METHOD AND DEVICE FOR RADIOGRAPHING HUMAN JAW JOINTS

Technical Field

This invention relates to a method and device for radiographing the temporomandibular joints of a patient's head, and more particularly, to a film and X-ray coordina¬ tion device and method of using same for obtaining con¬ sistently good diagnostic X-ray film images of the pat¬ ient's temporomandibular joints using standard dental office X-ray equipment, film of dental X-ray size, and dental film developing equipment and procedures .

The human lower jaw or mandible is hinged to the temporal bone of the skull on both sides of the skull just in front of the ears. This hinge or joint is re¬ ferred to as the temporomandibular articulation or joint, which for convenience of description shall hereinafter be referred to as the TMJ.

While there are many reasons for radiographing the TMJ, a particularly significant problem for dentists is that should dental work done on the patient, such as fillings and the like, result in even minor projections or protrusions above the normal tooth engagement level that would block or impede normal occlusion when the patient's jaws are brought together, one or both of the patient's TMJs may be thrown out of line on occlusion. Over a period of time, this can develope into an ex¬ tremely painful condition. Diagnosis and treatment can be greatly enhanced with the availability of good X-ray film images of the patient's TMJ articulations.

Background Art Existing techniques for radiographing the TMJ are less than satisfactory for many reasons. Equipment and

practices employed require a substantial investment in both equipment and highly trained technicians, yet re¬ sults are all too frequently indeterminate and inaccurate Furthermore, available equipment is cumbersome to. operate and most techniques require the patient to assume an un¬ comfortable and awkward position of the head to prac¬ tice the techniques involved. Some of the problems and proposed improvements in TMJ radiology techniques are discussed in the paper by Dr. Lawrence A. Weinberg en¬ titled "Technique for Temporomandibular Joint Radiographs which appeared in the Journal of Prosthetic Dentistry, Volume 30, No. 6.

While from cost and technology standpoints, TMJ radiology has been for all practical purposes out of rang of many dental practices, and the patient discomforture involved has tended to discourage use of existing TMJ radiology techniques, the fact remains that good TMJ diagnostic X-ray film images can alert the dentist to TMJ problems that can lead to major patient discomforture unless promptly corrected. This is because TMJ displace¬ ment is readily apparent from good TMJ diagnostic X-ray film images where conditions impeding normal occlusion exist.

Disclosure of Invention

In accordance with the invention, a film holder and X-ray target equipped frame is provided that is arranged for support on the patient's head by application to the external auditary meatus of the patient's ears and brac¬ ing elsewhere against the patient's head for a firm three point support on the patient's head without inducing patient discomfiture.

The frame includes a base portion having associated with same a pair of film holders and an X-ray position¬ ing target for each, in which the holders and targets

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are arranged in a pair of sets, in which the respective, film holders are disposed, when the device is applied in its operating position to the patient's head, adjacent the TMJ to be radiographed onto a particular film, and the positioning target therefor is disposed on the other side of the patient's head on an X-ray axis that is to pass through the joint that is to be imaged on the parti¬ cular film in question and be oblique to a straight line connecting the patient's TMJs .

The film and X-ray beam locating target of each TMJ radiographing set are mounted on the frame on separate opposed mounting members respectively connected to the frame for adjustment toward and away from each other, with the mounting members each being equipped with an applicator for applying same to the external auditary meatus of the patient's ears. The mounting members are positionally maintained by their connections with the frame to keep the respective film holder and target sets properly oriented relative to each other while accommo¬ dating adjustment for variations in head size and shape. The frame is arranged to be referenced to the patient's Ala-tragal plane to coordinate the film holder and tar¬ get sets with the patient's TMJ' s, and includes a rest or seat for engagement with the patient's head at a position spaced from but between his ears for providing the aforementioned three point support for the device.

The device is applied to the patient's head by in¬ serting the mounting member applicators in the external auditary meatus of the patient's ears, with the device base portion disposed crosswise of the patient's head. The frame is referenced to the patient's Ala-Tragal plane and engaged with the patient's head at the indicated third point of support to coordinate the frame holder and

target sets with the patient's TMJ's. In this position, the device is ready for use in connection with the den- tits' s conventional dental X-ray beam generating and emit ting apparatus. The patient, in accordance with the in¬ vention, remains in a normal upright position, whether sitting or standing, in using the device, and the X-ray apparatus PID is sequentially aligned with the X-ray axes defined by the respective TMJ radiographing sets provided by the coordinating device, for sequential makin of X-ray images on the respective films carried by the device.

