GB2329341A

GB2329341A - Mouldable dental impression tray

Info

Publication number: GB2329341A
Application number: GB9720073A
Authority: GB
Inventors: Anthony Lewis Lovat
Original assignee: ORAL PROTECTORS Ltd
Current assignee: ORAL PROTECTORS Ltd
Priority date: 1997-09-23
Filing date: 1997-09-23
Publication date: 1999-03-24
Also published as: GB9720073D0

Abstract

A method of producing a dental impression of a set of teeth using a dental impression material (18) in an impression tray (10), wherein the tray (10) is formed from mouldable material and is moulded partly to the teeth in vivo. The tray (10) is of thermoplastic material and is heated to make it mouldable in vivo, and is then set rigid. The tray (10) and impression material (18) are moulded also to teeth opposing said set of teeth, part of the impression material (18) being pushed through holes (30) in the tray (10) to be moulded to the opposing teeth. A member (10) of U-shape, with a cross-section of U-shape, is used as a dental impression tray and has keying means (12, 14, 16) or adhesive means to retain impression material in the tray (10). A kit comprises a member of such a shape and means to adapt it for use as a dental impression tray (10); said means comprise adhesive and/or a tool. The cross-section may be an H-shape of which the said cross-section U-shape is part. A mouth guard (26) or denture may be produced.

Description

"Dental Devices" Fisid of ihe Invention This invention relates to dental devices and more particularly but not exclusively dental impressions and mouth guards.

B-round The normal method of making a dental impression of a person's upper or lower set of teeth is to take a rigid tray of U-shape (like the shape of a normal set of teeth) and of cross-section comprising a U-shape, sometimes with a handle, usually projecting from the bottom of the U-shape of the tray in the plane thereof, and to fill this with a suitable quantity of dental impression material, and for the dentist then to place Q; carefully and precisely so that the material moulds precisely to the teeth and hold it there until the material sets. The moulded material in the tray is then known as a dental impression. From this, usually in a dental laboratory, there is made a plaster cast of the teeth, a denture, a mouth guard or other article conforming to the teeth. A mouth guard produced by this method is quite expensive.

--*re recently, a much cheaper mouth guard has been produced, which is a thennoplastic member of mouldable material of U-shape with a cross-section comprising a square-bottomed U-shape. This is heated in boiling water for ten to fifteen seconds and then placed around a person's upper set of teeth and moulded with the fingers and thumb to fit to the teeth. Because the fit is not very good, it is recorninended that the process be repeated several times, improving the fit each time.

er, while this device is very cheap, it does not provide a good fit to the teeth and therefore does not protect them very well and tends not to stay in place. Such a mouth guard, for example that known under the trade name "Senior Mouthguard", is obtainable from the chain of shops in England known as Olympus Sports, now part of Sports Division Limited of Scotland and is made of a suitable EVA (ethylene vinyl acetate).

Thus, the production of a good quality mouth guard requires the expertise of a qualified dentist; and, for example, a dentist may visit a school to prepare dental impressions of all those pupils who require mouth guards.

The Invention The present inventor has realised that a much cheaper procedure could be advantageous; but realised that, if a traditional dental impression tray and dental impression material were supplied to a user, even a staff member at a school, the quality of the dental impressions produced would be very poor, partly due to the lack of expertise and partly due to the relatively large size of the dental impression tray compared with the set of teeth and the relatively large amount of dental impression material that is required. Accordingly, first and second aspects of the invention provide a method as claimed in claim 1 or 2. This causes the tray to be made only slightly larger than the teeth and the quantity of impression material then to be used can be relatively small. This has the advantages not only of reducing the quantity of impression material required but also of using such a small quantity that there is little room for error in making the dental impression and, perhaps more importantly, the small quantity of impression material ensures that there is minimum deformation (skewing) or other change, e.g. especially shrinkage, of the dental impression once it is taken away from the teeth. In fact, these advantages are such that even a good dentist may well find he can obtain improved reliability and precision using this method to make a dental impression, and can therefore have produced from the dental impression improved (e.g. directly or by way of a plaster cast) articles conforming to the teeth, eSg. plaster casts, dentures, crowns, caps, implant prostheses, adhesive bridges1 veneers, night guards, stents or splints, as well as mouth guards.

Obviously, once the tray has been moulded to the teeth, it must retain this shape by some mechanism to set it. This may be inherent in the material, such as by inclusion in it of a curing or cross-linking component, or may be effected by external means, e.g. drying. The moulding may be termed a plastic deformation, ie without retaining memory of its former shape, as opposed to an elastic deformation in which tbe material returns to its former shape. Most or all materials have a mixture of plastic and elastic properties but usually have one vastly more than the other at any one time so that the material is then said to be in a plastic state or an elastic state as the case may be. The tray, once moulded and having thereafter substantially tost its plastic properties, may still be somewhat elastic provided this does not detract from its ability to retain the dental impression in use. The features of claim 3 provide a pr tical method of putting into effect the moulding action on the tray and then setting of the tray, since a thermoplastic material, when its temperature is again lowered, will be substantially no longer plastic and mouldable but only somewhat elastic, having a memory of its moulded shape. Once the dental moulding material has been placed in the tray and used to take an impression of the teeth, this material becomes set and further helps to retain the impression shape accurately.

The features of claim 4 allow the dental impression to be even truer since it is held more rigidly and is therefore less likely to change in the manner mentioned above once taken away from the teeth.

