US2315660A

US2315660A - Clamp for dental impression trays

Info

Publication number: US2315660A
Application number: US358799A
Authority: US
Inventors: Benjamin F Sahr
Original assignee: Individual
Current assignee: Individual
Priority date: 1940-09-28
Filing date: 1940-09-28
Publication date: 1943-04-06
Anticipated expiration: 1960-04-06

Description

April 6, 1943.

B. F. SAHR CLAMP FOR DENTAL IMPRESSION TRAYS Fil'ed Sept. 28, 1940 2 Sheets-Sheet l BIYjd/ill April 6, 1943. s. F. SAHR CLAMP FOR DENTAL IMPRESSION TRAYS Filed Sept. 28, 1940 2 Sheets-Sheet 2 0 xx 12 0 f Patented Apr. 6, 1943 UNITED STATES PATENT OFFICE CLAMP FOR DENTAL IMPRESSION TRAYS Benjamin F. Sahr, gHu'tchinson, Minn.

Application September 28, 1940, Serial No. 358,799

8 Claims.

This invention relates to the dental art. In this art in making the mold impression of the lower denture the impression material is contained in a tray. Such a tray is disclosed and claimed in my prior Patent No. 1,629,177 of May 17, 1927, and in the use of such a tray it is of the utmost importance not only that the pressure on the two sides of the tray be equalized, but that, while the setting of the material in the tray is taking place the tray be held against the lower jaw under constant and unvarying pressure.

In the common practice of using both hands to apply pressure to hold the tray in position, it is known that a muscle movement or twitching exists in the hands and arms which reduces the chances for a successful and perfect impression.

It is also known that in the use of a pressure machine duplicating the acts of impression taking of the lower jaw, the dentist, if right handed,

exerts unconsciously up to thirty per cent more pressure with his right hand than with his left hand and that the reverse is true if left handed. This unequal pressure is coupled with muscular twitching of both hands in a two-handed technique,

Another fact of great importance is that resilient tissue covers the bony process of the lower law. This tissue can be compressed on applying pressure to it, and being resilient it will spring back or resume its natural position when the pressure is taken away. This movement is very slight, but very quickly lifts the denture from the ridge. Equal pressure must be applied to this resilient tissue in impression taking or the denture will not occlude perfectly with the tissue of the jaw. If the denture does not occlude perfectly we cannot obtain vacuum, so to speak, between the denture and tissue.

The present invention provides an extremely simple and highly efficient clamp for holding the impression tray against the lower jaw ridge or stress bearing area in the desired manner above indicated.

In the accompanying drawings, which illustrate the invention, like characters indicate like parts throughout the several views.

Referring to the drawings:

Fig. 1 is a perspective showing the tray and clamping device applied in use, the outline of the human head being indicated by dotted lines; Fig. 2 is a transverse section taken through the lower jaw and showing the tray and clamp in cross section;

ing shown in elevation;

Fig. 4 is a side elevation showing a modified form of the clamp;

Fig. 5 is a view in perspective corresponding to Fig. 1, but illustrating a somewhat modified structure;

Fig. 6 is a transverse section taken through the lower jaw and showing the tray and clamping cross-section of the modified structure illustrated in Fig, 5; and

Fig. 7 is a side elevation of the clamp shown in Figs. 5 and 6.

Referring first to the preferred construction illustrated in Figs. 1, 2 and 3, the U-shaped dental tray is indicated by the numeral 6. This tray is provided with a transverse pressure bar 7, which at its central portion has a depression or pocket 8. In Fig. 2 the fleshy part of the lower jaw is indicated by the character a, the jaw bone by the character I) and the tongue base by the character 0. In Fig. 2 this tray is shown as holding the molding plastic material 9 preferably positioned on the lower jaw.

