Patent Description:
Cartridges suitable for the mixing and dispensing of material are particularly interesting for dental restoration applications, in order to mix a multi-component dental restoration material and dispense it on a tooth of a subject. A dental restoration material classically comprises a powder component and a liquid component, which are mixed to form a dental cement. Especially, cartridges have been developed for dental restoration applications, in which certain amounts of a powder component and of a liquid component are previously weighed and accommodated in isolated chambers so as to prevent any accidental mixing of the two components. In such cartridges, the components can be released from the isolated chambers at a desired time and mechanically mixed with each other to form a dental cement that is dispensed from the cartridge.

For dispensing the material contained in the cartridge, a dispensing device is generally required. Especially, in the dental field, several dispensing guns have been developed for dispensing a dental material contained in a cartridge.

For example, <CIT> discloses a dispensing gun having a cartridge holder for receiving a cartridge. In <CIT>, there is no means for locking the cartridge to the dispensing gun so that the dispensing gun of <CIT> cannot guarantee a safely handling when the practitioner operates.

Other dispensing devices, such as that disclosed in <CIT>, require the practitioner to operate the lever of the device several times for delivering the material contained in the cartridge. These dispensing devices are not ergonomic and often are not able to dispense the whole amount of the material.

<CIT> discloses a dispensing gun for a cartridge ("compute <NUM>") comprising a frame having a handle and a lever comprising at least two teeth and a piston comprising at least two notches.

It is these drawbacks that the invention is intended more particularly to remedy by proposing a dispensing gun for dispensing a material from a cartridge which is easy to operate while making the dispensing of the material more secure, in particular by limiting the risks of loss of a part of the material. The dispensing gun also advantageously allows the extrusion of the entire material contained inside the cartridge, in one single stroke of the piston of the dispensing gun.

For this purpose, a subject of the invention is a dispensing gun as defined in claim <NUM>.

In a conventional manner, within the frame of the invention, the terms "proximal" and "distal" refer to a position of portions of the dispensing gun with reference to an operator (e.g. a dentist), i.e. the term "proximal" refers to a position closer to the operator of the cartridge, while the term "distal" refers to a position that is more distant from the operator.

Another object of the invention refers to a system as defined in claim <NUM>, the system comprising the dispenser as defined in claim <NUM> and a cartridge having a base section with two opposite locking wings.

Another subject of the disclosure is a method of dispensing a material by a system comprising a cartridge having a base section with at least two opposite locking wings and a dispensing gun according to the present invention, in which the injection gate comprises a distal plate with an aperture whose shape corresponds to the shape of the base section of the cartridge, said method comprising steps in which:.

Another subject of the disclosure is a method of dispensing a material comprised in a cartridge by means of the dispensing gun as described above, comprising the following steps:.

Features and advantages of the invention will become apparent from the following description of several embodiments of a dispensing gun according to the invention, this description being given merely by way of example and with reference to the appended drawings in which:.

<FIG> shows an exploded view of a dispensing gun <NUM> according to a first embodiment of the invention, suitable both for locking the base section of a cartridge and then, for dispensing a material contained in the cartridge.

As visible in <FIG>, the dispensing gun <NUM> comprises a frame <NUM> with a handle <NUM> and an injection gate <NUM> located at the distal end of the frame <NUM>. In this first embodiment, the dispensing gun <NUM> includes a lever <NUM>, a piston <NUM>, a washer <NUM>, a spring <NUM>, a retaining ring <NUM>, a spring plunger <NUM> and a pivot pin <NUM>.

As seen in <FIG>, the frame <NUM> has the shape of a gun and has a handle <NUM> allowing the practitioner to handle the dispensing gun with one hand, either the left hand or the right hand. In the first embodiment of the dispensing device presented in <FIG>, the palm of the practitioner's hand has to be placed on the handle <NUM> and the fingers of the practitioner's hand have to be placed on the lever <NUM>.

