US3851178A

US3851178A - Contour dental x-ray film

Info

Publication number: US3851178A
Application number: US00338821A
Authority: US
Inventors: J Borden
Original assignee: Individual
Current assignee: Individual
Priority date: 1973-03-07
Filing date: 1973-03-07
Publication date: 1974-11-26
Anticipated expiration: 1991-11-26

Abstract

An improved dental X-ray film pack is provided with one end contoured differently than the other end with the result that a greater area of undistorted film can be positioned in the mouth for a single exposure.

Description

United States Patent 1191 1111 3,851,178 Borden Nov. 26, 1974 CONTOUR DENTAL X-RAY FILM 1,719,106 7/1929 Cressler 250/479 2,127,365 8/l938 McHugh 250/478 [76] Invent Bmden, 3815 Chanel 3,374,353 3/1968 Saffir 250/479 Annandale, Va. 22003 [22] Filed: 1973 Primary Examiner-James W. Lawrence [21] Appl. No.: 338,821 Assistant ExaminerB. C. Anderson [52] U.S. Cl 250/478, 250/475, 250/473 51 Int. Cl. (10111 23/04 [57] ABSTRACT Fleld of Search An improved denta X ray pack is provided one end contoured differently than. the other end with 56 R f Ct d the result that a greater area of undistorted film can 1 e erences l e be positioned in the mouth for a single exposure.

UNITED STATES PATENTS v 1,437,827 12/1922 Sulzer et al. 250/478 19 Claims, 21 Drawing Figures .PAIENTE HBVZEIBH 3 J78 SHEET 10F 3 PR'OR ART PRHOR ART PATEN IL; K531261974 SHEET 2 OF 3 PRIOR ART FIGIZ PAIENIEL km! 2 81974 saw so; 3

' PRIOR ART 6 7 71 34 IN f 66 3 it? Y L J FIG I? Y6 I I FIG [6 mm A;

CONTOUR DENTAL X-RAY FILM Dental X-ray technique is a unique problem because it requires placement of a film inside the mouth. Up to the present, all film of this type commonly used for this purpose has been square and flat, whereas the oral cavity is curved. The corners of the pack containing the film press upon soft, sensitive tissue, causing pain, discomfort and gagging. These factors require deft positioning of the film and often requires bending of the corners of the pack, resulting in distortion of the image on the film body. Although an accurate image requires that the film be flat and undisturbed, this rule is constantly compromised because of the curved environment.

In addition, because portions of the image on each film is distorted, it is necessary to take 14 l8 overlapping exposures in the quest for accurate information. This is time consuming, uncomfortable and subjects the patient to considerable excess radiation.

' In the lower jaw, the problem is less severe only because one film can be placed in the molar area without distortion. Toward the front, however, the jaw curvature begins in the bicuspid area, once again requiring film distortion and bending of the retangular corners of presently available film packs. Also, in the lower jaw, the tissues are more sensitive and the muscles under the tongue tend to reject the film, causing movement and displacement. The reflex swallowing act, for example, can lift the film completely out of position.

The new contour films decribed herein provide not only a new shape forthe standard size film, but also a new, larger size which, because of the contour shape, can be positioned to replace two regular size standard rectangular films. In addition, as will be described, this same larger size can also be usd as a bite wing" film pack, replacing two additional standard size films.

The contourfilm is shaped differently at one end, in order to better accommodate the curvatures encountered in film placement within the oral cavity. Thefilm can also be used flat without any bending of the corners, thereby increasing the image accuracy. Where sensitive tissues are encountered, the rounded contour is better tolerated than the comers on a standard film pack. The contoured end does eliminate some film area, but, as can be demonstrated, the area lost is either distorted and useless or shown on another film. The contoured film pack permits a larger sized film to be used, resulting in a gain of effective area in certain locations. Thus, the contour film provides advantages without loss of valuable film area.

So called bite wing X-ray films are so described because the film pack has attached a flexible wing, or tab,

at right angles to film, on which the patient bites to hold the pack in place. Thus, a portion of both upper and lower teeth appear on the film. The angle of the X-rays can be perpendicular to the film plane, and thus provide most accurately to detect small details often lost on the other films because of bad angulation.

The standard bite wing film has a length based upon including the area from the cuspid to last molar. It is narrower and longer than standard film because with the teeth closed, the vertical space available becomes more restricted as the curvatures of upper and lower jaws come together. It is interesting that this film shape is not popular. Many dentists prefer using the wider regular film by attaching a tab to the center of the pack.

