WO2017044029A1

WO2017044029A1 - Dental syringe and needle tip shielding system for a dental needle

Info

Publication number: WO2017044029A1
Application number: PCT/SE2016/050831
Authority: WO
Inventors: Per Knutsson
Original assignee: Vigmed Ab
Priority date: 2015-09-10
Filing date: 2016-09-06
Publication date: 2017-03-16

Abstract

Needle shielding systems for a dental syringe (100, 200) are disclosed. The needle shielding system (100, 200) comprises a needle (300) and a needle shield (400). The needle (300) has a needle tip (304) and a needle bulge (308) spaced apart from the needle tip (304). The needle shield (400) is slidably mounted over the needle (300) distally from the needle tip (304). Needle shield (400) comprises a base plate (404) and at least one resilient arm (416) extending distally from the base plate (404) towards the needle tip (304), wherein the base plate (404) or the at least one resilient arm (416) has at least one protrusion (424, 428) extending laterally away from the base plate (404) or the at least one resilient arm (416). In use the system (100, 200) is dragged against another structure to move the needle shield (400) along the needle (300) though interaction between said structure and said at least one protrusion (424, 428), until the needle shield (400) contacts the needle bulge (308) and the resilient arm (416) covers the needle tip (304). The syringes (100, 200) generally comprise a barrel (104, 204), plunger (108, 208), an anesthetic (112, 212), and a needle (300). The barrel (104, 204) has proximal and distal ends. The plunger (108, 208) is inserted into the proximal end of the barrel (104, 204) and is slidably moveable within the barrel (104, 204). The anesthetic (112, 212) is in contact with and between the plunger (108, 208) and the distal end of the barrel (104, 204). The needle (300) is connected to the distal end of the barrel (104, 204). In use the needle (300) is inserted into the gum or inner cheek of a patient and the plunger (108, 208) is depressed to inject the anesthetic (112, 212) though the needle (300) and into the patient. The dental syringes (100, 200) may also include a needle shield (400) slidably mounted over the needle (300).

Description

DENTAL SYRINGE AND NEEDLE TIP SHIELDING SYSTEM FOR A

DENTAL NEEDLE

Field of the Invention

The present invention relates to a needle tip shielding system for a dental syringe for use with a dental injection needle that prevents accidental contact of the needle tip with an animal or human, such as patients, dentists, and other medical personnel and a dental syringe and in particular a dental syringe pre-filled with an anesthetic, even more particularly, a pre-filled dental syringe with a needle shield.

Background of the Invention

The clinical utilization of a pointed hollow needle in dental and related arts for the administration of anesthetics or medicaments to humans and animals is well known. After puncturing of the gum tissue and introduction of the needle tip the content of a syringe barrel connected to the rear part of the needle is administered to the human or animal through the hollow needle. The needle has then done its duty and is withdrawn from the human or animal.

In recent years there has been great concern over the contamination of dentists and associated personnel with a patient's bodily fluids and recognition that fluid contaminated sharps including used needles must be disposed of safely to avoid an accidental needle stick. This concern has arisen because of the advent of currently incurable and fatal diseases, such as Acquired Immunosuppressive Deficiency

Syndrome (AIDS), hepatitis, etc., which can be transmitted by the exchange of bodily fluids from an infected person to another person.

Various needle shields have been developed to address the problem of accidental needlesticks by fluid contaminated sharps. It is known to arrange needle tip shielding devices on injection needles, said shielding device having the ability to pivot in front of the needle tip upon withdrawal of the needle.

US5603699 discloses a needle guard assembly comprising a mounting base and a jacket assembly pivotally mounted on the mounting base. The jacket assembly comprises a shield member, a lever member and activating means. The activating means are adapted for movement of the jacket assembly from a retracted position to a closed position around a needle. Disadvantages of this needle guard assembly include its complicated construction and inherent bulkiness, being specifically unwanted in the dental industry due to the inherently limited field of vision.

EP0887082 describes a safety cover which is pivoting around a point near the needle hub. The safety cover is folded forwards and to the side over the needle after injection and withdrawal of the needle from the skin. To assure sufficient locking force, the pivoting safety cover is provided with a locking hook mechanism that mates with the needle hub upon locking, which in turn demands the manual push of the pivoting safety cover to be sufficient to overcome the resistance of the locking hook mechanism. This safety cover has the same disadvantage with regard to limiting the field of view of the dentist.