The tray clamp, as preferably designed, involves a clamping frame that is made from a narrow piece of flat metal, preferably aluminum, plated with a non-corrosive material such as nickel, chromium or the like. The frame may be roughly described as made up of an approximately U-shaped upper portion In and a reversely formed and smaller approximately U- shaped lower portion ll. These portions in and ll are, as shown, preferably bent approximately rectangular, but might vary considerably from that rectangular form and could then be described also as approximately C-shaped. The upper prong of the upper body portion H] has a downturned bearing lug I2, the point of which is adapted to be seated in the pocket 8 of the pressure bar I of the tray 6. Extended through the base of the upper portions 10 and II, in axial alignment with the point of the bearing lug I2, is a stem or rod I3, which at its upper end is provided with a clamping bar l4 that is preferably bent to fit the under jaw and press against the fleshy portion immediately under the jaw bone 1). The stem I3 is screw-threaded and working thereon is a nut I5, between which and the lower prong H is interposed a coiled spring It. By adjustments of the nut IS on the stem I3 the clamping bar l4 may be raised and lowered and the tension of spring 16 may be varied. The character l5 indicates a nut that is screwthreaded on the extreme lower end of stem l3 to limit the upward movement thereof. Preferably the depending portion of frame I0 is graduated to indicate the amount of pressure exerted by spring l6.

Applying the device as shown in Figs. 1 and 2, the bearing lug I2 is located in the pocket 8 of the pressure bar I, and the nut 15 is screwed down on the stem it until the clamping bar M is pressed against the lower jaw with sufiicient force to properly seat the tray and hold the plastic material against the lower oral surface with exactly the right pressure. The spring l6 produces a yielding or cushioning action between the clamp id and the clamping frame, which is very desirable in most instances, but if very considerable pressure should be required the nut IE will be screwed down'until the spring it has been solidly compressed. In either event or even if the spring It should be omitted, the nut IE will react against the lower portion of the clamping frame and will cause the plastic ma- I terial in the tray to be pressed down and react against the lower denture stress bearing area of lower jaw surface. Obviously, when the clamp has been applied to hold the tray under the desired pressure, the pressure will be equalized on both sides of the tray and there will be no shaking, vibrating or variation in the applied pressure.

The device may be quickly applied, and while it is applied there is no necessity whatever for application of the dentists hand in the oral cavity.

In Fig. l, I have shown a modified device in which the clamping frame Ha is provided with a-stem or rod liia equipped at its upper end with a pressure bar Ma between which and the base of the frame section Ilia is interposed a coiled spring lta, the expansion of which is limited by a key or the like ll applied to the lower end of the stem. The use of this modified device is evident.

Figs. 5, 6 and 7 illustrate an important further modification of the invention in which the tray Ed has no bridge bar but has depressed contact bosses 6b, one on each prong or side thereof. In this modified structure many of the parts thereof are identical with or very similar to parts illustrated in Figs. 1 to 4, inclusive, and hence,

these parts will be designated by the same numerals with the exponents I) applied thereto.

In this modified structure, however, the upper arm of the frame i is shorter than in the earlier described structure and to this short upper arm a pair of arms it are pivoted by a nut-equipped bolt [9. At their free ends the arms l8 are provided with contact screws 2i! that are engageable with the depressions of the bosses 6b on the tray 6a. The arms [8 are adapted to be spread for proper engagement with the particular tray and the screws 29 can be independently adjusted to obtain proper distance between the pressure bar or chin rest 14?) and the points of said screws. By adjustments of the nut on the screw threaded stem, the device may be adjusted so as to produce an even pressure on the tray even when there is an uneven jaw recession.

It is important to note, in the several forms of the device above described, see particularly Figs. 1, and 7, that when either of the said devices is assembled and applied as illustrated and described, the chin-engaging clamp will be substantially in the same transverse vertical plane as the point of contact between the tray and the tray engaging element on the upper prong of said frame. In the one case the stem i3 will be in the same transverse plane with the upper contact point I 2 and in the other case the axis of said stem will be in the same transverse vertical plane that intersects the points of the screws 20.

