WO2000045732A1

WO2000045732A1 - Method for preparing a mixture consisting of at least two components and mixing capsule

Info

Publication number: WO2000045732A1
Application number: PCT/CH2000/000034
Authority: WO
Inventors: Daniel Schmid
Original assignee: Alfred Schmid Ag
Priority date: 1999-02-02
Filing date: 2000-01-26
Publication date: 2000-08-10
Also published as: AU3029400A; EP1150619A1

Abstract

The invention relates to a mixing capsule (11) for separately storing and mixing two components (37, 41) and for dispensing a dental material mixed therein. A closed connecting element (29) located in a partition wall (25) between a first chamber (31) and a second chamber (33) is perforated with an activating pin (17) and the liquid component (37) is then conveyed from the first chamber (31) through the connection element (29) into the mixing chamber (33') containing the other component (41). The mixing chamber (33') can be enlarged to match the volume of the liquid component so that the initial pressure can be maintained or, preferably, a lower pressure level can be regulated in the mixing chamber (33'). The first chamber (31) is provided between a cylinder (13) and a perfectly fitting hollow piston (19) guided therein while the second chamber (33) is located inside the hollow piston (19). The volume of the first chamber (31) is negligible in relation to the length of the capsule (11) after both components (37, 41) have been combined and mixed. A greater amount of dental material can be produced in the capsule (11) while its dimensions remain the same, wherein said material is not subjected to an overpressure before it is squeezed out.

Description

Process for producing a mixture of at least two components and a mixing capsule

The present invention relates to a method and a mixing capsule for producing a mixture of at least two components, in particular a dental mass for the dental field, according to the preamble of claims 1, 6 and 14.

A large number of mixing capsules for dental wet are known in the prior art, which are used for storing and mixing the starting components forming the dental composition. The mixing capsules have a length of approx. 32 mm according to a standard that has developed in the past. This length corresponds to the clear distance between the two holding forks of the mixing apparatus used in practice, of which one holds the capsule on both sides of the ejection cannula, the other holds it at the rear, usually rounded end of an ejection piston. For pressing out the capsule, a tool for pressing the ejection piston forward can be hung in a groove running around the capsule.

The fact that the mixing capsules are limited in their longitudinal extent also limits the amount of dental mass that can be accommodated in the capsules. This becomes disadvantageous in practice in such a way that while the ^'Dental mass contained in the capsules is sufficient for securing a dental crown or a two-tier dental bridge, but not for the fixing of three or more membered tooth bridges.

From DE 43 15 920 a mixing capsule with a mixing chamber is known, in which a hollow plunger is guided in a sliding part in a container part, in which a hollow plunger in turn Stamp is arranged to be movable. The container part with the mixing chamber has a discharge opening in the end wall which closes one side of the mixing chamber. The other side of the mixing chamber is closed off by the hollow piston with a stamp.

In the initial state, the mixing chamber is separated from the interior of the hollow piston by a film glued onto an annular projection of the hollow piston. The film has a predetermined breaking point, the holding strength of which is lower than the strength of the adhesive connection, so that when the capsule is activated by pressing in the stamp, the film tears at the predetermined breaking point and the liquid can flow into the mixing chamber. By reducing the interior of the hollow piston with the plunger, the liquid is pressed into the mixing chamber. The stamp has the same length as the hollow piston, so that when the end position in the hollow piston is reached, the stamp can no longer be displaced without also displacing the hollow piston. So that the hollow piston is not inadvertently pushed into the mixing chamber when the liquid is pressed into the mixing chamber by pressure on the plunger, the hollow piston has a recess into which a manually removable, U-shaped locking member engages, and thus the hollow piston opposite the mixing chamber forming container part locked.

