AU597791B2

AU597791B2 - Apparatus and method for determining relative motion of the jaw

Info

Publication number: AU597791B2
Application number: AU11904/88A
Authority: AU
Inventors: Horst Franke; Brigitte Kling
Original assignee: Ivoclar AG
Current assignee: Ivoclar AG
Priority date: 1987-02-27
Filing date: 1988-02-17
Publication date: 1990-06-07
Anticipated expiration: 2008-02-17
Also published as: AU1190488A; EP0288682A1; DE3706473C1

Description

P18/7/78 PHILLIPS ORMONDE FITZPATRICK Patent and Trade Mark Attorneys 367 Collins 'Street Melbourne, Australia STUART TAYLOR 4

AUSTRALIA

Patents Act 5977 91 CLMPIE SPECIFICATION

(ORIGINAL)

Class In~t. Class Application Number: Lodged: Complete Specification Lodged: Accepted: Published: *Priority Related Art: MThis documt contains the amendments mnade uinder Section 49 and is correct for printing.

APPLICANT'S REFERENCE: 2657-11-13.893 Name(s) of Applicant(s): Ivoclar AG Address(es) of Applicant(s): FL- 9494, Schaan,

LIECHTENSTEIN.

Address for Service is: PHILLIPS ORMORDE FITZPATRICK Patent and Trade Hark Attorneys 367 Collins Street Melbourne 3000 AUSTRALIA Complete Specification for the invention entitled: APPARAT1US AND METHOED FOR DETERMINING RELATIVE MO)TION~ OF THE JAW Our Ref 84930 POF Code: 1502/77261 The following statement is a full description of this invention, including the best method of performing it known to applicant(s); 6003q/1-1 1 2 o 0040 iJ O 0 0 3 O 0900 0 00 0 4w 0 0, 0 00 00o 0 00 APPARATUS AND METHOD FOR DETERMINING RELATIVE MOTION OF THE JAW The present invention relates to a device for determining the motion parameters of the lower jaw for its relative motion with respect to the upper jaw, and to a suitable procedure for this purpose.

Such a device has an impulse transmitter connected to the upper jaw as well as three sensors connected to the lower jaw. The clearance of each sensor from the transmitter can be determined by the some characteristic, such as duration, of the transmitted impulses from the transmitter to the sensors. Because the three sensors are configured in the form of a triangle, the relative position of the lower jaw to the upper jaw can be calculated for each position from the clearances that are then known.

Such a device, however, has not proven feasible in practice. For one, the configuration of the sensor and of the transmitters in the gum and tongue area of the patient was found to be uncomfortable. Because slightly different duration differences already lead to significant position differences, a very precise determination of the clearances has to be performed. But this requires very expensive and highly precise components. In particular, temperature influences can have very negative consequences.

Such a device also has additional disadvantages because electrical connecting wires have to be led through the tooth area so that unintentional biting by the patient regularly leads to a destruction of the connection.

Due to the steep sloped angular configuration of the sensors with respect to the transmitter, a coordinate transformation is required in order to determine the position of the lower jaw with respect to the upper jaw.

Such a device, in particular for the very important determination by the patient about the sliding way, is less suitable for preparing tooth replacement. This is based on the fact that the sliding way is determined to fractions of millimeters by the teeth that are in the patient's mouth and that very precise adjustment of the new teeth must be

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C s 2-- 0 000* oc 0 0 2nO 00 0 0 0 0 S0 0 0 o 0 it 20 0 00Q 0a0 0 00 0 00 0 00 00 0 0 0 0 00 Qn D 0 OD 00 (000000 0 0 performed, making this device inadequate.

Furthermore, it is known how to determine the condyle path and the rotation center of the condyles by means of so-called panthographs. For this, a piece of paper with millimeter markings on it is mounted on the side of the patient's head near the condyle area. A recording device is mounted at the lower jaw of the patient and it indicates the motion of the lower jaw at this point. The condyle inclination and the rotation center of the condyles can be determined from the recorded curves. For this, however, it is not possible to simulate the exact motion of the teeth on an articulator, which is used for producing tooth replacement.

Therefore, it is an object of the invention to create a device and a procedure for determining motion parameters of the lower jaw for its relative motion with respect to the upper jaw with the general concept contained in the following disclosure in which it is possible to determine all relevant motion parameters for the sliding way without having to use complicated coordinate transformation.

4-4 a rA-In 16with the fo! ;owing disclouro, this problem is solved by by the apparatus and the method of Ke present invention, as defined in the claims hereof.

The configuration of one sensor with to sensor elements alongside the two other sensors havi g one sensor element each, at a measuring point, is particularly advantageous. As a result, a p ctical, jaw-related coordinate system can be determineu whereby the one sensor with two sensor elements whi adelivers two measuring data transmits these data onto different coordinate axes.

In order to simp ify the determination of the relative position and dire, ion of the lower jaw with respect to the upper jaw, it an be assumed that a lateral movement along the hingei xis is not possible for human condyles. Except for c es of extreme jaw fluxation, this practically always isrue in a good approximation.

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According to the present invention, there is provided a device for determining the motion parameters of the lower jaw in relation to the upper jaw, comprising at least one transmitter means, fixed to one of the jaw elements comprising a jaw contact element and a transmitter element and which actuates at least three sensor means disposed on the other jaw, each said sensor means disposed on a jaw contact element, whereby the connected sensors have a fixed spatial relationship to each other and are also configured on a common axis, wherein one measured value can be determined with one pair of the said sensor means and at least two measured values can be determined with the third sensor in separate metering directions and said measured values model the relative motion with a resolution through a measuring range which is considerably smaller than the path which the lower jaw transgresses during the motion of the mouth from the closed position to the maximum open position; and wherein at least one of said sensor means is adapted to be disposed adjacent the incisal teeth of a patient and at least one of said sensor means is adapted to be disposed adjacent the molar teeth of a patient.

The present invention also provides a procedure for determining the motion parameters of the lower jaw for its relative motion with respect to the upper jaw comprising fixing at least one transmitter means to one jaw by means of a jaw contact element, fixing at least 3 sensors to the other jaw section by means of another jaw contact element and a sensor element in which the connected sensors in a fixed spatial configuration to each other outside of a common axis, and measuring a plurality of values representing a model of the motion of the lower jaw with respect to the upper jaw and after completing the measurements, removing the jaw contact elements, whereby the jaw contact elements can be taken from the mouth of the patient and attached to an articulator which serves to produce a tooth substitute for this patent to replicate the relative motion of the jaws of the patient, and wherein a measured value is determined with one pair of the sensors I I tI Ii t o 4 ~3 0 cli C 0 0 0 4

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I i t t II 1 -2 band two measured data in various measuring directions are determined with the third sensor, and wherein at least one of said sensors is adapted to be disposed adjacent the incisal teeth of a patient and at least one of said sensors is adapted to be disposed adjacent the molar teeth of a patient.

