temporomandibular joint purchase record system

Description

[0001] The invention relates to a temporomandibular joint recording system (condylograph) for the electronic recording of the mobility of a patient's lower jaw close to the joint, wherein a Cartesian coordinate system is defined through the patient's skull, starting from a zero point as the bisector of a line between the two temporomandibular joints on the joint axis, and from an x-axis lying in the horizontal plane defined by the joint axis and a frontal reference point and pointing frontally, a y-axis along the connecting line of the two temporomandibular joints, and a z-axis along the vertical axis of the skull, wherein the condylograph comprises an upper arch, which is firmly connectable to the patient's skull and which has at least one camera on at least one side of the patient, as well as a lower arch,which is firmly connectable to the lower jaw and has at least one reference marker in the field of view of the at least one camera, wherein the reference marker(s) is / are arranged at a left and / or right end of the lower arch, and wherein the left and right ends of the lower arch are firmly connected to one another.

[0002] When recording mandibular movement, the movement of the common hinge axis of both temporomandibular joints is particularly important. The human temporomandibular joint can exhibit both rotatory and translational movements. Functional movement patterns of the mandible therefore usually consist of a combination of these two components. From a diagnostic and therapeutic perspective in dentistry, the translational component of the movement is particularly important. Translational movements primarily serve as the basis for calculating patient-specific settings for dental movement simulators in the articulator. The rotational component of the movement distorts the recorded results in graphical notation, reducing reproducibility and rendering the diagnostic results doubtful. Therefore, it is advantageous to record mandibular movements directly on the rotational axis of the mandible.

[0003] Previously known devices for recording mandibular movements in relation to a patient's skull serve to precisely record the joint movement of the mandible for diagnostic purposes and to determine key data for dental articulators. In addition, they are intended to provide information about the pathological condition of the mandibular joints. This allows abnormal movement patterns of the temporomandibular joints caused by the influence of muscles or the cartilage disc to be detected, enabling a diagnosis and treatment planning. Devices for recording mandibular movement are divided into so-called "near-joint" and "distant-joint" recording systems. Near-joint systems measure directly on the patient-specifically located joint axis within a measuring range of 3 mm or on a joint axis approximately determined using anatomical skull points.Remote joint recording systems do not measure near the joint, but rather in front of the face, for example. The location of the hinge axis is usually done virtually, i.e., calculated by a computer. In such systems, the movement paths of the joint axis are mathematically recalculated to the hinge axis.

[0004] Since the 1980s and 1990s, experiments have been conducted on filming temporomandibular joint movement using light sources. DE 10 2004 015 383 A1 describes a device or a remote recording method in which the patient wears a frame connected to their head, which has some type of transmitting and receiving device for transmitting and receiving electronic, optical, or acoustic signals. Another frame, which also has transmitting and receiving devices, is connected to the patient's lower jaw. Both frames are connected to an evaluation computer. The disadvantage of this approach is that the frames are complex to assemble, must be relatively heavy and front-heavy, as both are connected to an evaluation device via cables, and that the rudimentary electronic transmission devices limit measurement accuracy.The measurement accuracy of remote joint recording systems is also reduced by the system-required geometric / mathematical conversions from the position of the measuring sensors to the hinge axis of the temporomandibular joints. A further disadvantage of this remote joint recording method is the calculation of the individual hinge axis and the resulting virtual hinge axis, and the resulting inaccuracies and systematic errors, since direct mechanical verification of the hinge axis location with such systems is only possible with considerable additional effort. Furthermore, it is of didactic importance in teaching and training to demonstrate the methodology of hinge axis localization to students using direct adjustability.

[0005] EP 1 981 403 B1 discloses a near-joint recording device in which the patient's head is temporarily connected to a stationary device that films the patient via cameras from above and from both sides. The patient wears a frame temporarily connected to the lower jaw, which has approximately fourteen graphic markers in all spatial directions. A disadvantage here is that a laboratory or dental practice wishing to perform mandibular joint measurements must reserve a relatively large space for the stationary device.

[0006] DE 10 2004 002 953 A1 shows a condylograph in which ultrasound sensors attached to the skull record the signals from ultrasound transmitters on an arch on the jaw.

[0007] DE 20 2004 004 955 U1 teaches a condylograph in which receiving means attached to the skull record the signal from a corresponding transmitting means attached to the jaw. US 2013 / 0157218 A1 discloses something similar, in which the receiving means are cameras.

[0008] US 5,143,086 A shows a device in which cameras attached to the skull film the movement of a patient’s teeth.