The lever <NUM> is attached to the frame <NUM> thanks to a pivot pin <NUM> allowing to connect the lever <NUM> to the frame <NUM> while keeping the ability for the lever <NUM> to move in a hemi-circular movement about the axis of the pivot pin <NUM>. The pivot pin may be surrounded by a protecting sleeve <NUM> in order to avoid friction between the pivot pin <NUM> and the lever <NUM>, especially when the pivot pin <NUM> and the lever <NUM> are both in metal. Preferably the protecting sleeve is made from plastic material and has a shape of open-ended cylinder. The lever <NUM> comprises a grip part and a head. The head of the lever <NUM> comprises one or more teeth <NUM>. According to one embodiment, the head of the lever <NUM> comprises <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM> or <NUM> teeth. According to one embodiment, the teeth of the head of the lever <NUM> are configured for cooperating with the gun piston <NUM>. According to one embodiment, the gun piston <NUM> is a rod. According to one embodiment, the gun piston <NUM> comprises one or more notches <NUM>. According to one embodiment, the number of teeth <NUM> is the same as the number of notches <NUM>. According to one embodiment, the gun piston <NUM> is a rod comprising at least two notches, preferably from <NUM> to <NUM> notches, more preferably <NUM> notches, said notches being located in the central part of the gun piston <NUM>.

As presented in <FIG> and <FIG>, when using the dispensing gun, the lever <NUM> successively takes three distinct positions: an actuating state (<FIG>), an intermediate state (<FIG>) and a final state (<FIG>).

The "actuating state" in the present invention refers to the position of the lever <NUM> in which the first notch (<NUM>) of the gun piston (<NUM>) and the first tooth (<NUM>) of the lever (<NUM>) are engaged together prior to connecting the cartridge so that the lever (<NUM>) and the handle (<NUM>) form an angle ranging from <NUM>° to <NUM>°, preferably of almost <NUM>°. According to one embodiment, in the actuating state, the lever (<NUM>) and the handle (<NUM>) form an angle of about <NUM>°, <NUM>°, <NUM>°, <NUM>°, <NUM>°, <NUM>°, <NUM>°, <NUM>°, <NUM>°, <NUM>°, <NUM>°, <NUM>°, <NUM>°, <NUM>°, <NUM>°, <NUM>°, <NUM>°, <NUM>°, <NUM>°, <NUM>°, <NUM>°, <NUM>°, <NUM>°, <NUM>°, <NUM>°, <NUM>°, <NUM>°, <NUM>°, <NUM>°, <NUM>°, <NUM>°, <NUM>°, <NUM>°, <NUM>°, <NUM>°, <NUM>°, <NUM>°, <NUM>°, <NUM>°, <NUM>° or <NUM>°. According to one embodiment, the term "about" preceding a figure means plus or less <NUM>% of the value of said figure, preferably more or less than <NUM>% of this value, more preferably more or less than <NUM>% of this value. As seen in <FIG>, in the actuating state, the distal end of the gun piston <NUM> is located at the proximal end of the injection gate <NUM>. According to one embodiment, in the actuating state, the distal end of the gun piston <NUM> is not inside the inner volume of the injection gate <NUM>. According to one embodiment, in the actuating state, the rod of the gun piston <NUM> is not inside the inner volume of the injection gate. According to one embodiment, in the actuating state, the cartridge is not connected, retained and/or locked on the dispensing gun <NUM>. According to one embodiment, the actuating state enables to keep the gun piston <NUM> inside the frame <NUM>, at a non-zero distance ex from the distal end of the injection gate <NUM>. According to one embodiment, the distance ex ranges from <NUM> to <NUM>, preferably ranges from <NUM> to <NUM>, more preferably from <NUM> to <NUM>. According to one embodiment, the distance ex is of <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>.

The "final state" in the present invention refers to the position of the lever <NUM> in which the lever <NUM> is fully depressed. As seen in <FIG>, in the final state, the longitudinal axis of the lever <NUM> is parallel to the longitudinal axis of the handle <NUM> of the dispensing gun. According to one embodiment, in the final state, the pivot of the lever from the actuating state to the final state leads to the maximum displacement of the gun piston <NUM> inside the dispensing gun and/or leads to the maximum displacement of the piston of the cartridge locked on the dispensing gun. According to one embodiment, in the final state, the pivot of the lever from the actuating state to the final state causes the extrusion of the whole material contained in the cartridge, preferably in one single stroke of the gun piston <NUM> inside the dispensing gun and/or in one single stroke of the piston of the cartridge locked on the dispensing gun.