The present invention further provides a method for determining the motion parameters of the lower jaw in relation to the upper jaw, comprising fixing at least one transmitter means to one of the jaw elements said transmitter means comprising a jaw contact element and a transmitter element and fixing at least three sensor means on the other jaw, each said sensor means disposed on a jaw contact element, whereby the connected sensors have a fixed spatial relationship to each other and are also configured on a common axis, and simultaneously transmitting a signal from said transmitter means said sensor means while the lower jaw is articulated through a limited range of motion from the closed position to a partially open position, and recording the output of said sensors as a measure of the relative motion throughout the range of articulation, and wherein at least one of said sensor means is adapted to be disposed adjacent the incisal teeth of a patient and at least one of said sensor means is adapted to be disposed adjacent the molar teeth of a patient.

The configuration of one sensor with two sensor elements alongside the two other sensors having one sensor element each, at a measuring po~t is particularly advantageous. As a result, a pra.;tical, jaw-related coordinate system can be determined whereby the one sensor wi'th two sensor elements which delivers two measuring data transmits these data onto different coordinate axes.

In order to simplify the determination of the relative position and direction of the lower jaw with respect to the upper jaw, it can be assumed that a lateral movement along the hinge axis is not possible for human condyles. Except for cases of extreme jaw fluxation, this practically always is true in a good approximation.

It is especially advantageous that the determination

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3of position is a function of the sliding way with the maximum precision possible. Whereas the condyle path is subjected to dynamic fluctuations, because the joint parts consist of elastic cartilage which can change shape due to muscle tension so that precise condyle paths cannot be determined, the mouth fitting of the upper and lower jaw teeth row can be precisely determined with respect to each other.

By using the same device in an articulator, which serves to produce tooth replacement for these patients, measuring errors as appear necessarily when other devices are used, are excluded in this instance.

The limitation of the measuring range of the sensors O~o to the closed and almost closed position of the mouth is especially advantageous. As a result, a higher degree of sensitivity is achieved in this range so that the condyle path motion can be precisely determined. By determining at least four measuring data, the movements of the lower jaw with respect to the upper jaw can be determined if one starts from a known condyle path inclination. Given a known distance of the sensor part or the transmitter part connected to the lower jaw connecting part from the hinge axis, the motion of the lower jaw with respect to the upper jaw can be determined with these measured data, regardless of the known starting position. The lower jaw movements can easily be reproduced by the configuration of the sensor measuring directions in an orthogonal coordinate system.

The shift in the hinge axis resulting from the movement of the lower jaw does not distort the measuring results. For one, this is a result of the determination of four or, if necessary, five measuring data if the distance of the hinge axis is also not supposed to be measured in addition. On the other hand, the movements of the lower jaw are measured true to the surface of the teeth. The measuring precision during movement in the lateral and frontal direction is at least not less than the measuring precision for the movement in the vertical direction.

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4o #0 5 oFF' Nevertheless, the degree of complexity for this measurement is low; the direct introduction of the measuring data without coordinate transformation on an XY plotter already provides directly interpretable results if the alignment of the sensor elements is suitably selected.

Given the procedure presented by the invention, in which the measurement is done by moving the lower jaw with respect to the upper jaw, the motion is provided in the area near the occlusion whereby the movement occurs in all horizontal directions.

In addition, given the procedure provided by the invention, it is especially advantageous that the patient for the measurement only has to guide the lower jaw in the Bennet motion and in protrusion. As a result, the types of movement area easily reproduceable and the sliding way is comparably easy to measure. Because both movements are done by the patient himself, the influence of the patientspecific muscle force is also taken into account; due to the elasticity of certain joint parts at the condyles, this leads to slightly different motion processes than in performing movements without muscle power, that is by the dentist.

In accordance with another embodiment provided it is advantageous that the calculation of the movement of the lower jaw with respect to the upper jaw is comparatively simple as a result of the combination of two sensor elements to form one sensor which is activated by the motion of one area of the transmitter part, especially if the two other sensors record the motion of the lower jaw at the corresponding measuring points in the third coordinate or in the direction of measurement.

In another embodiment, one can assume movement of the hinge axis in the lateral and frontal direction whereby the hinge axis is shifted on a level which is essentially parallel to the Frankfurt horizontal level. Hereby it is assumed that the distance of all sensor elements from each other and to the hinge axis is constant.

0r 0 a 0 0 OF 050 0,t a 4 *o I *1 t a.

o o 4t4oa S The position change of the lower jaw with respect to the upper jaw can be completely determined by the aid of a rod assembly for determining the rotation center a socalled face bow.

For still another configuration, the movement curve of the teeth rows can be determined suitably in the occlusion position for the lateral and frontal movement of the lower jaw.

The condyle path inclination or slope can be determined by the face bow and, from the curve compensation with the measured data, the articulator can be adjusted to the patient-specific movement parameters.

For still another configuration, an easy determination of the vertical movements of the lateral and frontal shift of the lower jaw is possible in the occlusion position because the sensor in the incisal area can have three directions of measurement in an orthogonal coordinate system. In particular, with such a device having five sensor elements, it can easily be determined at what point of the teeth rows there is a relatively significant strain placed on the teeth. With this embodiment, a face bow is dispensable and it is advantageous if the sensor elements provided in the incisal area function in the lateral, frontal and in the mouth opening directi n. On the basis of the determined five measured values in an empirical way, the articulator can be adjusted to the patient-specific movement parameters by means of curve balancing.

In another embodiment, if the connection between the jaw connecting parts and the sensor or the transmitter part is mounted in such a way that it can be separated, the jaw connecting parts can be adjusted without the patient having to wear sensor or transmitter parts, even if they are light weight.

It is advantageous that the connecting cable does not have to be guided into the mouth area so that the cables cannot be damaged by accident. With a correspondingly smaller configuration of the sensor elements, it is also I 1; I: i 6i0 o 00000 0000 o 0 oaooo :o o 0 0 0 0 000000 0 0 0 0* 0 20 0 00 00 0 0 0 0 00 0 005 0 00 0 0 possible to place the two sensor elements which are located alongside the molars and which function in the mouth opening direction and, therefore, are relatively narrow, within the mouth area, but outside of the teeth row, whereby the connecting cables have to be installed carefully.

The complexity of the calculations is decreased because, no angles have to be determined. Influences by the data determined by another sensor element in another measuring direction can be avoided and the precision of the measurement is greater as a result of the concomitant complete disengagement of the direction of measurement because each movement viewed vectorally is subdivided into the shortest individual movement components. The individual vectors and movement components are completely independent of each other and the resulting measurement error is minimal.

The corresponding sensor elements may be disposed to be effective only in the area near occlusion. Outside of the measuring area, the sensor elements are disengaged.

The lower jaw can move freely so that the device presented by the invention is highly compatible. Furthermore, the measuring range can be concentrated on the particularly relevant area near occlusion so that there the resolution and precision are greater.

In an individual design, a separate guide is advantageous which for example can be produced by a suitable penetration hole in which the transmitter element is easily mobile.