After mixing the liquid component with the powdery component present in the mixing chamber by means of a shaker mixer, pressure is exerted on the plunger and the hollow piston to dispense the dental mass obtained. A sliding movement takes place between the hollow piston with the plunger on the one hand and the mixing chamber on the other. DE 39 20 537 C2 describes a multi-component mixing capsule with a container part, which forms a cylindrical mixing chamber. The mixing chamber is closed in the axial direction on the one hand by an end wall having an ejection opening and on the other hand by a hollow piston. The hollow piston is closed to the mixing chamber with a perforated wall. In the interior of the hollow piston, a stamp can be moved in translation. The hollow piston and the cylindrical mixing chamber therefore form two cup-like containers pushed into one another for two components to be mixed, the cup edges on the one hand and the perforated wall or end wall on the other hand of both containers being aligned.

The hollow piston is in the basic position with its cup edge beyond the cup edge of the container part. At the rim of the cup, the hollow piston has a projection, via which forces acting on the hollow piston are dissipated onto the container part. This projection is used so that when the capsule is activated, the liquid component in the hollow piston can be pressed with the plunger from the hollow piston through the perforated wall into the mixing chamber in the container part without the hollow piston shifting relative to the container part. The liquid component is in a film container in the cavity of the hollow piston. By pressing the stamp, the liquid is pressurized until the film container breaks open and the liquid passes through the hole in the hole wall into the mixing chamber. When the stamp is in contact with the perforated wall, the liquid component is completely brought together with the powdery component present in the mixing chamber and the two components can now be mixed by shaking. Then, in order to express the dental mass, the stamp is moved together with the hollow piston in the container part in such a way that the mixing chamber becomes smaller. The protrusion on the cup rim of the hollow piston is folded over or torn off. The mixture is then expelled through the ejection opening. A disadvantage of the mixing capsules described is, inter alia, that they contain a relatively small amount of dental material in a relatively large total volume.

The US Pat. No. 5,026,283 proposes a mixing capsule in which a mixing chamber for receiving a powdery component is formed by a cylindrical hollow piston and a plunger which can be displaced therein. An activation pin is arranged on the stamp. The cylindrical hollow piston has an end face with an opening which is closed on the outside by a film burstable by means of excess pressure. A holding part with an ejection cannula is screwed onto the hollow piston. Between this holding part and the hollow piston, respectively. a liquid package is placed on the burstable film, which has a skin made of a stable, plastic-reinforced aluminum film which is connected to the burstable film in a liquid-tight manner at the edges.

In order to activate the capsule, ie to bring the liquid and the powder together, the holding part and the hollow piston are first screwed together until the aluminum foil bursts at a certain excess pressure and the liquid component from the liquid package can flow through the opening into the mixing chamber. By screwing the holding part together with the hollow piston, the entire liquid is pressed into the mixing chamber, a corresponding excess pressure being established in the mixing chamber. The components are then mixed in a known shaker. After this Mixing, the stamp is pressed with a tool in the direction of the spray cannula. The activation pin perforates the plastic-reinforced film so that the mixture can flow into the ejection cannula. This is then opened so that the finished mixture with the plunger can be pressed out of the mixing chamber through the ejection cannula and introduced at the intended location, for example as a tooth filling or the like.

An advantage of this capsule is that it can be used to produce a larger amount of dental mass with practically identical dimensions to the capsules discussed above, since the chamber for the liquid hardly influences the length specified by the shaking apparatus. On the other hand, it is disadvantageous that the mixing capsule is relatively complex to manufacture and complicated to use. This is due to the fact that the film separating the liquid from the powder has to be destroyed by means of excess pressure. In order to be able to generate the necessary pressure, the holding part and the hollow piston must be provided with a screw thread. This in turn has the disadvantage that it is very troublesome for a dentist assistant to have to screw the two parts together under time pressure. Another disadvantage is that when the opening of the mixing capsule is opened, the dental compound under relatively high pressure can spray out and thereby contaminate the hands of the dentist using the mixing capsule and the device. Part of the dental mass is of course lost in the process. A further disadvantage is that when the film separating the liquid from the powdery component bursts, film snippets can get into the dental mass by overpressure. In the capsule described, the stamp with the activation pin is only used to pierce the plastic-reinforced film. If one wanted to pierce the film with the activation pin beforehand, the excess pressure generated inevitably when the stamp was moved would get powder into the liquid package. There is also the danger that when the stamp is moved with the activation pin, not only the burstable film but also the plastic-reinforced film would be accidentally pierced.