As visible in <FIG>, the "intermediate state" refers to a position of the lever <NUM> between the actuating state and the final state as defined above. According to one embodiment, in the intermediate state, the gun piston <NUM> is engaged in the injection gate <NUM> and the distal end of the gun piston <NUM> is located out of the distal end of the injection gate <NUM>. According to one embodiment, in the intermediate state, the cartridge is locked on the distal end of the injection gate and the distal end of the gun piston <NUM> is located close to the piston of the cartridge, preferably is in contact with it, so that the system is ready to extrude the material, without extruding the material.

As presented in <FIG>, the injection gate <NUM> comprises a distal plate <NUM> with an aperture <NUM>. The shape of the aperture <NUM> corresponds to the shape of the base section of the cartridge. In this way, the cartridge can be engaged in the injection gate <NUM> of the dispensing gun. The shape of the aperture <NUM> corresponds to the shape of the base section of a cartridge having two opposite locking wings.

The injection gate <NUM> also comprises means for locking the cartridge upon received inside the injection gate <NUM>. According to one embodiment, means for locking the cartridge to the dispensing gun <NUM> (and to the injection gate <NUM>) comprise or consist of at least one hole on at least one side wall of the distal plate <NUM> of the injection gate <NUM>. According to one embodiment, means for locking the cartridge to the dispensing gun <NUM> (and to the injection gate <NUM>) comprise or consist of one hole <NUM> on each vertical side wall of the distal plate <NUM> of the injection gate <NUM>. In this way, when the cartridge is pushed inside the injection gate through the aperture on the distal plate <NUM>, then rotating the cartridge a quarter turn about the longitudinal axis of the cartridge leads to displace the locking wings of the cartridge inside the two holes of the vertical side walls of the injection gate <NUM> and leads to safely lock the cartridge on the dispensing gun <NUM>. According to one embodiment, the side walls of the injection gate <NUM> have a thickness higher than the thickness of the base section and/or of the locking wings of the cartridge.

The present invention also refers to a system comprising the dispensing gun <NUM> of the invention and a cartridge <NUM>. In the present invention, the cartridge is any cartridge suitable with the dispensing gun <NUM> of the invention. Especially, the cartridge may contain any suitable material able to be delivered with the dispensing gun <NUM> of the invention, preferably the material is a medical composition such as for example a bone filling material or a dental material. According to one embodiment, the cartridge may be a medical cartridge such as a dental cartridge. According to one embodiment, the cartridge described in <CIT> is particularly suitable to be used with the dispensing gun <NUM> of the invention. According to one embodiment, the cartridge comprises a base section with at least one protrusion, a chamber containing the material to be dispensed, a piston and a dispensing nozzle. According to the invention, the cartridge comprises a base section with means to be locked in the dispensing gun <NUM> of the invention, on the injection gate <NUM> of the dispensing gun <NUM>. According to the invention, means of the cartridge to be locked in the dispensing gun <NUM> comprise or consist of two opposite locking wings.

<FIG> shows an exploded view of a cartridge <NUM> suitable both for the mixing and the dispensing of a two-component dental restoration material comprising a powder component and a liquid component and suitable for use with the apparatus according to the invention. As visible in <FIG>, the cartridge <NUM> comprises successive tubular members with circular cross sections, which are configured to be inserted one inside the other while being aligned along their longitudinal axis X-X'. In this embodiment, the tubular members of the cartridge <NUM> include, going from the outermost element to the innermost element, an external sleeve <NUM>, a barrel <NUM>, a liquid receptacle <NUM> and a plunger <NUM>. The sleeve <NUM> comprises a body <NUM> including a proximal open end <NUM> and a distal end <NUM> defined by a distal wall <NUM> of the sleeve. The distal wall <NUM> is provided with a dispensing hole <NUM>, from which extends a tubular dispensing nozzle <NUM> formed in one piece with the body <NUM> of the sleeve. The thickness t<NUM> of the peripheral wall 70a of the dispensing nozzle <NUM> decreases from the dispensing hole <NUM> toward a free end 70b of the dispensing nozzle. Thanks to this specific geometry combined to the constitutive material of the dispensing nozzle <NUM>, which is a polymer, preferably a transparent polymer such as a transparent amorphous copolyester in this example, the dispensing nozzle <NUM> is deformable while being capable of retaining a constant internal diameter even when it is bent. In this way, the dispensing nozzle <NUM> is steerable while having a constant diameter for the dispensing of material.