But because the regular film is shorter, in order to be accommodated in the curvatures of the closed jaws, four exposures are required.

The reason is that the narrow film is designed to show cavities and defects between the teeth. but is not wide enough to show bone loss areas between the roots, especially in older adults with pyorrIhea conditions. Also, the narrow film isvery easily tilted, resulting in loss of the image at opposite corners.

The contour bite film is the width of the standard film and because of the contoured end, can be positioned to include the cuspid tooth forward. It therefore captures the information being sought by four standard films.

In smaller mouths, and children, the regular size contour film is used as a bite wing, thereby providing more information than the small standard size bite wing.

FIG. 1 is a plan view looking upwardly at the palate of an average human mouth;

FIG.- 2 is a cross-section of the anterior-posterior (AP) section on the right showing the placement of the prior art rectangular X-ray film;

FIG. 3 is a cross-section of the anterior section showing placement of a prior art film;

FIGS. 4, 5 and 6 illustrate the bending required for propeer placement of prior art films during the usual sequence of exposures in the posterior, bicuspid and anterior portions, respectively;

FIGS. 7 and 8 are plan views of two basic contours employed for the X-ray film of the present invention;

which a bite-wing film pack is held between the teeth.

FIG. 14 shows in solid lines the incomplete image obtained by a bite-wing film which has become tilted to the position shown in the dotted lines;

FIGS. 15 and 16 illustrate the overlapping images obtained by using two standard periapical films, with bitewing tabs applied;

FIG. 17 illustrates the single image obtained by film of the present invention under the same conditions as the two films of FIGS. 15 and 16;

FIG. 18 illustrates the image obtained by the smaller film of the present invention when used as a bite-wing film in a small mouth;

FIG. 19 shows a holder containing a complete set of X-ray images for a mouth when using the prior art films, and;

FIG. 20 shows a holder containing a complete set of images when using the film of the present invention.

In the drawings, FIG. 1 illustrates the nature of the surface area of the upper part, or palate, indicated generally by numeral 30, of an average human oral cavity. Each of the curved lines 31a through 31i represents the intersection of a horizontal plane with surface of the palate in an upwardly ascending direction in the same way that irregular surface features are identified on a topographic map. Thus, the palate 30 resembles, in reverse, an enclosed cove in a body of water having a shoreline which rises at an increasing rate on all sides to a crest, around the rim of which are mounted the incisor teeth 32 at the anterior center, flanked successively on each side in the posterior direction, by the canine, or cuspid, teeth 33, the bicuspids 34 and the molars 35. The normal arrangement of teeth in the lower jaw, or mandible, is similar to that of the upper jaw and, while not illustrated in the drawings, the contour of the inner surface of the mandible adjacent the teeth is similar; but more complex in the center because of the presence of the tongue, the muscles connected therewith, and the entrance to the throat. However, the problems connected with the placement of X-ray film packs in the oral cavity are similar in the case of both jaws and can be discussed by reference to the upper aw.

Ideally, to secure an accurate radiographic image on a film, it should be positioned in a plane normal to the path of radiation and as close as possible to the objects being recorded. The conventional X-ray film pack, indicated generally by numeral 36 comprises a rectangular outer covering of moisture resistant material, such as plastic, having slightly rounded corner margins to protect a sheet of film or corresponding shape contained therein. Usually, there is a sheet of black lightproof paper folded around the front and back of the film and an additional lead-foil sheet to limit the passage of radiation beyond the back of the film pack.

FIG. 2 illustrates what would happen if an attempt were made to position the pack 36 in the posterior portion of the jaw while maintaining the film in its ideal, flat condition. The engagement of the corners of the pack with the curved surface of the mouth makes it impossible to capture an image on the film of the roots of the teeth in the central portion of the straight margin. FIG. 3 illustrates a similar situation if the film were to be used for the anterior portion of the mouth. An approach to a solution which permits the film to remain flat, is to move the film pack further away from the teeth into the central area of the cavity, but this results in loss in the definition and clarity of the radiographic image due to the scattering of the X-rays after passing through the teeth and jaw.

In practice, it is a common expedient for the dentist to attempt to conform the shape of the pack to that of the patients mouth by bending one or more of the corners of the pack so that it can be placed directly against the skin and held in place by the patient. For example, as shown in FIG. 4, to place the film pack 36 in the posterior position, the dentist will first bend one corner along the dotted line 37 in an attempt to conform to the double curvature of the jaw surface in that area. While it would be desirable to include as many teeth as possible in a single exposure to radiation, as a practical matter it is impossible to encompass the area including the cuspid, bicuspid and molar teeth with a single film pack of rectangular marginal configuration.