The devices disclosed by US5603699 and EP0887082 are not utilised in the field of dentistry in view of the disadvantages referred to.

Typically, a glass cartridge containing an injectable anesthetic liquid is first inserted into the syringe body. The needle is then attached to the syringe so that the needle penetrates a membrane on one end of the cartridge. After puncturing of the gum tissue with the needle tip, the content of the cartridge is administered to the human or animal through the hollow needle. The syringe and needle have then done their duty and are withdrawn from the human or animal. WO 2003/047664 discloses a dental syringe with a plunger, barrel, and a sleeve around the barrel. The sleeve is longitudinally slidable between a rearmost position in which the needle is exposed for use (figure lb) and a forwards position in which the needle is covered (figure la). At the plunger end of the sleeve there is a locking collar that rotates between two limit positions around the axis of the sleeve. Rotation of the collar to one limit position allows sliding of the sleeve between the rearmost and forwards positions. The sleeve can be releasably retained in the rearmost position or releasably locked in the forwards position by rotation of the collar to the other limit position. The document further discloses an anesthetic-filled cartridge in the form of a glass tube sealed with a rear end bung and a front end membrane is used with the syringe, wherein the cartridge is insertable through a side opening of the barrel (figure la) when the collar is in the forwards position. The needle penetrates the front end membrane of the cartridge and the plunger is moved forward to engage the cartridge bung and inject the anesthetic.

While the WO 2003/047664 dental syringe does not obscure the dentist's vision into the mouth of the patient, the shielding procedure following injection is cumbersome as the dentist must use two hands to hold the syringe, rotate the collar to unlock the sleeve, slide the sleeve to the forwards position, and rotate the collar again to lock the sleeve. The dentist's fingers also come into close proximity with the needle when rotating the collar and sliding the sleeve. US 2002/0103471 Al discloses a disposable injection syringe for use in dentistry. A cartridge containing a product to be injected is introduced into one end of the syringe body prior to use. The syringe also has a protective sheath moveable along the syringe body between two extreme positions that uncover and cover the needle tip.

A problem with existing dental syringes is formation of a poor seal between the needle and cartridge membrane when the needle penetrates the membrane. This results in leaking of the anesthetic into the patient's mouth during injection and / or contamination of the anesthetic which in turns leads to insufficient dosing of the anesthetic in the desired area, overdosing in the oral cavity, and infection in the patient. Another problem is the fragility of the glass cartridges containing the anesthetic which causes transport and handling difficulties.

It would be desirable to provide an alternative needle tip shielding system for use with a dental injection needle which addresses the drawbacks associated with the above described needle tip shielding devices. It would also be desirable to provide an alternative dental syringe which addresses the drawbacks associated with the above described syringes.

Summary of the Invention

The present invention seeks to mitigate, alleviate, circumvent or eliminate at least one of the above identified deficiencies in the art.

Accordingly an aspect disclosed herein relates to a needle shielding system for a dental syringe comprising: a needle having a needle tip and a needle bulge spaced apart from the needle tip; and a needle shield slidably mounted over the needle distally from the needle tip, the needle shield comprising: a base plate and at least one resilient arm extending distally from the base plate towards the needle tip, wherein the base plate or the at least one resilient arm has at least one protrusion extending laterally away from the base plate or the at least one resilient arm, wherein in use the system is dragged against another structure to move the needle shield along the needle though interaction between said structure and said at least one protrusion, until the needle shield contacts the needle bulge and the resilient arm covers the needle tip.

Another aspect disclosed herein relates to a needle shield for a dental syringe comprising: a base plate having a centrally located hole for receiving a needle therethrough and a plurality of plate protrusions at the periphery of the base plate; and two resilient arms extending distally from the base plate and ending in hooked tips, wherein each resilient arm has an arm protrusion. Yet another aspect disclosed herein relates to a pre-filled dental syringe comprising: a barrel having proximal and distal ends; a plunger inserted into the proximal end of the barrel, the plunger being slidably moveable within the barrel; an anaesthetic in contact with and between the plunger and the distal end of the barrel; and a needle connected to the distal end of the barrel; wherein in use the needle is inserted into the gum or inner cheek of a patient and the plunger is depressed to inject the anesthetic though the needle and into the patient.

Further advantageous embodiments are disclosed below and in the appended patent claims.