The distal wall <NUM> of the sleeve <NUM> comprises an internal piercing element <NUM> in the alignment of the dispensing hole <NUM>, which is intended to break a breakable distal wall <NUM> of the barrel <NUM>. The piercing element <NUM> is a tubular element projecting internally from the distal wall <NUM> of the sleeve so as to be in fluid communication with the dispensing hole <NUM>. Thanks to this arrangement, once the distal wall <NUM> of the barrel <NUM> has been broken, the tubular piercing element <NUM> forms a privileged passageway guiding the material contained in the barrel <NUM> directly to the dispensing hole <NUM>, which limits the losses of material in the interspace between the barrel <NUM> and the sleeve <NUM>.

The inner diameter d<NUM> of the piercing element <NUM> is slightly higher than the diameter d<NUM> of the dispensing hole <NUM>. In this way, the opening created in the distal wall <NUM> of the barrel <NUM> under the action of the piercing element <NUM> has a size suitable to ensure a proper flow of the material to be dispensed. Around the piercing element <NUM>, the sleeve <NUM> comprises an annular (or ring-shaped) cavity <NUM> whose bottom is formed by the inner surface of the distal wall <NUM>, while the central wall of the ring is formed by the peripheral wall of the tubular piercing element <NUM> and the external wall of the ring is formed by a beveled inner surface complementary to a corresponding beveled outer surface <NUM> of the barrel <NUM>. The complementary beveled surfaces are designed to provide an efficient sealing at the interface between the sleeve <NUM> and the barrel <NUM> adjacent to the piercing element <NUM> and the dispensing hole <NUM>, so as to limit the passage of material in the interspace between the barrel <NUM> and the sleeve <NUM>.

As visible in <FIG>, the barrel <NUM> of the cartridge <NUM> comprises a proximal open end <NUM> and a distal end <NUM> defined by the breakable distal wall <NUM>. The barrel <NUM> delimits a chamber <NUM> configured to receive the powder component of the two-component dental restoration material. The constitutive material of the barrel <NUM> is selected to have a Water Vapor Transfer Rate (WVTR) at <NUM> and <NUM>% RH, for a film thickness of <NUM>, of less than <NUM>/(m<NUM>-day), so as to maintain a constant humidity level in the chamber <NUM> suitable to protect the moisture sensitive powder component. In particular, in this example, the barrel <NUM> is made of a cyclic olefin copolymer (COC) having a WVTR at <NUM> and <NUM>% RH, for a film thickness of <NUM>, of the order of <NUM>/(m<NUM>-day). According to another embodiment, the constitutive material of the barrel <NUM> is selected to have a Water Vapor Transfer Rate (WVTR) at <NUM> and <NUM>% RH, for a film thickness of <NUM>, of higher than <NUM>/(m<NUM>-day).

The distal wall <NUM> of the barrel <NUM> comprises a central breakable portion surrounded by a sealing portion configured to cooperate with the inner surface of the distal wall <NUM> of the sleeve. Advantageously, the ratio of the surface area of the breakable portion to the surface area of the sealing portion is such that, after opening, the fins of the open breakable portion leave the dispensing hole <NUM> of the sleeve completely cleared, while the bearing surface of the sealing portion is a sufficiently thin ring to limit the contact area. In this way, the seal is easier to achieve with the distal wall <NUM> of the sleeve and the contact pressure is maximized to ensure sealing during the dispensing of the material. This arrangement ensures a proper flow of the material to be dispensed while limiting the material losses.

The diameters of the breakable portion and the piercing element <NUM> are also adjusted to maximize the breakage efficiency of the piercing element <NUM>. For example, in the illustrated example, the diameter d<NUM> of the piercing element <NUM> is of the order of half the diameter d of the breakable portion. The breakable portion comprises six weakened lines distributed radially in a star shape, starting from a central portion of the distal wall <NUM>. Each weakened line has a thickness t lower than the thickness t<NUM> of the rest of the distal wall <NUM>. The central portion of the star makes it possible to have a stress concentration so that the breaking starts in the center of the star.