Thus, as shown in FIG. 5 a second radiograph must be made of the anterior-posterior teeth, in which both corners at one end of the film pack are bent along the dotted lines 37 and '38 to attempt to conform to the steep double curvature of the jaw in the anterior area. This results in a considerable overlap in the resultant image, which is unavoidable and, to some extent necessary. The image produced in the bent corners of the film, beyond the

lines

37 and 38 is inferior because that area of the film has been disposed in a plane which is not at all normal to the path of the radiations from the X-ray source.

Again, as shown in FIG. 6, the two corners of the film pack are usually bent along the

lines

37 and 38 before positioning the film in the anterior region of the mouth because of the steep double curvature in that area.

However, as should be apparent to those who have been subjected to dental treatment involving the techniques explained above, the presence of the angular corners of the conventional film pack are often painfully evident when they press into delicate tissues.

To remedy the foregoing disadvantages, a preferred form of contoured film and film pack is shown in FIGS. 7 and 8, in which a small size pack is indicated gener' ally by numeral 39 and a larger one by numeral 40. The basic constituents of the pack, as shown in FIG. 8a, are similar to conventional practice in that it comprises a sheet of radiographic material sensitive to X-rays, such as an emulsion coated film 4l enclosed over both surfaces by a visible light opaque material, such as a folded sheet of black paper 42, the lower sheet of which is somewhat longer than the film to provide an overlapping portion 43 which is folded over the top sheet when the pack is manufactured. In addition, a radiation shield, such as a sheet of lead foil 44, is usually added to prevent excessive radiation into the mouth beyond the film pack itself. The foregoing assembly of sheets is finally provided with a moisture resistant cover, which may include sheets of flexible plastic 45 having an overall configuration closely conforming to that of the contained film 41 and bonded to each other along their margins.

For convenience in opening the pack, it is conventional practice to extend one of the plastic sheets around one end of the pack to overlap the other sheet, after which the margins of the sheets are bonded together and the overlapping sheet is heat sealed to the top sheet along the transverse dotted lines 46 to provide an exposed opening tab 47 which, when pulled away from the top sheet, exposes one end portion of the contents, as shown in FIG. 8a. As a convenience for removing the exposed film 41 from the pack by itself, the end margins of the overlying sheets of material such as the black paper and radiation shield may be provided respectively with

cutouts

48 and 49 so that the area of film may be engaged by a fingernail, or attached to the clip of a developing rack without difficulty, especially in the subdued light of a darkroom.

Ideally, the marginal configuration of the pack 39 would be irregular and would preferably represent the area defined by the intersection of a plane disposed normal to the path of the rays from a source of X- radiation and the inner surface of the jaw of a patient at the location of the teeth whose radiographic image is desired. Since the contours of patients oval cavities vary considerably it is obviously impossible to manufacture successfully an infinite variety of shapes, so that a compromise partly dictated by the limitations of automatic machinery must be made which has resulted in the configurations illustrated in FIGS. 7 and 8.

The main body of the pack may have one straight end margin 50 to facilitate the formation of the overlapping plastic cover 46, the end margins being joined to a pair of parallel side margins 51 at right angles thereto by rounded corners, as is the usual practice. However, the

other end of the pack has a differently shaped masrgin 52 which for convenience may be defined by a convex curve which merges smoothly into the side margins 51. It has been found in practice that the overall width .of the pack can be approximately the same as the conventional periapical film pack namely, about 33 mm, and the overall length of the smaller contoured pack may also be about the same as the standard pack, about 44 mm, although in no respect are these dimensions considered to be limiting. In the case of the larger size contoured film pack 40, the width may be the same, as this has been found sufficient to provide a good image of root and bone structure, but the overal length may be extended to about 65 mm, more or less. It goes without saying that the radiation sensitive material 41 contained within the pack will extend over as much of the area as can be contained within the protective covering 45. The contents and construction of this size pack resembles that of the smaller pack 39 and need not be separately described FIG. 9 illustrates in solid lines the placement of the standard sized pack to make a radiograph of the central incisor teeth, while the dotted lines show the two placement positions for obtaining radiographs of the other incisors and adjacent cuspid teeth. In these positions the contoured margin 52 is placed in the arch of each jaw, with the other end margin projecting unobstructed above the projecting portions of the teeth.