Brief Description of the Drawings

These and other aspects, features and advantages of which the invention is capable will be apparent and elucidated from the following description of non-limiting embodiments of the present invention, reference being made to the accompanying drawings, in which

Fig. 1 illustrates a cross-sectional top view and a front view of a needle shielding system prior to use according to an embodiment of the present invention;

Fig. 2 shows the needle shielding system of Fig. 1 after use;

Fig. 3 is a perspective view of the needle shielding system of Fig. 2;

Fig. 4 illustrates a cross-sectional top view and a front view of a needle shielding system prior to use according to an alternate embodiment of the present invention;

Fig. 5 shows the needle shielding system of Fig. 4 after activation of the needle shielding system;

Fig. 6 is a perspective view of the needle shielding system of Fig. 5;

Fig. 7 illustrates two perspective views of a shield activator for use with the needle shielding system of Figs. 1 to 6; and

Fig. 8 shows front, side, and top views of the shield activator illustrated in

Fig. 7.

Fig. 9 illustrates a cross-sectional top view and a front view of a dental syringe pre-filled with anesthetic in accordance with one embodiment of the invention;

Fig. 10 shows a cross-sectional top view and a front view of a dental syringe pre-filled with anesthetic and having a needle shielding system according to another embodiment of the invention; Detailed Description of the Embodiments

Embodiments of the present invention will be described in more detail below with reference to the accompanying figures in order for those skilled in the art to be able to carry out the invention. The invention may also be embodied in alternative forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. The invention is only limited by the appended patent claims.

Figures 1 to 3 illustrate a needle shielding system for a dental syringe 100 for use with a dental needle hub 104 while figures 4 to 6 illustrate a needle shielding system for a dental syringe 200 for use with a syringe 204. The needle hub 104 may be provided with a needle 300 extending distally away from the needle hub 104 with a needle tip 304 at the distal end. The needle hub 104 may further have a needle hub cavity 105, opening up proximally, for receiving a top portion of a syringe with a medicament ampoule receptacle. The needle 300 continues proximally through the hub cavity 105 and proximally beyond the proximal end of the needle hub 104. The proximal end of the needle 300 may also be provided with a needle tip 304 for facilitating penetration of the medicament ampoule, such as a medicament ampoule carrying an anesthetic therein. The inner wall of the needle hub 104 may be provided with threads 106, for facilitating mounting of the needle hub 104 on a syringe with a medicament ampoule receptacle. The syringe 204 may be a pre-filled syringe, such as a syringe pre-filled with an anesthetic. Apart from these differences, the needle shielding systems 100, 200 are identical in structure and function.

Needle shielding systems for a dental syringe 100, 200 have a needle 300 and a needle shield 400. Needle 300 has a needle tip 304 and a needle bulge 308 located on the shaft of the needle away from the needle tip. Needle shield 400 has a base plate 404 and a plate shaft 412 with a hole 408 extending through the shaft 412 for receiving the needle 300 through the centre of the plate 404. The base plate 404 also has at least one plate protrusion 428 at the periphery of the plate as shown in figures 3 and 6. A plurality of plate protrusions 428 may be evenly spread around the periphery of the base plate 404. The plate protusions 428 need not be shaped as truncated triangles as illustrated. For example, the plate protusions 428 could be rectangular in shape. In use the plate protrusions 428 facilitate easier activation of the shield 400 following withdrawal of the needle from the patient as will be described below. Two resilient arms 416 extend away from the base plate 404 in the same general direction as the longitudinal axis of the needle 300. Each arm 416 ends in hooked tip 420. At least one arm protrusion 424 is illustrated on each resilient arm 416. Although not shown, a plurality of arm protrusions 424 may be present on each resilient arm 416 such as 2, 3, or 4 arm protrusions 424 spaced apart from each other. Like the plate protrusions 428, the arm protrusions 424 allow for easier activation of the shield 400 following withdrawal of the needle from a patient. This will become clearer from the description below. However, a person skilled in the art will understand it is not essential for the needle shield 400 to have both plate protrusions 428 and arm protrusions 424. Sufficient shielding of the needle tip 304 is attainable from the presence of either at least one plate protrusion 428 or at least one arm protrusion 424. Figures 1 and 4 show the hooked tips 420 and the arms 416 urged apart from each other into a tension state in which free passage of the needle 300 is possible through hole 408 and the hooked tips 420 are in contact with the surface of the needle 300. Figures 2 and 5 show the resilient arms 416 in a resting state in which the needle 300 is enclosed within the needle shield 400.