This arrangement of the weakened lines is configured to guide a deformation of the distal wall <NUM> of the barrel, when it is submitted to the action of the piercing element <NUM>, in a corolla shape oriented away from the dispensing nozzle <NUM>. In practice, the rupture of the distal wall <NUM> is obtained through a displacement of the barrel <NUM> in the sleeve <NUM> along the longitudinal axis X-X' between a first position, visible in <FIG> in which the distal wall <NUM> of the barrel is at a distance e<NUM> from the distal wall <NUM> of the sleeve, and a second position, (visible in <FIG>), in which the sealing portion of the distal wall <NUM> of the barrel is in contact with the inner surface of the distal wall <NUM> of the sleeve and the complementary beveled surfaces <NUM>;<NUM> cooperate, thus providing a sealing between the sleeve <NUM> and the barrel <NUM>. As seen in <FIG>, the distance e<NUM> between the distal wall <NUM> of the barrel and the distal wall <NUM> of the sleeve is higher than <NUM> in order to avoid any unintentional dispensing of the material contained in the cartridge when the lever of the dispensing gun is in an actuating state and/or is in an intermediate state as defined above. According to one embodiment, the distance e<NUM> between the distal wall <NUM> of the barrel and the distal wall <NUM> of the sleeve ranges from <NUM> to <NUM>, preferably from <NUM> to <NUM>, more preferably is about <NUM>.

The barrel <NUM> also comprises two diametrically opposed tabs <NUM> near its proximal end <NUM>. Each tab <NUM> is configured to be received in a corresponding housing <NUM> defined by a locking wing <NUM> of the sleeve <NUM> arranged near the proximal end <NUM>, so as to lock the barrel <NUM> in the first position with respect to the sleeve <NUM>. This locked configuration of the cartridge <NUM> ensures that the distal wall <NUM> of the barrel <NUM> remains at the distance e<NUM> from the distal wall <NUM> of the sleeve, so that the cartridge <NUM> can be manipulated without any risk of the distal wall <NUM> being pierced by the piercing element <NUM>, which makes it possible to implement a mixing step prior to the dispensing step.

In addition, the barrel <NUM> comprises an outer radial collar <NUM> configured to cooperate with inner radial recesses <NUM> formed by six clipping members <NUM> distributed circumferentially inside the body <NUM> of the sleeve <NUM>. The cooperation between the outer radial collar <NUM> and the inner radial recesses <NUM> makes it possible to keep the barrel <NUM> in the first position with respect to the sleeve <NUM> even when the tabs <NUM> are disengaged from the housings <NUM>, thus allowing the cartridge <NUM> to be secured in a storage configuration even when the locking system <NUM>/<NUM> is not active.

As can be seen particularly in <FIG>, the body <NUM> of the sleeve <NUM> also comprises two diametrically opposed longitudinal grooves <NUM> near its proximal end <NUM>, which are configured to guide the displacement of the tabs <NUM> of the barrel <NUM> when the barrel is moved from the first position to the second position. The longitudinal grooves <NUM> ensure a guiding of the barrel <NUM> near the proximal end <NUM>, in its movement towards the piercing element <NUM>, while another guiding is ensured near the distal end <NUM> by six guiding ribs <NUM> distributed circumferentially inside the body <NUM> of the sleeve. The guiding means <NUM> and <NUM> improve the stability of the displacement of the barrel <NUM> to reach the dispensing configuration of the cartridge <NUM>.

The chamber <NUM> of the barrel <NUM> is sealed by means of a piston formed by the combination of the liquid receptacle <NUM> and the plunger <NUM>. In this illustrative example, the receptacle <NUM> is made of low-density polyethylene (LDPE) and the plunger <NUM> is made of acrylonitrile butadiene styrene (ABS). The receptacle <NUM> comprises a proximal open end <NUM> and a distal end <NUM> defined by an openable distal wall <NUM>. The receptacle <NUM> delimits a chamber <NUM> configured to receive the liquid component of the two-component dental restoration material. The distal wall <NUM> of the receptacle <NUM> comprises a detachable portion <NUM> attached to the rest of the distal wall by an annular connecting part <NUM>. The annular connecting part <NUM> comprises a solid portion extending over an angle α of the order of <NUM>°, and a weakened portion having a thickness t less than the thickness t of the solid portion, so as to form a hinge. This arrangement makes it possible to open the distal wall <NUM> of the receptacle <NUM> by rupturing only the weakened portion, so that the detachable portion <NUM> flips out of the receptacle <NUM> while remaining connected to the distal wall <NUM> of the receptacle <NUM> through the hinge formed by the solid portion.

