WO1998057597A1

WO1998057597A1 - Dental syringe assemblies

Info

Publication number: WO1998057597A1
Application number: PCT/GB1998/001754
Authority: WO
Inventors: Alan Julian Segal
Original assignee: Segal Alan J
Priority date: 1997-06-17
Filing date: 1998-06-16
Publication date: 1998-12-23
Also published as: GB9712462D0

Abstract

A dental syringe assembly has a handpiece body (1) which is connected to an air and water supply hose (4). A disposable tip (2) is detachably connected to the handpiece body for directing air and water into a patient's mouth. A non-return valve is provided between the tip (2) and the handpiece body (1) to prevent return of contaminated material into the handpiece body (1). The tip (2) may be connected to the handpiece body (1) via an adaptor (13) in which case the valve is incorporated in the adaptor (13). Alternatively the tip (2) can be connected directly to a dedicated handpiece body (1) in which case the valve is incorporated in the body (1).

Description

DENTAL SYRINGE ASSEMBLIES

TECHNICAL FIELD

This invention relates to dental syringe assemblies such as are used

by dentists to direct air and/or water into a patients mouth for cleansing and

drying purposes.

BACKGROUND ART

An assembly of this kind is described in prior patent specification

WO 90/07912. The assembly described has a disposable plastics syringe

tip which is connected via an adaptor to a handpiece body to which air and

water are supplied. The tip can be discarded after use to avoid spread of

infection between patients. The adaptor is selected for the particular

handpiece body to permit use of a tip having a standardised connection. It

is also possible to connect a disposable plastics syringe tip directly (i.e.

without an adaptor) to a dedicated handpiece body.

Whilst this known arrangement provides an effective means of

preventing transfer of infection via material retained within the tip, there is

the possibility of infected material from one patient gaining access beyond

the tip to the handpiece body or adaptor from where it can be passed on to

the next patient through a fresh tip.

An object of the present invention is to provide means to

avoid such transfer of infection due to access of infected material beyond

the tip. DISCLOSURE OF THE INVENTION

According to the invention therefore there is provided a dental syringe

assembly comprising a handpiece body adapted to be connected to sources

of air and water, and a tip arranged to be connected to the handpiece body

for directing flow of air and water from the handpiece body into the patients

mouth, characterised by the provision of a non-return valve arranged to be

connected between the tip and the handpiece body.

With this arrangement, the valve can help prevent draw back along

the tip from the open end thereof of contaminated fluids and can also block

access of infected material beyond the tip into the handpiece body and

thereby help prevent transmission of infection between patients.

In the case where the syringe assembly is arranged for separate

delivery of air and water, the non-return valve is preferably applied to the

water delivery, although alternatively or additionally, the valve may be

applied to the air delivery.

In a particularly preferred embodiment, the tip has separate air and

water passages which may be arranged coaxially or alongside each other

and these are connected separately to air and water inlets at the handpiece

body, and in this case the non return valve is preferably applied to the water

passage only.

The non-return valve may be of any suitable form. In a preferred

embodiment, the valve has a spring loaded valve member, such as a ball, which is urged into sealing engagement with a valve seat, fluid pressure

during normal operation being sufficient to move the member off the seat

to permit passage of fluid.

Other kinds of non-return valve can also be used. For example, in an

alternative embodiment, the valve is of the constriction kind whereby valve

parts, such as silicon rubber reeds, tend to collapse or are urged into sealing

contact with each other but move apart in normal operation to permit

passage of fluid.

In the case where the valve is applied to water delivery which is

separated from air delivery, the valve may incorporate an outlet flow nozzle

to direct flow into the water passage of the tip and help prevent

communication, and hence transfer of material, between the air and water

passages.

This nozzle may be such as to extend into the water passage of the

tip and help form a seal therewith. The nozzle may be tapered to form a

tight wedging fit within the tip passage and this may contribute to or

establish the seal. Alternatively or additionally there may be an O-ring seal

or other sealing arrangement to fit around the tip passage, for example an

O-ring seal concentrically around the said nozzle whereby a tubular part of

the tip defining an inlet to the water passage fits tightly between the nozzle

and the O-ring seal.

In one embodiment, the valve may form part of an adaptor used between the handpiece body and the tip such adaptor having one end

arranged to be screwed or otherwise tightly and securely mated with the

particular handpiece, and an opposite end having means for detachable

engagement with the tip.

As described in the above mentioned prior patent specification, the

tip may be disposable and the means on the adaptor for detachable

engagement with the tip may be adapted for use with a standardised tip.

The means on the adaptor for detachable engagement with the tip

may comprise a bayonet connection, although other connections may also

be used.