Prior to use the needle shield 400 is slidably mounted on the needle 300 through the hole 408 so that the needle shield 400 is in the tension state referred to above with respect to figures 1 and 4. The dentist then inserts the needle 300 into the gum or inner cheek of a patient and injects an anesthetic. The needle is then

withdrawn from the gum or inner cheek and moved away from the mouth of the patient. While still holding the needle shielding system 100, 200, the dentist drags the system against a nearby structure to activate the shielding effect. As the systems 100, 200 are dragged, the plate protrusion(s) 428 or the arm protrusion(s) 424 interact with the nearby structure to move, such as slide, the needle shield 400 along the needle shaft towards tip 304.

Suitable nearby structures include the arm of the dental chair, the edge of the tray containing the dentist's tools, or a dental brick. An alternative suitable structure is shield activator 500 depicted in figures 7 and 8. Shield activator 500 has an activation plate 504, a clip 512, and a shaft 508 extending between the activation plate 504 and the clip 512. The clip 512 is configured to snap fit onto a rod 516 or other similar supporting equipment in the immediate vicinity of the dentist. Shield activator 500 may be made of plastic or metal. In use the plate protrusion(s) 428 and / or the arm protrusion(s) 424 of the systems 100, 200 interact with an edge of the activation plate 504 to move the needle shield 400 along the needle shaft towards tip 304.

When the hooked tips 420 pass over the needle tip 304 the arms 416 snap centrally in front of the needle tip. The plate shaft 412 then contacts needle bulge 308 as shown in figures 2 and 5. The needle shield 400 can then move no further along the needle shaft and the dentist, patient, and associated personnel are protected from accidental contact with the needle tip. The needle shield 400 may be made of a plastic material having a suitable combination of tenacity, rigidity, fatigue resistance, elasticity, and creep deformation resistance. A suitable plastic material has a high creep deformation resistance, i.e. it has a low tendency to slowly move or deform permanently under the influence of an applied external pressure. Hence, needle shield 400 may be stored in an assembled ready mode (tension state) for a prolonged time without extensive creep deformation of the arms 416. A plastic needle shield 400 may be colored for ease of recognition. The needle shield 400 may be a monolithic homogenous injection molded plastic needle shield. An advantage of a monolithic needle shield 400 is a lower production cost in comparison to other devices made of more than one part requiring subsequent assembly. The needle shield 400 may be made of a thermoplastic polymer. The thermoplastic polymer could be crystalline, amorphous, or comprising crystalline and amorphous alternating regions. A creep resistance of the thermoplastic polymer of choice may be at least 1200 MPa (ISO 527, ASTM D638). Suitable plastics for the needle shield 400 may be selected from the group comprising of polyoxymethylene (POM), polybutylen terephthalate (PBTP), polymethyl methacrylate (PMMA), acrylonitrile butadiene styrene (ABS), styrene acrylonitrile (SAN), acrylonitrile styrene acrylate (ASA), polystyrene (PS), styrene butadiene (SB), liquid crystal polymer (LCP), polyamide (PA), polysulfone (PSU), polyetherimide (PEI), polycarbonate (PC), polyphenylene oxide (PPO), and/or PPO/SB, and co- and terpolymers thereof. These polymers have the advantages of providing enhanced storing capacity, even in a strained state, due to the excellent structure memory of these polymers.

Figure 9 illustrates a pre-filled dental syringe 100 that has a barrel 104, plunger 108, anesthetic 112, and a needle 300. The plunger 108 is inserted into the proximal end of the barrel 104 and is slidably movable within the barrel 104 while maintaining a tight fit against the barrel's walls. The solution of the anesthetic 112 is contained within the barrel 104 in between the plunger 108 and the distal end of the barrel 104. The anesthetic 112 is in contact with the walls of the barrel 104 and the end of the plunger 108. The needle 300 is connected to the distal end of the barrel 104. A needle cap (not shown) is placed over the needle 300 to seal the anesthetic inside the syringe. This arrangement allows for reduced leakage of the anesthetic from the syringe into the mouth of the patient during use and decreases the chance of microbial contamination of the anesthetic. The need for insertion of a separate cartridge containing the anesthetic is also eliminated. Another advantage of pre-filled syringes over cartridge syringes is that aspiration may be controlled through piston displacement. In use the needle 300 is inserted into the gum or inner cheek of the patient and the plunger 108 is depressed to inject the anesthetic 112 though the needle 300 and into the patient. The dental syringe is then disposed of appropriately. The syringe may be made of glass or plastic although plastic is preferred given the single use and disposable nature of the syringe. Any suitable dental anesthetic 112 may be used in the dental syringe 100. For example, the dental anesthetic 112 may be selected from the group consisting of lidocaine (xylocaine or lignocaine), procaine

(novocaine), articaine (septocaine or ubistesin), marcaine, mepivacaine and combinations thereof. The solution of the anesthetic 112 may contain additional ingredients such as vasoconstrictors (e.g. epinephrine), sodium hydroxide, and / or sodium chloride.

