to initiate the software while a second switch 210 starts and stops the recording.

The recording system of the present invention represents a combination of multiple degrees of freedom in a mechanical system to acquire positional information of mandibular movement as collected by the sensor assemblies 168a, 168b, 168c and stored within a data storage medium controlled and included within the computer 106. The positional information from the sensor assemblies 168a, 168b, 168c, however, is not used directly for mandibular or tempormandibular joint motion analysis, but must first be converted into an output file, such as trajectory information of the tempormandibular joint's condyles, or motion of the lower jaw, before it can be understood and interpreted by the practicing dentist. To achieve this, a set of coordinate systems mathematically connects to and associates with key parts of the recorder 102. It is also important to establish all major sets of parameters called domains for each coordinate system. Such domains include TMJ domain, Sensor Domain, Joint Domain and Lower Jaw Domain.

The TMJ Domain is associated with coordinates of each center of the condyles and the rotational angle about the axis through each condyle. It can be represented as a set of three-dimensional coordinates, namely Left(X,Y,Z) for the left condyle, Right(X,Y,Z) for the right condyle, and an angle A. In reality, however, there are only six independent parameters, instead of seven, because the distance from the left condyle right condyle stays relatively constant. The Sensor Domain includes the nine sensors contained within the three sensor assemblies. The Sensor Domain is considered to be a nine degrees of freedom domain. There is a cross -coupling relationship between these nine parameters to provide only six independent degrees of freedom information for the position of the recording bar 184.

Joint Domain represents all mechanical joints used by the recorder device 102 as a part of the multiple degrees of freedom linkage. Represented by Kinematic Mode or Diplacement Mode.

Lower Jaw Domain, also referred to as World Domain, reflects the six degrees of freedom of the lower jaw measured relative to the reference or home coordinate system. Lower Jaw Domain, with its coordinate system rigidly associated with the recording bar 184, or lower transfer bar 204 which is just a simple offset away from the recording bar 184, has six parameters, or six degrees of freedom, with three translational degrees of freedom, X, Y and Z off the center of the recording bar, and three rotational degrees of freedom, consisting of pitch, yaw and roll.

When attached to the lower jaw of the patient, the lower clutch 200 and recording bar 184 move in World Domain, but each sensor assembly detects positioning of the recording bar 184 in Sensor Domain. These readings, referred to as feedbacks, are sent to the computer system 106 for processing. The processing in this case means converting information from Sensor Domain into the Lower Jaw Domain. This transformation is required to establish a kinematic model of the entire system using coordinate systems associated with each individual element of the sytsem. It should be noted that there are two major kinematic transformations, namely Direct Kinematic Transformation ("DKT") and Inverse Kinematic Transformation ("IKT"). Both transformations convert known information in one domain into information for another domain. The Direct Kinematic Transformation is performed when the A(I) parameters of the patient's jaw are known or given. This transformation would convert it into sensor domain information. The Inverse Kinematic Transformation is used when the information from all nine sensors is obtained in the form of feedback information from each sensor, and the position of the jaws in World Domain shall be obtained. DKT is always unique and relatively fast. IKT is constrained to the Sensor Domain. However, if the number of degrees of freedom in Sensor Domain is greater than six, a damped least square method is used to determine the optimal solution for the World Domain. Thus the use of over constrained and redundant sensor systems increases the accuracy and repeatability of the conversion process going from Sensor Domain into World Domain. Use of direct and inverse Jacobian matrices allows both transformations to be performed at very high sampling rates in real time application such as recording by the software application.