Because of the contoured margin the pack, as a whole, can be positioned further into the arch of the jaw, and this can be done without substantially bending of the film as in the case of conventional packs.

Those portions of the image lost at the inserted corners of the film is made up by the overlapping positioning of the three positions over and by the fact that the central area of the film in each position can capture a deeper image of the root and bone structure. More important is the fact that, because there is substantially no curvature, or bending, of the film the entire image will be clear and accurate.

FIG. 10 illustrates placement of the larger sized film pack 40 in the posterior periapical region of a jaw. As shown, the contoured end margin 52' is placed in the anterior region but, the shape of the jaw may, in some cases dictate that the positions be reversed, with the end 50' being positioned anteriorly. It will be evident that, in either case, the provision of the contour allows the pack to be positioned close to the teeth without distortion of the film while the additional area covered by the film will provide an image of the molar, bicuspid and canine teeth in a single radiograph.

Comparison of FIG. 11 with FIG. 12 shows how the use of the contoured film pack eliminates excessive radiation exposure by a reduction of radiographs necessary for coverage of a single jaw. Present practice is shown in FIG. 11, in which numerals 53, 54, 55, 56, 57,

58 and 59 indicate diagrammatically the successive positions of the conventional rectangular film packs, whereas numerals60, 61, 62, 63 and 64 diagrammatically identify the placement of contoured film packs. It can be seen that the entire side region requiring three conventional film packs 53, 54 and can be covered by the two contoured film packs 60 and 61; similarly,

conventional packs

57, 58 and 59 on the other of the jaw can be replaced by contoured

packs

63 and 64. The net saving in exposures for a complete set of radiographs of upper anda lower jaws totals four.

Use of the conventional bite-wing film pack is shown in FIG. 13, in which the film pack itself is identified by numeral 65, to which there is attached at the center of one side a flexible strip of material 66 to be gripped between the occluded upper and lower teeth 67 and 68. The standard bite-wing pack is rectangular, having a length of about 55mm and a width of about 27mm, while the flexible strip of material 66 is only about 25mm square. This is appreciably longer and narrower than standard periapical film. Since the tab 66 is positioned near the center, is relatively narrow, and is flexible, it often happens that the pack becomes tilted out of its correct position during the final coming together of the upper and lower teeth with the result that the image obtained is similar to that of the radiograph 69 shown in solid lines in FIG. 14, wherein the diagonally opposite upper right, and lower left corners display an insufficient amount of root structure, caused by the tilting represented by dotted lines 70.

As previously mentioned, many dentists prefer to fabricate their own bite-wing film packs by attaching readily available wings, similar to tab 66, to the wider standard periapical film pack, in order to insure obtaining an image of the root and bone structure, especially any perodontal loss of bone. But this means that two exposures must be made because the average mouth cannot tolerate a rectangular film pack having the width of the standard periapical and the length of the standard bite-wing when placed close enough to the teeth to show accurate detail with the jaws closed.

The radiographs 71 and 72 of FIGS. 15 and 16 are images obtained by the foregoing makeshift method employing periapical film, and the double arrows 73 and 74 indicate the extent of longitudinal overlapping of the respective images of the two radiographs 71 and 72.

On the other hand, numeral 75and FIG. 17 is a radiograph produced by the use of the larger contoured film pack 40 which shows all of the root and bone structures of the upper and lower molar and

bicuspid teeth

35 and 34 requiring the overlapping radiographs 73 and 74, with some additional features of the canine teeth 33 as well.

Another advantage of the smaller sized film pack 39 is its adaptability for use in childrens mouths, or in adults with small mouths. Numeral 76 of FIG. 18 illustrates the image of a radiograph obtained when the film pack 39 is employed as a bite-wing pack in the mouth of a child whose mouth was of size which could not tolerate the use of the standard elongated bitewing 65, nor the rectangular standard pack with a bite-wing tab attached.

FIG. 19 shows a conventional mounting strip 77, usually of translucent plastic sheet material, provided with suitable punched fingers 78 for mounting and filing a complete set of periapical radiographs of the upper and lower jaw of a single patient consisting of six images 79 of the anterior regions and eight images 80 of the posterior regions. FIG. 20 shows a mounting strip 81, similar to sheet 77, for mounting a complete set of periapical radiographs produced in accordance with this invention. While the set may include six radiographs 82 of the anterior regions of the jaws, the posterior regions of both jaws require the use of only four radiographs 83.