[0009] The invention aims to create a condylograph as mentioned above that overcomes the disadvantages of the prior art. Furthermore, the device should be less susceptible to failure, offer high measurement accuracy, be easy to operate, and be ergonomic for the patient. At the same time, the manufacturing and maintenance costs of the condylograph should be kept as low as possible.

[0010] The condylograph according to the invention achieves this in that two cameras are provided on the upper arch on at least one side of the patient, which cameras have viewing axes that enclose an angle α of between approximately 30 and approximately 150 degrees with respect to one another in a plane parallel to the xz plane, and wherein the cameras are each directed at the at least one reference marker of their patient side and the reference marker(s) is / are adjustable to a joint axis anatomically determined according to facial landmarks or to the individual hinge axis of the patient's temporomandibular joint and a range of up to approximately 3 mm.

[0011] The invention is defined by the appended independent claim 1. Advantageous embodiments emerge from the appended dependent claims.

[0012] A preferred embodiment of the condylograph is characterized in that the reference marker(s) is / are spheres.

[0013] In one embodiment of the invention, the reference markers are one or more spheres on one or both sides of the patient, wherein the spheres of one side of the patient are spaced at a predefined distance.

[0014] To further develop the invention, the angle α of the cameras is between approximately 80 and 100 degrees.

[0015] In one embodiment of the invention, it is preferred that the cameras are infrared cameras and the reference markers are coated with an infrared paint, and the condylograph has one or more light sources by which the reference marker(s) can be illuminated with light in the infrared spectral range. Alternatively, the reference marker(s) can be actively light-emitting, for example, in the form of internal infrared LEDs.

[0016] A preferred embodiment of the condylograph is characterized in that the cameras on each patient side are arranged in a housing that is essentially closed in all spatial directions.

[0017] In one embodiment of the invention, the housing(s) is / are pivotally mounted on the upper arch.

[0018] To further develop the invention, the condylograph is part of a condylographic device, wherein the upper arch is connected to a computer-like control and recording device by means of a cable, preferably according to the USB system.

[0019] Furthermore, in a preferred embodiment of the invention, it is possible for the data transmission from cameras and the control signals to the cameras and the light sources to be carried out from and to a computer-like control and recording device via a radio connection.

[0020] In one embodiment of the invention, it is preferred that the condylographic device comprises a display device.

[0021] In one embodiment of the invention, the control and recording device comprises software with which characteristic data for dental articulators can be determined automatically.

[0022] The invention is explained in more detail below with reference to an embodiment illustrated in the drawings. They show: Fig. 1 a schematic side view of a patient’s skull with a partially drawn coordinate system, Fig. 2 a perspective view of an articulator lower part with a coordinate system drawn in, Fig. 3 and Fig. 4 Front and side view of the condylograph according to the invention, Fig. 5 bis Fig. 8 External views of the housing, which contains two cameras, and Fig. 9 a schematic view of a reference marker pair.

[0023] The skull, together with the lower jaw in the centered joint position of the patient, defines a Cartesian coordinate system, to which the components of the condylograph according to the invention are oriented. The common hinge axis of the right and left temporomandibular joints forms the y-axis of this coordinate system. It is Fig. 1 not visible due to the chosen perspective, or the y-axis points vertically into the plane of the paper. The x-axis is perpendicular to the y-axis and runs along the connecting line between the back of the head and the nose, or from the joint axis at the level of an anterior reference point of the patient's skull to the front. The joint axis is usually the common hinge axis of both temporomandibular joints in a centric temporomandibular joint position; the anterior reference point is usually the orbital point as the lowest point of the anterior rim of the left eye socket. The z-axis is again perpendicular to the x- and y-axis, which lies in the vertical axis of the patient's skull 6, or essentially parallel to the longest extension of the spine of a patient in a standing or sitting position with the head raised. Fig. 2 The same coordinate system is shown on a technical model of a lower jaw 7. All axes are perpendicular to one another, which, however, is not essential for explaining or practicing the invention. Even in the ideal model case, the components of a patient's lower jaw 7 move both in the xz plane and in the y direction. Jaw movements in the y direction cannot be ruled out in principle and should also be able to be measured with sufficient accuracy by the device according to the invention.