Prior to beginning the recording process, the clutch 200 is secured to the upper jaw and the lower jaws of the patient before each being attached to the recorder device 102. As is known in the art, the tray 202 of each clutch 200 is fillable with a compound material and formed in the patient's mouth in a centered relation position. The clutches are then temporarily cemented to the teeth. The trays 202, when positioned inside the mouth of the patient contact through the lower pin and the upper dome surface and keep the teeth of the upper and lower jaw apart and work as an interface between the recording device 102 and jaws of the patient. The clutches 200 also permit exclusive recording of the tempormandibular joint movements without interference from the teeth. While this type of clutch pairing is similar to manual pantograph recording processes known in the art, it should be noted that practicing of the present invention is not meant to be limited to any particular type of clutch, and any other type of suitable clutch is well within the scope of the present invention. The recording process can be started after both jaws of the patient are secured to the respective clutch system 200, with the upper clutch being secured to the upper bar 198 of the recording device 102, and the lower clutch being secured to the recording bar 184. At this reference or home position, the recording bar 184 is locked in place by the docking pins 190 positioned on the locking bar 194 just below the upper bar 198. Recording can begin at this home position to determine the home coordinates. Thereafter, the recording bar 184 is released from the docking pins 190 and the mandible becomes free of any unnatural constraints to be moved relative to the maxilla. There are four different movements during recording which in dentistry are defined as border movements. During border movement recording, the patient moves the jaw guided by the dentist to the border, or limit, of the envelope of function. The four border movements are the right and left lateral, protrusion and jaw hinging movements. The four aforementioned border movements are typical of a traditional recording process as currently used by dental professionals. However, the recording device of the present invention is not limited to those four motions, but can be employed for any arbitrary jaw movement within the physiological constraints of the jaw, including chewing process or any other movement within the border. Recording the four border movements permits establishing a hinge axis. The hinge axis represents an imaginary line connected between geometric centers of the left and right condyles of the tempormandibular joint. More precisely, this line passes through those centers. As it is known in dentistry, during about the first 1 to 20 millimeters of mouth opening, the tempormandibular joint performs nearly pure rotational motion around the hinge axis which is functioning at this point as an instant hinge. Upon establishing the hinge axis, the computer system utilizes a software program to determine the location of the aforementioned center points in the Lower Jaw Domain coordinate system. This is accomplished by determining in the first 1 to 20 mm of mouthing opening the least variation in the condyles. From the rotation about this point, which is assumed to be pure rotational movement, an ideal arc can be extrapolated, upon which can be determined the position of the hinge axis C, and horitzonal H and vertical V values for use in setting up an alignment device 224 to properly position dental casts 214 of the patient, as will be discussed. Now on those points C, H and V, their coordinates become a part of the transfer bar coordinate system are moved within this coordinate system during any other moves of the lower jaw. During the border movements to determine right and left lateral movement, the recording device obtains and sends the raw information to the data acquisition channels 206, which the computer 106 stores in the data storage medium 212 the trajectory of both central points of the left condyle and the right condyle, as well as the angle of rotation of the jaw about the hinge axis. The last movement is called protrusive motion wherein the jaw is moved forward and is recorded in much the same manner. Results are stored in the data storage medium 212 in the form of multi- degree of freedom time history files. Any cross section of this multi-degree of freedom data structure represents all information about the position and orientation of the lower jaw with its condyle center points in three-dimensional space. The results thereof can be presented in traditional form as recognized by one skilled in the art as a series of two-dimensional graphs using Frontal, Horizontal and Sagital projections. Alternatively, the results can be represented in three-dimensional space using either a mechanical articulator 300 or within a virtual environment.

Upon recording and obtaining the positional data of the patient's mandibular movement, the dental casts 214 of the patient's upper and lower jaw are made to more accurately analyze the occlusal relations in either the virtual or mechanical format. Figure 8 illustrates an upper dental cast 216 positioned in relation to a lower dental cast 218, each mounted to a magnetic base base. Each magnetic base base is mateable with a corresponding receiving base 222 positioned on the articular 224. It should be noted, though, that some analysis can be done during or immediately after the recording process by the computing means 106 and the user interface 104 by using a generic dental cast previously scanned and stored within the computer. However, for the most accurate analysis, dental casts of the actual patient are preferred.

While the making of dental casts 214 has long been known and practiced within the art, the present invention provides a unique method of making the dental casts such that their spatial relationship with one another is preserved throughout the entire recording and replicating process, whether such replication be done either a virtual environment or mechanically. Further, it should be noted that the casting of the patient's upper and lower jaw can be done prior to recording. If done prior to recording, virtual representation of the mandibular movement is viewable in real-time on the user interface during the recording process.

To begin, the tempormandibular joint parameters are obtained during the recording process and used by the software program to determine a set of corresponding parameters H and V to establish proper mounting conditions of the dental cast of the lower jaw on an alignment device to form the dental casts in a static occlusal relation. As illustrated in Figure 9, the set of parameters include vertical V and horizontal H settings, and are measured from point C representing the hinge axis of the left and right condyles in the Lower Jaw Domain coordinate system. The user reads these values off the user interface 104 and adjusts the alignment device to correspond thereto. To create a support, the lower jaw is positioned into the same location relative to the tempormandibular joint hinge C obtained during the recording. The alignment device 224 has two degrees of freedom to manipulate the location of the lower cast, corresponding to the H and V parameters. Adjusting the alignment device 224 includes attaching a clutch base to a mounting bracket 225. The mounting bracket rests upon a threaded bolt 226 and is vertically adjustable by rotating the bolt to obtain the proper V value. Adjust for the H value, the two halves of the alignment device are moved relative to one another by loosening set screw 227. The upper dental cast 216 and the lower dental cast 218 are then formed in much the same fashion as is known in the art by filling the gaps between the dental cast and the respective magnetic base with plaster. At this position, the adjustable alignment device 224 allows the lower cast 218 to pivot around the true hinge axis C determined by the tempormandibular joint during recording. It should be noted that the previously described method of forming the dental casts is not limited to any one type of alignment device 224, and modifications to its structure while still accomplishing the same result is well within the scope of the present invention.