The device is arranged to be readily reapplied to the same setting at a later date for subsequent making of X-ray images at the same locations with reference to the patient's TMJ's.

The film holders of the device are arranged to hold standard Periapical size film packets, which when exposed may be processed in the usual manner utilizing the den¬ tist's standard film processing equipment and procedures to provide the needed TMJ images.

Brief Description of Drawings

The details of my invention will be described in connection with the accompanying drawings, in which like reference numerals indicate like parts throughout the several views.

In the drawings:

Figures 1 and 2 are representations of the left side of the human skull and jaw bone, illustrating the jaw articulation or joint that is to be radiographed in ac¬ cordance with this invention, and showing in phantom as¬ sociated portions of the human nose, mouth and ear;

Figure 3 is a front elevational view of the pre¬ ferred embodiment of the invention, with the human skull

being shown in outline and as the device is to be posi¬ tioned, in use, with respect thereto;

Figure 4 is a fragmental elevational view, partial¬ ly in section, and on an enlarged scale, of the head rest device shown in Figure 3;

Figure 5 is an elevational view of the device of Figure 3, taken from the right hand side of Figure 3, with a portion of the device broken away;

Figure 6 is a view similar to that of Figure 5, show¬ ing the device of Figures 3 and 5 as applied to the patient; and

Figure 7 is a top plan view of the device as shown in Figure 3, with parts broken away. ^'

Best Mode for Carrying Out the Invention Referring first to Figures 1 and 2, the human jaw bone, indicated at 10, has a joint portion 12 on either side of the skull which is lodged in a socket 13 defined by the skull 14 to form what is known as the temporomandi¬ bular joint 16, hereinafter referred to as the TMJ.

As has been indicated, it has been found that the TMJ 16 is subject to apparent minor dislocations, as for example, should normal occlusion be prevented by upstanding dental filling residue and the like that would preclude the upper and lower jaws from fully closing normally. Experience has shown that good diagnostic X-ray images of the TMJ will show when such minor mis¬ alignments and dislocations are or will occur due to occlusion obstructions, so that the dentist can make proper adjustments promptly and thereby avoid significant pat¬ ient discomfiture -that might otherwise be hard to diagno¬ sis.

The device 20B (Figures 3 - 7) is arranged to pro¬ vide the practicing dentist with a ready way of making

X-ray film images of the patient's TMJs while the patient remains seated in the dental chair, if desired, and using standard periapical size film that can be processed by standard dental film processing equipement and pro¬ cedures. This permits the dentist to have access to X-ray film images of a patient's TMJ articulations with the same speed and efficiency that he can obtain X-ray film images of the patient's teeth using conventional Dental X-ray equipment.

The device 20B of Figures 3 - 7 is arranged to provide a three point type mounting support for same on the patient's head whereby the device is applied to the patient's external auditory meatus, of both ears, and is braced against the top of the patient's head.

The device 20A comprises sets 44B and 46B of co¬ ordinated X-ray beam locating and film holder means of which the set 44B comprises X-ray beam locater or posi¬ tioner target 48B secured to mounting member 24B and X-ray film holder 50B suitably mounted on mounting member 26B, while the set 46B comprises X-ray beam locater 52B mounted on mounting member 26B and X-ray film holder 54B mounted on the mounting member 24B. The mounting mem¬ bers 243 and 26B are provided with the applicators 38 and 40 that are proportioned to make a plug fit type application to the external auditary meatus of the pat¬ ient's ears, in a manner similar to dictation transcribin equipment and the like.

The locators 48B and 52B in the form shown each comprise a ring member 200 suitably mounting a collimator plate 202 formed at its mid portion to define the usual window opening 204 that is shaped to limit the size of th X-ray beam to be projected therethrough to a size ap¬ proximating but slightly larger than the size of the film employed. Plates 202 are formed from lead, as is the practice for collimators.