A common feature of the known mixing capsules is that the one component of the dental material, usually a liquid, is pressed into the mixing chamber by means of excess pressure, in which the other component, usually a powder, is present, and the mixing chamber is thus pressurized. This has the disadvantage that more air than normal is dissolved in the dental mass that solidifies later. After the dental mass is pressed out of the mixing capsule, bubbles can form in the mass and negatively affect the quality of the tooth filling.

It is an object of the invention to provide a method and a mixing capsule with which the disadvantages mentioned at the outset can be avoided as far as possible and according to which the greatest possible volume of filling quantity can be used for the given standard dimensions for mixing capsules for dental material. Furthermore, a method and a mixing capsule are to be proposed with which the annoying blistering can be avoided as far as possible. Another goal is to reduce the risk that foil snippets can get into the dental material. According to the invention, the object is achieved in that, in a method of the type mentioned at the outset, the second chamber is enlarged by at least the volume of liquid to form a mixing chamber before the components are mixed. This has the advantage that the components can be mixed in the chamber at normal or negative pressure. This largely prevents the formation of bubbles in the hardening composition, in particular if the mixing chamber has a larger volume than the individual chambers in the starting position, ie if there is a negative pressure in the mixing chamber. If the mass is mixed under negative pressure, the mass will even degas during mixing. Another advantage of the method is that when the mixing capsule is opened, the dental compound cannot be sprayed out due to the normal or negative pressure prevailing in the mixing chamber.

The second component expediently initially only partially fills the second chamber of the mixing capsule, so that a certain volume of gas remains at a certain outlet pressure in the second chamber, the second chamber being enlarged to a mixing chamber at least to such an extent before the components are mixed that the initially outlet pressure prevailing in the second chamber is essentially restored. In order to achieve thorough mixing, the mixing chamber may only be filled up to a maximum of 40% of its volume.

Before the components are mixed, the second chamber is advantageously enlarged by more than the volume of liquid to form a mixing chamber, so that a negative pressure, ie a lower pressure than the initial pressure, is generated in the second chamber. The chambers are therefore expedient tightly formed so that no air can enter when the volume is increased.

The liquid component is expediently drawn from the first chamber into the second chamber by the negative pressure generated. This is done by holding the mixing capsule vertically with the outlet cannula upwards when the second chamber is expanded. In this way, the first chamber can be completely emptied, and the mixing ratios can be maintained exactly.

According to an advantageous process variant, the two chambers can be connected by a connection, e.g. a connection channel, communicate with one another, the connection initially being closed by a film which is pierced by an activation pin when the capsule is activated.

A mixing capsule according to the invention of the type mentioned at the outset is characterized in that in the starting position of the mixing capsule, i.e. if the components are separate, the chambers at least one of the liquid volume to be absorbed or. have a chamber volume corresponding to the amount of powder to be taken up, so that after the film has been destroyed, the second chamber can be expanded by moving the plunger to the mixing chamber, corresponding to a mixing position, the volume of the mixing chamber corresponding at least approximately to the volume of the second chamber increased by the liquid volume in the starting position . The advantages already described by the method described above are achieved.

It is advantageous to extend through the outlet cannula and to be displaceable in the longitudinal direction of the mixing capsule Activation pin provided for pushing back the stamp. This pen can also be used to open or Cut the film. By inserting a pin through the outlet cannula, the second chamber can be easily expanded to the desired mixing chamber volume. The pin advantageously has a defined length so that it can be inserted into the cannula up to a stop, for example a head. However, it is also conceivable to pull back the stamp, for example by means of a pull handle which is molded onto or can be attached to the stamp, instead of pushing back by means of a pin.