[0024] According to Fig. 3 and Fig. 4 The condylograph comprises two parts, namely a lower arch 2, which is temporarily connected to the lower jaw 7, for example, via a dental clamp 11, and an upper arch 1, which can be temporarily connected to the patient's skull 6. The upper arch 1 can be attached in the illustrated embodiment like a pair of glasses, resting on the bridge of the nose and the ears. Additional fastening devices are conceivable. The upper arch 1 can also be designed like a pair of glasses, with one frame part in front of each eye of the patient, as shown in the Fig. 3 and 4shown to allow the patient a normal, unobstructed view of the surroundings during the measurement, but it can also be of any other shape as long as the upper arch 1 also extends to the two patient sides, left and right. A housing 8 containing two cameras 13 is attached to the parts of the upper arch 1 that extend over one side of the patient. When attached to the upper arch 1, the two cameras 13 look out of the housing 8 onto parts of the lower arch 2. Both the upper arch 1 and the lower arch 2 cover an angular range of 180 degrees in the xy plane around the patient's face. When attached, the two arches 1, 2 are approximately parallel to one another.

[0025] Alternatively, the camera(s) 13 or a housing 8 with internal cameras 13 can be attached to the lower arch 2.

[0026] For ease of handling, the lower arch 2 is firmly connected to the patient's lower teeth or palate, and thus to their lower jaw 7, at essentially only one point by gluing, clamping, or other temporary fixation. The lower arch 2 can also take any shape; however, it is advantageous that, to save weight and thus facilitate handling and portability, it is as light as possible and is therefore made of a lightweight, relatively thin material. The lower arch 2 also extends around the patient's skull 6, so that at least the ends 3, 3' of the lower arch 2 on both sides are at the level of the patient's temporomandibular joints. The lower arch 2 is advantageously constructed in one piece, which simplifies manufacture and ensures long-term use; however, it can also be assembled from a few parts, as long as all the joined parts form a single, solid construction.At the ends 3, 3' of the lower arch 2, which are located on the patient's sides and approximately on the anatomically located joint axis or the individual hinge axis of the patient's temporomandibular joint, which are thus at the height of the point of the patient's joint axis and within a range of up to a maximum of 3 mm around it, at least one reference marker 4 is arranged on each side, which is located in the intersecting fields of view of the cameras 13 of the housing 8. For better measurement, a maximum distance of less than 1 mm from the patient's individual hinge axis is desirable. Using simple mechanical adjusting means, the ends 3, 3' or the reference markers 4 can be quickly and individually adjusted to the desired area or position shortly before the measurement.

[0027] In the alternative embodiment (not shown), the reference markers 4 are attached to the upper arch 1. The cameras 13 on the lower arch 2 are arranged in a particularly lightweight construction where the reference markers 4 are in the first embodiment, namely at the ends 3, 3' of the lower arch 2, which lie approximately on the anatomically located joint axis or the individual hinge axis of the patient's temporomandibular joint, i.e., at the height of the point of the patient's joint axis and within a maximum area of ​​3 mm around it. The exact point is expediently not touched by one of the cameras 13, but by the midpoint of the connecting line between, for example, two cameras 13 on each side of the patient. In this second embodiment, the upper reference markers 4 are also ultimately located in the intersecting fields of view of the cameras 13.

[0028] The area 10 visible by both cameras 13 thus records the movement of one or more reference markers 4 (see Fig. 9 ), while the patient performs prescribed jaw movements. The invention solves this problem with a reference marker 4, which can be a geometric point and does not need to be a pattern. However, the use of two or more reference markers 4 per patient side can be advantageous (see below); the measurement of a rotational component in the jaw movement is only possible with at least two reference markers 4 per side. A corresponding embodiment is described in the Fig. 3 and 4 shown, whereby the two reference markers 4 per patient side are spaced from each other not only in the x-direction, but also in the y- and z-direction.

[0029] According to Fig. 5 , a side view of the housing 8, the cameras 13 are located in boxes 9 at the ends of the housing 8, which can already specify an angle to each other. This is why it is bone-shaped, although other shapes are also conceivable. The viewing axes 12 of the cameras 13 intersect at an angle α, which in the example shown is 90 degrees. Other angle ranges are also possible. The angle can also have a selectable value, for example, between approximately 30 and 150 degrees, whereby every movement of the filmed reference marker in the xz plane is recorded by the cameras 13.

[0030] Fig. 6 shows the rear view of the housing 8 with the two boxes 9, Fig. 7 shows the bottom view of the housing 8 with an opening for each of the cameras 13. Fig. 8 shows the housing 8 in plan view, which represents a housing 8 that is essentially closed in all spatial directions, so that sufficient protection for the cameras 13 as well as a predefined fixed spacing and angular position of the two cameras 13 is achieved, furthermore, due to at least relative watertightness, good washability or wipe disinfection of this component of the condylograph and finally a reduced risk of injury to its components when handling the condylograph according to the invention.