To adapt the device for application to exceptionally large chin formations, it may be desirable, in some instances, to make the socalled U-shaped frame vertically adjustable so as to increase or decrease the distance between the chin-engaging clamp or bar and the tray. In Fig. 4, I have illustrated a means for accomplishing such vertical adjustment and which means consists in dividing or making in sections the vertical portion of the frame [0a and providing one of the sections with vertical slots 2| and dividing the other section with screws 22, and which screws work in the slots of the one section and have threaded engagement with the other section. This same kind or similar vertical adjustment may be applied to the other forms of the device illustrated.

These features just noted are of very great importance in maintaining the clamp in good position and applying the pressure on the tray in a vertical or downward direction.

From the foregoing it will be understood that the various other modifications may be made within the scope of the invention herein disclosed and claimed.

This case is being filed as a continuation-inpart of my copending application Clamp for dental impression trays, filed May 16, 1938, under S. N. 208,239, and allowed April 4, 1940.

It will be noted that the chin-engaging clamp I4 is in the form of a bar that is substantially the same width as the U-shaped clamp and is capable of being turned to a position parallel to the body of the U-shaped clamp thereby producing a substantially flat formation capable of being readily placed in an envelope or the like.

What I claim is:

1. A dental device comprising an impression tray, an approximately U-shaped clamping frame having upper and lower prongs and provided at its upper prong with means for detachable contact with said tray and provided at its lower prong with an approximately reversely U- shaped minor portion, a chin-engaging clamping bar having a depending stem that is freely movable endwise in said U-shaped minor portion, and a spring applied around said stem and reacting against said frame to yieldingly press said stem and chin-engaging bar upward.

2. A dental device comprising an impression tray, an approximately U-shaped clamping frame having upper and lower prongs and prov1ded at its upper prong with means for detachable contact with said tray provided at its lower prong with an approximately reversely U- shaped minor portion, a chin-engaging clamping bar having a depending stem that is reely movable endwise and rotatively in said U-shaped minor portion, and a spring applied around said stem and reacting against said frame to yieldingly press said stem and chin-engaging bar upward.

3. The structure defined in claim 2 in which said stem is threaded and in further combination with a nut working on said threaded stem and operative to vertically adjust said chin-engaging bar and stem and to vary the tension of said spring.

4. A dental device comprising an approximately U-shaped clamping frame having upper and lower prongs and provided at its upper prong with means for detachable contact with a dental tray and provided at its lower prong with an integral depending minor portion which is also approximately U-shaped, a chin-engaging clamping bar having a depending stem that is freely movable endwise and rotatable in said U-shaped lower prong and minor portion, and a spring ap-- plied on said stem and reacting against the same and said frame with a force yieldingly pressing said chin-engaging bar and its stem upward, said chin-engaging clamping bar having approximately the same width as said clamping frame so that it may be turned on its mounting into a plane aligned with the body of the frame.

5. The structure defined in claim 4 in which said stem is externally threaded and in further combination with a nut applied on said threaded stem and operative to vertically adjust the latter and to vary the tension of said spring.

6. The structure defined in claim 1, in which the said stem is threaded, and in which the said spring is located in the minor U-shaped portion of the clamping frame and seats against the bottom thereof, and in further combination with a tension adjusting nut working on said threaded stem within the minor U-shaped portion and against the upper end of said spring.

7. A dental device comprising an impression tray, an approximately U-shaped clamping frame having upper and lower prongs and provided at its upper prong with means for detachable contact with said tray, a chin-engaging clamping bar having a depending stern that is freely movable endwise through the lower prong of said frame, and a spring applied around said stem and reacting against said frame to vieldably press the chin-engaging bar upwardly in sub stantial alignment with the means for detachably contacting the tray.

8. The structure defined in claim '7 in which said stem is threaded and in further combination with a nut working on said threaded stem and operative to adjust the tension of said spring.

BENJAMIN F. SAHR.