It is advantageous and often preferred that the transmitter elements are connected firmly with each other in the position of the lower jaw that is in a near occlusion position, and the connection can separate by itself with a defined force as soon as the distance between the lower jaw and the upper jaw is greater. With this type of configuration, a very precise subdivision of the motion is possible into the measuring direction of each sensor Cs r i i i 1' 7i 00 o oo o o 0 0004 son

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0 0 20 0 0I 00a 0 0 00 0 00 00 0 0 04 00 0 0 00a 0 00 element. With a suitable configuration, the required coordination of the sensor elements to the concomitant transmitter element is always maintained and the sensor elements do not influence each other.

A contactless determination of the measured values is possible in connection with a comparably small structural size and without expensive measurement electronics. Hall elements are also unsusceptible to dirt and comparatively light. The use of permanent magnets for the transmitter elements is recommendable.

It is advantageous that the transmitter elements can be magnetized by means of flux adaptors from a central permanent magnet.

It can be prevented that a movement in one direction, which is different from the measuring direction of the corresponding transmitter element, can be transferred to this element. It is especially advantageous that the attachment of the taansmitter element to the connecting part is provided due to the magnetic holding power which functions precisely to the degree that reliable mounting is assured and a separation of the connecting part from the transmitter elements is possible when the mouth is opened into the clear area. This also applies to the sensor elements whose measuring directions are vertical to the mouth opening direction.

Errors caused by the sloped position of the stop face with respect to the measuring direction of the sensor element that is vertical to this plane are avoided.

The possibility of a low-friction guide is especially advantageous in some circumstances. However, tilting has to be avoided by too much play. The design of the magnetically effective area of the plate which essentially is level, avoids linearity errors.

The measuring range can be linearized even more by some arrangements, especially if the magnetically effective part of the transmitter element is shaped in the form of a concave spherical segment.

00 0 0 0044 4*40U o p 0081 o 20 o oo 0s 0 00g 4I 4 ~B 00) 4r 0 4* 04 4 4 0 0er 8-- The strength of the magnetism having an effect on the stop faces can be controlled over broad ranges.

The hyperbolic characteristic curve of the sensor element can be further linearized so that a linearized measuring area of about 10 mm is possible. The flux adaptors can be connected to the transmitter element or to the sensor element. For even more desired miniaturization, the transmitter elements can also be designed as powerful miniature magnets whose characteristic curves are electrically linearized.

For some embodiments, the connection between the transmitter element and the transmitter part can be limited to the magnetic holding power whereby the magnetic transfer resistance can be set using suitable means.

For example, the ferro-magnetic material in the stop faces can be covered with a thin coating, e.g. a coating made of plastic material with a low friction coefficient and in this way the desired holding force can be established. Such a configuration also has hygienic advantages.

The load does not act within the actual measuring range, but rather only takes effect if the required lateral degree of motion is supposed to exceed, in exceptional cases, the doubled measuring range of a normal sensor element. This extreme lateral retrusion range plays no role for gnathological information.

The maximum design size of the sensor elements, which can be at 4.5 mm in its simple form, can be doubled. The limitation to comparably small maximum shifts or measuring ranges has advantages with respect to precision and linearity and the configuration is sufficient for determining the sliding way motion at the protrusion and for the Bennet motion or lateral retrusion range. Most expediently, the switching in the output signals of the sensor element parts is done electrically.

Natural motions and the easy mobility are in no way obstructed.

ii 1 ~c 7 p 9a~a 0- 00 009 0 C 00 0 0 O 0 *7 0 o) The motion of the lower jaw with respect to the upper jaw can already be determined exactly with only five measured data corresponding to five sensor elements whereas for this embodiment and the known hinge axis, only four measured data are required. The determination of the movement of the lower jaw in the three dimensions is possible. For the destruction-free functioning of the teeth rows, it is necessary that the patient can make the same chewing motions with the tooth replacement as with his natural teeth so that as natural a reproduction of the movements as possible should be endeavored.

By means of patient-specific production of the jaw connecting parts sample scatterings between various devices can be taken into account.

One can begin right away with the measurement once the jaw connecting parts have hardened. Preferably, the jaw connecting parts can be cleaned and, if necessary, removed if this is supposed to be required.

An example of the invention is described by means of Figures 1 to 7: Figure 1 a schematic plan view of a lower jaw connecting part which is connected to a sensor part; Figure 2 a schematic plan view of an upper jaw connecting part which is connected to the transmitter part; Figure 3 a side view of the part depicted in Figure 1, of the device according to the present invention; Figure 4 a lateral view of the part of the device presented by the invention as depicted in Figure 2; and Figure 5 a lateral illustration of a sensor element in relation to the transmitter element and the directly adjacent area of the transmitter part; and Figure 6 an illustration of another embodiment of a sensor element in a form which is further miniaturized than the one in Figure 5; and Figure 7 the jaw connecting parts in connection with each other and separated from the sensor part and the transmitter part.

00 a d poor00 O 0 S_ :iA i i 2 er0oo 40006 O V 00 0 4 0 20 4 00 0u tn 0 4a0 0 a 0 a 0e 0 4 The lower jaw connecting part depicted in Figure 1 has a material 10 which has internal teeth impressions, 12, corresponding to the lower jaw teeth row of the patient following its internal application to the patient. A bite fork, 14, is inserted into the material, 10, from the outside. The bite fork encloses about two-thirds of the material 10 and simultaneously stabilizes it. The bite fork, 14, also has a contact area, 16, which as can be seen better in Figure 7 is folded upward. The contact area, 16, serves both to form a connection to the bite fork of the upper jaw as well as to form a contact to a sensor part, 18, and has a hole, 20, for this purpose in which a screw bolt or another suitable, removable, but stable connection can be mounted. The bite fork, 14, and the material, 10, form the jaw connecting part, 22, for the lower jaw.

The sensor part 18 has a number of sensors of which one sensor, 24, is located to the left side of the molars and one sensor, 26, is located to the right side of the molars and one sensor, 28, is located in the front center in front of the incisors. Sensor 24 and sensor 26 have one sensor element each, 30 and 32, which only are activated in the mouth opening direction. The sensor elements, 30 and 32, are mounted to the sensor part, 18, by means of masts, 34 and 36. The masts are rigid in the mouth opening direction and can be shaped with less rigidity in other directions. They stretch directly along the bite fork, 14.

For a correspondingly smaller configuration, the sensor elements, 30 and 32, can be located at the bite fork so that they are located in the mouth of the patient during the measurement. Selectively, however, the distance can be set greater so that the sensor elements, 30 and 32, are located outside of the mouth of the patient.

The sensor, 28, has a frontally sensitive sensor element, 40, and a sensor element, 42, that is sensitive in the lateral direction. The sensor element, 42, that is sensitive in the lateral direction consists of two parts, j I1 1 I i 11-- 42a and 42b, whose function is described in greater detail below. The sensor part, 18, is relatively thin in the area of the sensor, 28, because only forces in the horizontal direction, that is the main movement direction of the sensor part, have to be recorded.

The rigidity of the masts, 34 and 36, can, for example, be achieved by the fact that the masts are bent into a U-shape so that the sensor part, 18, can consist of a single-unit, thin plate, for example made of aluminum.

