Dispensing Device for Dental Retraction Material

Abstract

A dispensing device for dental retraction material. The dispensing device has a cannula that forms a free front end. The free front end is formed by a first cannula portion and a second cannula portion that is arranged directly adjacent the first cannula portion. The first cannula portion has a first elongated section and a first rounded section. The second cannula portion has a second elongated section and a second rounded section. A first outer diameter (D1) of the cannula is defined on the first rounded section at the free front end, and a second outer diameter (D2) of the cannula is defined on the second rounded section at the transition between the second rounded section and the first cannula portion. The second outer diameter is greater than the first outer diameter. The first cannula portion comprises a predetermined separation structure directly adjacent the second cannula portion. The first cannula portion can be broken or cut off to provide the dispensing device with a new free front end.

Claims

1. A dispensing device for dental retraction material, comprising a cannula forming a free front end, the free front end being formed by a first cannula portion that extends from the free front end to a second cannula portion that is arranged directly adjacent the first cannula portion, wherein the first cannula portion has a first elongated section and a first rounded section extending between the first elongated section and the free front end, a first outer diameter (D1) of the cannula being defined on the first rounded section at the free front end, wherein the second cannula portion has a second elongated section and a second rounded section extending between the second elongated section and the first cannula portion, a second outer diameter (D2) of the cannula being defined on the second rounded section at the transition between the second rounded section and the first cannula portion, wherein the second outer diameter is greater than the first outer diameter, and wherein the first cannula portion comprises a predetermined separation structure directly adjacent the second cannula portion, wherein the predetermined separation structure is a groove.

2. The dispensing device of claim 1, wherein a third outer diameter (D3) of the cannula being defined on the first elongated section at the transition between the first rounded section and the first elongated section, and wherein a fourth outer diameter (D4) of the cannula being defined on the second elongated section at the transition between the second rounded section and the second elongated section.

3. (canceled)

4. The dispensing device of claim 1, wherein the groove is V-shaped.

5. The dispensing device of claim 1, wherein the first outer diameter is within a range of 0.5 mm to 0.8 mm and the second outer diameter is within a range of 0.8 mm to 1.0 mm.

6. The dispensing device of claim 1, wherein the first rounded section is based on a radius within a range of 0.5 to 10 and the second rounded section is based on a radius within a range of 0.5 to 10.

7. The dispensing device of claim 1, wherein a channel extends through the cannula and forming a dispensing opening at the free front end, wherein the channel comprises a first channel section that has a first cylindrical channel section and a second channel section that has a second cylindrical channel section.

8. The dispensing device of claim 7, wherein the first channel section extends between the dispensing opening and the second channel section, the first cylindrical channel section having a first channel diameter and the second cylindrical channel section having a second channel diameter, wherein the first channel diameter is smaller than the second channel diameter.

9. The dispensing device of claim 8, wherein the first channel diameter is within a range of 0.5 mm to 0.8 mm and the second channel diameter is within a range of 0.8 mm to 1.0 mm.

10. The dispensing device of claim 1, wherein the second channel section comprises a third cylindrical channel section having a third channel diameter that is greater than the second channel diameter.

11. The dispensing device of claim 10, wherein the third channel diameter is within a range of 1.0 mm to 1.5 mm.

12. The dispensing device of any of claim 1, further comprising a chamber for storing the dental retraction material, wherein the chamber is in fluid communication with the cannula.

13. The dispensing device of claim 1, further having a piston for expelling the dental retraction material from the dispensing device.

14. The dispensing device of claim 1, further comprising the dental retraction material.

15. A method of preparing a dispensing device for dental retraction material for use, excluding any steps for treatment of the human or animal body, the method comprising the steps of: providing a dispensing device according to claim 1, in particular having a first and a second cannula portion; separating the first cannula portion by breaking or cutting the first cannula portion off from the cannula directly adjacent the second cannula portion.

16. A dispensing device for dental retraction material, comprising a cannula forming a free front end, the free front end being formed by a first cannula portion that extends from the free front end to a second cannula portion that is arranged directly adjacent the first cannula portion, wherein the first cannula portion has a first elongated section and a first rounded section extending between the first elongated section and the free front end, a first outer diameter (D1) of the cannula being defined on the first rounded section at the free front end, wherein the second cannula portion has a second elongated section and a second rounded section extending between the second elongated section and the first cannula portion, a second outer diameter (D2) of the cannula being defined on the second rounded section at the transition between the second rounded section and the first cannula portion, wherein the second outer diameter is greater than the first outer diameter, and wherein the first cannula portion comprises a predetermined separation structure directly adjacent the second cannula portion, wherein a channel extends through the cannula and forming a dispensing opening at the free front end, wherein the channel comprises a first channel section that has a first cylindrical channel section and a second channel section that has a second cylindrical channel section.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0045] FIG. 1 is a perspective view of a dispensing device according to an embodiment of the invention;

