US3065543A

US3065543A - Method of and apparatus for creating dental amalgam

Info

Publication number: US3065543A
Application number: US796401A
Authority: US
Inventors: Robert C Mcshirley
Original assignee: Individual
Current assignee: Individual
Priority date: 1959-03-02
Filing date: 1959-03-02
Publication date: 1962-11-27
Anticipated expiration: 1979-11-27

Description

Nov. '27, 1962 R. c. MOSHIRLEY 3,065,543

METHOD OF AND APPARATUS FOR CREATING DENTAL AMALGAM Filed March 12 1959 2 Sheets-Sheet 1 v1-76. FIG. Z FIG. 8.

Z: 4.9 EIIIII 42 ml 28 60 FIG. [0.

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IN VE/V TOR E0195?! 6. 1 /6 SIN/71f) A TTORNE Y Nov. 27, 1962 R. c. MOSHIRLEY METHOD OF AND APPARATUS FOR CREATING DENTAL AMALGAM Filed March 2, 1959 2 Sheets-Sheet 2 FIG. 5.

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A T'TOl-PNEY Patented Nov. 27, 1962 3,065,543 METHOD F AND APPARATUS FOR CREATING DENTAL AMALGAM Robert C. McShirley, 6533 San Fernando Road, Glendale 1, Calif. Filed Mar. 2, 1959, Ser. No. 796,401 15 Claims. (Cl. 32-40) This invention relates to the manufacture or creation of dental amalgam and more particularly to an improved method therefor, as well as a device by which the said improved method may be practiced with efliciency and with assurance that the successive batches thus produced will be uniform and in conformance with a pre-determined standard. The basic specifications for dental amalgam and restorations made therefrom are contained in Federal Specifications U-A-451a promulgated by the United Bureau of Standards. The said specifications require that amalgam shall, in addition to desirable working qualities meet the following tests:

(1) Flow:. The specimen when subjected to a constant pressure of 250 kg. per sq. cm., shall not show more than four percent shortening in length of the specimen in a period of 21 hours.

(2) Setting changes: Twenty-four hours after amalgamation, the length of the specimen shall have increased between 3 and 13 microns per centimeter.

The specifications further require that each package of the alloy, i.e., the metal powder to be mixed with the mercury, shall include on the label the directions for use. Such directions will include the proportions of the alloy and mercury, the recommended equipment for mixing the amalgam, the method of mixing the alloy and mercury to produce the amalgam including the time and effort to be applied and the preferred means of expressing excess mercury from the amalgam. Each of these factors involves the judgment of the individual mixing the batch and regardless of how careful such individual may be, successive batches will not be alike nor will the batches produced by different individuals be alike although following the directions and will often result in amalgams which are below the optimum standards set forth in the specifications.

There are different theories about the physical chemistry involved in the formation of amalgams. One theory is that pressure and agitation of alloy powder and the mercury is required to cause the alloy grains to abrade the surfaces of each other and thus break down any oxidized surface thereof so that the mercury can quickly unite with the metal of the powder. Another theory is that the function of the agitation and pressure merely operates to break down the surface tension of the mercury so that it will wet and adhere to the surfaces of the metal grains. Whether either of these theories is or is not correct is not a concern of the present invention. It is concerned only with the facts of superior results attained by the method and apparatus. As will be more definitely set forth hereinafter, the invention is concerned, both as to apparatus and method, with the elimination of factors which have heretofore depended upon the personal judgment of the individual mixing the batch of amalgam.

Considering first the measuring of the proportions of alloy and mercury, if the mercury is in excess, the amalgam will have excessive shrinkage and flow. If the proportion of mercury is too low, the resultant amalgam will pack poorly in the cavity and will lack structural qualities.

Mixing may be either manual with a mortar and pestle or it may be mechanical as by one of several machines available for that purpose. Considering first mixing in a mortar and pestle, it is necessary to have a mortar with an optimum roughness condition on the surface. Secondly, the amount of pressure applied by the pestle is a very highly Variable quality depending on the individual making the batch as is also the rate of stirring by the pestle and the length of time. In hand mixing, the successive pressures of the pestle on portions of the inter mingled alloy and mercury accomplish the union of mercury and alloy little by little. The result is that some portions amalgamate in advance of other portions of the total mass and thus tend to set sooner. Generally, hand mixing takes from 30 to 40 seconds. In mechanical mixing, the speed of mixing is greatly increased by the use of a machine and the time required is very considerably reduced, not more than 5 or 6 seconds being required to produce a satisfactory amalgam (providing other conditions have been met). It is to he noted however that assuming an optimum time of 5 seconds for mechanical mixing, an increase of 1 second is an increase of 20% in the mixing time.