Figures 4 to 6 and figure 10 show an another pre-filled dental syringe 200 which includes a needle shielding system for preventing accidental contact of the needle tip with the patient or the dentist thereby reducing the risk of spreading disease. Like syringe 100 described in figure 9, the dental syringe 200 has a barrel 204, plunger 208, anesthetic 212, and a needle 300. The plunger 208 is slidably moveable within the barrel 204. The solution of the anesthetic 212 is again contained within the barrel 204 in between the plunger 208 and the distal end of the barrel 204. The needle 300 is connected to the distal end of the barrel 204 and a needle cap (not shown) is placed over the needle 300. The needle shielding system is made up of a needle shield 400 and a needle bulge 308 located on the shaft of the needle 300 away from the needle tip 304. Needle shield 400 has a base plate 404 and a plate shaft 412 with a hole 408 extending through the shaft 412 for receiving the needle 300 through the centre of the plate 404. The base plate 404 also has at least one plate protrusion 428 at the periphery of the plate as shown in figure 6. A plurality of plate protrusions 428 may be evenly spread around the periphery of the base plate 404. The plate protusions 428 need not be shaped as truncated triangles as illustrated. For example, the plate protusions 428 could be rectangular in shape. In use the plate protrusions 428 facilitate easier activation of the shield 400 following withdrawal of the needle from the patient as will be described below. Two resilient arms 416 extend away from the base plate 404 in the same general direction as the longitudinal axis of the needle 300. Each arm 416 ends in hooked tip 420. At least one arm protrusion 424 is illustrated on each resilient arm 416. Although not shown, a plurality of arm protrusions 424 may be present on each resilient arm 416 such as 2, 3, or 4 arm protrusions 424 spaced apart from each other. Like the plate protrusions 428, the arm protrusions 424 allow for easier activation of the shield 400 following withdrawal of the needle from a patient. This will become clearer from the description below.

However, a person skilled in the art will understand it is not essential for the needle shield 400 to have both plate protrusions 428 and arm protrusions 424. Sufficient shielding of the needle tip 304 is attainable from the presence of either at least one plate protrusion 428 or at least one arm protrusion 424. Figures 10 and 4 show the hooked tips 420 and the arms 416 urged apart from each other into a tension state in which free passage of the needle 300 is possible through hole 408 and the hooked tips 420 are in contact with the surface of the needle 300. Figures 3 and 6 show the resilient arms 416 in a resting state in which the needle tip 304 is enclosed within the needle shield 400.

Prior to use of the dental syringe 200, such as during manufacture of the syringe 200, the needle shield 400 is slidably mounted on the needle 300 through the hole 408 so that the needle shield 400 is in the tension state referred to above with respect to figures 10 and 4. The dentist then inserts the needle 300 into the gum or inner cheek of a patient and depresses the plunger 208 to inject the anesthetic 212. The needle 300 is then withdrawn from the gum or inner cheek and moved away from the mouth of the patient. While still holding the dental syringe 200, the dentist drags the syringe against a nearby structure to activate the shielding effect. As the syringe 200 is dragged, the plate protrusion(s) 428 or the arm protrusion(s) 424 interact with the nearby structure to move, such as slide, the needle shield 400 along the needle shaft towards tip 304.

Suitable nearby structures include the arm of the dental chair, the edge of the tray containing the dentist's tools, or a dental brick. An alternative suitable structure is shield activator 500 depicted in figures 7 and 8. Shield activator 500 has an activation plate 504, a clip 512, and a shaft 508 extending between the activation plate 504 and the clip 512. The clip 512 is configured to snap fit onto a rod 516 or other similar supporting equipment in the vicinity of the dentist. Shield activator 500 may be made of plastic or metal. In use the plate protrusion(s) 428 and / or the arm protrusion(s) 424 on the needle shield 400 interact with an edge of the activation plate 504 to move, such as slide, the needle shield 400 along the needle shaft towards tip 304.