After making the casts, a calibrating bar 228 is used to determine a home or initial reference position of the alignment device 224. As illustrated in Figure 10, the calibrating bar 228 includes a cylinder 230 connected to a magnetic base 232, and another magnetic base 234. As illustrated in Figure 11, the calibrating bar 228 is fitted within the alignment device 224 an plaster 236 is filled in the space between the cylinder 230 and the magnetic base 234. Each base 232, 234 is mateable with bases 222 of the articlulator such that rotation motion is not permitted. Alternatively, the calibrating bar can be adjusted prior to making the dental casts, as all that is needed to do either is a knowledge of the H and V values. Regardless of when the calibration takes place, this procedure is done only once to calibrate the fixture.

The calibration bar 228 is used to homogenize positioning 238 fixtures for scanning each dental cast and applying the casts to a mechanical articulator. By employing the aforementioned steps, the correct relationship between the two casts is preserved at a given home or initial reference position during scanning, mechanical articulation, or virtual modeling. Once the H and V values are known for a specific patient, they do not need to be recalculated, nor do any of the instruments need to be recalibrated upon using the calibrated calibration bar 228. This has been found to be quiet advantageous, especially in regards to replicating movement in the virtual environment. For example, as illustrated in Figure 12, a dental cast is secured to a fixture 228. The fixture contains a magnetic base 240, along with apertures 242 for securing the fixture during the scanning process. Because the H and V values are known for either the upper dental cast or the lower dental cast, a three dimensional scan of either cast can be later used by a computer software program having the proper occlusion and mandibular movement about a known hinge axis C. The prior art was unable to do this because there was no technique available to preserve both the occlusal relationship between each jaw and tempormandibular joint movment.

To view the results using three-dimensional space in the virtual environment, the dental casts 216, 218 must first be digitally scanned. To achieve high precision images and at the same time preserve the integrity of the data, each dental cast 216, 218 is mounted to a fixture 238 to hold the cast 216, 218 at a fixed position during scanning, as is illustrated in Figure 12. Preferably, the scanners primarily include a device capable of surface scanning with high resolution and being able to format or convert the information from the scanning device into a data file. Each dental cast 216, 218 is then scanned or digitized, and this information transferred to the data storage medium 212, operated by the computer 106, in the form of three-dimensional meshes. At this point, a matrix of coordinate transformations is determined which is used later on during the virtual modeling for proper handling of the position of parts on the screen. Scanning of each dental cast individually on the fixture maintains the integrity and association between both jaws in its reference coordinate system, enabling a digital representation and proper storage of the scanned data for future display and analysis.

To demonstrate movement of the lower jaw relative to the upper jaw in a virtual environment, a set of animation software is used. Preferably, the software tool for the development of the three-dimensional package is one as developed by the inventors of the present invention. Said software was developed using a DirectX® package developed by Microsoft® and widely used by other developers in the field of three-dimensional animation, including CAD/CAM packages. A program called PolyTrans, as distributed by Okino Computer Graphics of Mississauga, Ontario, Canada, was used to convert the scanned data from the industry standard .STL format into an .X format which is supported by DirectX®. Implementation of the entire virtual articulator package in DirectX® for three-dimensional motion of the scanned surfaces was done in a Visual Basic environment. The software program can simulate practically any motion of the tempero mandiublar joint on the screen of the user interface 104.

When using the program as developed by the present inventors, the positional data obtained during the recording process can be used to synthesize or replicate motion of the tempormandibular joint. Further, either software package can interface the virtual environment with the recording device, so virtual representation of the mandibular movement can be viewed in real time throughout the recording process.

Virtual mandibular motion can be controlled by a mouse as well as by a joystick, or the like. Virtual mandibular motion allows the user to change not only the position on the user interface screen of the upper and lower jaws, or portions thereof, but also the location of the light source and view point. An unguided, nonborder chewing movement can also be recorded and observed on the virtual articulator. Also, the user can virtually rotate the jaws in all directions to observe the movements in different views The user may also turn the entire image and work it from different perspectives, which indicates the base moving together with the lower jaw as an option. Alternatively, the product may display both jaws as well.