Considering next the removal of excess mercury from the amalgam, several methods are employed, viz., the use of adequate pressure in packing the cavity with the restoration, the use of a squeeze cloth through which the excess mercury may be forced or by the use of a press, several devices of this character being available on the market.

It is to be noted that at least the first two methods are subject to variation depending on the force employed by the individual.

Of the factors which affect dimensional changes in the amalgam and in a restoration formed therefrom, excessive shrinkage may result from inaccurate measuring of proportions, over-mixing or over-trituration, the use of excessive pressure in packing the amalgam in a cavity, or aninitially insufficient proportion of mercury to alloy in the amalgam. Over-expansion of the amalgam may result from under-mixing or under-trituration, the introduction of foreign material into the amalgam as, for example, by use of a squeeze cloth in the removal of excess mercury, the handling of the soft amalgam as in hand-mulling, under-packing, i.e., use of insufficient pressure in packing the amalgam in the cavity, the trapping of excess mercury embodied in the restoration or the failure to remove excess mercury from the amalgam either during or prior to packing the amalgam in the cavity, or the inaccurate measuring of the proportions of alloy and mercury.

In addition to the above stated desirable requirements for flow and expansion, the hardened or set amalgam should meet a compression test in which it should withstand from 40,000 to 50,000 lbs. per square inch before fracture. This test is conducted after the amalgam has been set for five days.

The compression and flow properties of the amalgam may be adversely affected by one or more of the following conditions, viz., inaccurate measuring of proportions, over-mixing, or over-trituration, excess or too little time involved in mixing the amalgam, the introduction of foreign material into the amalgam, excessive pressure in packing the cavity or the trapping of uncombined mercury within the restoration.

It is to be noted that all of these difficulties in the preparation of an amalgam that meets all standards depend almost entirely upon the judgment of the individual preparing the batch of amalgam and it is with these considerations in mind that it is the principal object of this invention to provide an improved method by which uniform batches of amalgam may be created within the shortest possible time, i.e., a very few seconds with little, if any, dependence upon the judgment of the individual preparing the batch, and with the optimum proportions of alloy and mercury to make an amalgam that will work easily and adapt itself to the cavity and which, because enemas of the shorter time required for preparation, gives the dentist valuable additional time for packing.

Another object of the invention is to provide a device whereby high quality batches of uniform dental amalgam may be created according to the foregoing method under conditions not requiring a high degree of special skill or critical accurate judgment to achieve uniformity in successive batches of the amalgam so formed.

A further object of the invention resides in the provision, a method for creating dental amalgam comprising the subjection of the amalgam components, alloy powder and mercury, to predetermined pressure in an enclosed chamber while permitting a controlled rate of escape for excess mercury in response to the applied pressure together with means whereby a predetermined continuous pressure may be applied to the mass contained in the chamber for the time required to form the amalgam.

With the foregoing objects in view, together with such additional objects and advantages which may subsequently appear, the invention resides in all such changes and modifications in the method and in the steps thereof as well as in the parts, construction, combination and arrangement of parts in the device above referred to, reference being had to the accompanying drawings which form a part of said specification and in which drawings:

FIG. 1 is a side elevational view of a somewhat diagrammatic representation of a device by which the principles of the novel method of the invention may be practiced.

FIG. 2 is a side elevation in medial section of a presently preferred form of a device for practicing the method, the device being shown loaded with the charge of mercury and powder preparatory to being operated to form the amalgam therefrom.

FIG. 3 is a top elevational View taken generally in the direction of the staggered, arrowed line 3-3 on FIG. 2.

FIG. 4 is a fragmentary medial sectional View taken on the staggered line 44 of FIG. 3, the charge receiving tube being swung to vertical position for reception of the charge of mercury and metal powder.

FIG. 5 is a transverse fragmentary sectional view taken on the line 55 of FIG. 2 and particularly showing the arrangement of the compressor actuating means, and

FIGS. 6 through are similar medial sectional views through the mixing chamber showing the progressive steps in forming a batch of amalgam and in which:

FIG. 6 shows the mixing chamber with the charges of mercury and metal powder as initially introduced therein.