[0046] FIG. 2 is a cross-sectional view of a cannula of the dispensing device shown in FIG. 1;

[0047] FIG. 3 is a perspective view of the cannula of the dispensing device shown in FIG. 1;

[0048] FIG. 4 is a perspective cross-sectional view of the cannula of the dispensing device shown in FIG. 1; and

[0049] FIG. 5 is a perspective view of the cannula of the dispensing device shown in FIG. 1 with a cutting tool positioned relative to the cannula.

DETAILED DESCRIPTION OF THE INVENTION

[0050] FIG. 1 shows an exemplary dispensing device 1 according to the invention. The dispensing device 1 has a container 2 in which a dental retraction material is stored. A piston 3 (not visible) closes the container 2. The container 2 forms a chamber (not visible) in which the dental retraction material is or can be stored. The piston 3 further is movable within the container for expelling the dental retraction material from the dispensing device 1. For expelling the dental retraction material the dispensing device 1 can be retained in a dispensing gun (not shown). The dispensing device 1 has an annular rim 4 for retaining the dispensing device 1 during dispensation of the dental retraction material.

[0051] The dispensing device 1 further comprises a cannula 5. The cannula 5 extends along a longitudinal axis A. The cannula 5 has a free front end 6. The cannula 5 particularly is shaped such that it is insertable within the sulcus of a human gums in a patient's mouth. Therefore the free front end 6 of the cannula 5 has a rounded shape without any sharp edges. The free front end 6 is in particular formed by a first cannula portion 7 that extends from the free front 6 end to a second cannula portion 8. The second cannula portion 8 is arranged directly adjacent the first cannula portion 7. Further, the first and second cannula portion 7, 8 are monolithically formed, preferably by injection molding from a plastic material, for example from polybutylene terephthalate (PBT). The first cannula portion 7 has a first elongated section 9 and a first rounded section 10. The first rounded section 10 extends between the first elongated section 9 and the free front end 6. The first rounded section 10 particularly extends over the entire distance between the first elongated section 9 and the free front end 6. The first rounded section 10 in the example is based on a radius of 8 mm. The radius is defined in a plane on the longitudinal axis A. A first outer diameter D1 of the cannula 5 is defined at the free front end 6. The first outer diameter D1 also forms a front most outer diameter. Further, the first outer diameter D1 is defined in a plane that is perpendicular to the longitudinal axis.

[0052] The second cannula portion 8 has a second elongated section 11 and a second rounded section 12. The second rounded section 12 extends between the second elongated section 11 and the first cannula portion 7. A second outer diameter D2 of the cannula 5 is defined on the second rounded section 12 at the transition between the second rounded section 12 and the first cannula portion 7. The second outer diameter D2 is defined in a plane that is perpendicular to the longitudinal axis.

[0053] Accordingly, the cannula 5 can be broken or cut at the second outer diameter D2 to provide the cannula 5 with a new front most diameter than is increased with respect to the first outer diameter D1. Therefore the cannula 5 is configured for being provided with different front most outer diameters. This helps a dentist to adapt the dispensing device to different clinical situations in a patient's mouth.

[0054] A third outer diameter D3 of the cannula 5 is defined on the first elongated section 9 at the transition between the first rounded section 10 and the first elongated section 9. A rear end of the first rounded section 10 therefore also has the third outer diameter D3. The third outer diameter D3 is greater than the first outer diameter D1. And (in the example) the third outer diameter D3 is greater than the second outer diameter D2. Further, a fourth outer diameter D4 of the cannula 5 is defined on the second elongated section 11 at the transition between the second rounded section 12 and the second elongated section 11. The fourth outer diameter D4 is greater than the second outer diameter D2.

[0055] The first elongated section 9 in the example comprises a conical section between the third outer diameter D3 and a fifth outer diameter D5. The fifth outer diameter D5 is greater than the third outer diameter D3. Accordingly, the conical section of the first elongated section 9 widens from the third outer diameter D3 toward the fifth outer diameter D5. The first cannula portion 7 comprises a predetermined separation structure 13 directly adjacent the second cannula portion 8. In particular, the first elongated section 9 comprises the conical section and additionally the predetermined separation structure 13. The predetermined separation structure 13 is formed by an annular constriction with respect to the conical section of the first elongated section 9, in particular with respect to the fifth outer diameter D5. Further, the predetermined separation structure 13 is arranged between the second rounded section 12 and the conical section of the first elongated section 9. In the example the predetermined separation structure 13 is a groove that has the second outer diameter D2 at the transition between the first and second cannula portion 7, 8. The predetermined separation structure 13 can weaken the first cannula portion so that it preferably breaks at the predetermined separation structure 13. Or the predetermined separation structure can be used for guiding a cutting tool (for example a scalpel) during cutting off the first cannula portion 7.