The sensor elements, 42a and 42b, have each a double actuation way with respect to the sensor elements, 30, 32, and 40. The linearized area of these sensor elements, 42a and 42b, however is just as large as that of the sensor 0 elements, 30, 32, and 40; only the guide is extended. As a os result, it is possible to double the measuring area of the U00 o sensor element, 42. If the output signal of the sensor element part, 42a, is larger than that of the sensor element part, 42b, the corresponding transmitter element is closer to the sensor element part, 42a, than the sensor element part 42b, and the sensor element part, 42a, is used for the measurement. The same applies in reverse to sensor S element part 42b. This reversal can most expediently be done electrically and automatically whereby the size of the o 6o output signals of the sensors be measured by means of a comparator. A switch circuit is then triggered as a function of the output signal of the comparator. In order 0 0 0 0 to achieve a linear measuring range, the characteristic curve of one of the sensor element parts, 42a or 42b, also have to be reflected. Furthermore, adjustment devices for compensating the two characteristic curves of the sensor elements, 42a and 42b, particularly in the area of zero transition, are provided in a known way.

Along the side of the sensor, 40, there is a recess in which a connecting rod, 45, of a face bow can be inserted.

A jaw connecting part, 44, for the upper jaw is depicted in Figure 2. It is connected to a transmitter part, 46. The upper jaw connecting part, 44, essentially _i 'Li iii--_li iil~i -lil-_ lilyiiiii 12has the same design as the lower jaw connecting part, 22, with a material, 48, and a bite fork, 50. The transmitter part, 46, is connected to a contact area, 52, of the bite fork, Both the transmitter part, 46, as well as the sensor part, 18, have a short type of construction in the frontal direction which contributes to an increase in the measuring precision and also reduces the required weight and also is felt to be less uncomfortable by the patient. But the contact areas 16 and 52, can be adjusted to be somewhat longer and more compatible with the lips so that the sensor, 28, is located clearly outside of the mouth.

The transmitter part, 46, has masts, 54 and 56, which OQ are designed in a way that corresponds to masts 34 and 36.

0A stop face, 58, which is adjoined to the sensor element, P~ PC oo 30, is connected to the masts, 54 and 56 and a stop face, aoo. 60, which is associated with the sensor element, 32, is 0 P also connected to the masts. The stop faces, 58 and are each connected to a transmitter element, 62 or 64. The more precise configuration of the combination of the sensor element, 30, with the transmitter element, 62 and of the sensor element, 32, with the transmitter element, 64, can be seen in Figures 5 and 6.

A stop face, 66, for the sensor element, 42, and a stop face, 68, for the sensor element, 40, are provided in an azea of the transmitter part, 46, that is connected to a

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sensor, 28. The stop face, 66, consists of an area, 66a, connected to the sensor element, 42a, and of an area, 66b, that is connected to the sensor element, 42b. The areas, 66a and 66b, can be located immediately adjacent to each other, but can also have a distance between them whereby the stability is improved. The transmitter part, 46, is so rigid in the horizontal direction that the stop face, 68, which is connected to the sensor element, 40, cannot shift to the side.

The illustration in Figure 3 shows a lateral view of the lower jaw connecting part, 22. The same reference

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r 13-- 1 o 0a 0 0r 4.an 0ni 20D 4. 00 4.00 000 30 numbers indicate the same parts as in the other Figures.

The sensor element, 32 as well as the sensor element, 30, which is not illustrated here is sensitive in the vertical direction, that is in the mouth opening direction. The sensor element, 42, is sensitive in the lateral direction. The sensor element, 40, is sensitive in the frontal direction. All sensor elements are firmly connected to each other and essentially have the design shown in Figures 5 or 6. The sensor part, 18, secured to the lower jaw connecting part, 22, is positioned relatively high in the mouth of the patient whereas on the other hand the transmitter part, 46, secured to the upper jaw connecting part, 44, is positioned relatively low. But the sensor part, 18, and the transmitter part, 46, may not have contact; they may also not contact in the maximum occlusion position of the teeth of the patient. The lower jaw connecting part, 22, is connected to the sensor part, 18, by means of a screw bolt, The upper jaw connecting part, 44, and the transmitter part, 46, are illustrated in Figure 4 whereby these parts are connected by means of a screw bolt, 72. The stop faces, 60, 66 and 68 and 58 (not shown), are located at one such point and designed in such a way that the right stop face contacts the concomitant transmitter element within the three-dimensional measuring range of the device presented by the invention. But as soon as the measuring range for a sensor element, for example for sensor element 32, is left, it is not necessary for the vertical stop faces, 66, and the stop face, 68, to remain at the concomitant parts of the transmitter elements, 74 and 76, which are indicated by dashes in Figure 4. The stop faces, 66 and 68, of the transmitter elements, 74 and 76, and the stop faces, 58 and 60, of transmitter elements, 62 and 64, are connected to each other by means of a connecting part, The stop faces can always be set in such a way that the complete measuring area can be used for all sensor elements, but both material and weight can be saved, as I 'I 14-- L08 II0* o t 0 90 0 0* a 94 I 4 9 I.

required. If a sensor element becomes disengaged, the other affected sensor elements can also automatically enter the clear area.

The sensor element, 32, is illustrated in an engaged position with the transmitter element, 64, in Figure All sensor elements and transmitter elements used in this embodiment of the invention have a similar design, but the guide path is maintained twice as long here for the sensor elements, 42a and 42b.

The sensor element, 32, consists of a frame, 78, which is firmly mounted to the sensor part, 18 for example, by adhesives. The frame has a rectangular basic structure whereby a base leg, 80, supports a Hall element, 81, and is connected at both ends to side legs, 82 and 84, which each hold a terminal leg, 86. A guide, 88 shown in dashes is provided in the terminal leg which guides a part of the transmitter element, 64.

The transmitter element, 64, consists of a shlaft, and a plate, 92, and is connected to the stop face, 60, of 20 the transmitter part, 46. The plate, 92, is so large that is essentially can cover the Hall element, 0k8 and extends along the side from side leg, 82, to side leg, 84. The plate, 92, but preferably the shaft, 90, is designed as a i permanent magnet. Because the plate, 92, and the stop face, 60, are made of ferro-magnetic material, they hold together these three parts forming the transmitter element, 64, without having to use additional mounting measures.

SInstead of the guide, 88, or in addition to it, the plate, 92, can be placed at the side of tne frame, '78, it being also possible to use guide surfaces, 94 and 96 (shown in points), at the side legs, 82 and 84. The side legs then essentially have a U-shape and the plate, 92, is securely mounted.

The terminal leg, 86, and a contact near the Hall element, 81, function each as a transmitter element, 64, guided in such a way that it can slide in guide, 88.

FThe assembly of the plate, 92, in the pre-fabricated

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6 0009* r-7 v;7 I 00 a I F. 0 00O 00 0 0t 00a* 20 0 00p 04, o *0 0 0*~ 00 0 Q 00) 0 0I 4 0 *4 01 00r 4-.r

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ararb 0 frame, 78 for example, as a plastic part occurs simply by inserting it from the side. If guide surfaces, 94, 96, are provided, the plate, 92, can be slightly sloped for insertion into the frame, 78.