The receptacle <NUM> is configured to move in sealing engagement in the chamber <NUM> of the barrel <NUM>. To this end, the receptacle <NUM> is provided externally with a peripheral sealing rib <NUM> configured to prevent the passage of the liquid component, initially contained in the chamber <NUM> of the receptacle <NUM>, toward the interspace between the barrel <NUM> and the receptacle <NUM>, when the distal wall <NUM> of the receptacle is open and the receptacle <NUM> is moved towards the distal wall <NUM> of the barrel.

In practice, the opening of the distal wall <NUM> of the receptacle <NUM> is obtained thanks to a rod <NUM> extending distally from the distal wall <NUM> of the plunger <NUM>. More precisely, the chamber <NUM> of the receptacle <NUM> is sealed by means of the plunger <NUM>, which is movable in the chamber <NUM> and whose distal rod <NUM> is configured to apply a pressure on the detachable portion <NUM> of the distal wall <NUM> of the receptacle. Before the opening of the distal wall <NUM>, the powder component is hermetically received in the chamber <NUM> of the barrel <NUM> and the liquid component is hermetically received in the chamber <NUM> of the receptacle <NUM>. The two components can then be easily mixed together at a desired time, so as to form the material to be dispensed, by opening the openable distal wall <NUM> of the receptacle through application of a pressure on the detachable portion <NUM> with the distal rod <NUM> of the plunger and applying a vibration to the cartridge <NUM> in this activated configuration, either manually or by means of a vibration mixer.

The receptacle <NUM> comprises two inner peripheral grooves <NUM>, <NUM>' configured to cooperate with two corresponding outer peripheral ribs <NUM>, <NUM>' of the plunger <NUM> to keep the plunger <NUM> at a distance e<NUM> from the openable distal wall <NUM> of the receptacle <NUM> in a storage configuration of the cartridge <NUM>. The cooperation between the inner peripheral grooves <NUM>, <NUM>' and the outer peripheral ribs <NUM>, <NUM>' is releasable under the effect of a thrust force F<NUM> applied on the proximal end <NUM> of the plunger <NUM>, e.g. by means of an activation machine so that to reach the activated configuration in <FIG>. The cooperating radial features <NUM>, <NUM> and <NUM>', <NUM>' between the receptacle <NUM> and the plunger <NUM> make it possible to secure the cartridge <NUM> in the storage configuration where the powder component and the liquid component are separated, the first one being received in the chamber <NUM> of the barrel while the second one is received in the chamber <NUM> of the receptacle, without risk of accidental mixing of the two components.

The barrel <NUM> also comprises an inner peripheral groove <NUM> near its proximal end <NUM>, which is configured to cooperate with an outer peripheral rib <NUM> of the receptacle <NUM> to keep the distal wall <NUM> of the receptacle <NUM> at a distance from the distal wall <NUM> of the barrel <NUM> before the piston formed by the combination of the receptacle <NUM> and the plunger <NUM> is moved towards the distal wall <NUM> of the barrel for the dispensing of the material. The cooperating radial features <NUM>, <NUM> between the barrel <NUM> and the receptacle <NUM> make it possible to have a two-step transition of the cartridge <NUM> towards the dispensing configuration, obtained through the application of a thrust force Fi on the proximal end <NUM> of the plunger <NUM>, e.g. by means of the dispensing gun of the invention.

The present disclosure also concerns a method of dispensing a material contained in a cartridge as defined above, by means of the dispensing gun <NUM> according to the invention as defined above, and comprises steps as described below.

Initially, the dispensing gun <NUM> is in the actuating state as shown in <FIG>, in which the lever <NUM> cooperates with the gun piston <NUM> so that the gun piston <NUM> is kept inside the frame <NUM>, at a distance ex from the distal end of the injection gate <NUM>. In this actuating configuration, the cartridge is not yet connected to the dispensing gun <NUM>.