[0056] The second elongated section 11 in the example also comprises a conical section between the fourth outer diameter D4 and a sixth outer diameter D6. The sixth outer diameter D6 is greater than the fourth outer diameter D4. Accordingly, the conical section of the second elongated section 11 widens from the fourth outer diameter D4 toward the sixth outer diameter D6. In the example the cannula 5 only has two cannula portions (the first and second cannula portion 7, 8). Therefore the second elongated section 11 does not comprise a further predetermined separation structure. However, in another example the cannula may have three (or more) cannula portions with the second (and further) elongated section comprising (a) further predetermined separation structure(s).

[0057] FIG. 2 shows a cross-section of the cannula 5. In particular, the cannula 5 comprises a channel 14. The channel 14 extends from the chamber (not shown) through the cannula 5 and forms a dispensing opening 15 at the free front end 6 of the cannula 5. Thus, the chamber (in which the dental retraction material may be stored) is in fluid communication with the channel 14. For keeping the dental retraction material encapsulated within the chamber a cap (not shown) can be placed over the free front end 6 of the cannula 5 to close the dispensing opening 15.

[0058] The channel 14 has a stepped configuration formed of a plurality of cylindrical channel sections (instead of a conical or non-stepped cylindrical configuration). It has been found that the dental retraction material tends to block if it is urged through a conical channel and that this tendency is minimized if a stepped configuration of a plurality of cylindrical channel sections are used instead.

[0059] In particular, the channel 14 comprises a first channel section 16 and a second channel section 17. The first channel section 16 corresponds to a first cylindrical channel section 16a. In the example the second channel section 17 comprises a second cylindrical channel section 17a, a conical channel section 17b and a chamfer 17c. The conical channel section 17b is provided to account for a sufficient wall thickness between an inner surface of the channel 14 and an outer surface of the cannula 5. The skilled person will however recognize that the conical channel section 17b is optional. Further, it has been found that in combination with the second cylindrical channel section 17a the tendency of the dental retraction material to block is still lower than for a channel that is conical only.

[0060] The first channel section 16 extends between the dispensing opening 15 (or the free front end 6) and the second channel section 17. The first cylindrical channel section 16a has a first channel diameter C1 and the second cylindrical channel section 17a has a second channel diameter C2. The first channel diameter C1 is smaller than the second channel diameter C2. Further, the dispensing opening 15 corresponds in its diameter to the first channel diameter C1. The second channel section 17 further comprises a third cylindrical channel section 17d having a third channel diameter C3 that is greater than the second channel diameter C2.

[0061] FIG. 3 shows a portion of the cannula 5 with the predetermined separation structure 13 in further detail. The predetermined separation structure 13 in the example is an annular groove within the first cannula portion 7. The groove weakens the first cannula portion so that it preferably breaks along the groove. The groove can further be used for positioning a separation tool (for example a knife or scalpel) directly adjacent the second cannula portion 8. Once positioned, the separation tool may be used for cutting the first cannula portion 7 off from the cannula 5. A separation line S along which the cutting may be performed is indicated in the Figure. The separation line S extends transverse to the longitudinal axis A.

[0062] The cannula 5 in the example is provided with (optional) reinforcement structures 18 which are shown in more detail in FIG. 4. The reinforcement structures 18 in the example are formed by elongated bulges that protrude into the channel 14. The bulges have an elongated length along the longitudinal axis A and are shorter transverse thereto. The protrusions extend radially inwardly from the inner surface of the channel 14. The reinforcement structures 18 support the wall between the inner surface of the channel 14 and the outer surface of the cannula 5 during cutting through the predetermined separation structure 13. Thus, a deformation of the cannula 5 (and restriction of the channel 14) due to a force exerted on the cannula 5 during cutting can be minimized.

[0063] FIG. 5 shows the cannula 5 and a scalpel 100. In the example the cannula 5 has an alternatively shaped predetermined separation structure 13, although the predetermined separation structure 13 of FIG. 3 may be likewise used. In the example, the scalpel 100 is positioned within the predetermined separation structure 13 and may be used for cutting off the first cannula portion 7 of the cannula 5.