[0031] The upper arch 1 should also be as lightweight as possible to improve patient comfort. This means that as many components as possible should be made of lightweight materials, and these materials should be used sparingly. The electronic components, or those components that actually participate in the measurement, should be as simple and miniaturized as possible.

[0032] According to Fig. 9 The reference markers 4 consist of spheres, which are connected to the lower arch 2 via an adapter 5. It has proven advantageous to use two spheres per patient side, which must be at least, as shown in Fig. 9shown, when connected to the lower arch 2, they are spaced apart from one another in the x-direction and, if appropriate, in the negative y-direction in order to detect a three-dimensional movement of the lower jaw 7 and also a rotation of the lower jaw 7 during its movement. Ideally, only a spacing in the x-direction is necessary; however, in order to reliably rule out mutual obscuration of the balls in practice, they are spaced apart from one another in all three spatial directions. The advantage of the invention is that the reference markers 4 do not have any further optical features. For example, patterns or other special shapes or a larger number of reference markers 4 are not required.

[0033] It has been found that for a fast and precise evaluation of the measurement results, an automatic image analysis of the material from the cameras 13 is performed. Again, it has been found that the cameras 13 film the reference markers 4 clearly visible to the evaluation software when working in the infrared spectral range. This means that the housing 8 is either equipped with light sources (not shown) in addition to the cameras 13, which sufficiently illuminate the field of view 10 of the cameras 13 with infrared light, or the reference markers 4 are actively designed and emit light independently. LED light sources have the advantage of precisely defining the frequency of the emitted light, as well as being lightweight and cost-effective. The reference spheres are coated with an infrared paint, and the cameras 13 are particularly sensitive in the infrared spectral range.

[0034] Alternatively, the reference markers 4 themselves can be equipped with internal infrared light sources, e.g., infrared LEDs. This is advantageous because, on the one hand, the temperature development around the cameras 13 is drastically reduced, and, on the other hand, the field of view can be adjusted to the exact required frequency. This also allows for better filtering out background information via thresholding. It also requires less energy and reduces the weight of the upper arch.

[0035] By operating in the infrared range, the measurement can be performed in virtually any ambient light. This has the advantage that the existing light and shadow conditions in the dental practice do not need to be adjusted or altered in any way for the measurement itself. This simplifies the handling of the condylograph according to the invention. To further enhance this advantage, the ends of the lower arch 3, 3' or the entire lower arch 2 are coated with a paint that absorbs infrared light particularly strongly. The reference spheres thus stand out more clearly in the field of view of the cameras 13.

[0036] A specific measurement can thus be carried out in just a few simple steps. The patient can, while standing or comfortably sitting, first put on the upper arch 1 and then have the lower arch 2 attached to their lower jaw 7. In most cases, the cameras 13 and the reference markers 4 are already in the correct spatial arrangement relative to one another. If necessary, readjustment is carried out using simple mechanical means. The condylograph according to the invention does not require a stationary device or complex connections between equipment and the patient that could restrict or alter movement. Nor are any disruptive connections between the two arches necessary. Only one or two cables (one per patient side) lead from the upper arch 1 to the computer or a processing unit that is supplied as part of the system (neither shown), in which the evaluation of the measurement results takes place automatically.This cable can be used with the USB system and is therefore comparatively thin, lightweight, and very flexible, which will neither disturb the patient nor alter their jaw movement. Furthermore, a USB cable is easily replaceable. The low weight of the lower archwire 2 also does not bother the patient. The software installed on the evaluation computer now controls the cameras 13 in the housing 8 and records the images from the cameras 13 while the patient performs the specified jaw movements. No further changes to the patient or the dental practice are necessary. The measurement is then already complete.

[0037] It is conceivable to also establish the data transmission from cameras 13 and the control signals to the cameras 13 and the light sources via a radio connection, whereby miniaturized electronics are used, which, including the battery, also contributes little weight to the overall weight of the condylograph.

[0038] It is also planned to pivot the housing 8 onto the upper arch 1. This allows the housing 8, and with it the field of view 10 of the cameras 13, to be pivoted, for example, in the xz plane if the reference markers 4 on the lower arch 2 are located at a different height or in a different area on the patient side, where measuring jaw movement appears more advantageous. For this purpose, the housing 8 is connected via a joint that allows and temporarily locks predefined pivoting positions of the housing 8.