The last segment of the virtual environment includes a 'fly-through' capability. As a part of he virtual world package, this feature allows the dentist to control with a joy stick, similar to a pilot in a small airplane, and fly through all the parts and components on the screen and observe all the specific parts of the jaw in minute detail. This is extremely useful in the virtual diagnosis and redesigning of new teeth as use of three-dimensional displays makes an enormous difference in understanding the problem.

Alternatively, scanning of the jaws or the tempormandibular joint is done with high resolution computed tomography (CT) technology, so the density of both the bones and the tissues can be determined. This has been termed volumetric scanning versus surface scanning that obtains only the mesh for the models using surface scanners. The information is stored in standard Digital Imaging and Communications in Medicine (DICOM) format. Just as .STL is standard for surface scans, the DICOM is standard for any CT scan machine, whatever the application may be. As a result, the scan shows the density of bones for a pair of jaws which is very important information for the dental restoration process. For implant dentistry, it is critical to know the character and density of the bone. If bone material is insufficient, a graft will be placed to increase the size and density. The next step would be to superimpose these images of the casts (outside mesh only) with image of the CT scan. This image would be a shell around the volumetric area and besides moving them together the doctor can always click a particular location and see the density of the bones around this area, whether the patient has a sufficient support for the bridge, crown or an implant. That information may be taken in form of the three- dimensioinal volumetric image from the NewTom type of machine and can be incorporated with a surface image, and then be displayed and moved on the screen based on any desired trajectory.

The virtual environment package of the present invention uses the same drive files obtained from the recorder to display the movement of a jaw in three- dimensional space. The virtual mandibular movement can be used for analysis of tooth geometry as well as TMJ kinematics. The virtual environment package also allows user to move/adjust the jaw in any of six degrees of freedom. The virtual environment package was developed by using the aforementioned DirectX technology and can be considered as a "plug and play" option for Dental CAD packages. This virtual articulator of the present invention has an interface to a joystick so the user can control the position of the jaw not only with the computer mouse but with a three- dimensional joystick as well. This capability is critical for the virtual articulation when it is extended by a few more features such as the fly-through option.

A second embodiment of the present invention including an apparatus to replicate mandibular movement in real time is generally indicated at 300 in Figures 13 and 14. Generally, the apparatus includes a computer controlled mechanical system driven by information derived from a recording device to create, amongst other things, exact duplication of movement between a dental cast of the lower jaw 302 relative to a dental cast of the upper jaw 304 in real time.

The replicator apparatus 300 is either supported by or mountable to a work surface 306. The replicator 300 includes a base frame 308 having opposing first and second side walls, 310 and 312 respectively, joined together by a rear wall 314. The sidewalls 310, 312 provide the main support for the apparatus 300 and are engageable with the work surface 306. To support the dental cast of the upper jaw 304, the apparatus 300 includes vertically extending post members 316 attached to opposing ends of the rear wall 314. Terminal upper ends of the post members 316 each contain bearings 318 mounted therein for supporting a pivotal shaft 320. The shaft 320 supports a proximal end of a swing arm 322 which is positionable between a working and non-working position (not shown). Attached to a terminal end of the swing arm 322 is a mounting block 324 having a pair of through-bores for receiving rods 328 attached to a mounting bracket 330. The mounting bracket 330 includes a magnetic base 332 for accepting a corresponding mateable base 334 to which is attached the dental cast of the upper jaw 304. The position of the mounting bracket 330 relative to the mounting block 324 is adjustable by sliding the rods 328 through the mounting block 324. Set screws 336 permit frictional engagement of the rods 328 with the mounting block 324 when the desired position of the mounting bracket 330, or the dental cast 304, is achieved. Further, the angle at which the swing arm 322 rests relative to the work surface 306 can be adjusted by positioning a threaded burr 338 on a threaded bolt 340 which extends through an aperture in the swing arm 322. The threaded bolt 340 and swing arm 322 attach to a platform 344 supported by a cross beam 346 having terminal ends attached to each post 316. The swing arm 322 rests upon the threaded burr 338, and by rotating the burr 338, the swing arm 322 can be raised or lowered to the desired position. The swing arm 322 is also positionable transverse to the shaft 320. Bolts 348 dispose through slotted apertures contained within the swing arm 322 and threadably engage a second mounting block 352 fixedly attached to the shaft 320.