FIG. 7 shows the application of the compressing piston at the beginning of the compression of the charge,

FIG. 8 shows the completion of the compression of the charge and the resultant formation of the amalgam and the means by which the predetermined amount of pressure is applied,

FIG. 9 shows the charge receiving cylinder removed from the cap which closes the end thereof, and

FIG. 10 shows the further movement of the piston element into the chamber with resultant expulsion of the formed batch.

In general, the method contemplates the placing of a quantity of mercury in a chamber, herein shown as the bottom of a closed end tube, then pouring in a predetermined amount of the metal powder into the tube on top of the mercury, then reducing the volumetric capacity of the chamber which may, for example, be done by placing a piston element in the tube and which fits the wall thereof very closely and thus serves to form the enclosed chamber. The first portion of the piston movement upon contacting the metal powder forces the powder into the mercury allowing the air entrapped in the voids between the metal grains to escape past the sides of the piston. When all of the powder has been thus moved into the mercury and all of the air has thus been expelled, further movement of the piston against the combined amalgam components will allow some of the mercury to escape through the clearance between the piston head and the wall of the tube. This clearance space is so reduced that the surface tension of the mercury will prevent it from passing therethrough, wherefore, the mercury will move through it only in response to an applied pressure, of a magnitude greater than that required to cause the mercury to fill the voids in the powder wherefor, a pressure of said magnitude will thus expel any mercury in excess of a certain proportion which has adhered to and amalgamated with the grains of the alloy powder. It is not necessary that the mercury be allowed to escape past the piston since any restricted orifice leading to the chamber, if sufficiently restricted, would serve as well. The fact that the piston allows entrapped air to escape may conveniently be used to control the extent of flow of excess mercury. It has been found by experiment that using this method, the best re sults have been obtained if the time during which the components are subjected to pressure after the expulsion of air from the mixture, is from say, 5 to 8 seconds.

Due to the fact that, as stated above, this entire action takes place within a very few seconds, the uniform application of a predetermined amount of pressure during such period has been found to result in successive batches having uniform characteristics and, by the determination of the results obtained with various metal powders, the optimum characteristics can be readily achieved by appropriate determination of the amount of pressure to be applied and the time during which the pressure is so applied. So far as is known, it has not heretofore been proposed to thus introduce the unmixed mercury and metal powder into a closed chamber and subject these components to a continuous predetermined pressure to first force the mercury into the voids between the powder grains and then unite with the grains to thus quickly achieve the amalgamation With immediate expulsion of any excess mercury. It is recognized that the prior art contains numerous proposals in the form of extraction presses which are employed for the purpose of extracting superfluous mercury after the amalgam mix has been achieved by some other process. As previously discussed, this pressure or expressing as proposed in the prior art occurs only after the mercury and alloy powder have been associated and intermixed by means other than the expressing means for a period which may be as much as a minute with resultant over-trituration and the consequent impossibility of extracting such mercury as should have been extracted to produce an amalgam of superior quality, it being noted that the present invention affords the dentist added, critically valuable time for packing the cavity.

Considering next the preferred embodiment of the device for practicing the method of the invention shown in FIGS. 2 through 10, the device comprises a frame member 1 of elongated, hollow, inverted box-like configuration; said frame being hingedly mounted at 2. to a base 3 at one end thereof, said base having a longitudinally extending slot 4 therein engaged by a head 55 of a brace rod 6, the other end of said rod being hingedly attached to the frame ii at 7 and thereby enabling the frame to be located and supported at an angle to the base 3 as illustrated in FIG. 2. When not in use, the lower end of the brace rod 6 is moved along the slot 4 towards the hinge 2 allowing the frame to rest on the base 3. The upper face of t e frame 1, at the end which is hinged to the base, is provided with spaced upstanding lug portions 8 which support a horizontal hinge pin 9 extending between them. Fixedly mounted on the hinge pin 9 is the cap element 10 of the mixing chamber assembly generally indicated at 11. The cap element pin is a cylindrical member having a bore 12 extending thereto from the end through which the hinge pin 9 extends,

said bore terminating in a slightly reduced threaded portion 13 at the opposite end of the cap member. Disposed in the bore 12 and fixedly secured to the hinge pin is a plug element 14 which confines a metal ball 15 within the bore 12, the threaded portion 1-3 being of lesser diameter than the ball and thus maintaining the ball loosely contained within the bore 12. By reason of its hinged mounting on the pin a the mixing chamber 11 may be moved from a position generally parallel to the upper surface of the frame member 1 to a vertical position for introducing the constituents of the amalgam and then back again to the said parallel position for the mixing action as will presently be explained. Means are provided for frictionally engaging the hinge pin 9 so that when the mixing chamber is moved to any desired position, it will remain in such position until it is moved to another position. This means comprises a bore 16 extending upwardly through one of the lugs S of the frame 1 and mounting therein a button 17 yieldingly pressed against the hinge pin 9 by a compression spring 18 contained within the bore and held in compressed relation therein by a plug 19 at the outer end of the bore 16.