When the hooked tips 420 pass over the needle tip 304 the arms 416 snap centrally in front of the needle tip. The plate shaft 412 then contacts needle bulge 308 as shown in figure 5. The needle shield 400 can then move no further along the needle shaft and the dentist, patient, and associated personnel are protected from accidental contact with the needle tip 304.

In the claims, the term "comprises/comprising" does not exclude the presence of other elements or steps. Although individual features may be included in different claims, these may possibly advantageously be combined, and the inclusion in different claims does not imply that a combination of features is not feasible and/or

advantageous. Singular references do not exclude a plurality. The terms "a", "an", "first", "second" etc do not preclude a plurality, and instead includes a both a singularity and a plurality. Reference signs in the claims are provided merely as a clarifying example and shall not be construed as limiting the scope of the claims in any way.

Claims

1. A needle shielding system for a dental syringe ( 100, 200) comprising:

a needle (300) having a needle tip (304) and a needle bulge (308) spaced apart from the needle tip (304); and

a needle shield (400) slidably mounted over the needle (300) distally from the needle tip (304), the needle shield (400) comprising:

a base plate (404) and at least one resilient arm (416) extending distally from the base plate (404) towards the needle tip (304), wherein the base plate (404) or the at least one resilient arm (416) has at least one protrusion (424, 428) extending laterally away from the base plate (404) or the at least one resilient arm (416),

wherein in use the system (100, 200) is dragged against another structure to move the needle shield (400) along the needle (300) though interaction between said structure and said at least one protrusion (424, 428), until the needle shield (400) contacts the needle bulge (308) and the resilient arm (416) covers the needle tip (304).

2. The system according to claim 1, wherein the at least one protrusion (424, 428) comprises at least one plate protrusion (428) at the periphery of the base plate (404).

3. The system according to claim 1 , wherein the at least one protrusion (424, 428) comprises at least one arm protrusion (424) on the resilient arm or arms (416).

4. The system according to claim 1 , wherein the at least one protrusion (424, 428) comprises:

at least one plate protrusion (428) at the periphery of the base plate (404); and at least one arm protrusion (424) on the at least one resilient arm (416).

5. The system according to any one of the preceding claims, wherein the at least one protrusion (424, 428) is shaped as a truncated triangle or as a rectangle.

6. The system according to any one of the preceding claims, wherein the needle shield (400) has a plurality of protrusions (424, 428), preferably between 6 to 10 protrusions (424, 428).

7. The system according to claim 6, wherein the plurality of protrusions (424, 428) are plate protrusions (428) spread evenly around the periphery of the base plate (404).

8. The system according to any one of the preceding claims, wherein the needle shield (400) has two resilient arms (416).

9. The system according to any one of the preceding claims, wherein the resilient arm or arms (416) end in a hooked tip (420).

10. The system according to any one of the preceding claims, wherein the base plate (404) further comprises a plate shaft (412) with a hole (408) for receiving the needle (300) through the centre of the base plate (404).

11. The system according to claim 10, wherein in use the plate shaft (412) contacts the needle bulge (308).

12. The system according to claim 11, further comprising a dental needle hub (104) or a syringe (204) distally from the needle tip (304).

13. The system according to any one of the preceding claims, wherein the needle shield (400) is made of plastic.

14. The system according to any one of the preceding claims, wherein the needle shield (400) is injection molded.

15. The system according to any one of the preceding claims, wherein the system (100) comprises a needle hub (104) for mounting on a syringe top.

16. The system according to claim 15, wherein the needle hub (104) comprises a needle hub cavity (105) opening up proximally on the needle hub (104), and wherein the needle (300) extends through the needle hub ( 104), such that the needle (300) is extending distally away from the needle hub (104) and proximally through the hub cavity 105 and proximally beyond a proximal end of the needle hub ( 104).

17. The system according to claim 16, wherein an inner wall of the needle hub (104) in the needle hub cavity ( 105) is provided with threads (106), for facilitating mounting of the needle hub (104) on a syringe.

18. The system according to any one of claims 1 to 14, wherein the system comprises a pre-filled syringe proximally of the needle (300).