To lock the plunger in the mixed position, the plunger and the hollow piston are advantageously designed such that the plunger and the hollow piston are interlocked in the mixed position. This will e.g. achieved by a notch on the inner wall of the hollow piston and knobs or ribs on the outside of the plunger, which engage as soon as the plunger has reached the rearmost position and the mixing chamber has the mixing volume.

Advantageously, the hollow piston and the plunger together form a preferably gas-tight frictional connection, so that the plunger remains in the mixed position once assumed without external force. In principle, however, annular beads, in and out or a locking member can be provided for locking the stamp in the mixed position. A lock can e.g. can also be achieved by a high frictional resistance of the activation pin in the ejection cannula.

According to a preferred embodiment, the pin for closing the outlet cannula also serves for opening or. Cut through the film, meaning that the film does not go through Overpressure is burst. This has the great advantage that the risk that film residues can get into the mixture is greatly reduced.

The film is expediently arranged on that side of the hollow piston end wall from which side the pin for guiding the film through is guided. This has the advantage that fraying or tearing out of the film at the point where the activation pin penetrates the film can be largely avoided, since the film rests on the hollow piston end wall.

The plunger advantageously has a central recess on the mixing chamber side for receiving and centering the shaft tip of the pin. This ensures that the pin cannot slip when the stamp is pushed back.

In principle, the pin for piercing the film can also be provided on the stamp on the mixing chamber side, so that the film can be pierced by moving the stamp. In this case the stamp preferably protrudes from the hollow piston by so much that the film can be destroyed if the stamp reaches the stop in the hollow piston, i.e. flush with the rear edge.

The activation pin for opening the connection between the chambers can advantageously be actuated independently of the jacket, hollow piston and punch. In this case, the connection can be opened without having to change the pressure conditions.

The ejection cannula is advantageously closed with the activation pin, which is longer than the distance from the tip of the Ejection cannula from the connection of the chambers in the starting position. This pin can therefore be used to close the ejection cannula and to open the connection. However, it is also conceivable that the activation pin is guided through the stamp from behind.

According to a further aspect of the invention, which can be implemented with a mixing capsule regardless of the expansion of the mixing chamber, an activation pin which is displaceable in the longitudinal direction of the mixing capsule is provided for opening the partition wall closing the connection between the two chambers. This has the advantage that the partition wall, which is generally designed as a film, can be designed to be stronger than the films, which must be destroyed by applying excess pressure. A pin also has the advantage that when the film is destroyed, practically no residues are created that can get into the dental material. In addition, the film is advantageously provided on that side of the hollow piston end wall from which side the pin for cutting the film is guided.

The hollow piston in the jacket and the plunger in the hollow piston are advantageously essentially liquid and gas tight. For this purpose, a sealing ring, O-ring, for example, can be provided on the stamp. In principle, the required tightness can be achieved by observing the corresponding manufacturing tolerances.

Advantageously, the length of the hollow piston essentially corresponds to the standard dimensions for dental compound mixing capsules less the thickness of the front wall of the jacket. Such a mixing capsule is characterized by a maximum Filling volume, so that the dental mass is also sufficient for filling two or multi-unit dental bridges. Advantageously, the length and the shape of the hollow piston together with the part of the plunger projecting in the mixing position over the rear part of the hollow piston and the cylinder in the activated state of the capsule, ie when the chamber 31 is compressed, essentially corresponds to the standard dimensions of known dental compound mixing capsules. As a result, the conventional mixing devices and extracting tools can be used with the mixing capsule according to the invention.

Exemplary embodiments of the invention are described below with reference to the figures. It shows:

Fig. 1 shows a mixing capsule according to the invention in the starting position, i.e. before activation,

2 the capsule according to FIG. 1 activated and with an enlarged mixing chamber,

3 shows the mixing capsule according to FIGS. 1 and 2 after the dental compound has been pressed out,

4 a mixing capsule according to FIG. 2 with a handle,

Fig. 5 is a mixing capsule with a short stamp.