To support the dental cast of the lower jaw 302, and to provide three- dimensional positioning of the dental cast of the lower jaw 302 relative to the stationary dental cast of the upper jaw 304, a suspension system is provided 354. As illustrated in Figure 15, the suspension system 354 generally includes first and second spaced apart struts, 356 and 358 respectively, to which is mounted a support assembly 360. The support assembly 360 includes a platform 362 for supporting a magnetic base 364 attached to the dental cast of the lower jaw 302. The platform 362 is suspended from a yoke 366 by rods 368 extending from a connecting block 370 to which is attached the platform 362. Each rod 368 slidably disposes within a corresponding aperture 372 contained within the yoke 366. The position of the platform 362 relative to the yoke 366 is adjustable by allowing each rod 368 to slide within the respective aperture until the desired position of the platform is achieved, at which time set screws 374 frictionally engage the rods 368 to the yoke 366. To attach the support assembly 360 to the struts 356, 358, first and second blocks 376 extend from the yoke 366, each containing an aperture 378 for receiving a shaft 380. Threadably engaged to each end of the shaft 380 are rod end bearings 382 for receiving a ball joint 384 attached to an upper portion of each strut 356, 358. The ball joints 384 therefore permit fluid positioning of the support assembly 360 through the displacement of each strut 356, 358. The suspension assembly 354 is positionable within six degrees of freedom in a reference or coordinate system by means of articulators and linkages connected to the frame 308 and the suspension assembly 354. The six degrees of freedom are broken down into two groups, including five active degrees of freedom and one passive degree of freedom. Providing the five active degrees of freedom are angular actuators 386. Referring again to Figures 13 and 4, each angular actuator 386 is preferably a servomotor. Servomotor 386a attaches to the first sidewall 310 and connects to a lower portion of the first strut 356 by means of a linkage 390. Such attachment of the linkage 390 to the strut 356 is accomplished by means of a rod end bearing 392 and mateable ball joint 394. The rod end bearing 392 attaches to the strut 356 and the ball joint 394 attaches to the linkage 390. However, it is well within the scope of the present invention to attach the rod end bearing 392 to the linkage 390 and the ball joint 384 to the strut 356. When selectively activated, the servomotor 386a pivots the linkage 390 in either a clockwise or counter-clockwise relation, which in turn imparts a vertical movement to the lower portion of the first strut 356 at the point of attachment, either upwardly or downardly. A corresponding servomotor 386b attached to the second side wall 312 provides similar vertical movement to a lower portion of the second strut 358 when activated. As such, servomotor 386b connects to the second strut 358 by means of linkage 396, rod end bearing 398 and ball joint 400, in much the same manner that servomotor 386a connects to the first strut 356. Also attached to the first side wall 310 is servomotor 386c. Servomotor 386c connects to the first strut 356 proximately midway along the length of the strut. The servomotor connects to the strut 356 by means of a linkage 402 and connecting arm 404. Both the linkage 402 and the strut 356 each include a ball joint 406 for journaling with corresponding rod end bearings 408 attached to terminal ends of the connecting arm 404. When activated, the servomotor 386c pivots the linkage 402 in either a clockwise or counterclockwise relation, which in turn imparts a translational movement, either rearward or forward, to the first strut 356. A corresponding servomotor 386d attached to the second side wall 312 provides similar translational movement to a middle portion of the second strut 358 when activated. As such, the servomotor 386d connects to the second strut 358 by means of linkage 410, connecting arm 412 with rod end bearings 416 and ball joints 414, in much the same manner that servomotor 386c connects to the first strut 356.

To laterally position the suspension system 354, servomotor 386e is provided. Servomotor 386e connects to the frame 308 by an "L"-shaped bracket 418 having a first leg 420 attached to the frame 308 and a second leg 422 for attaching the servomotor 386e thereto. Servomotor 386e is positioned substantially orthogonal to the other servomotors 386a through 386d and connects to an upper portion of the first strut 356 by means of a linkage 424 and connecting arm 426. Both the linkage 424 and the strut 356 each include a ball joint 428 for journaling with corresponding rod end bearings 430 attached to terminal ends of the connecting arm 426. When activated, the servomotor 386e pivots the linkage 424 in either a clockwise or counterclockwise relation, which in turn imparts a lateral movement, either left or right, to the upper portion of the first strut 356.