The mixing chamber component 11 in addition to the cap member 9 and the ball 15 contained therein, further includes a tube 20 externally threaded at one end to engage the threaded portion 13 of the cap member and having at its other end a large diameter head element 21 having the outer periphery thereof knurled for grasping incident to threading it tightly into the cap element In or unscrewing it therefrom. The internal bore 22 of the tube 2% terminates at the threaded end of the tube in a slight chamfer engageable with the ball 15 to form a tight seal therebetween. At the upper end of the tube, the bore 22 communicates with a tapered or funnel-like surface 23 on the head member 21 for the ready introduction into the tube of the amalgam constituents.

Closely fitting the interior of the tube member is a piston element 24, the head 25 of which is so closely fitted to the bore 22 that mercury in the bore, when subjected to the pressure applied by the movement of the piston into the bore, can escape between the piston and the walls of the bore 22 only in response to the imposition of pressure imposed thereon by the piston of sufiicient magnitude to overcome the surface tension of the mercury. In other words, the space or clearance between the piston head 25 and the bore 22. is so small that the surface tension of the mercury will prevent it from entering that clearance space in the absence of pressure upon the mercury of a magnitude sufficient to overcome the surface tension of the mercury. In rear of the piston head portion 25, the piston element 24 has a peripheral groove 26 affording a space into which any mercury thus escaping past the piston head may collect incident to the formation of a batch of amalgam as will later be described.

The end of the frame member ll opposite the end carrying the bosses 8% is provided with an inte rally formed sleeve portion 27 the axis of which is in substantial alignment with the axis of the mixing chamber assembly 11 when that assembly is moved down into parallel relation with the top surface of the frame member. Slideably mounted in the sleeve portion 27 is a sleeve element 28 which on its lower face is provided with a set of gear teeth 29 forming a rack engageable with a gear pinion 3% carried by and secured to a shaft 31 extending transversely of the frame member 1 and journaled in bearings 3232 in the frame member. At one side, the shaft extends externally of the frame member and carries a radially extending handle 33 having a hub portion 34 secured to the shaft 31 by any appropriate means such as, for example, a set screw 35. The gear or pinion is provided with a set screw 37 located in the hub and engaging the shaft prevents relative rotation between the pinion and the shaft. The combined pinion and hub extend between the adjacent ends of the bearing portions 3232 thus securing the pinion to the shaft additionally prevents endwise movement either of the pinion or of the shaft.

The sleeve 28 at the end thereof adjacent the end of the frame member 1 is closed by a plate 38 secured therein by a snap ring 39 engaging a mating groove in the sleeve 28. Contained within the sleeve 2@ is an axially disposed heavy compression spring 40, one end of which engages the plate 38 and the other end of which engages the flange 41 of a head element 42 including a cylindrical plug portion 43 extending rearwardly on the interior of the spring the spring at being under a predetermined amount of initial compression. A snap ring 44- engaging an appropriate groove in the sleeve 2? prevents the head element or member 42 from being forced out of the sleeve 28 by the spring 40. The upper surface of the sleeve 27 is provided with a longitudinally extending slot 45 and the sleeve 28 is likewise provided with a mating slot 46. The head member 42 carries a pointer element 57 which extends through the aligned

slots

45 and 46 and the position of this point relative to a set of graduations 49 on the outer surface of the sleeve 23 indicates the amount of compression on the spring 40 incident to operation of the device as will presently be explained.

The outer end of the head member 42 is provided with a shallow socket 50 disposed in the axial line thereof and with which the head 51 of the piston rod 24 may be engaged. It will be obvious from a consideration of FIG. 2 that rotating the shaft and pinion counter-clockwise by movement of the handle 33 will cause the head element 42 to be moved toward the mixing chamber assembly and will cause the piston element 24 to be moved into the mixing chamber assembly, to some desired extent.