The mixing capsule 11 shown in FIGS. 1 to 3 consists of a cylinder or jacket 13, a hollow piston 19 which is displaceable in the longitudinal axis in the jacket 13 and a plunger 21 which is also displaceable in the longitudinal axis in the hollow piston 19. The jacket 13 has an end wall 23 which is molded onto an ejection cannula 15 having an opening 27. The hollow piston 19 has an end wall 25 with an opening 29 which is flush with the first opening 27. The space between the end walls 23, 25 defines a first chamber 31 for receiving a liquid 37. The space between the end wall 25 and the plunger 19 defines a second chamber 33 for receiving a second, preferably powdery component 41.

In the initial state of the capsule, the connection of the chambers 31 and 33 is closed with a partition or film 35 applied to the end wall 25 (FIG. 1). The liquid component 37 is enclosed in the chamber 31 between the cylinder 13 and the hollow piston 19. The second, powdery component 41 is stored in the chamber 33 in the interior of the hollow piston 19. When mixed, the liquid and powder components 37, 41 react together to form a dental compound 39 that hardens within a short time.

The chambers 31, 33 advantageously enclose a minimal space suitable for filling in the components 37, 41. For reasons of filling technology, in particular in the case of powdery components, the chambers 31, 33 can usually not be completely filled with the components 37 or. 41 are filled, so that usually an air space 43 remains in the chamber 31 and an air space 45 in the chamber 33. The air spaces 43, 45 are expediently kept as small as possible.

With the activation pin 17, the film 35 is pierced to activate the capsule. For this purpose, the pin shaft 17 ′ has a pointed or sharp-edged end 49, so that the film 35 is broken when the pin 17 is pushed through, but nevertheless no part is cut off from the film 35. The opening 29 in the end wall 25 is expediently wider than the diameter of the pin shaft 17 'so that the liquid 37 can pass between the pin and the opening edge can without having to remove the activation pin 17 again.

In the non-activated state, the outer end or the head 51 of the pin 17 protrudes beyond the tip of the ejection cannula 15, so that a region of the pin shaft lies outside the ejection cannula 15, while the inner end of the pin shaft 17 'is at a distance from the point 49 to the slide 35. So that the pin 17 does not accidentally destroy the film 35, securing means, not shown in the form of spacers, e.g. a protective tube which can be placed around the ejection cannula and which keep the head of the pin at a distance from the hollow piston.

FIG. 2 shows the capsule in the activated state, in which the volume of the chamber 31 is practically zero and the entire liquid component is displaced into the mixing chamber 33. The film 35 is penetrated by the activation pin, so that the two chambers 31, 33 can communicate with one another.

The chamber 33 is expanded in volume to the mixing chamber 33 '. The extension is determined by the length of the pin shaft 17 'minus the length of the ejection cannula 15 and the thickness of the end walls 23, 25. The pen tip 49 engages in a recess 53 in the stamp 21, so that the pen shaft 17 'can transmit a relatively high pressure to the stamp 21 without having to fear that the tip 49 will move laterally.

A vacuum is present in the expanded mixing chamber 33 if the expansion is greater than the volume fed into the chamber 33. In this state (Fig. 2) Capsule shaken in a special mixer. The distance between the holding forks of the mixer determines the maximum length of the capsule housing. This length is optimally used thanks to the minimal space requirement for the chamber 31 and the stamp 21 originally containing the liquid component.

So that the negative pressure is maintained in the mixing chamber 33 and this does not automatically pull the chamber 33 together, the plunger 21 is locked in the rearmost position. This is achieved very simply by a high resistance of the sross and activation pin 17 in the ejection cannula 15. Alternatively, for example, an increase in the recess 21 in the punch 21 can be provided on the hollow piston 19.

So that the casing 13 remains fixed on the hollow piston in the activated state of the capsule, a bead 57 is arranged on the hollow piston 19 which engages in a recess 59 in the wall of the cylinder 13 as soon as the casing 13 and the hollow piston 19 have collided completely. This prevents the chamber 31 from opening again when the mixing capsule is pressed out and the dental mass 39 from being able to pour into it.