I claim:

1. An elongated X-ray film strip having end margins and side margins, one of said end margins being curved and defined approximately by the intersection of a plane disposed generally at right angles to the path of radiant energy from a source of X-rays positioned to produce an image on said film strip disposed in said plane and the soft tissues covering the body contours of a human jaw.

2. The invention defined in claim 1, wherein the opposite end margin of the package and film is generally straight.

3. The invention defined in claim 2, wherein said one end margin is defined by a convex curve.

4. A dental X-ray film pack containing a single elongated sheet of radiographic material having an essentially straight transverse marginal configuration at one end and a convex transverse marginal configuration at the other end to enable it to be acceptably accommodated in the human oral cavity without substantial planar distortion to provide a single radiograph of the root and bone structure adjacent each of the molar and bicuspid teeth in one side of a single human jaw.

5. The invention defined in claim 4, wherein said radiographic material is shaped to provide a single radiograph of the root and bone structure adjacent each of the occluded molar and bicuspid teeth in one side of both of the jaws of a human oral cavity.

6. The invention defined in claim 4, wherein the outline of said radiographic material is other than rectangular.

7. The invention defined in claim 6, wherein said radiographpic material is elongated and the distance between opposite end margins thereof varies with respect to various sections taken in lengthwise parallel directions.

8. The invention defined in claim 7, wherein the maximum distance between opposite end margins occurs in a section taken medially of the opposite side margins.

9. The invention defined in claim 8, wherein both side margins of the radiographic material extend at right angles to said one end margin.

10. Method of making a dental X-ray radiograph comprising the steps of shaping a sheet of radiographic material having an outline other than rectangular having a generally elongated configuration with a generally convex end margin and capable of being disposed substantially flat without bending against the interior surface of a human jaw in the area extending posteriorly of the canine tooth, and enclosing said radiographic material in a protective covering.

11. The method of claim 10, wherein the radiographic material is also sensitive to visible radiation and said protective covering is light-opaque.

12. The method of claim 11, which includes the step of placing said radiographic material enclosed in said protective covering against the inner anterior or posterior periapical area of a jaw with said convex end margin facing the anterior area.

13. The method of claim 11, wherein said radiographic material is an X-ray sensitive film and said protective covering includes two layers of synthetic plastic sheet material respective opposite surfaces of said film, at least one of said plastic sheets having an area greater than said film, and includes the step of joining the complementary margins of the two sheets of plastic material.

14. The method of claim 11, which includes the step of producing the outline of the protective covering in conformity with the configuration of the radiographic material.

15. The method of making a dental X-ray radiographic film pack which includes the steps of shaping a rectangular film pack having a protective covering, by removing all of the material of the pack at one corner of a rectangular film pack including portions of a side and end margin to provide a curved end margin and covering the exposed marginal portion of radiation sensitive material with light-opaque material.

16. The method of claim 15, which includes the step of removing all of the material at both corners of one end of said rectangular film pack to provide a curved end margin.

17. Method of making a set of intra-oral dental radiographs which comprises the steps of selecting a sheet of X-ray sensitive film having an area sufficient to include the image of the root and crown detail of the five poste rior teeth of a human jaw, forming the peripheral margin of said sheet of film to fit comfortably in the mouth adjacent said five posterior teeth without bending the sheet, placing said formed sheet in said position and exposing said film to radiation from a fixed source.

18. The method of claim 17, in which the selected X-ray sensitive film is generally elongated and the dimensions are approximately 33mm in width and an overall length of approximately 65mm.

19. The method of claim 17 which includes the steps of obtaining images of the two pairs of five posterior teeth in both jaws on four of said sheets of film and images of the root and crown detail of all of the anterior teeth of both jaws on six other separate radiographs.

Claims

1. An elongated X-ray film strip having end margins and side margins, one of said end margins being curved and defined approximately by the intersection of a plane disposed generally at right angles to the path of radiant energy from a source of Xrays positioned to produce an image on said film strip disposed in said plane and the soft tissues covering the body contours of a human jaw.

17. Method of making a set of intra-oral dental radiographs which comprises the steps of selecting a sheet of X-ray sensitive film having an area sufficient to include the image of the root and crown detail of the five posterior teeth of a human jaw, forming the peripheral margin of said sheet of film to fit comfortably in the mouth adjacent said five posterior teeth without bending the sheet, placing said formed sheet in said position and exposing said film to radiation from a fixed source.