If the holding force of the shaft, 90, designed as a permanent magnet at the plate, 92, is desired to be clearly larger than the one of shaft 90 at the stop face, 60, no additional measures need be take:i for securing it because all parts of the transmitter element are securely mounted.

The same applies if the plate, 92, is itself designed as a magnet.

If desired, the size of the plate, 92, used, the Hall element, 82, and the measuring area, 98, indicated to the side of the sensor element, 32, which essentially corresponds to the length of the side legs, 82 and 84, minus the thickness of the plate, 92, can be adapted to the desired conditions.

The use of a Hall element, 82, with an integrated amplifier, which is less sensitive to outside disturbances, is especially preferred. The electrical connection of the Hall element, 82, is done with three connecting cables, 100a, 100b, 100c.

The connecting cables of each sensor are connected to an electronic analyzer which is not depicted; for example, this could be XY display equipment such as plotters, terminals, computers, or the like.

The embodiment illustrated in Figure 6 of a sensor element, 32, is designed considerably smaller than the one shown in Figure 5. But no linearization of the Hall element can be achieved with the dimensions shown in Figure 6. This element provides, however, an essentially hyperbolic characteristic curve so that the sensitivity is very large with the maximum approximation of the transmitter element, 64, to the Hall element, 82. The sensitivity, however, reduces with further distance from it.

Particularly toward the end of the measuring range,

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16-- 0000 0 e Q o 0 0*60 0400 (I C C 000660 o P* 6 6 066606 0 4a O00v 0s 6 i 0 0 0t 60 60 0 0 Ut 6 6 98, the sensitivity is considerably smaller for this emibodiment than for the embodiment depicted in Figure Therefore, a correspondingly stronger permanent magnet is used as a shaft, 90, without also requiring a plate. Due to the miniaturization, an additional rib, 102, is provided for stabilizing the frame, 78.

The shaft, 90, has a semi-spherical shape at the end, 104, near the stop face, 60, of the transmitter part, 46, for both embodiments of the transmitter element, 64. In order to reduce the friction, a plastic coating, 106, in the form of a painted layer was applied to the stop face, 60. This helps to keep a distance between the ferromagnetic transmitter part area and the shaft, 90, that is designed as a permanent magnet so that the end, 104, can slide onto the stop face, 60, with a minimum amount of force applied. In any event, the holding power has to be greater than the friction of the shaft, 90, in the guide, 88.

The embodiment of a transmitter element/sensor element combination illustrated in Figure 6 has dimensions of only about 2 mm x 3 mm x 7 mm for a measuring range, 98, of 5 mm and represents the maximum possible degree of miniaturization. The size of the plate, 16, essentially corresponds to the measuring range, 98, because it is transgressed across its entire length when another transmitter element is moved relative to the sensor part, 18.

The upper jaw connecting part, 44, and the lower jaw connecting part, 22, are illustrated in a connected state in Figure 7. This state occurs during the hardening of the materials, 10 and 48, at the patient's teeth. After the materials, 10 and 48, have been applied and have partially hardened, the two connected bite forks, 14 and 50, are inserted into the materials, 10 and 48.

The bite forks must be exactly positioned to each other in the basic position because this is important for the precise functioning of the device as presented by the i; b i iii ii r nm; 17invention. Therefore, the bite forks, 14 and 50, are connected to each other with a screw joint. The distance between the contact areas, 16 and 52, is securely determined by means of a range spaces 108 that maintains the distance and which can be inserted between the corresponding contact areas, 16 and 52, during the assembly of the bite forks. As a result, a rigid and easily removable connection can be achieved with simple means because in order to remove the connection and to assemble io the sensor part, 18, and the transmitter part, 46, to the 0 0 00 *d I S S

S

S SI jaw connecting parts, 22 and 44, only the range spaces 108, has to be removed and the screw joint, 106, needs to be loosened. This is especially advantageous when the assembly is supposed to occur without removing the jaw connecting parts, 22 and 44, from the mouth of the patient.

In the connected position of the jaw connecting parts, 22 and 44, the device presented by the invention is attached to the articulator. As a result, the basic position of the articulator is known automatically and the articulator can be easily adjusted.

In accordance with another configuration of the invention, a fifth sensor element with concomitant transmitter element, is provided at the measuring point of the sensor, 28. This sensor element, for example, can be positioned in the center below the stop faces, 66a and 66b, whereby they are then pulled apart somewhat from each other.

I,

S

IS

The invention relates to a device for determining motion parameters of the lower jaw for its relative movement with respect to the upper jaw. For this purpose, transmitter elements (62, 64, 74, 76), which are connected to the upper jaw by means of a jaw connecting part (44) and a transmitter part (46) act upon at least three sensors (24, 26, 28) which are positioned at the lower jaw by means of another jaw connecting part (22) and a sensor part (18) The connected sensors (24, 26, 28) are positioned in a spatially fixed relationship to each other and are outside

V

I I I 18i0 to aor 0000 o co 0 0 0 0000 000 0 0 00090 0; 0 0 0a 0 00 0 009 00 0 00 000 00 0 00 of a common axis. One measuring data is measured with two of the sensors (24, 26) and at least two measuring data in various measuring directions are determined with the third one The sensors each have a measuring area which is considerably less than the motion of the mouth from the closed position to the maximum open position.

The present invention is contemplated to encompass a device for determining the motion parameters of the lower jaw for its relative motion with respect to the upper jaw, with at least one transmitter, which is connected to one of the jaw parts by means of a jaw connecting part and a transmitter part and which actuates at least three sensors which are located on the other jaw by means of another jaw connecting part and a sensor part, whereby the connected sensors have a fixed spatial relationship to each other and are also configured on a common axis, characterized by the fact that one measured value can be determined with two sensors (24, 26) and two measured data at least can be determined with the third sensor (28) in separate metering direction and that the sensors (24, 26, 28) determine one measuring range which is considerably smaller than the path of the lower jaw during the motion of the mouth from the closed position to the maximum open position.

The invention also includes a device in accordance with all the foregoing characterized by the fact that the third sensor (28) has two sensor elements (40, 42) with which movements of the lower jaw can be determined with respect to the upper jaw in two measuring direction and that at least one of the two other sensors (24, 26) especially both, determine both motions in the third measuring direction.

The invention further encompasses a device in accordance with the foregoing disclosure characterized by the fact that at least one of the sensors elements is Located to the side of the sensor elements (42) emitting the measuring data and at least one is frontal to it and, in particular, one sensor element (42) in the incisal 9-- 0DD 0000 0 0 0 00 0 00 0as o a a 40 oa area is located to a lateral measuring direction and one sensor element in the molar area (40) is located to a vertical measuring direction.

Also included is a device in accordance with the foregoing disclosure characterized by the fact that four measuring data can be determined with the three sensors (24, 26, 28) and that four sensor elements (30, 32, 40, 42) are provided with which the measuring data can be transmitted.

Another variation includes a device in accordance with the foregoing disclosure characterized by the fact that at the side, next to the molars, there is provided a sensor (24, 26) which has a sensor element (30, 32) which takes effect in the mouth opening direction.

SAnother variation includes a device in accordance with the foregoing disclosure characterized by the fact that a a rod for determining the rotational center has a bar (45) or the like which can be fixated laterally at the sensor part (18) or the transmitter part (46) that is connected to the 20 lower jaw connecting part (22) 0 Another variation includes a device in accordance with the foregoing disclosure characterized by the fact that the rod is located swingably and is changeable with respect to its length to the lower jaw connecting part (22).

Another variation includes a device in accordance with 0 the foregoing disclosure characterized by the fact that five sensor elements are provided for determining five measuring data; that the five sensor elements are distributed to three sensors; and that the sensor, particularly in the incisal area, has three sensor elements.

Another variation includes a device in accordance with the foregoing disclosure characterized by the fact that the sensor part (18) is connected to the lower jaw connecting part (22) and the transmitter part (46) is connected to the upper jaw connecting part (44) Another variation includes a device in accordance with

F

i k oo 0000 0a 0 0 0 0 04 4 oo 0a 0 4 C the foregoing disclosure characterized by the fact that the sensor part (18) and the transmitter part (46) are located outside of the mouth area.

Another variation includes a device in accordance with the foregoing disclosure characterized by the fact that the sensors (24, 26, 28) have sensor elements (30, 32, 40, 42) which can determine a translatory motion and that each sensor element is responsive to one motion in one direction only after there is motion.

Another variation includes a device in accordance with the foregoing disclosure characterized by the fact that the sensor elements (30, 32, 40, 42) are aligned in such a way that their directions of actuation form a perpendicular coordinate system.

Another variation includes a device in accordance with the foregoing disclosure characterized by the fact that the measuring data of two sensor elements (30, 40; 32, 42; 42; 32, 40; 40, 42), which are situated at a right angle to each other, are fed to an XY recording device, in particular an XY plotter.

Another variation includes a device in accordance with the foregoing disclosure characterized by the fact that during an opening motion of the mouth across the measuring range (98) at least of the sensor that is activated in the direction of mouth opening (24, 26), the clear range is passed in which a motion of the lower jaw with respect to the upper jaw at least does not influence the sensor that is activated in the mouth opening direction (24, 26) Another variation includes a device in accordance with the foregoing disclosure characterized by the fact that the sensors (28) that take effect in the other directions as well are not engaged in the clear range and do not transmit measuring data.

Another variation includes a device in accordance with the foregoing disclosure characterized by the fact that the transmitter part (46) is aligned to transmission elements (62, 64, 74, 76) of which each one acts on a sensor (24, GrI I I 21-- 0 d* O it o it i flt it~(I ittiti it i o iti ro it 309 26, 28) and that the transmission elements are led particularly to the sensor part (18) Another variation includes a device in accordance with the foregoing disclosure characterized by the fact that the transmitter part (46) has a connecting part (75) to which the transmitter elements (62, 64, 72, are connected detachably.

Another variation includes a device in accordance with the foregoing disclosure characterized by the fact that the transmitter elements (62, 64, 74, 76) are guided free from play to the connecting part (75) which each of the sensors in the direction of measurement, but can move freely in every other direction so that a relative moticn of the transmitter part (46) with respect to the sensor part (18) leads to a relative motion of each transmitter element (62, 64, 74, 76) with respect to the corresponding sensor element (30, 32, 40, 42) only in the corresponding direction of measurement of the sensor element.

Another variation includes a device in accordance with the foregoing disclosure characterized by the fact that the transmitter elements (62, 64, 74, 76) are guided in a translatory fashion to the sensor pa:rt (18) and that the stops (86, 82) are provided which limit the motion of the transmitter elements with respect to the sensor part.

Another variation includes a device in accordance with the foregoing disclosure characterized by the fact that a stop is formed by the sensor element.

Another variation includes a device in accordance with the foregoing disclosure characterized by the fact that magnetically sensitive sensor elements, in particular Hall sensor elements are used as sensor elements and that the transmitter elements (62, 64, 74, 76) use ferromagnetic material.

Another variation includes a device in accordance with the foregoing disclosure characterized by the fact that the area of the transmitter element (62, 64, 74, 76) near the transmitter part (46) is made of ferro-magnetic material

L-

I'

22crQ 0 1f o, QeV Voa -o8 0 '44 0*00 and that the area of the transmitter part adjacent to each transmitter element is made of ferro-magnetic material.

Another variation includes a device characterized by the fact that each transmitter element (64) has thoroughgoing ferro-magnetic material from the area (104) near the transmitter part (46) to the area (plate 92) opposite the sensor element (81) and that either the transmitter element (64) or in addition the area (60) of the transmitter part (46) opposite the transmitter element (64) has a permanent magnet or in addition the transmitter part (46) has a central permanent magnet which is connected V by means of the ferro-magnetic material to the area (60) of the transmitter part (46) opposite the transmitter element.

Another variation includes a device in accordance with the foregoing disclosure characterized by the fact that the transmitter part (46) has a stop face (58, 60, 66, 68) at oeach area opposite each transmitter element (62, 64, 74, 76) which is level and is aligned perpendicular to the measuring direction of the sensor element (30, 32, 40, 42) 20 corresponding to the corresponding transmitter element.

Another variation includes a device in accordance with the foregoing disclosure characterized by the fact that the end (104) of a transmitter element (64) near -he transmitter part (46) has a spherical shape, in particular a semi-spherical shape.

Another variation includes a device in accordance with the foregoing disclosure characterized by the fact that the area of the transmitter element opposite the sensor element (32) is formed by a ferro-magnetic plate (92) which is vertical to the measuring direction of the corresponding sensor element (32) Another variation includes a device in accordance with the foregoing disclosure characterized by the fact that the maximum shift of the transmitter element (62, 64, 76) is 3 to 10 mm, in particular 6 to 7 mm, with respect to the sensor element (30, 32, 42) and that in the measuring area the non-linear output signal of the sensor element is '4: j t 23linearized due to the configuration of the transmitter elements (62, 64, 74, 76).

Another variation includes a device in accordance with the !"oregoing disclosure characterized by the fact that the plate (92) functions as a linearizing element and that no additional linearizing elements connected it to the sensor element (30, 32, 40, 42) or to the transmitter element (62, 64, 74, 76) are provided.

Another variation includes a device in accordance with the foregoing disclosure characterized by the fact that adaptors, essentially in the measuring direction of the sensor element are provided for enlarging the aeoo 0 oao linearized range.

Another variation includes a device in accordance with 0 o the foregoing disclosure characterized by the fact that the transmitter element (64) in its guided area has a relatively thick round steel piece (shaft 90) which is 0 a guided by a frame (78) of the sensor element (32) made of non-magnetic material.

0 00i 0 20 Another variation includes a device in accordance with S-,o the foregoing disclosure characterized by the fact that the transmitter element (64) is maintained without a spring °0 0 element by the magnetic force at the transmitter part (46) Another variation includes a device in accordance with the foregoing disclosure characterized by the fact that the 00 ",transmitter elements (74) or the sensor elements 42b) which measure the lateral motion of the lower jaw with respect to the upper jaw, are guided swing loaded and movable so that a lateral motion of the lower jaw is possible across the measuring area (98) without any destruction.

