BACKGROUND OF THE INVENTION Various types of material, such as medical or dental materials are often packaged in preloaded sealed cartridges or in preloaded syringes. For example, US Patent No. 5,707,234 discloses a cartridge for dispensing dental materials. The cartridge is preloaded and is inserted into an ejector device at the time of use. The ejector device is manipulated such that a piston is caused to enter the cartridge and the material in the cartridge is expelled through a nozzle.

It also often the case a none-mixing tip is placed onto a syringe containing a material to be dispensed.

Especially in the case of preloaded cartridges, it is often the case that a material must first be mixed with another material in order to form the final product. These materials are often preloaded into cartridges used for a single application of the material. These types of cartridges are sometimes referred to as being a"unit dose." When a material is mixed at the time of use, especially in the case of a unit dose of dental material, it is often important to not only precisely mix the two components but to also place the components in the proper location in the oral cavity.

A need exists therefore for a mixing tip which will not only mix materials but will facilitate their exact application in for example, the oral cavity.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a front elevational, partially sectional view of a mixing tip according to the present invention.

Fig. 2 is a top plan view of one embodiment of a mixing tip according to the present invention.

PREFERRED EMBODIMENT FOR CARRYING OUT THE INVENTION As shown in the drawings, the present in invention is directed to a mixing tip 10 which can be alternatively preloaded or used with a loaded ejection device or syringe (not shown). More particularly, the mixing tip 10 is used with a dual-component material (not shown) which may be required to be mixed substantially immediately before application.

While useful with any number of such materials, the present invention has particular application to dual-component dental materials.

Mixing device 10 has a dual-chamber housing generally designated by the number 11 on the drawings. Dual-chamber housing 11 is preferably provided with first and second chambers 12 and 13 which are separated by a web or plenum 14. Chambers 12 and 13 have separate input passages 15 and 16 respectively, and separate output passages 17 and 18, also respectively. Output passages 17 and 18 fluidly communicate with first mixing chamber 19.

Mixing chamber 19 is in turn in communication with the interior passage 20 of a dispensing barrel 21. It will be appreciated therefore, that material flowing through input passages 15 and 16 or held within chambers 12 and 13 when tip 10 is pre-loaded, will be held separately by the division provided by plenum 14 while held within chambers 12 and 13 and will then be dispensed into chamber 19 to be expressed through interior passage 20.

Disposed within interior passage 20 is a static mixing device 30. Static mixing device 30 is preferably a length of twisted wire which is generally designated by the number 31 on the attached drawings. While the length of twisted wire 31 is not necessarily critical to the practice of the present invention, it is preferred that the wire be approximately the same length as barrel 21.

In another preferred embodiment of the invention, static mixing element 30 is provided at one end with a brush 32. It is to be appreciated that material flowing through

barrel 21 will be caused to physically contact brush 32. By manipulating mixing tip 10, brush 32 can be used to facilitate precise application of the expressed material. The material from which brush 32 is fabricated is not critical to the practice of the present invention. The material should be substantially impervious to degradation caused by the material expressed through the mixing tip 10, and should not cause substantial discomfort or would be otherwise detrimental for the intended purpose. One preferred type of brush would be nylon bristles that are attached to static mixing device 30 in any conventional manner.

According to another embodiment of the invention, barrel 21 is made of a flexible, preferably plastic material that can be bent at any of a variety of angles in order to facilitate application of the expressed material.

First and second chambers 12 and 13 are preferably provided at an end distal to static mixing device 30 or at some other location therein, with a detent or snap bead 40 and a flange 41 which will mate to the device which is used to express material through mixing tip 10.

While this is one preferred method of mating and affixing to the expressing device, any other conventional such method is also within the scope of the present invention.

According to another embodiment of the present invention, as in shown in drawing figure 2, static mixing device 10 can be sealed with a snap-off cap 50. This is especially useful when mixing device 10 is preloaded with dental material, or when mixing device 10 is placed upon a preloaded syringe or other expressing device prior to use. In use, cap 50 encloses the open end 51 of barrel 21. At the time of use, or at some other time, cap 50 is snapped, broken or otherwise removed from barrel 21, thereby exposing open end 51 and brush 32 for use.

A mixing and dispensing syringe is shown by way of example in US Patent 4,776,704 which is hereby incorporated by reference or its disclosure.

It is apparent therefore, that a mixing tip according to the present invention is an advantageous improvement over dispensing tips previously known, and otherwise provides an improvement in the art.

WHAT IS CLAIMED IS: