US2748482A

US2748482A - Dental appliance

Info

Publication number: US2748482A
Application number: US463530A
Authority: US
Inventors: Mccully Charles Roland; Marsh Edward S De
Original assignee: Individual
Current assignee: Individual
Priority date: 1954-10-20
Filing date: 1954-10-20
Publication date: 1956-06-05
Anticipated expiration: 1973-06-05

Description

June 5, 1956 c. R. MCCULLY ET AL DENTAL APPLIANCE Filed Oct. 20, 1954 14 .Fzgz

Charles Poland McCu/{y Edward 5'. De Marsh United States Patent DENTAL APPLIANCE Charles Roland McCully, Chicago, Ill., and Edward S. De Marsh, Seattle, Wash.

Application October 20, 1954, Serial No. 463,539

7 Claims. (Cl. 32-40) The present invention is concerned with an improved dental appliance and is particularly concerned with an improved mechanism for assuring uniform quality and composition in dental amalgams used as fillings in teeth.

In the manufacture of dental amalgams, it is customary to compound the silver or silver alloy with an excess of mercury, after which the combination is very thoroughly mixed to assure uniformity in the final composition. When this has been done, it is common practice to place the amalgam on a small piece of cloth and then twist the amalgam in the cloth or possibly even squeeze the amalgam in the folded cloth with a pair of pliers or other suitable instrument. The purpose of this operation is to express excess mercury out of the composition and into the pores of the cloth.

As might be expected, the above described operation for removing excess mercury does not produce amalgams of uniform composition, as it is impossible to control accurately the pressure on the amalgam while the mercury is being expressed from it. Hence, it frequently occurs that two succeeding amalgams made from identi cally the same original composition may have considerably difierent properties due to the differences in pressure used in expressing the excess mercury. This difference in pressure ultimately shows up as differences in the mercury content of the final amalgam.

An object of the present invention is to provide an improved device for expressing mercury from freshly compounded dental amalgams under conditions of accurate and reproduceable pressures.

Another object of the invention is to provide an improved device for expressing mercury from amalgams which is substantially automatic in operation.

Still another object of the present invention is to provide an improved device of the character described which is simple in structure and in operation and yet capable of producing a series of amalgams of identical composition after the excess mercury has been removed.

A further description of the present invention will be made in connection with the attached sheet of drawings which illustrates a preferred form thereof;

In the drawings:

Figure l is a view in elevation of the device illustrating the manner in which the device is secured to a supporting surface;

Figure 2 is a fragmentary cross-sectional view of the interior of the housing of the device, the view being taken at the time the amalgam is first introduced into the pressure chamber; and

Figure 3 is a view similar to Figure 2, but illustrating the condition of the elements at the time the mercury is being expressed from the amalgam.

In the dental appliance of the present invention, the amalgam, containing an excess of mercury, is first conveniently wrapped in a small piece of porous fabric which serves the dual function of making the amalgam easier to handle and providing a medium for absorbing the expressed mercury. The amalgam, wrapped in its 2,748,482 Patented June 5, 1956 fabric cover, is then placed into a pressure chamber formed in a suitable housing. Included within the pressure chamber is a resiliently flexible membrane subject to variations in fluid pressure in the pressure chamber. The wrapped amalgam is preferably disposed between the outer side of membrane and a stationary part of the housing.

The pressure in the pressure chamber is adjusted and controlled by the operation of a reciprocating piston which may be actuated to draw a hydraulic fluid from a suitable reservoir into the cylinder in which the piston reciprocates, and upon the downward stroke of the piston to force the hydraulic fluid into the pressure chamber. In a preferred form of the invention, means are also provided to bleed off some of the fluid under pressure being introduced into the chamber when the desired pressure is reached.

Turning now to the specific embodiment of the invention illustrated in the drawings, it will be observed from Figure 1 that the housing may consist of a G-shaped bracket 10 arranged to engage the surface of a table 11 or other supporting structure with a threaded bolt 12 supplying suflicient pressure against the bottom edge of the table surface 11 to hold the frame member 10 rigidly against the table 11.

As best seen at Figures 2 and 3, the frame member 16 is provided with an internal bore which defines a cylinder 13 in which a headed piston 14 is arranged to reciprocate. The head 14a of the piston 14 is suitably notched to receive an 0 seal ring 16 to provide a fluid seal between the piston 14 and its cylinder 13. The piston 14 is free to reciprocate within the cylinder 13 to a'limit defined by the position of a hollow bushing 17 threaded into the frame member 10.

The outer end of the piston 14 is pivotally secured to a pin 18 carried by an operating lever 19. As illustrated in Figure l, the operating lever 19 may be quite long in comparison with the stroke of the piston 14.

The fulcrum for the operating lever 19 is provided by means of a pin 21 secured to a link 22 which in turn is pivotally secured to a pin 23 carried by the frame member 10. As evident from Figures 2 and 3, the presence of the link 22 permits the piston 14 to reciprocate freely in an upward direction within the cylinder 13. It will also be seen from Figure 1 that the length of the operating lever 19 is considerably greater than the distance between the pin lfiand the pin 21, so that an eifective mechanical advantage is provided.

The cylinder 13 is arranged to be placed in fluid communication with a reservoir 24 of hydraulic fluid such as oil 25. A port 26 provides this fluid communication when the pressure conditions are such that a check valve, including a ball 27 and a helical spring 28 located in the port 26 is open to permit flow of the hydraulic fluid from the reservoir 24 into the cylinder 13.

The pressure chamber previously mentioned, is, in the form of the invention illustrated in the drawings, formed 'by a top plate 30 pivotally secured to the frame member lil by means of a hinge 31. The top plate 30 cooperates with a hollowed metal insert 32 which fits into a suitable recess provided in the top of :the frame member 10. included within the hollowed-out portion of the insert 32 is a resiliently flexible membrane 33 composed of rubber or similar material, the membrane 33 having an edge portion 33a securely received and clamped between the bottom of the insert 32 and the base of the recess in the frame member 10 which receives the insert 32. The inner walls of the membrane 33 define a pressure chamber 34 into which the hydraulic fluid is pumped during the operation of the device.

An eyebolt 36 engages a pin 37 in the frame member 10 and is received within a slot 38 formed in the :top

- 3 plate 30. A wing nut 39 engages the threaded end of the eyebolt 36 to hold the top plate 30 against displacement when pressure is being applied in the pressure chamber.

A pressure chamber 34 communicates with the cylinder 13 through a port 41. Another check valve member, including a ball 42 and a helical spring 43 is provided to prevent return flow from the pressure chamber 34 to the cylinder 13. The spring 43 normally urges the 'ball 42 into seating relation in a reduced diameter portion of the port 41.

As a means for controlling the pressure in the pressure chamber 34, We may provide another valve element including a needle valve member 44 having a conical seati-ng face 46 arranged to close off fluid communication between the reservoir 24 and a port '47 which extends to the port 41. The needle valve member 44 is freely slidable Within a threaded bushing 57 which is secured in the frame by means of a lock nut 48. The needle valve member 44 may, if desired, be provided with a peripheral recess to receive an O-ring 49 which provides a liquid seal.

The needle valve member 44 also has an enlarged flange portion 51 at one end thereof which serves as a stop to bottom a helical spring 52 extending between the end of the bushing 57 and the flange portion 51. As will be evident from the drawings, the spring 52 normally urges the needle valve seating face 46 into seated relation with the port 47, thereby preventing flow of the hydraulic fluid back into the reservoir by the pumping action of the piston 14 during normal operation. If, however, the pressure in the pressure chamber 41 should exceed a predetermined value, the fluid pressure in the port 47 may be suflicient to unseat the needle valve member 14 and bleed oif some of the pressure fluid back into the reservoir 24. The positioning of the bushing 47 within the wall of the frame member 10 provides an accurate means for adjusting the pressure at which the needle valve member 44 will become unseated, as this position controls the compression of the spring 52.

In the operation of the device, a freshly compounded amalgam is placed Within a cloth wrapper 54 and is placed on the top surface of the flexible membrane 33.

The top plate 30 is then clamped down into position, as illustrated in Figure 2, so that the amalgam in its wrapper 54 is disposed between the membrane 33 and the bottom surface of the top plate 30. The operating lever 19 is then actuated one or more times to draw hydraulic fluid from the reservoir 24 into the cylinder 13. The suction provided by the upward movement of the piston 14 is sufiicient to provide a pressure differential across the ball 27 of suflicient magnitude to unseat it and permit the flow of fluid 25 through the port '26 and into the cylinder 13.