Another variation includes a device in accordance with the foregoing disclosure characterized by the fact that the sensor (28) responsible for measuring the lateral and the frontal motion of the lower jaw has a sensor element functioning in the frontal direction and two sensor element parts (42a, 42b) functioning in the lateral direction and fi sensitive in tne la-eri ai u-.Lc-uii 77 ~9 p ~y

-'I

24-- 0006 o o 0* 4 0 o \O *6 4 06 00 00 o 1)a o nov 040,04 0 4 that the lateral sensor element parts (42a, 42b) each have bordering measuring areas and form a sensor element (42).

Another variation includes a device in accordance with the foregoing disclosure characterized by the fact that the sensor element parts (42a, 42b) measuring the lateral jaw motion have a joint transmitter element (74) which is located in the center between the sensor element parts (42a, 42b).

Another variation includes a device in accordance with the foregoing disclosure characterized by the fact that the sensor element parts (42a, 42b) actuated by the lateral jaw motions are electically activated alternatively as a function of which of the transmitter element (74) is closer to the sensor element parts (42a, 42b).

Another variation includes a device in accordance with the foregoing disclosure characterized by the fact that a switch circuit is provided for the sensor element parts (42a, 42b) actuated by the lateral motion of the lower jaw with which a switching to the sensor element is caused which transmits the higher voltage and whereby the characteristic curve of the one sensor element part is reflected with respect to the other one.

Another variation includes a device in accordance with the foregoing disclosure characterized by the fact that weight-saving construction techniques are used for the transmitter part (46) and the sensor part (18) and that the length of the transmitter part (46) and of the sensor part (18) in front of the mouth as well as the weight of these parts are held as low as possible and that the distance of the sensor elements among each other is selected as low as possible without the sensor elements (30, 32, 40, 42) negatively influencing each other.

The invention also encompasses a procedure for determining the motion parameters of the lower jaw for its relative motion with respect to the upper jaw in which at least one transmitter element connected to one of the jaw sections by means of a jaw connecting part and a br 'Li part, 4 6. The upper jaw connectLiiy p.CLtL, I .3 3*0.3.3 043.30 .30.30 l.a 0 0 0 00 .3 P0 43 .30 .3 00 .3.3 .3 0,* 00 0 C.

.3, .3 *0 43*341 transmitter part acts on at least 3 sensors which are attached to the other jaw section by means of another jaw connecting part and a sensor part in which the connected sensors have a fixed spatial configuration to each other outside of a common axis, the measurement occurring by the motion of the lower jaw with respect to the upper jaw and after completing the measurement, the jaw connecting parts are taken from the mouth of the patient and are attached to an articulator which serves to produce a tooth replacement for this patient characterized by the fact that one measured value is determined with two of the sensors and two measured data in various measuring directions are retermined with the third sensor and that the patient, .3 during the measurement, moves the lower jaw, with respect to the upper jaw, in almost a closed or closing position of -the mouth, that is essentially in the horizontal direction.

Another variation includes a procedure in accordance wi'th the foregoing disclosure characterized by the fact that the position of the rotational center of the condyles and/or the condyle path inclination are measured by a rod .3 which maintains the motion of a point connected to the lower jaw connecting part along the side of the condyles with respect to the part that is firmly affixed to the head.

Another variation includes a procedure in accordance with the foregoing disclosure characterized by the fact that the motion of the point is recorded on the part that is firmly affixed to the head for determining the condyle path inclination from a point along the side of the condyles by a recording device that is connected to the rod and that the condyle path inclination is projected by an adjustable matrix that has a line and which rotates around a point.

Another variation includes a procedure in accordance with the foregoing disclosure characterized by the fact that the jaw connecting parts are manufactured in a patient-specific fashion in that a curable, physiologically -Th 2 6safe material is applied comprehensively in a known fashion to the set of teeth and/or jaws and that prior to complete hardening of the material, an upper jaw bite fork and a lower jaw bite fork are inserted and that the material and the concomitant bite forks form the jaw connecting part.

The bite forks are inserted into the material in a connected state.

Another variation includes a procedure in accordance with the foregoing disclosure characterized by the fact that the filtration of the jaw connecting parts to each other is disconnected for measurement purposes after the 1 hardening of the material consisting in particular of o..o plastic and the transmitter part and the sensor part are connected to the jaw connecting parts and that the jaw connecting parts are first removed from the mouth of the patient when the measurements have been concluded and the jaw connecting parts remain undamaged.

Another variation includes a procedure in accordance with the foregoing disclosure characterized by the fact that the jaw connecting parts are removed prior to measurement and are cleaned and that the jaw connecting parts connected to the transmitter part and the sensor part are re-inserted into the mouth of the patient for the purpose of measurement.

Another variation includes a procedure in accordance with the foregoing disclosure characterized by the fact that when the jaw connecting parts are fitted into the articulator, a pre-adjustment step is taken by the renewed preparation of the solid connection between the two jaw connecting parts.

Hall effect devices, the preferred transmitter and sensor elements of the present invention, and other such devices are well known to the art, and their use and adaptation to the present invention is well within the skill of those in the art. Those of ordinary skill in the art will clearly understand that a diversity of measurement techniques may be employed with equivalent results, given i 27the guidance of the present disclosure. The employment of such techniques, and the algorithms and circuits for the resolution of the motions on the basis thereof are also familiar, and form no novel aspect of the present invention.

As those of ordinary skill in the art will also recognize, the foregoing disclosure affords a number of approaches to meet the requirements of the development of a flexible and effective measurement system. The iteration of specific features and optional variations is not intended to be limiting on the scope of the invention, which should be construed solely in light of the following a4m a o claims.