FIG. 4 shows a further embodiment of a mixing capsule 11 'in the activated position. In contrast to the capsule 11 shown in FIGS. 1 to 3, the stamp 21 in the capsule 11 'is provided with a hook 61 which can be attached and removed again. The handle 61 can be used several times. The stamp is withdrawn with the handle as soon as the film 35 is pierced. Then the hollow piston 19 and the cylinder 13 are collided. The handle 61 is removed for mixing. After that, as before, with a Special tool of the stamp are guided against the openings 29, 27 going into the ejection cannula 15 and the mass 39 is expressed.

Figure 5 shows a mixing capsule with a short stamp 21 '. The stamp length of the stamp 21 in FIGS. 1 to 4 corresponds to the stamp length of conventional stamps which contain the liquid component. Due to the minimized punch length, the maximum volume of the mixing chamber 33 * is maximized. Compared to the volume of the mixing chamber 33 'in FIG. 2 or 4, the volume of the mixing chamber 33 * in FIG. 5 is increased by approximately 28%. The stamp 21 'is shown in FIG. 5 in a position which it can assume shortly before the capsule is activated after the stamp has been withdrawn. Pulling the plunger 21 'back into this position creates a negative pressure in the mixing chamber 33 *. So that this negative pressure does not pull the stamp forward again and thereby reduces the mixing chamber 33 *, a rib 65 or knobs is formed at the rear around the stamp. On the other hand, a circumferential depression or notch 67 is formed on the hollow cylinder 19. In the position shown, the rib 65 engages in the notch 67 so that the punch 21 'is held in this position.

The mixing capsule is used as follows: First, the protective device, which is not shown in more detail and which fixes the activation pin 17, is removed. The mixing capsule is supported vertically with the ejection cannula upwards on a base, and then the activation pin is pushed into the cannula. Alternatively, the jacket 13 and the hollow piston 19 can be pushed together. The activation pin penetrates the film separating the two chambers, so that the liquid can flow from the first chamber into the second. Basically, the liquid in the first chamber also be present as a liquid package, the pin piercing the package on two opposite sides. If the activation pin is pressed further into the cannula, it comes into abutment against the plunger 21 and pushes it back in the hollow piston 19, so that the volume of the chamber 33 is expanded to a volume 33 ′ suitable for mixing the components. The expansion of the second chamber corresponds at least to the volume of liquid and is preferably greater than the volume of the chamber 31. Alternatively, the chamber 33 can also be expanded to the mixing chamber 33 ′ or 33 * before the film 35 is pierced by pulling back the plunger. After the two components have been brought together, the capsule is placed in a shaker and shaken for a certain time.

After mixing, the activation pin 17 is removed from the capsule 11 and the mixed dental mass 39 is pressed out through the ejection cannula 15 and e.g. used to fill voids. For this purpose, the punch 21 is pressed against the end walls 23, 25 using a tool which is hooked into the groove 55 at the rear edge of the hollow piston 19.

The plunger 21 can, as shown in FIG. 5, be made very short because, in contrast to known mixing capsules, the hollow piston in the preferred embodiment does not serve to store the liquid component but rather as a mixing chamber. As a result, the stroke in the mixing chamber 33 'and also the amount of the dental material can be at a maximum. In the case of a shortened punch and thereby increased lifting height, the punch 21 "can be pushed into the hollow piston 19 by hand and with the aid of the negative pressure, at most when using a conventional ejection tool. Thereafter, if necessary using an additional punch extension, for example accordingly trained head 51 of the pin 17, even with conventional tools, the stamp advanced enough to squeeze out the entire contents of the capsule 11 ".

In summary, it can be said that in the case of a mixing capsule 11, 11 'for separate storage in two chambers 31, 33 and for mixing two components 37, 41 which are reactive with one another and for dispensing the dental compound 39 mixed therein, a connection 29 in a partition wall 25 between the is broken through both chambers 31, 33 with an activation pin 17 and the liquid component 37 is conveyed out of the first chamber 31 through the connection 29 into the mixing chamber 33 with the other component 41. The mixing chamber 33 is enlarged by a larger volume than the volume conveyed into it, so that the mixing chamber 33 with both components 37, 41 has a lower pressure level than the surroundings. The first chamber 31 is arranged between a cylinder 13 and a hollow piston 19 guided with a precise fit therein, the mixing chamber 33 in the interior of the hollow piston 19. The volume of the first chamber 33 is negligible with regard to the length of the capsule 11, 11 'after the two components 37, 41 have been brought together and mixed. Therefore, a larger amount of dental mass 39 can be produced in this capsule 11, 11 'with standard dimensions than in others and the dental mass 39 is not under overpressure before it is pressed out. The usable amount of dental mass is therefore increased with the same dimensions of the capsule 11, 11 '.

Claims

claims

1. A process for producing a mixture of at least two components, in particular a dental mass for the dental field, by mixing a first liquid component (37) with at least one second component (41) within a mixing capsule (11, 11 '), the first being the first Component (37) in a first chamber (31) and the second component (41) in a second chamber (33) of a mixing capsule (11, 11 '), in which method a connection (29) between the two chambers (31, 33) and the liquid component (37) is pressed by reducing the volume of the first chamber (31) through the connection (29) into the second chamber (33), characterized in that the second chamber (33) before mixing of the components (37, 41) is increased by at least the liquid volume to a mixing chamber (33 ').

2. The method according to claim 1, characterized in that initially the second component (41) only partially fills the second chamber (33) of the mixing capsule (11, 11 '), so that in the second chamber (33) a certain gas volume ^' (45 ) remains at a certain outlet pressure, the second chamber (33) being enlarged to a mixing chamber (33 ') at least to the extent that the outlet pressure initially prevailing in the second chamber (33) before the components (37, 41) are mixed is restored.

3. The method according to claim 1 or 2, characterized in that the second chamber (33) before the mixing of the components (37, 41) by more than the liquid volume a mixing chamber (33 ') is enlarged so that a negative pressure, ie a lower pressure than the outlet pressure, is generated in the mixing chamber (33').

Method according to one of claims 1 to 3, characterized in that the liquid component (37) is sucked from the first chamber (31) into the second chamber (33) by the negative pressure prevailing in the mixing chamber (33 ').

Method according to one of claims 1 to 4, characterized in that the two chambers (31, 33) can communicate with one another by means of a connection (29), the connection initially being closed by a film (35), and in that the film (35 ) is pierced by an activation pin (17) and thus the connection (29) between the two chambers (31, 33) is released.

Mixing capsule (11, 11 ') for storing and mixing at least two components, in particular for producing a dental mass for the dental field, with a first chamber (31) serving to receive a first, liquid component (37), which is separated by a jacket ( 13) or cylinder with an injection cannula (15) arranged on the front and a hollow piston (19) arranged in the jacket (13) and having a hollow piston end wall (25), and a second chamber (33) serving to receive a second component (41) which is formed by the hollow piston end wall (25) of the hollow piston (19) and a plunger (21) which is also displaceably mounted in the hollow piston (19), which second chamber (33) also the mixing chamber (33) with an opening (29) connecting the chambers (31, 33) in the hollow piston end wall (25), which opening (29) is closed with a film (35) or skin in the starting position of the capsule (11, 11 ') characterized in that in the starting position of the mixing capsule, ie when the components (37, 41) are present separately, the chambers (31) and (33) have a volume that corresponds to the volume of liquid. have a chamber volume corresponding to the quantity of powder to be taken up, so that after the film (35) has been cut through, the second chamber (33) can be expanded by moving the plunger (21) onto a mixing chamber (33 ') corresponding to a mixing position, the volume of the mixing chamber ( 33 ') corresponds at least approximately to the volume of the second chamber (33) in the starting position increased by the liquid volume.

Mixing capsule according to claim 6, characterized in that a pin (17) which extends through the outlet cannula and is displaceable in the longitudinal direction of the mixing capsule is provided for pushing back the plunger (21).