In using this preferred form of the device, the device is first moved to the inclined position shown in PEG. 2 and the mixing chamber assembly is then moved to a vertical position as shown in FIG. 4. The desired charges of first mercury and then metal powder are then introduced into the mixing chamber as shown in FIG. 6 and the piston element 24 is then placed in the cylinder of the mixing chamber as shown in FIG. 7 and the mixing chamber assembly is then swung about the axis of the pin 9 into alignment with the compressing means.

The handle 33 is then operated to cause the shaft 31 and pinion 3% to be rotated quickly in a counter-clockwise direction, as viewed in FIG. 2, moving the piston element 24 into the cylinder and forcing the alloy powder 52 into the mercury 53 which was first introduced into the mixing chamber. This movement of the powder into the mercury expels any air between the powder grains past the piston and when the alloy is completely pressed down into the mercury, pressure is applied by continued movement of the handle, pinion and shaft until the pointer 47 is moved to the desired point along the scale 49 with incident compression of the spring 449 as indicated in FIG. 8 and it is then held for, say, five to about eight seconds at that position. Under the load thus applied by the compression of the spring 40, any remaining excess mercury will be forced from the voids between the grains and thence between the more closely fitting wall of the bore 22 and head 25, of the piston and will collect in the groove 2s. When this has been done, the movement of the handle is reversed, freeing the outer end 25 of the piston 24. The mixing chamber assembly is then swung again into vertical position and unscrewed from the cap member 10 as shown in FIG. 9. Then by manual pressure on the piston element the batch of the completed amalgam is ejected as a cylindrical pellet from the cylinder element as indicated at 5 in FIG. 10; the batch then being ready for immediate use by the dentist.

The practice of the method above described is not necessarily limited to the specific preferred embodiment of the device illustrated in FIGS. 2 through 10. H6. 1 shows somewhat diagrammatically a very simple appare: tus for achieving the same result. In this apparatus, a

speasaa bracket 6d is attached to a vertical surface such as, for example, a wall and spaced directly above it a hingedly mounted lever arm 61 is also mounted on the same surface. Adjacent the hinged end of the lever arm, it is provided with a socket 62 engageable with a piston element 63 which is slideable in a mixing chamber tube 6d detachabiy ciosed by a cap member 65 and the cap memher is adapted to rest on the shelf or bracket 69. The outer end of the lever carries a bail element 66 placeable at a selected position thereon and on which a series of weights 6% may be carried. In general, the steps of the method are the same as heretofore described, the charges of mercury and metal powder are first introduced into the mixing chamber, the piston-element is then placed in the chamber and the combined piston and mixing chamber are then placed between the bracket and the weighted lever arm and a predetermined quantity or" the weights 68 applied to the outer end of the ar 0. wiil determine the pressure applied by the piston to the mixture. The time element would be about the same and excessive movement of the lever arm would be prevented by a stop element such as, for example, the arm 69 engaging the plate to which the lever arm is hingedly mounted, such stop being beyond the point at which com pression is completed. The resulting batch would be the same as that formed by the preferred device. The mixing chamber and piston would, of course, have the same close interfitting relation so as to allow surplus mercury to escape past the piston head only with greater diificulty under the influence of a predetermined amount of pressure within a given short time interval such as previously described than to flow into the voids in the powder.

It is believed to be obvious that by the practice of the described method, the use of the same pressure and time elements on the successive batches using any given alloy powder will create batches of amalgam having identical working qualities and structural characteristics. Once these two factors are established to the satisfaction of the dentist, he can be assured that each batch or pellet of amalgam prepared for or by him will result in a restoration having maximum life and strength.

While in the foregoing specification there has been described a preferred succession of steps in the practice of the method and preferred and other devices useful in the practice of the method, it will be understood that such disclosure relates to presently preferred embodiments of the invention. Accordingly, it will also be understood that the invention is not to be deemed to be limited to the foregoing disciosure and that the invention includes'as well all such changes and modifications in the devices for practicing the method and in the construction, combination and arrangement of the parts of such devices and in such changes and modifications in the various steps of the disclosed method as may come within the purview of the appended claims.

I claim:

1. The method of creating a batch of amalgam for use as a dental restoration material which comprises, providing a receptacle for at least the quantities of mercury and metal alloy powder from which the batch is to be formed, the receptacle having an opening in the top there of through which the mercury and alloy powder are separately introduced first by placing the desired quantity of mercury in the receptacle through said opening, then introducing the complementary quantity of alloy powder in the receptacle through said opening on top of the mercury, then forming the receptacle into an enclosed chamber by closing said opening in the receptacle by means aifording space through which air can move freely but through which rnercur j can move only in response to pressure of a magnitude sufiicient to overcome the surface tension of the mercury, then reducing the volumetric capacity of the chamber sufficiently to cause the alloy powder to be immersed in the mercury and the air in the voids between the grains of the powder to be expelled through said space, then completing the creation of the amalgam by immediately applying a pressure of said magnitude to the combined mercury and alloy powder sufficient to expel any mercury which will flow in response to the imposed pressure before the pressure hecomes static or the excess mercury, of any, becomes trapped in the voids, then releasing the pressure and finally removing the completed batch from the chamber.