Downward movement of the piston upon the return stroke of the operating lever 19 forces the fluid collected Within the cylinder 13 to travel into the pressure chamber 34 by unseating the ball 42. Return of the hydraulic fluid to the reservoir 24 is prohibited, since the port 47 is closed off by the position of the needle valve element '44.

The fluid enters and fi'l-ls the pressure chamber 34, causing the flexible membrane '33 to expand in response to this increase in pressure. The pressure is transmitted uniformly along the walls of the membrane, and when the membrane is fully extended, it begins to exert a compressive action against the wrapped amalgam 5'4, squeezing it between the membrane 33 and the lower surface of the top plate 30. Suflicient pressure is built up in this manner to express the desired amount of excess mercury from the amalgam. If desired, some means of pressure measurement such as a gauge may be included with the pressure chamber 34 so that the pressure in that chamber can be exactly reproduced in succeeding runs. Normally, however, the needle valve 44 will control the pressure obtained in the device with suflicient accuracy to make additional pressure control means unnecessary.

When the mercury has been expressed, the top cover 30 may be opened by releasing the latch provided by the eyebolt 36, and the pressure in the pressure chamber 34 relieved by a straight pull on a pin extending through the needle valve element 44. When a pull sufficient to counteract the action of the spring 52 is applied, the valve element 46 is unseated from the port 47 so that the hydraulic fluid may flow from the pressure chamber 34 into the port 41, and finally into the reservoir 24 through the port 47.

It should be noted that the arrangement of the needle valve member 44 provides an automatic pressure limiting system. When the pressure in the chamber 34 has built up to the desired value, the fluid pressure will be suflicient to unseat the conical valve seating face '46 of the needle valve member 44, thus permitting some of the hydraulic fluid to bleed 'back into the reservoir 24.

From the foregoing, it will be apparent that we have herein provided a simple but effective mechanism for controlling the expression of the excess mercury from dental amalgams. The device is inexpensive to manufacture and to maintain and provides a convenient means for producing a series of dental amalgams of uniform concen-tration.

It will be evident that various modifications can be made in the described embodiment .without departing from the principles of the present invention.

We claim as our invention:

1. A pressure applicator comprising a housing, means in said housing providing a reservoir for a hydraulic fluid, means in said housing providing a cylinder in fluid communication with said reservoir, a check valve disposed between said reservoir and said cylinder permitting flow of fluid from said reservoir to said cylinder, a piston reciprocable in said cylinder, a pressure chamber communicating with said cylinder, a check valve between said pressure chamber and said cylinder permitting flow of fluid from said cylinder to said pressure chamber zone, and a flexible membrane associated with said pressure chamber and operable in response to fluid pressure in said pressure chamber to expand and apply pressure against a stationary portion of said housing.

2. A device for expressing excess mercury from a dental amalgam comprising a housing, means in said housing providing a reservoir for a hydraulic fluid, means in said housing providing a cylinder in fluid communication with said reservoir, a check valve disposed between said reservoir and said cylinder permitting flow of fluid from said reservoir to said cylinder, 2. piston reciprocable in said cylinder, a pressure chamber communicating with said cylinder, a check valve between said pressure chamber and said cylinder permitting flow of fluid from said cylinder to said pressure chamber, a flexible membrane associated with said pressure chamber and operable in response to fluid pressure in said pressure chamber to compress an amalgam between said membrane and a stationary portion of said housing, and means communicating said pressure chamber with said reservoir to return fluid from said pressure chamber to said reservoir.

3. A device for expressing excess mercury from a dental amalgam comprising a housing, means in said housing providing a reservoir for a hydraulic fluid, means in said housing providing a cylinder in fluid communication with said reservoir, a check valve disposed between said reservoir and said cylinder permitting flow of fluid from said reservoir to said cylinder, a piston reciprocable in said cylinder, a pressure chamber communicating with said cylinder and defining a pressure Zone, a check valve between said pressure chamber and said cylinder permitting flow of fluid from said cylinder to said pressure chamber, a flexible membrane associated with said pressure chamber and operable in response to fluid pressure in said pressure chamber to compress an amalgam be- .wrrav r tween said membrane and a stationary portion of said housing, means communicating said pressure chamber with said reservoir, and adjustably positionable valve means associated with said last named means, and spring means urging said valve means to a closed position.