Mixing capsule according to claim 6, characterized in that a pull handle (61) is provided or can be attached to the stamp (21) for withdrawing the stamp (21) into the mixing position.

Mixing capsule according to claim 6, characterized in that for locking the plunger in the mixed position, the plunger (21) and the hollow piston (19) are designed such that the plunger (21) and the hollow piston (19) are interlocked in the mixed position.

10. Mixing capsule according to one of claims 6 to 9, characterized in that the hollow piston (19) and the plunger (21) together form a frictional connection, so that the plunger (21) remains in the mixing position without external force.

11. Mixing capsule according to one of claims 6 to 9, characterized in that for locking the plunger (21) in the mixing position on the inner wall of the hollow piston (19) and on the plunger (21) interacting beads and indentations are provided.

12. Mixing capsule according to claim 7, characterized in that the pin (17) for closing the outlet cannula (15) also the opening or. Cutting the film (35) is used.

13. Mixing capsule according to one of claims 6 to 12, characterized in that the film (35) is arranged on that side of the hollow piston end wall (25) from which side the pin (15) is guided to pierce the film (35).

14. Mixing capsule according to one of claims 6 to 13, characterized in that the plunger on the mixing chamber side has a central recess (53) for receiving and centering the shaft tip of the pin (17).

15. Mixing capsule (11, 11 ') for storing and mixing at least two components, in particular for producing a dental mass for the dental field, with a first chamber (31) serving to receive a first, liquid component (37), which is separated by a Jacket (13) or cylinder with one arranged on the front Ejection cannula (15) and a hollow piston (19), which is displaceably arranged in the jacket (13) and has a hollow piston end wall (25), and a second chamber (33) serving to receive a second component (41), which chamber is passed through the hollow piston end wall (25 ) of the hollow piston (19) and a plunger (21) which is also displaceably mounted in the hollow piston (19), which second chamber (33) is also the mixing chamber (33), with an opening (29) connecting the chambers (31, 33) ) in the hollow piston end wall (25), which opening (29) is closed with a film (35) or skin in the starting position of the capsule (11, 11 '), characterized in that the two chambers (31) and (33 ) separating film (35) a pin (17) displaceable in the longitudinal direction of the mixing capsule is provided.

16. Mixing capsule according to claim 15, characterized in that the pin (17) for piercing the film (35) also serves to close the outlet cannula (15) and has a corresponding length.

17. Mixing capsule according to claim 15 or 16, characterized in that the pin (17) has a length such that the stamp (21) can be displaced into the mixing position by this.

18. Mixing capsule (11, 11 ') according to one of claims 15 to 17, characterized in that in the starting position of the mixing capsule, ie when the components (37, 41) are present separately, the chambers (31) and (33) one volume of liquid to be taken up, respectively. the have the appropriate volume of powder to be taken up, that the chamber (31) after cutting through the film (35) can be expanded by moving the stamp (21) onto a mixing chamber (33 ') according to a mixing position, the volume of the mixing chamber (33') at least corresponds approximately to the volume of the second chamber (33) in the starting position increased by the liquid volume.

19. Mixing capsule (11, 11 ') according to one of claims 15 to 18, characterized in that the hollow piston (19) in the jacket (13) and the plunger (21) in the hollow piston (19) are guided essentially liquid and gas tight .

20. Mixing capsule (11, 11 ') according to one of claims 15 to 19, characterized in that the length of the hollow piston essentially corresponds to the standard dimension for dental compound mixing capsules.

21. Mixing capsule (11, 11 ') according to one of claims 15 to 20, characterized in that the length of the hollow piston together with the part of the plunger projecting over the rear part of the hollow piston in the mixing position essentially the standard dimension of known dental compound mixing capsules corresponds.

22. Use of a mixing capsule according to the preamble of claim 6 in such a way that the second chamber (33) is enlarged into a mixing chamber (33 ') before the components (37, 41) are mixed.