2. The method of creating a batch of amalgam for use as a dental restoration material which comprises, separately introducing the quantities of mercury and metal alloy powder from which the batch is to be created into an enclosed chamber, the chamber having means for reducing the volumetric capacity thereof and means effective both to permit the escape of air and for preventing the escape of mercury therefrom except in response to a magnitude of pressure imposed thereon sufficient to overcome the surface tension of the mercury; the alloy powder initially resting on top of the mercury when introduced into the chamber, then reducing the volumetric capacity of the chamber with resultant immersion of the alloy powder in the mercury and expulsion through the escape means therefor of the air from the voids formed by the grains of the alloy powder, then applying pressure of said magnitude to the then combined mercury and alloy powder with incident expulsion through the escape means therefor or" any mercury in excess of that which remains with the alloy after the resistance to applied pressure becomes static, then releasing the applied pressure, and finally removing the completed batch from the chamber.

3. The method of creating a batch of amalgam for use as a dental restoration material which comprises, separately introducing the quantities of mercury and metal alloy powder from which the batch is to be created into an enclosed chamber, the chamber having means for reducing the volumetric capacity thereof and means effective to permit the escape of air therefrom, and to prevent the escape of mercury therefrom except in response to a magnitude of pressure imposed thereon sufiicient to overcome the surface tension of the mercury; the alloy powder initially resting on top of the mercury when introduced in the chamber, then reducing the volumetric capacity of the chamber with resultant immersion of the alloy powder in the mercury and expulsion through the escape permitting means therefor of the ai from the voids formed by the grains of he alloy powder, then applying a predetermined load on the means for reducing the volumetric capacity of the chamber with resultant imposition of pressure of said magnitude on the then combined mercury and alloy powder for a time not substantially exceeding about 8 seconds and with incident expulsion through the escape means therefor of mercury in excess of that which remains in the chamber after the completion of applied pressure, then relieving said load and said pressure, and finally removing the completed batch from the chamber.

4. The method of creating a batch of amalgam for use as a dental restoration material which comprises, providing a tubular member closed at its lower end and adapted to be placed in either an inclined or vertical position, putting not less than the quantity of mercury required for the batch in the tubular member and then putting in at least the required quantity of metal. alloy powder in the tubular member on top of the mercury, then placing a close fitting piston in the tubular member, the clearance between'the piston andithe wall of the tubular member being such that air can pass therethrough but being so close that mercury cannot pass therethrough except in response to pressure of a magni tude suflicient to overcome the surface tension of the mercury, then effecting relative movement between the piston element and the tubular member in the axial line thereof in a direction and to an extent sufficient to completely immerse the alloy powder in the niecury with incident expulsion past the piston of air from the voids formed by the grains of the alloy powder, then completing the creation of the amalgam by applying a pressure of said magnitude through a continuation of said relative movement on the then combined mercury and alloy powder with incident expulsion past the piston of any mercury not amalgamated with the alloy powder, then releasing the pressure on the amalgamated mercury and alloy powder, and finally removing the batch of amalgam from the tubular member.

5. The method of creating a batch of amalgam for use as a dental restoration material which comprises, providing a tubular member closed at its lower end and adapted to be placed in either an inclined or vertical oosition, putting not less than the quantity of mercury equired for the batch in the tubular member and then putting in at least the quantity of metal alloy powder in the tubular member on top of the mercury, then placing a close fitting piston in the tubular member, the clearance between the piston and the wall of the tubular member being such that air can pass therethrough but being so close that mercury cannot pass therethrough except in response to pressure of a magnitude sufiicient to overcome the surface tension of the mercury, then moving the piston downwardly against the alloy powder to an extent sufiicient to completely immerse the alloy powder in the mercury with incident expulsion past the piston of air from the voids formed by the grains of the alloy powder, then immediately completing the creation of the amalgam by applying a predetermined load on the piston for a time not substantially exceeding about 8 seconds with resultant imposition during said time of a pressure of said magnitude on the amalgamated mercury and alloy powder with incident expulsion past the piston of any mercury not then amalgamated with the alloy powder, then releasing the applied load and pressure, and finally removing the batch of amalgam from the tubular member.