In an alternative embodiment, and especially in the case where the

tip is detachably connected directly to a dedicated handpiece, the valve may

form part of or be incorporated in the handpiece.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described further by way of example only

and with reference to the accompanying drawings in which:-

Figs. 1 & 2 are diagrammatic sectional views of alternative forms of

syringe assemblies according to the invention; and

Fig. 3 is a detail of a modified version of the arrangement of Fig. 2.

BEST MODE OF CARRYING OUT THE INVENTION

Referring to Fig. 1 this shows a three way dental syringe assembly

having a handpiece body 1 , and a tip 2. The body 1 comprises a tubular structure connected at one end 3 to

a flexible coaxial hose arrangement 4 with inner and outer conduits

respectively connected to pressurised sources of water and air (not shown) .

These conduits are in communication with respective passageways running

through the tubular structure to air and water outlets at the opposite end 4.

This opposite end 4 is of the form of an internally threaded cap.

Two levers or buttons 5, 6 are mounted on the body and operate

flow control mechanisms. When one lever or button 5 is pressed this

allows flow of water through the respective passageway in the tubular

structure 1 . When the other lever or button 6 is pressed this allows flow

of air through the other passageway in the tubular structure 1 .

The tip 2 is a moulded disposable plastic structure having inner and

outer coaxially arranged tubes 7, 8. At one end 9 the tip 2 has an angled

section.

At the other end 10 the tip has an enlarged outer sleeve 1 1 in

communication with the outer tube 8. The inner tube 7 extends within this

sleeve 1 1 . The sleeve 1 1 has opposite side bayonet slots 12.

The tip 2 is connected detachably to the body 1 by means of an

adaptor 13. This adaptor 1 3 comprises a cylindrical adaptor body 14

secured within an outer cylindrical sleeve 1 5. The adaptor body 14 has a

central through passageway 16.

One end portion 17 of the passageway 1 6 is enlarged and contains a valve ball 18 which is urged by a coil spring 19 into sealing engagement

with a valve seat 20 at the junction between the enlarged end portion 17

and the adjacent small diameter portion 21 of the passageway 16.

The coil spring 19 is held captive within the enlarged end portion 1 7

of the passageway 1 6 by means of an inserted tube 22 having a central

tapered nozzle 23 directed away from the ball 18. Concentrically around

the nozzle 23 at the free end of the enlarged end portion 17 of the

passageway 1 6 there is mounted an O-ring seal 24. A further, smaller O-

ring seal 25 is set into opposite free end 21 of the passageway 16.

The adaptor body 14 has a further passageway 26 extending

therethrough alongside the central passageway 16. This further

passageway 26 opens at one end 27 adjacent the narrower end of the

central passageway 16. At its opposite end 28, this passageway 26 opens

to one side of the adaptor body 14.

The end part of the adaptor body containing the enlarged end

portion 17 of the passageway 16 is within the confines of the sleeve 15.

The opposite end part projects beyond the sleeve 1 5 and has an outer

peripheral screw thread 29. The adaptor body 14 has an outer flange 30

which retainingly abuts an inner flange 31 at one end of the sleeve 15. At

the opposite end of the sleeve 1 5 there are opposed inwardly directed

bayonet pins 32.

An annular space is defined between the sleeve 1 5 and the end part of the adaptor body 14 containing the enlarged end portion 1 7 of the

central passageway 16. This annular space is bounded at its inner end by

an O-ring seal 33 mounted on the flange 30. The side-opening end 28 of

the side passageway 26 opens into the annular space.

The projecting end of the adaptor body 14 having the outer

screw thread 29 is screwed tightly into the internally threaded cap end 4 of

the handpiece body 1 . The central water passageway outlet engages the

O-ring seal 25 to form a water tight sealed connection with the central

passageway 16 in the adaptor body 14. The outer coaxial air passageway

connects with the side passageway 26 in the adaptor body 14.

The enlarged end 10 of the tip 2 is inserted within the annular space

and is held in position by engagement of the bayonet slots 12 with the

bayonet pins 32. The free edges of the outer sleeve 1 1 bear against the

outer O-ring seal 33, and the inner tube 7 fits tightly on the tapered nozzle

23 and is engaged on its outer periphery by the O-ring seal 24.

The inner tube 7 is thereby connected with the central passageway

1 6 and the outer tube 8 is connected with the side passageway 26 in a

secure manner and with water-tight sealing between the air and water

passageways.

When the lever or button 6 is actuated to admit pressurised air this

flows through the side passageway 26 in the adaptor body 14 into the outer

tube 8 of the tip 2 to exit from the free end thereof. In this position the ball 18 is pressed tightly against the valve seat 20 ensuring that the inner

tube 7 in the tip is sealed relative to the water passageway 1 6 in the

handpiece body 14.