19. The system according to claim 18, wherein the pre-filled syringe is pre-filled an anesthetic.

20. A needle shield (400) comprising:

a base plate (404) having a centrally located hole (408) for receiving a needle (300) therethrough and a plurality of plate protrusions (428) at the periphery of the base plate (404); and

two resilient arms (416) extending distally from the base plate (404) and ending in hooked tips (420), wherein each resilient arm (416) has an arm protrusion (424).

21. A kit comprising:

a needle shielding system (100, 200) according to any one of claims 1 to 19 or a needle shield (400) according to claim 20; and

a shield activator (500) comprising:

an activation plate (504) for interacting with the at least one protrusion (424, 428) of the needle shielding system ( 100, 200) or the needle shield (400);

a clip (512) configured to snap fit onto a rod (516); and

a shaft (508) extending between the activation plate (504) and the clip (512).

22. A pre-filled dental syringe (100, 200) comprising:

a barrel ( 104, 204) having proximal and distal ends;

a plunger (108, 208) inserted into the proximal end of the barrel (104, 204), the plunger (108, 208) being slidably moveable within the barrel (104, 204);

an anesthetic (112, 212) in contact with and between the plunger (108, 208) and the distal end of the barrel (104, 204); and

a needle (300) connected to the distal end of the barrel (104, 204);

wherein in use the needle (300) is inserted into the gum or inner cheek of a patient and the plunger (108, 208) is depressed to inject the anesthetic (112, 212) though the needle (300) and into the patient.

23. The dental syringe (200) according to claim 22, further comprising:

a needle bulge (308) spaced apart from a needle tip (304) on the needle (300); and a needle shield (400) slidably mounted over the needle (300) adjacent to the distal end of the barrel (204), the needle shield (400) comprising: a base plate (404) and at least one resilient arm (416) extending distally from the base plate (404) towards the needle tip (304),

wherein the needle shield (400) is slidable on the needle (300), such that the resilient arm (416) covers the needle tip (304) once the needle shield (400) contacts the needle bulge (308).

24. The dental syringe (200) according to claim 23, wherein the base plate (404) or the at least one resilient arm (416) has at least one protrusion (424, 428) extending laterally away from the base plate (404) or the at least one resilient arm (416), such that after injection the dental syringe (200) may be dragged against another structure to move the needle shield (400) along the needle (300) through interaction between said structure and said at least one protrusion (424, 428), until the needle shield (400) contacts the needle bulge (308) and the resilient arm (416) covers the needle tip (304).

25. The dental syringe (200) according to claim 24, wherein the at least one protrusion (424, 428) comprises at least one plate protrusion (428) at the periphery of the base plate (404).

26. The dental syringe (200) according to claim 24, wherein the at least one protrusion (424, 428) comprises at least one arm protrusion (424) on the resilient arm or arms (416).

27. The dental syringe (200) according to claim 24, wherein the at least one protrusion (424, 428) comprises:

28. The dental syringe (200) according to any one of claims 24 to 27, wherein the at least one protrusion (424, 428) is shaped as a truncated triangle or as a rectangle.

29. The dental syringe (200) according to any one of claims 24 to 28, wherein the needle shield (400) has a plurality of protrusions (424, 428), preferably between 6 to 10 protrusions (424, 428).

30. The dental syringe (200) according to claim 29, wherein the plurality of

protrusions (424, 428) are plate protrusions (428) spread evenly around the periphery of the base plate (404).

31. The dental syringe (200) according to any one of claims 23 to 30, wherein the needle shield (400) has two resilient arms (416).

32. The dental syringe (200) according to any one of claims 23 to 31 , wherein the resilient arm or arms (416) end in a hooked tip (420).

33. The dental syringe (200) according to any one of claims 23 to 32, wherein the base plate (404) further comprises a plate shaft (412) with a hole (408) for receiving the needle (300) through the centre of the base plate (404).

34. The dental syringe (200) according to claim 33, wherein in use the plate shaft (412) contacts the needle bulge (308).

35. The dental syringe (200) according to any one of claims 23 to 34, wherein the needle shield (400) is made of plastic.

36. The dental syringe (200) according to any one of claims 23 to 35, wherein the needle shield (400) is injection molded.

37. A kit comprising:

a pre-filled dental syringe (200) according to any one of claims 24 to 36; and a shield activator (500) comprising:

an activation plate (504) for interacting with the at least one protrusion (424,

428) of the needle shield (400);

a clip (512) configured to snap fit onto a rod (516); and

a shaft (508) extending between the activation plate (504) and the clip (512).