6. The method of creating an amalgam for use a a dental restoration material comprising, confining the unmixed mercury, the alloy powder and the incidental air in an enclosed chamber having means constantly available for the escape of air and of mercury only when the mercury in said chamber is subjected to a magnitude of pressure sufiicient to overcome the surface tension of the mercury; the alloy powder initially floating on the mercury, then reducing the capacity of the chamber sufficiently to cause inter-mixing of the alloy powder and mercury and expulsion of all entrained air through said means, then applying a predetermined pressure on the mixture formed by so reducing the capacity of the chamber with resultant expulsion of excess mercury therefrom to an extent at which the mixture becomes an amalgam which is static at the applied predetermined pressure, then releasing the pressure and finally, removing the thus created amalgam from the chamber.

7. A device for creating batches of amalgam for use as a dental restoration material comprising a frame struc ture, a tube having an open end and a normally closed end, said tube serving as a receptacle for initially uncombined quantities of mercury and metal alloy powder from which a batch of amalgam is to be created, a close fitting piston element removably inserted in said open end of said tube, the clearance between said piston element and the interior of said tube being sufiiciently close to prevent the passage of the mercury component of the amalgam except in response to sufficient pressure upon the mercury to overcome the surface tension thereof, a supporting means mounted on a portion of said frame structure upon which said tube is detachably mounted with incident closure of the closed end of said tube when mounted on said supporting means, a piston element engaging means aiso mounted on said frame structure operable toward and away from said tube supporting means effective to apply and maintain a predetermined longitudinal load upon said piston element while inserted in said tube operable to cause relative movement between said tube and said piston element in a direction tending to effect intermixing of the amalgam components and then apply a pressure of said magnitude upon the then intermixed amalgam components, and means operable to effect extraction of the created amalgam from said normally closed end of said tube upon detachment thereof from said supporting means.

8. A device for creating batches of amalgam for use as a dental restoration material comprising a frame structure, a tube having an open end and a normally closed end; said tube serving as a receptacle for initially uncombined quantities of mercury and metal alloy powder from which a batch of amalgam is to be created, a close fitting piston element removably mounted in the open end of said tube, the clearance between said piston element and the interior of said tube being sufficiently close to prevent the passage through said clearance of the mercury component of the amalgam except in response to pressure to overcome the surface tension thereof on the mercury of sufficient magnitude, a supporting means mounted on a portion of said frame structure, upon which said tube is detachably mounted, a piston element engaging means operable to cause said piston element to effect intermixing of the amalgam components with incident expulsion of the air entrained in the alloy powder through said clearance and then to apply and maintain a predetermined load axially of said tube and the inserted piston element tending to apply a pressure of said magnitude on the intermixed amalgam components contained in said tube, and means operable to permit the extraction of the created amalgam from said closed end of said tube upon removal of said tube from said supporting means.

9. A device for creating batches of amalgam for use as a dental restoration material comprising a supporting member, a tube having an open upper end and screw threaded means engaging with other screw threaded means effective to close the lower end thereof, said tube serving as a receptacle for initially uncombined quantities of mercury and metal alloy powder from which a batch of amalgam is to be created, a close fitting piston element removably inserted in the open end of said tube, the clearance between said piston element and the interior of said tube being sufficiently close to prevent the passage therethrough of the mercury component of the amalgam except in response to pressure of sufficient magnitude on the mercury to overcome the surface tension thereof, means for successively intermixing and then compressing the amalgam components within said tube comprising a support for said tube mounted on said supporting member and including said screw threaded means engaging and closing said threaded end of said tube and apiston element engaging means operable toward and away from said support including a lever arm pivotally mounted on said supporting member and carrying a predetermined weight and having a portion thereof movable toward and away from said support and eifective to tend to produce relative movement between the inserted piston element and said tube with resultant initial intermixing of the amalgam components and subsequent application of a pressure of said magnitude on the intermixed amalgam components in said tube, and means operable to permit the extraction of the created amalgam from said lower end of said tube upon detachment of said lower end of said tube from said other screw threaded means.