Providing the sixth passive degree of freedom is a linear actuator 440 mounted to the rear wall 314 of the frame 308 and connected to the connecting block 370 attached to the platform 362. The linear actuator 440 provides a constant force to the support assembly 360, and therefore preferably includes a pneumatic cylinder. However, the amount of force can be controlled to increase or decrease the amount of pressure to simulate chewing conditions. A port 442 allows introduction of air into the cylinder 440, which in turn forces a piston against the connecting block 370 of the support assembly 360. To provide for constant force throughout all movements of the support assembly 360, a distal end of the cylinder 440 includes a ball joint 444 which mateably engages a corresponding housing 446 attached to the connecting block 370. As described, the servomotors, 368a through 368e, connect to the suspension assembly 354 and deliver five active degrees of freedom along a hinge line of an imaginary tempormandibular joint. This imaginary line extends through the center of each ball joint 384 connecting the platform assembly 360 to each strut 356, 358. The ball joints 384 represent a pivot axis for the hinge, or an axis around which the platform assembly, and subsequently the dental cast of the lower jaw 302, pivots. The angle of rotation about this hinge is the sixth degree of freedom, and is referred to herein as the passive degree of freedom. The passive degree of freedom represents an approach motion between both jaws about the tempormandibular joint hinge. The passive degree of freedom is controlled in force mode, as compared to the other five active degrees of freedom which are controlled in displacement mode by the servomotors. The difference between force mode and displacement mode is that the active degrees of freedom effectively deliver the tempormandibular joint hinge into the desired position and orientation, while the passive degree of freedom in force mode maintains constant, or any desired force, on the platform 362 to achieve proper contact between upper and lower teeth of the respective dental casts 302, 304. Thus, the passive degree of freedom is controlled by the pneumatic cylinder 440 to provide a selected force to simulate the forces of working, or rather chewing, teeth. Preferably, the amount of pressure maintained on the pneumatic cylinder rangers from about 1 psig to 3 psig. However depending upon the effective piston area, or the application process, the force can be as high as 20 psig.

To provide a realistic motion of the lower jaw dental cast 302 relative to upper jaw dental cast 304, a synchronized motion of all the active degrees of freedom must be simultaneously controlled in real time. Any time delay creates an error in trajectory as well as wrong positioning of the lower jaw dental cast 302 versus the upper jaw dental cast 304. Positioning of the suspension system 354 is controlled by the servomotors 386a through 386e, which each include optical encoders (not shown) as a source of the feedback information. This network of motors and linkages represents a system having multiple degrees of freedom with high cross -coupling effects between input parameters, such as command signals, to the servomotors 386, or motor shaft positions of the servomotors, to provide true positioning of the lower jaw dental cast 302 versus the upper jaw dental cast 304. This is achieved through a closed loop control of the lower jaw in real time using both Direct and Inverse Kinematic Transformations, which are performed by a computer 448 running a software application and based upon positional data received during the recording process. It should be noted that use of the apparatus 300 of the present invention is not meant to be limited to any particular recording process, especially any process which is capable of recording or obtaining mandibular movement in an electronically stored format.

As part of the set-up prior to using the apparatus 300, it is necessary that an initial reference position be set to establish the proper relationship between the dental casts, 302, 304 when mounted on their respective bases 364, 332. In order to do so, several calibration devices are used. The calibration devices ensure the user that the integrity of information transferred from the recorder 102 to the replicator 300 is not lost and both jaws will be placed into replicator with the proper relative alignment.

To properly adjust the swing arm 322 and platform assembly 360 to receive the dental casts 302, 304, two parameters are obtained during the recording process, namely the vertical and horizontal positioning of the platform relative to the center points of the ball joints or hinge axis. The vertical positioning includes the distance as measured between two imaginary planes substantially horizontal to the work surface, one passing through the condylar ball joints 384 and the other consisting of a plane through the platform 362. The horizontal positioning includes the distance between two imaginary planes substantially orthogonal to the work surface, one passing through the condylar ball joints 384 and the other passing through the center of each magnetic base member 332, 364 respectively attached to the swing arm 322 and platform 362. The position of both the platform 362 and the swing arm 322 are then adjusted adjustable as described herein. Upon making the proper adjustments, the dental casts are attached to their respective bases and are brought together to define to the home occlusal position. The calibration bar 220, as used during the setting up of the dental casts 302, 304 is then used to establish the proper distance between each upper base 332 and the lower base 364. The articulator 300 is then calibrated with the computer 448 to determine the initial reference or home position. With reference to Figures 16 and 17, this is accomplished by using a calibration frame 456 and adjustable support device 458. The calibration frame 456 rests upon the works surface 306 and supports the suspension assembly 354 at a fixed position. The adjustable support device is then positioned between the work surface 306 and the platform 362 to provide support to the platform 362. When the calibration frame 456 and adjustable device 458 are in place, the computer 448 zeros out all optical encoders used for feedback to control servo loops. Thus, by use of the calibrating frame 456 and adjustable support device 458, the reference or zero position can be calibrated which can be verified and compared with other fixtures. This initial reference position is critical because closed loop control is used around each individual servo motor 386, meaning that the apparatus 300 is controllable in Joint Domain and not TMJ Domain, as is fully described in concurrently filed application previously referenced herein. Joint Domain represents all mechanical joints used by the recording device as a part of the multiple degrees of freedom linkage, while TMJ Domain is associated with coordinates of each center of the condyles and the rotational angle about the axis through each condyle. That type of control requires a transfer function between the Joint Domain and the TMJ Domains, which is performed by a software program within the computer 448 to be performed in real time or in preprocessed mode.

The servomotors 386 are controlled by an interface module which is controlled by the computer 448 by a motion interface board. The interface board is preferably includes Model No. DMC- 1800 as made commercially available by Galil Motion Control of Rocklin, California. As illustrated in Figure 18, a separate power source 462 runs all of the servomotors 386. Running the software application, the computer 448 selectively and synchronously activates each servomotor 386a through 386e to position the suspension assembly 354 to move the lower dental cast 302 relative to the upper dental cast 304 to accurately replicate the actual movement obtained during the recording process. The upper jaw dental cast 304, attached to the swing arm 322, remains stationary with respect to the replicator 300 and does not move during the replicator process. However, the arm 322 can be preset for any given settings and still perform during replication wherein the computer 448 recalculates command signals to control the servomotors 386a through 386e to follow the desired trajectory from the pre-recorded settings into any the actual settings used during the replication. The swing arm 322 can be pivoted away from the platform assembly 360, whereby the similar dental casts 302, 304 can be removed or replaced if testing on dental casts from the same patient is desired. Because all of the settings are preserved, recalibration of the apparatus 300 is not required. Also, the swing arm 322 is designed to pivot out of place if the force supplied to the lower dental cast 302 is too great, thereby minimizing damage to the dental casts 302, 304, the swing arm 322 or the suspension assembly 354 is such an event should occur.

Although the present invention has been described with reference to preferred embodiments, workers skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the invention.

Claims

CLAIM(S):

1. An apparatus for use in dentistry to obtain positional data related to movement of a mandible about a maxilla, the apparatus comprising: a support frame; a maxilla support member fixedly attached to the support frame; a mandibular member positionable proximate the maxilla member; a first sensing assembly attached to the support frame and connected to the mandibular member, the first sensing assembly to obtain a first set of positional data of the mandibular member proximately along a x-axis; a second sensing assembly attached to the support frame and connected to the mandibular member, the second sensing mechansim to obtain a second set of positional data of the mandibular member proximately along a y- axis; and a third sensing assembly attached to the support frame and connected to the mandibular member, the third sensing assembly to obtain a third set of positional data of the mandibular member proximately along a z-axis.

2. The apparatus of claim 10 wherein each set of positional data includes data related to pitch, yaw and translational positioning of the mandibular member proximately along the respective axis.

3. The apparatus of claim 10 wherein each sensing assembly comprises: a base member attached to the support frame; a first gimbal assembly pivotally secured to the base member; a second gimbal assembly connected to the first gimbal assembly, the second gimbal assembly pivotal orthogonal to the first gimbal assembly; a first elongated member attached to the second gimbal assembly; and a second elongated member slidably engageable with the first elongated member, the second elongated member connected to the mandibular member.

4. The apparatus of claim 12 wherein each sensing assembly further comprises: a first sensor to obtain data relative to movement of the first gimbal assembly; a second sensor to obtain data relative to movement of the second gimbal assembly; and a third sensor to obtain data on the movement of the first elongated member relative to the second elongated member.

5. The apparatus of claim 12 wherein each sensing assembly further comprises: a first sensor to detect positioning of the first gimbal assembly; a second sensor to detect movement of the second gimbal assembly; and a third sensor to detect positioning of the first elongated member relative to the second elongated member.

6. The apparatus of claim 10 wherein the positional data each sensor assembly obtains includes pitch, yaw and translational positioning of the mandibular member proximately along the respective axis.

7. An apparatus to replicate and analyze movement of a mandible relative to a maxilla with dental casts thereof, the apparatus comprising: a base frame; an arm connected to the base frame for supporting the dental cast of the maxilla in a fixed position relative to the base frame; a suspension assembly to support the dental cast of the mandible in working relation to the dental cast of the maxilla, the suspension assembly including opposing first and second sides; a first actuator to selectively impart lateral movement upon the suspension assembly; a second actuator to selectively impart forward or rearward movement to the first side of the suspension assembly; a third actuator to selectively impart forward or rearward movement to the second side of the suspension assembly; a fourth actuator to selectively elevate or lower the first side of the suspension assembly; and a fifth actuator to selectively elevate or lower the second side of the suspension assembly, whereby selectively activating each actuator to impart said respective movement, the suspension assembly is positionable to replicate movement of the mandible relative to the maxilla.

8. The apparatus of claim 1 wherein the first actuator connects to the base assembly and an upper portion of either side of the suspension assembly, wherein the second actuator connects to the base assembly and a mid portion of the first side of the suspension assembly, wherein the third actuator connects to the base frame and a mid portion of the second side of the suspension assembly, wherein the fourth actuator connects to the base frame and a lower portion of the first side of the suspension assembly, wherein the fifth actuator connects to the base frame and a lower portion of the second side of the suspension assembly.

9. The apparatus of claim 2 wherein each actuator connects to the suspension assembly by a rod end bearing.

10. The apparatus of claim 1 and further comprising a piston attached to the base frame and the suspension assembly to impart a substantially constant force onto the suspension assembly.

11. The apparatus of claim 1 wherein each actuator includes a servomotor.

12. The apparatus of claim 1 wherein the suspension assembly comprises: a support member; a first positionable stanchion defining the first side of the suspension assembly, the first stanchion having an upper portion pivotally attached to a first side of the support member; a second positionable stanchion defining the second side of the suspension assembly, the second stanchion having an upper portion pivotally attached to an opposing second side of the support member; and a platform suspended from the support member between the first stanchion and the second stanchion to support the dental cast of the mandible.

13. The apparatus of claim 6 and further comprising a piston attached to the base frame and pivotally connected to the platform, the piston providing a substantially constant moment onto the platform.

14. A method of analyzing gnathological factors, the method comprising: providing a recording apparatus to obtain positional data pertaining to the movement of a lower jaw relative to an upper jaw of a patient, the recording apparatus comprising: a rigid support frame; a maxilla support member fixedly attached to the support frame; a mandibular member attachable to and positionable proximate the maxilla member; a first sensing mechanism attached to the support frame and connected to the mandibular member, the first sensing mechanism for obtaining positional data of the mandibular member substantially along an x-axis; a second sensing mechanism attached to the support frame and connected to the mandibular member, the second sensing mechansim for obtaining positional data of the mandibular member substantially along a y-axis; and a third sensing mechanism attached to the support frame and connected to the mandibular member, the third sensing mechanism for obtaining positional data of the mandibular member substantially along a z-axis; acquiring the positional data; storing the positional data into a data storage medium; processing the positional data with a central processing unit to achieve a first output file; and manipulating the output file to achieve a visualization of the movement between the upper jaw and the lower jaw, whereby the gnathalogical factors between the upper jaw and the lower jaw are analyzable.

15. The method of claim 16 and further comprising: obtaining dental casts of the lower jaw and the upper jaw of the patient; providing a mechanical articulator comprising: a base frame; an arm connected to the base frame for supporting the dental cast of the maxilla in a fixed position relative to the base frame; a suspension assembly to support the dental cast of the mandible in working relation to the dental cast of the maxilla, the suspension assembly including opposing first and second sides; a first actuator to selectively impart lateral movement upon the suspension assembly; a second actuator to selectively impart forward or rearward movement to the first side of the suspension assembly; a third actuator to selectively impart forward or rearward movement to the second side of the suspension assembly; a fourth actuator to selectively elevate or lower the first side of the suspension assembly; and a fifth actuator to selectively elevate or lower the second side of the suspension assembly, whereby selectively activating each actuator to impart said respective movement, the suspension assembly is positionable to replicate movement of the mandible relative to the maxilla; mounting the dental casts onto the mechanical articulator; and wherein manipulating the output file to achieve a visualization of the upper jaw and the lower jaw includes interfacing the mechanical articulator with the central processing unit, wherein the central processing unit utilizes the first output file to selectively activate each actuator of the mechanical articulator to replicate movement of the lower jaw relative to the upper jaw.

16. The method of claim 17 and further comprising: obtaining dental casts of the lower jaw and the upper jaw of the patient; scanning each dental cast to obtain topographical data representative of each dental cast; inputing the topographical data of each dental cast into the data storage medium; processing the topographical data with the central processing unit to achieve a second output file; providing a user interface; manipulating the data from the first output file and the second output file to achieve a virtual representation of the movement of the lower jaw relative to the upper jaw, said movement viewable on the user interface.

17. The method of claim 16 and further comprising: obtaining dental casts of the lower jaw and the upper jaw of the patient; scanning each dental cast to obtain topographical data representative of each dental cast; inputing the topographical data of each dental cast into the data storage medium; processing the topographical data with the central processing unit to achieve a second output file; providing a user interface; manipulating the data from the first output file and the second output file to achieve a virtual representation of the movement of the lower jaw relative to the upper jaw, said movement viewable on the user interface.