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The locater 48B is affixed to holder arm 208 having a rectilinear portion 210 at approximately right angles with respect thereto for sliding engagement with corres¬ ponding rectilinear portion 212 of holder arm 209 on which locater 52B is affixed.

The holder arm portions 210 and 212 are slotted longitudinally thereof as at 213 and 215 (see Figure 10) and receive the shanks of screws 214 and 216 that extend through clamp plate 218 and the respective bar portions 212 and 210 for application to suitable nuts 220 and 222 to lock the legs 208 and 210, and thus the applicators 38 and 40 of the device 20B at a desired distance be¬ tween the applicators 38 and 40. The screw .214 and its nut 220 forms fastener device 217 while the screw 216 and its nut 222 forms fastener device 219. Devices 217 and 219 are suitably positioned so that holder arm por¬ tions 210 and 212 are frictionally held against relative shifting movement, but can be readily shifted relative to each other by the operator suitably grasping the arms 208 and 209 and moving them toward or away from each other, as needed.

Carried by the clamp bar 218 is a head rest device 230 comprising a rest pad 232 secured to the end of holder rod 234 that extends through slots 213 and 215 to and through collet body 236 that is sui-tably secured to clamp plate 218 in the manner indicated in Figure 4. The collet body 236 is of the usual split configuration ex¬ ternally threaded for cooperation with collet nut 238 for releasably clamping the collet body 236 against the rod 234 at a desired position of adjustment of the rest 232 with respect to the holder arms 208 and 210. Collet body 236 and its nut 231 form collet device 239 for hold¬ ing head rest at a desired position of adjustment. Rod 234 is equipped with hand grip handle 237 for moving rod 234 when collet device 239 is released.

The film holders 5OB and 54B are suitably arranged to hold the indicated film packets. In the form shown they comprise a body 240 having a single lower holding plate 242 suitably affixed thereto (as by bonding) and spaced from the respective bodies 240 to define the res¬ pective slots 241 that receive the individual film pac¬ kets. Of course, the plates 242 may be replaced by suit ble spring wire clips or the like, or the holders 50B and 54B may be the same as holders 50 and 54.

The holder arms 208 and 209 form a frame 130B that defines an adjustable bridge portion 250 which receives the patient's head in the use of the device, in which the component parts thereof including the head rest de¬ vice 230 are in coplanar relation, as indicated in Figur 5. Holder arms 208 and 209 are angled to provide the illustrated angulation of the locaters 48B and 52B and the film holders 50B and 54B are similarly angled, in accordance with the invention.

A fundamental aspect of the invention is concerned with arranging the device in question so that the film holder and X-ray axis to be directed to the film will be located, when the device employed is applied to the patient, with reference to a portion of the human head anatomy that may serve in the nature of a benchmark ap¬ plicable to all patients for properly and reliably co¬ ordinating the film holder (and thus the film on which t image is to be formed) and the X-ray axis with the patient's TMJ to be radiographed, and on a basis that is consistently repeatable for re-X-raying at the same loca tion at a later time or date. My studies of the subject have revealed that this may be done with reference to self locating parts of the human anatomy associated with the face and head. Referring to Figure 1, indicated in broken lines are the human nose 21, including nostril 23 and the Ala 25 of the nose (which is where the lower

portions of the sides 27 of the nose that meet the cheek 29 at what may be termed the Ala line 31) . Also similar¬ ly indicated in Figure 1 are the ear 33 and its Tragus 35 (which projects posteriorly over the entrance to the meatus 37) .

In accordance with the invention, the film holder and the X-ray axis to be associated with same are coordinated with, for proper location with respect to the patient's TMJs, a plane 39 that connects the inferior portion of the Ala line 31 with the mid portion of the tragus 35. Plane 39, which may be called the Ala-tragal plane, and which intersects the exterior meatus 37, thus becomes the datum reference, that is readily established for each patient, with respect to which the X-ray coordinating devices of this invention are located, for effecting correct and restorable positioning relative to the TMJ to be radio¬ graphed.