10. A device for creating a batch of amalgam for use as a dental restoration material comprising a frame structure, a tube having an open upper end and screw threaded means closing the lower end thereof; said tube serving as a receptacle for initially uncombined quantitie of mer cury and metal alloy powder from which a batch of amalgam is to be created, a close fitting piston element removably inserted in said tube, the clearance between said piston element and the interior of said tube being suiticiently close to prevent the passage of the mercury component of the amalgam except in response to pressure of sufficient magnitude on the mercury to overcome the surface tension thereof, means for applying compressive force on the intermixed amalgam components within said tube comprising a support for said tube mounted on said frame structure and means for producing relative movement between said tube and said piston axially of sai tube including devices also carried by said frame structure comprising a manually operable lever arm and mechanism actuated thereby including a spring and a piston element engaging means indicating the extent of stress placed on said spring by movement of said lever arm and Operable to efiect relative movement between the inserted piston element and said tube through application of a selected predetermined force thereon, as indicated by said indicating means, with resultant application of a pressure of a magnitude deriving from said force on the contents of said tube, and means for detaching said tube and said screw threaded means closing the lower end thereof preparatory to effecting the removal of the created batch of amalgam from said tube.

ll. A device for creating a batch of amalgam for use as a dental restoration material comprising a tube having an open upper end and a threaded lower end, a cap element threaded on and normally closing said lower end of said tube, a supporting frame structure, means hingediy mounting said cap element on said supporting frame structure for movement about an axis which is non-parallel to the axis of said tube, a separate piston element inserted in said open end of said tube, said piston element fitting the interior of said tube sufficiently close to prevent the passage of the mercury component of the amalgam therebetween except in response to pressure on the mercury of a magnitude sufficient to overcome the surface tension of the mercury, manually operable means carried by said frame structure and reciprocable in a straight line effective to apply a predetermined force on said piston element when inserted in said tube with resultant successive intermixing of the amalgam components and imposition of a pressure of said magnitude on amalgam components contained in said tube, said hinged mounting of said cap element permitting said tube to be moved from a substantially vertical position for introduction of amalgam components therein through said open end and subsequent insertion of said piston element in. said open end to a position in alignment with the path of movement of said manually operable means, the detachment of said tube from said cap element permitting the extraction of the created batch of amalgam therefrom.

12. An amalgam creating device as claimed in claim 10 in which said manually operable means includes a cylindrical guide on said supporting frame structure, a rock shaft journaled in said supporting frame structure extending transversely to said cylindrical guide and at one side thereof, a sleeve element guided for reciprocation in said guide, a rack extending longitudinally of said sleeve element, a gear on said shaft meshing with said rack and a handle on said shaft for oscillating said shaft with resultant endwise movement of said sleeve in said guide, a piston element engaging head element mounted in said sleeve and a compression spring extending between said head element and an abutment in said sleeve.

13. An amalgam creating device as claimed in claim ll in which said frame structure includes a base adapted to rest upon a horizontal surface, a rigid frame member pivotally mounted on said base adjacent to the pivotal mounting of said cap element and a collapsible brace rod adapted, when extended, to position said frame element at an acute angle relative to said base.

14. An amalgam creating device as claimed in claim ll in which said hinged mounting for said cap element includes friction applying means effective to hold said cap element and the tube mounted therein in any angular position to which it may be moved about the axis of said hinged means.

15. An amalgam creating device as claimed in claim it in which said sleeve and said head element respectively carry a reference mark and a set of graduations effective to indicate the degree of compression applied to said spring incident to operation of said hand lever.

References Cited in the tile of this patent UNITED STATES PATENTS UNITED STATES PATENT. OFFICE CERTIFICATE OF CORRECTION Patent No. 3,065,543 November 27, 1962 Robert C. McShirley I It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 8, line 7, for "of any" read if any Signed and sealed this 7th day of May 1963.

(SEAL) Attest:

DAVID L. LADD Commissioner of Patents ERNEST W. SWIDER Attesting Officer

Claims

1. THE METHOD OF CREATING A BATCH OF AMALGAM FOR USE AS A DENTAL RESTORATION MATERIAL WHICH COMPRISES, PROVIDING A RECEPTACLE FOR AT LEAST THE QUANTITIES OF MERCURY AND METAL ALLOY POWDER FROM WHICH THE BATCH IS TO BE FORMED, THE RECEPTACLE HAVING AN OPENING IN THE TO THEREOF THROUGH WHICH THE MERCURY AND ALLOY POWDER ARE SEPARATELY INTRODUCED FIRST BY PLACING THE DESIRED QUANTITY OF MERCURY IN THE RECEPTACLE THROUGH SAID OPENING, THEN