[0039] It is possible to provide a housing 8 only on the right or only on the left side of the patient and use it for the measurement, since this allows the entire jaw movement to be captured due to the statics of a human jaw. However, a possible dysfunction on one side of the patient cannot be detected by a measurement on the other side. Therefore, measurement using pairs of cameras on both sides of the patient is advantageous. For this purpose, a second housing 8 is attached to the then still free side of the upper arch 1 (as well as corresponding reference markers 4 on the lower arch 2) in order to also measure in parallel or alternately on the now second side of the patient.

[0040] Advantageously, the condylograph is connected directly or via a computer-like control and recording device that performs control and evaluation to a display device that shows the caregiver the measurement results, the status of the condylograph, or simply a rudimentary signal confirming successful measurement. From the filmed movement of the reference markers 4, software can automatically determine characteristic data for dental articulators without human intervention and without any significant time elapse. Furthermore, the recorded data can be converted to any desired intercondylar distance (for example, the patient's actual intercondylar distance) with bilateral and simultaneous recording. This characteristic data can be conveniently saved and delivered in the form of a printout, a file, or similar.

Claims

1. Condylograph for the electronic recording, close to the joint, of the mobility of a patient's lower jaw (7), wherein a Cartesian coordinate system is defined by the patient's skull (6), starting from a zero point as the bisecting point of a line between the two jaw joints on the joint axis and consisting of an x-axis lying in the horizontal plane defined by the joint axis and a third reference point pointing in a frontal direction, a y-axis along the connecting line of the two jaw joints, and a z-axis along the vertical axis of the skull (6), wherein the condylograph comprises an upper bracket (1) which can be firmly connected to the patient's skull (6) and which has at least one camera (13) on at least one side of the patient, and a lower bracket (2) which can be firmly connected to the lower jaw (7) and which has at least one reference marker (4) in the field of view (10) of the at least one camera (13), wherein the reference marker or markers (4) are respectively arranged at a left and / or right end (3, 3') of the lower bracket (2), and wherein the left and right ends (3, 3') of the lower bracket (2) are firmly connected to one another, characterised in that on at least one side of the patient, two cameras (13) are provided on the upper bracket (1) which have viewing axes (12) which enclose an angle α between about 30 and about 150 degrees with one another in a plane lying parallel to the x-z plane, and wherein the cameras (13) are respectively directed towards the at least one reference marker (4) on their patient side, and the reference marker or markers (4) can be adjusted to a joint axis determined anatomically according to facial landmarks or to the individual hinge axis of the patient's jaw joint and a range of up to about 3 mm round it.

2. Condylograph according to claim 1, characterised in that the reference marker or markers (4) is / are spheres.

3. Condylograph according to claim 1 or 2, characterised in that the reference markers (4) are one or more spheres on one or both sides of the patient, wherein the spheres on one side of the patient are spaced apart at a predefined distance.

4. Condylograph according to one of the claims 1 to 3, characterised in that the angle α of the cameras (13) is between about 80 and about 100 degrees.

5. Condylograph according to one of the claims 1 to 4, characterised in that the cameras (13) are infrared cameras and the reference markers (4) are coated with an infrared colour, and wherein the condylograph has infrared light sources by which the reference marker or markers (4) can be illuminated with light in the infrared spectral range.

6. Condylograph according to one of the claims 1 to 4, characterised in that the reference marker or markers (4) are designed to be light-emitting and have an infrared light source inside.

7. Condylograph according to one of the claims 1 to 6, characterised in that the cameras (13) on each patient side are arranged in a housing (8) which is essentially closed in all spatial directions.

8. Condylograph according to claim 7, characterised in the housing or housings (8) are attached to the upper bracket (1) in a pivoted manner.

9. Condylographic device consisting of a condylograph according to one of the claims 1 to 8, characterised in that the upper bracket (1) is connected to a computer-like control and recording device by means of a cable, preferably according to the USB system.

10. Condylographic device consisting of a condylograph according to one of the claims 1 to 8, characterised in that the data transmission from cameras (13) and the control signals to the cameras (13) and the light sources from and to a computer-type control and recording device takes place via a radio connection.

11. Condylographic device according to claim 9 or 10, characterised in that the device has a display device.

12. Condylographic device according to one of the claims 9 to 11, characterised in that the control and recording device has software with which characteristic data for dental articulators can be determined automatically.