Thus, as to the radiographing set 44B, the locating target 48B and the film holder 50B are in parallel rela¬ tion, and are disposed normally of and define X-ray axis 56 that may be assumed to be approximately aligned with the center points 58 and 60 of the target 48B and holder 50B. The radiographic set 46B has its target 52B and holder 54B disposed in parallel relation and normally of X-ray axis 62, which is assumed to be approximately aligned with the center points 64 and 66 of locater tar¬ get 52B and film holder 54B.

In accordance with the invention, the radiographic sets 44B and 46B are applied to the device 20B with such orientation and coordination that, when the device 20B is mounted on a patient's head in the manner indicated in the drawings, the X-ray axis 56 will pass through the patient's TMJ on the right side of his head while the X-ray axis 62 will pass through the patient's TMJ on the left side of the patient's head. Axes 56 and 62 are oblique

to an imaginary straight line connecting the patient's joints 16, or a similar straight line connecting the patient's external auditory meatus (or external auditory canal) on either side of his head.

The frame 13OB adjacent one of the mounting members 24B or 26B (member 26B in the illustrated embodiment) has secured thereto an indicator arm 260, which, as indicated in Figure 7, has a projecting end portion 262 which is in tended to be employed for locating the device 2OB with respect to the patient's Ala-tragal plane 39, in the mann indicated in Figure 6. For this purpose ^" , the indicator arm 260 is angled as at 264 and is pivotally connected to the frame 130B, as at 266, with a friction type pivot action being preferred.

The locators 48B and 52B each have associated there¬ with the respective aiming members 270 and 272, for faci¬ litating alignment of the X-ray machine position indica¬ ting device (PID or cone) with the respective locators 48B and 52B. The members 270 and 272 are each shown in the form of a rod 274 having plastic end piece 276 and suitably secured to their respective holder members 208 and 209. Member 270 parallels axis 56 while member 272 parallels axis 62. Rods 276 may alternately be in the form of pretensioned coil springs for flexibly yielding if accidentally bumped by the operator when positioning the X-ray PID relative to the respective locators.

The device 20B, in use, may be applied and used while the patient sits in a normal upright position in the dental chair or other location of the dentist's stan¬ dard X-ray equipment. Of course, the patient may stand upright for this purpose if that is appropriate under the circumstances of a given X-ray set up.

Assuming the patient has been readied for applicatio of the device to the patient, the frame 130B is adjusted by shifting and disposing the holder arms 208 and 209 relative to each other as needed to apply the device

to the patient's head, with the applicators 38 and 40 comfortably seated in the patient's ears. The frame 130B is then pivoted about the axis represented by the imagi¬ nary line connecting the patient's external auditory meatus on either side of his head to bring the end portion 262 of indicating arm 260 into approximate alignment with the patient's Ala line 31, and specifically with the in¬ ferior portion of same. The arm 260 may be pivoted about its pivotal mounting to dispose its end portion 262 in close proximity with the patient's face, as needed, to do this. The operator then holding the frame 130B as so posi¬ tioned with respect to the Ala-tragal plane 39, head rest 232 is lowered against the patient's head in supporting relation thereto, with sufficient pressure to hold the device 20B in place, and then secured in place by opera¬ ting collet nut 238.

In this connection, it is pointed out that the ap¬ plicators 38 and 40 of this embodiment need not be per¬ forated, as no spring loading is involved in their fitting to the patient's ears, and sufficient upward force is generated by the action of the head rest 232 bearing on the patient's head to vent the ears.

The device 20B is arranged such that when applica¬ tors 38 and 40 are four and one quarter inches apart, axes 56 and 62 will be centered with respect to the res¬ pective radiographic sets 44B and 46B. This dimension represents the average patient head size that will be en¬ countered in practice; departure of the applicators 38 and 40 from this spacing up to about an inch in either direction can readily be accommodated by using an X-ray beam size that is_slightly larger than the film employed.

The respective sets of targets and film holders are angled such that their planes are disposed at an angle of approximately seventy-five degrees relative to the

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OMPI

Ala-Tragal plane 39 when the device is applied as indicat for use.

The PID or cone of the X-ray machine may then be successively aligned with the respective X-ray axes 56 and 62 and the film exposed accordingly for processing development in the usual manner customary with dental fil In this connection, the X-ray machine PID or cone is disposed in perpendicular relation with the planes of the respective locator targets 48B and 52B, in centered rela¬ tion therewith, for alignment with the respective X-ray axes 56 and 62.