When the lever or button 5 is actuated to admit pressurised water

this flows through the central passageway 1 6 in the adaptor body 14 and

displaces the ball 18 off its valve seat 20 to permit flow into the inner

tube 7 of the tip to exit from the free end thereof. When this lever or

button 5 is released to cut off flow of pressurised water the valve ball 18

is immediately spring urged onto its valve seat 20 to seal the tip 2 relative

to the handpiece body 1 and thereby prevent reverse flow of any infected

matter.

After use, the tip 2 can be removed from the adaptor 13, by

disengaging the bayonet fixing, and discarded. Subsequently a fresh tip can

be used with the adaptor.

The adaptor 13 is selected to fit the particular handpiece body 1 at

the screwed end. At its opposite end it is adapted for use with a

standardised disposable tip 2. Different adapters can be provided for use

with different handpiece bodies 1 , such adaptors differing with regard to the

size or dimensions or mode of attachment of the projecting end of the valve

body but having the same size, dimensions and structure at the other end.

Fig. 2 shows an alternative embodiment which differs essentially only

with regard to the valve member. Other parts are constructed in like manner to Fig.1 and the same reference numerals are used for these.

In place of the ball 18, the spring 19 and the nozzle 23, there is a

reed structure 34 held in place by a cylindrical structure 35. The reed

structure 34 has two silicone rubber strips or flaps shaped to lie against

each other at the end facing the tip 2 to define a closed tapering passage.

When water pressure is applied to the central passageway 16 the

strips or flaps move apart to permit passage of water. When the pressure

is turned off, the flaps collapse against each other and prevent backwards

flow from the tip 2.

As shown in Fig. 2, there is no nozzle for sealing engagement with

the inner tube 7 of the tip 2.

With the modification of Fig. 3, a nozzle 36 for this purpose is

shown, such nozzle being integral with the tube 35.

It is of course to be understood that the invention is not intended to

be restricted to the details of the above embodiment which are described

by way of example only. Thus, for example, although the foregoing

description is directed to an arrangement in which the tip 2 is connected to

the handpiece body 1 via an adaptor 13 it is to be understood that the tip

may be directly connected to a dedicated handpiece in which case the

releasable connection for the tip 2 and the one-way valve arrangement will

form part of or be incorporated in or attached to the handpiece body 1 , for

example essentially by integrating the structure shown in the drawings with the handpiece body 1 rather than having the detachable connection

established with the screwthread 29.

Claims

1 . A dental syringe assembly comprising a handpiece body adapted to

be connected to sources of air and water, and a tip arranged to be

connected to the handpiece body for directing flow of air and water from

the handpiece body into the patients mouth, characterised by the provision

of a non-return valve arranged to be connected between the tip and the

handpiece body.

2. An assembly according to claim 1 arranged for separate delivery of

air and water characterised in that the non-return valve is applied to the

water delivery.

3. An assembly according to claim 1 wherein the tip has separate air

and water passages which are connected separately to air and water inlets

at the handpiece body characterised in that the non-return valve is applied

to the water passage only.

4. An assembly according to claim 3 characterised in that the air and

water passages are arranged coaxially in the tip.

5. An assembly according to any one of claims 1 to 4 characterised in

that the valve has a spring loaded valve member urged into sealing

engagement with a valve seat.

6. An assembly according to claim 2 or 3 or any claim dependent

thereon characterised in that the valve incorporates an outlet flow nozzle to

direct flow into the water passage of the tip.

7. An assembly according to claim 6 characterised in that the nozzle is

tapered to form a tight wedging fit within the tip passage.

8. An assembly according to claim 6 or 7 characterised in that a sealing

arrangement is provided around the tip passage to form a seal with the

nozzle.

9. An assembly according to claim 8 characterised in that the sealing

arrangement comprises an O-ring seal.

10. An assembly according to claim 9 characterised in that a tubular part

of the tip defining an inlet to the water passage fits tightly between the

nozzle and the O-ring seal.

1 1 . An assembly according to any one of claims 1 to 10 characterised in

that the valve forms part of an adaptor used between the handpiece body

and the tip.

12. An assembly according to claim 1 1 characterised in that the adaptor

has one end arranged to be mated with the handpiece and an opposite end

having means for detachable engagement with the tip.

13. An assembly according to claim 12 characterised in that the means

on the adaptor for detachable engagement with the tip comprise a bayonet

connection.

14. An assembly according to any one of claims 1 to 10 characterised in

that the valve forms part of the handpiece body.