a r4Q4 t 4 4 44

Claims

2. The device of claim 1 wherein said transmitter means and said sensor means are adapted to be disposed outside the mouth of a patient.
3. The device of claim 1 or claim 2 wherein said incisal sensor means is adapted to be disposed frontally of and adjacent to the incisal teeth of a patient.
4. The device of any one of claims 1 to 3 wherein at least an incisal one of said sensor means is adapted to be disposed adjacent the incisal teeth of a patient, and comprises at least two sensor elements, so that a vertical sensor element of said incisal sensor means detects a signal from said transmitter means which models relative, mouth opening, vertical motion between said vertical sensor o element and said transmitter means, and a lateral sensor o element of said incisal sensor means detects a signal from C-2 said transmitter means which models lateral motion between 4AB 1' 'i i' -29- said lateral sensor element and said transmitter means. The device of any one of claims 1 to 4, wherein at least a molar one of said sensor means is adapted to be disposed adjacent the molar teeth of a patient, and comprises at least one vertical sensor element of said molar sensor means detects a signal from said transmitter means which models relative vertical motion between said vertical sensor element and said transmitter means.
6. The device of any one of claims 1 to 5 further comprising means for determining the rotational center of the articulation of a lower jaw in relation to an upper jaw.
7. The device of claim 6 wherein said means for determining the rotational center of the articulation of a lower jaw in relation to an upper jaw is adapted to be disposed frontally and externally of the mouth of a patient.
8. The device of claim 6 or claim 7 wherein said means for determining the rotational center of the articulation of a lower jaw in relation to an upper jaw is a face bow bar.
9. The device of claim 1 comprising at least five of said sensor elements, wherein one pair of said sensor elements are adapted to be disposed on opposed sides adjacent the rtmolar teeth of a patient, and at least three of said sensor irI t elements are adapted to be disposed adjacent the incisal teeth of a patient. 1 0. The device of claim 9 wherein each of said molar sensor pair independently measures relative, mouth opening, vertical motion of the lower jaw in relation to the upper jaw.
11. The device of claim 9 or claim 10 wherein a first one of said three incisal sensors independently measures t relative, mouth opening, vertical motion of the lower jaw in relation to the upper jaw, another, second one of said three incisal sensors independently measures relative lateral motion of the lower jaw in relation to the upper jaw, and a third one of said three incisal sensors independently o o o measures relative, protuding, frontal motion of the lower jaw in relation to the upper jaw. Ll1 12. The device of any one of claims 9 to 1 1 wherein the 0 AB 1 Li measuring data measured by each said sensor is converted to a visual display showing said relative motions in orthagonal axes.
13. The device of claim 12 wherein said visual display is an x-y plotter.
14. The device of claim 12 wherein said visual display is a cathode ray tube optical display. The device of any one of claims 1 to 14 wherein said transmitter means comprises at least one transmitter element for each of said sensor elements.
16. The device of any one of claims 1 to 15 wherein each said transmitter element is disposed on said transmitter means adjacent to a corresponding sensor element disposed on said sensor means in the mouth closed position of a patient.
17. The device of any one of claims 1 to 16 wherein said measured values of each of said sensor elements is responsive to its corresponding transmitter element.
18. The device of any one of claims 1 to 17 wherein data measurements of each of said sensor elements is controlled to preclude measurement from any transmitter means other than its corresponding transmitter.
19. The device of any one of claims 1 to 18 wherein each said sensor element is controlled by switching of each transmitter. The device of any one of claims 1 to 18 wherein each said sensor element is controlled by switching of each sensor element.
21. The device of any one of claims 1 to 18 wherein each said sensor element is controlled by transmitting different signals by each of said transmitter elements.
22. The device of any one of claims 1 to 18 wherein each said sensor elements is capable of detecting a magnetic field.
23. The device of any one of claims 1 to 18 wherein each said sensor elements is a Hall effect sensor.
24. The device of any one of claims 1 to 18 wherein each of said transmitter elements is a ferromagnetic material. The device of any one of claims 1 to 18 wherein each of 4 4. C C 4 00 CJ 44 i-Li-- -31- said transmitter elements comprises a permanent magnet.
26. The device of any one of claims 1 to 18 wherein each of said transmitter elements is capable of detecting a magnetic field, and each of said transmitter elements comprises a ferromagnetic material.
27. The device of claim 26 wherein said ferromagnetic material is a permanent magnet.
28. The device of claim 27 wherein said magnet is retained in place within the transmitter element by magnetic force.
29. The device of claim 26 wherein the surface of the ferromagnetic material adjacent the sensor element is a spherical section. The device of claim 29 wherein said spherical section is a hemisphere.
31. The device of claim 26 wherein the ferromagnetic material adjacent the sensor element comprises a flat plate section disposed in a plane perpendicular to the sensor surface.
32. The device of claim 26 wherein the ferromagnetic material adjacent the sensor element comprises a flat plate section disposed in a plane perpendicular to the direction of the measurement.
33. The device of claim 26 wherein the conformation of the transmitter element is configured to produce a substantially linear output of the said sensor means through the range of motion to be measured.
34. A procedure for determining the motion parameters of the lower jaw for its relative motion with respect to the upper jaw comprising fixing at least one transmitter means to one jaw by means of a jaw contact element, fixing at least 3 sensors to the other jaw section by means of another jaw contact element and a sensor element in which the connected sensors in a fixed spatial configuration to each other outside of a common axis, and measuring a plurality of values representing a model of the motion of the lower jaw with respect to the upper jaw and after completing the measurements, removing the jaw contact elements, whereby the jaw contact elements can be taken from the mouth of the rttrt 4 4 I t r I I 0 *a C 0 00 -32- I patient and attached to an articulator which serves to produce a tooth substitute for this patent to replicate the relative motion of the jaws of the patient, and wherein a measured value is determined with one pair of the sensors and two measured data in various measuring directions are determined with the third sensor, and wherein at least one of said sensors is adapted to be disposed adjacent the incisal teeth of a patient and at least one of said sensors is adapted to be disposed adjacent the molar teeth of a patient. A method for determining the motion parameters of the lower jaw in relation to the upper jaw, comprising fixing at least one transmitter means to one of the jaw elements said transmitter means comprising a jaw contact element and a transmitter element and fixing at least three sensor means on the other jaw, each said sensor means disposed on a jaw contact element, whereby the connected sensors have a fixed spatial relationship to each other and are also configured on a common axis, and simultaneously transmitting a signal from said transmitter means to said sensor means while the lower jaw is articulated through a limited range of motion from the closed position to a partially open position, and recording the output of said sensors as a measure of the relative motion throughout the range of articulation, and wherein at least one of said sensor means is adapted to be disposed adjacent the incisal teeth of a patient and at least one of said sensor means is adapted to be disposed adjacent the molar teeth of a patient.
36. The method of claim 35 wherein said transmitter means and said sensor means are subsequently fixed to an articulator for the reproduction of the measured relative motion as measured.
37. The method of claim 35 wherein the center of rotation of the condyles are measured by the employment of a rod, attached to the lower jaw element, and measuring the motion of said rod in relation to a planar element fixedly attached to the head. \38. The method of claim 37 wherein said planar element is #6t* U U i 14l I *1 44(@ a .14144 £e I Ir It It U *004 4J 0 9 01 1 i. -lii; i -33- a recording display device.
39. The method of claim 38 wherein said recording display device is a printing device. The method of claim 38 wherein said recording display device is a recording pantograph.
41. The method of any one of claims 35 to 40 wherein said transmitter means and said jaw contact elements are bonded to the teeth of the patient for the period of the measurement with a curable, physiologically safe adhesive.
42. The method of any one of claims 35 to 41 wherein the transmitter element transmits magnetic force.
43. The method of any one of claims 35 to 42 wherein the sensor elements detect magnetic force.
44. The method of any one of claims 35 to 43 wherein the transmitter element transmits magnetic force such that the field strength of the said magnetic field strength is varied in inverse proportion to the distance between the transmitter and sensor elements through the range of motion. The method of claim 44 wherein said magnetic field strength is varied in substantially linear proportion to the inverse of the distance between the transmitter and sensor elements through the range of motion.
46. A device according to claim 1 substantially as herein described with reference to any one of the embodiments shown in the accompanying drawings. DATED: 21 MARCH, 1990 PHILLIPS ORMONDE FITZPATRICK I Attorneys For: SIVOCLAR AG aq 4 9 tr i 4Q 11