The exposed film may then be promptly processed for analyzation of the patient's TMJ articulations and prompt modification of the occlusal surfaces of the teeth, as ma be deemed adviseable by the TMJ articulation images so produced. By reapplying device 2OB to the patient in the manner indicated, the patient's TMJs may again be radio¬ graphed with the same X-ray axis orientation as initially radiographed, for final checking of occlusion.

The device 20B is quickly removed from the patient by swinging the indicator arm 260 away from the patient's face, shifting the head rest 232 upwardly, and separating the holder arms 208 and 209 as necessary to separate the applicators 38 and 40 from each other for ready removal of the device 20B from the patient's head.

For retaking of the patient's TMJs, the device 20B is reapplied to the patient in the same manner as pre¬ viously described for a retaking of the desired X-rays under the same positioning and conditions as the first se of TMJ X-rays, the indicator arm 260 alignment with Ala line 31 supplying the datum reference needed to return the device 20B to the same positioning it had for the initial set of TMJ radiographs.

In accordance with the invention, it is preferred that the film holders employed be mounted on the device so that when the device in question is aligned with the

patient's Ala-tragal plane, the film holders will be more or less centered with respect to such plane. It is pre¬ ferred that in practice the centers of the film holders employed be approximately l/8th of an inch above the level of the indicated plane 39. It is also preferred ^• that ap¬ propriate film (such as the so called medical film) con¬ ventionally packaged in individual packets with intensi¬ fying screens, be used in using the disclosed devices, as film of this type is 80 per cent exposed by fluorescent light from the screens and 20 per cent exposed by X-ray, as compared to regular dental film being 100 per cent ex¬ posed by X-ray. When film of the type indicated is pre¬ packaged to have an intensifying screen on either side of same, in a conventional manner, film exposure is fast enough to avoid patient movement that could adversely affect the desired film image, and patient radiation exposure is kept to a minimum.

It will therefore be seen that the invention pro¬ vides a device ^' for making X-ray film images of TMJ arti¬ culations that has a number of significant advantages.

For instance, the operation of the device is very simple and requires no special training on the part of the user. The X-ray generating equipment may be and pre¬ ferably is one of the types now in common use by dentists for making dental X-ray images.

The device may be employed while the patient remains in a normal upright sitting or standing position, and since the device is mounted on the patient's head, the X-ray exposures can be made in any head position as the device will move with it.

The positioning and orientation of the components of the device are arranged for precise application of the X-ray beams to the respective TMJ articulations of the patient and provide a repeatable reference for future ex¬ posures of equal prospective and dimension. The exposures

can be taken in any desired occlusal contact of the teeth because the mounting of the device on the patient's head permits full access to the oral cavity. The device avoid the need for special equipment formerly required for making TMJ x-rays, including both the X-ray taking equip¬ ment and special equipment and office space for process¬ ing the films. As the device contemplates the use of medical film of standard dental film size, exposure and development time will be comparable to that. expected for dental film. Furthermore, the finalized films can be mounted and stored by using regular dental film mounts.

The device and method provided by the invention give the dentist the ability to define "ideal" condyle posi¬ tions in temporal fossa, and the ability to coordinate occlusion of the teeth with "ideal" TMJ relationships as well as to verify such relationships. The device also provides the ability to control target exposure to a minimum area on the order of 2-1/2 inches in diameter using lead collimators in the beam locators, as herein disclosed.

In the area of general dentistry, the device per¬ mits routine diagnostic procedures with regard to TMJ syndromes and incorrect occlusal relationships. Also, in using the device ready access to the oral cavity is permitted, so that positions of the patient's T J's as related to various desired relationships of the patient's upper and lower teeth can be compared and analyzed in a given series of X-rays. Other applications of the de¬ vice and resulting benefits will be obvious to those skilled in the dental arts.

The foregoing description and the drawings are given merely to explain and illustrate the invention and the invention is not to be limited thereto, except insofar as the appended claims are so limited, since those skille in the art who have the disclosure before them will be able to make modifications and variations therein without departing from the scope of the invention.