4. A device for expressing excess mercury from a dental amalgam comprising a housing, means in said housing defining a cylinder, a piston reciprocable in said cylinder, means in said housing providing a reservoir for a hydraulic fluid, means in said housing providing a first port connecting said reservoir with said cylinder, a first check valve in said first port arranged to permit flow from said reservoir into said cylinder, a first spring urging said check valve into its closed position in which said first check valve closes said first port, a cover hingedly secured to said housing, means for locking said cover in one position, means in said housing providing a pressure chamber, a flexible membrane actuated by differences in fluid pressure in said pressure chamber and underlying said cover, means in said housing providing a second port connecting said pressure chamber with said cylinder, a second check valve disposed in said second port and arranged to permit flow from said cylinder into said pressure chamber, and a second spring urging said second check valve into its port closing position.

5. A device for expressing excess mercury from a dental amalgam comprising a housing, means in said housing defining a cylinder, a piston reciprocable in said cylinder, means in said housing providing a reservoir for a hydraulic fluid, means in said housing providing a first port connecting said reservoir and said cylinder, a first check valve in said first port arranged to permit flow from said reservoir into said cylinder, a first spring urging said check valve into its closed position in which said first check valve closes said first port, a cover hingedly secured to said housing, means in said housing providing a pressure chamber, a flexible membrane actuated by difierences in fluid pressure in said pressure chamber and underlying said cover, means in said housing providing a second port connecting said pressure chamber with said cylinder, a second check valve disposed in said second port and arranged to permit flow from said cylinder into said pressure chamber, a second spring urging said second check valve into port closing postition, means in said housing providing a third port connecting said reservoir with said second port, a valve arranged to close said third port, and means urging said valve into a position in which said valve closes said third port.

6. A device for expressing excess mercury from a dental amalgam comprising a housing, means in said housing defining a cylinder, a piston reciprocable in said cylinder, means in said housing providing a reservoir for a hydraulic fluid, means in said housing providing a first port connecting said reservoir and said cylinder, a first check valve in said first port arranged to permit flow from said reservoir into said cylinder, a first spring urging said check valve into its closed position in which said first check valve closes said first port, a cover hingedly secured to said housing, means in said housing providing a pressure chamber, a flexible membrane actuated by differences in fluid pressure in said pressure chamber and underlying said cover, means in said housing providing a second port connecting said pressure chamber with said cylinder, a second check valve disposed in said second port and arranged to permit flow from said cylinder into said pressure chamber, a second spring urging said check valve into port closing position, means in said housing providing a third port connecting said reservoir with said second port, a needle valve arranged to close said third port, means in said housing receiving said needle valve in sliding relationship, and a spring urging said needle valve into a position in which said needle valve closes oif said third port.

7. A device for expressing excess mercury from a dental amalgam comprising a housing, means in said housing defining a cylinder, a piston reciprocable in said cylinder, means in said housing providing a reservoir for a hydraulic fluid, means in said housing providing a first port connecting said reservoir and said cylinder, a first check valve in said first port arranged to permit flow from said reservoir into said cylinder, a first spring urging said check valve into its closed position in which said first check valve closes said first port, a cover hingedly secured to said housing, means in said housing providing a pressure chamber, a flexible membrane actuated by differences in fluid pressure in said pressure chamber and underlying said cover, means in said housing providing a second port connecting said pressure chamber with said cylinder, a second check valve disposed in said second port and arranged to permit flow from said cylinder into said pressure chamber, a second spring urging said check valve into port closing position, means in said housing providing a third port connecting said reservoir with said second port, a needle valve arranged to close said third port, a hollow bushing threaded into said housing and receiving said needle valve in sliding relationship, and a spring urging said needle valve into a position in which said needle valve closes ofl said third port.

References Cited in the file of this patent UNITED STATES PATENTS 2,685,189 Watson Aug. 3, 1954