Then, the base section of the cartridge is pushed inside the aperture <NUM> of the injection gate <NUM>. The aperture <NUM> and the base section of the cartridge must have the same shape in order to fit together and enable the cartridge to be received in the inner volume of the injection gate. After that, the external sleeve of the cartridge is turned a quarter turn along the longitudinal axis of the cartridge in order to lock each locking wing <NUM> in the hole of each vertical side walls of the distal plate <NUM> of the injection gate <NUM>. In this way, when the dispensing gun is used with the cartridge, the locking wings <NUM> are retained by the frame of the injection gate <NUM>, ensuring a safely handling for the practitioner.

After locking the cartridge on the dispensing gun <NUM>, a thrust force F is applied on the lever <NUM> in order to pivot the lever <NUM> from the actuating state to the intermediate state as defined above. In this manner, the cooperation between the lever <NUM> and the gun piston <NUM> leads to the displacement of the gun piston <NUM> so that the distal end of the gun piston <NUM> is engaged in the inner volume of the injection gate <NUM> on which is locked the cartridge and so that the distal end of the gun piston <NUM> is close to the piston of the cartridge, ready to extrude the material of the cartridge but without implementing extrusion. The intermediate state of the lever <NUM> is achieved thanks to the action of the spring plunger <NUM>. During this intermediate step, the barrel <NUM> is displaced relative to the sleeve <NUM> from the first position to the second position, until the distal wall <NUM> of the barrel is in contact with the distal wall <NUM> of the sleeve and broken by the piercing element <NUM>. In this step, the radial features <NUM>, <NUM> between the barrel <NUM> and the receptacle <NUM> are mutually engaged so that the barrel <NUM>, the receptacle <NUM> and the plunger <NUM> move integrally with one another.

Finally, under the action of a thrust force F on the lever <NUM>, the gun piston <NUM> advances inside the cartridge so that the distal end of the gun piston <NUM> pushes the piston of the cartridge formed by the combination of the receptacle <NUM> and the plunger <NUM> which is displaced relative to the barrel <NUM>, the radial features <NUM>, <NUM> between the barrel <NUM> and the receptacle <NUM> being mutually disengaged in this step. In this way, the material to be dispensed is pushed as far as possible towards the dispensing nozzle of the cartridge, thus limiting the losses of material.

Advantageously, the thrust force F' to be applied by the practitioner on the lever <NUM> is slight and does not require the use of the two hands. Advantageously, the movement of the fingers of the practitioner to moves the lever <NUM> for extruding the material with the dispensing gun (i.e. for moving the lever <NUM> from the intermediate state to the final state) is of reduced amplitude. Thus, the dispensing gun is more ergonomic and easier to use than conventional dispensing devices.

Claim 1:
A dispensing gun (<NUM>) for a cartridge comprising a frame (<NUM>) having a handle (<NUM>), an injection gate (<NUM>) for connecting a cartridge having a base section with at least two opposite locking wings, said injection gate (<NUM>) being located at the distal part of the frame (<NUM>), a lever (<NUM>) comprising at least two teeth (<NUM>) and a piston (<NUM>) comprising at least two notches (<NUM>), wherein:
- the dispensing gun (<NUM>) comprises means for directly locking the cartridge on the injection gate (<NUM>); and
- the dispensing gun (<NUM>) comprises means for pushing the piston (<NUM>) inside the cartridge so that the material contained in the cartridge is extruded in a single piston stroke; and
- the dispensing gun (<NUM>) is configured so that the lever (<NUM>) comprises an actuating state in which the first notch (<NUM>) of the piston (<NUM>) and the first tooth (<NUM>) of the lever (<NUM>) are engaged together prior to connecting the cartridge so that the lever (<NUM>) and the handle (<NUM>) form an angle ranging from <NUM>° to <NUM>°, preferably being <NUM>°; and
- said injection gate (<NUM>) comprises a distal plate (<NUM>) with an aperture (<NUM>) whose shape corresponds to the shape of the base section of the cartridge having two opposite locking wings to enable the cartridge to be engaged in the injection gate (<NUM>) of the dispensing gun (<NUM>), wherein the injection gate (<NUM>) also comprises means for locking the cartridge upon received inside the injection gate.