The features of claims 5 and 6 can be used to improve the eventual mouth guard since this will fit snugly also to the opposing set of teeth. The features of claim 7 facilitate this method of obtaining the dental impression, particularly but not exclusively if the tray is formed as one with an inverted form of the tray for the opposing set of teeth, e.g. two back-to-back U-shaped cross-sections then becoming an H-shaped cross-section.

Other aspects of the invention consist in a tray and a member as claimed in claims 10 and 11. Some advantages are indicated above. Experiments with the prior art mouldable mouth guard mentioned above have shown that it is not suitable for use itself as a dental impression tray. The dental impression material tends to come free from it very easily after the impression has been made so that it is not sufficiently reliable to act as an impression tray. The features of claims 12 and 13 can be used to adapt it to be a dental impression tray. Another aspect of the invention consists in a kit of parts as claimed in claim 16. In this case, a member, which may for example be the prior art member, is provided together with means to adapt it for use as a dental impression tray in the manner just mentioned, for example by the means recited in claim 17 or 18. The features of claim 19 provide a member that has a shape particularly useful for moulding to both of opposing sets of teeth and then allowing the taking of a high quality impression of them both together.

Further aspects of the invention consist in a dental impression as claimed in claim 20, a method of producing an article conforming to a set of teeth as claimed in claim 23, and an article conforming to a set of teeth as claimed in claim 28.

Reference will now be made by way of example to the accompanying drawings in which: Figure 1 is a perspective view of a mouldable tray embodying the invention; Figure 2 is a corresponding view of the same when it has been partly moulded to a set of teeth; Figure 3 is a corresponding view of the same with dental impression material therein; Figure 4 is a corresponding view of the same when the dental impression material has been moulded to the teeth; Figure 5 is a corresponding view of a mouth guard produced by a method embodying the invention; and Figure 6 is a slightly turned corresponding view of a similar mouldable impression tray of H-shaped cross-section.

Referring to the drawings, a mouldable dental impression tray 10 is made of EVA s somewhat elastic and substantially not plastic at normal room temperature. It has keying means in the form particularly of side holes 12, and possibly of projections 14 and roughening (e.g. comprising grooves 16) to retain dental impression material when pressed into tray 10.

This is used in a method of producing a dental impression of a set of teeth using a dental impression material 18 in the dental impression tray 1Q the tray itself being inouldable and moulded partly to Lhe teeth, and then becoming substantially nonplastic The tray 10 is formed from mouldable material having the shape of a dental tray (as seen in Figure 1) and is moulded partly to the teeth in vivo. Tray 10 is heated in boiling water for 10 to 15 seconds and becomes plastic so that it can then be placed around a set of teeth in the usual way and then worked with the thumbs and fingers to conform to the shape of the teeth. This process may need to be repeated a few times. However, it is only a partial moulding to the teeth since the material cannot have the required flowability to produce an accurate moulding and at the same time have the thermoplastic properties required to enable it to be moulded and sufficiently set for the purposes mentioned above. Once the tray has been so moulded as shown in Figure 2, it is provided, as shown in Figure 3, with a dental impression material 18 which may be a twocomponent polyvinyl siloxane, for example that produced under the trade name PRESIDENT SYSTEM 75, MONOBODY by Coltene AG of Alst tten, Switzerland, for dental use. This can be dispensed into the tray 10 as in normal dental practice using a dispensing gun, e.g. that made under the trade name KERR, in conjunction with a nozzle having dual inlets and a single outlet, known as a "mixing tip", made under the trade name PRESIDENT SYSTEM 75, MONOBODY. This is then pushed firmly onto the set of teeth. Because of the partly conforming shape of the tray itself, there will be little impression material needed, only some 6-10ml, and in any case this will provide a good fit, flowing into the crevices of the set of teeth.

The person should be biting gently to aid this flow without deforming the tray 10.

The tray 10 and material are left in place for a couple of minutes or so until the dental impression material has cross-linked enough to retain its shape. The tray 10 and material 18 in it are then removed, having the appearance shown in Figure 4. This is then supplied to a dental laboratory to produce the required article, whether mouth guard 26, denture, plaster cast or other article conforming to the teeth.

For some dental purposes, e.g. where high accuracy is required, the tray 10 may be made of rigidly settable material and set rigid after being moulded to the teeth. A suitable material is a siloxane, polymerisable with cross-linkages by water, heated in boiling water to be thermoplastic while in a watertight bag to avoid the water causing pclymerisation at this stage, taken out of the bag and moulded to the teeth, and then exposed to water or steam to polymerise and set, e.g. in an autoclave. An alternative material is EVA mixed with a component sensitive to light, ultra-violet light, cFwave or the like actuation means to cause cross-linkages to be formed and/or otherwise to cause setting of the settable material. Such actuation means may be applied for a period from 10 minutes to 30 minutes, preferably about 15-20 minutes.

If necessary, special means may be used to ensure that the settable material of tray 10 does not lose its shape before it sets; for example, it may be exposed to cold water for 5 minutes before being put into the autoclave for a further 10 minutes, or again it may first be coated, e.g. by spraying or dipping, with an accelerator to harden the outside of it By using a tray 28 having the shape shown in Figure 6, this tray 28 can be moulded partly to teeth opposing the first said set of teeth and the impression material 18 can be moulded also to the opposing teeth. The upper and lower sides of the tray may be interconnected by holes 30, e.g. occupying about 20% to 40% of the at of the web between the two sides. This allows the dental impression material 18 to be provded by dispensing it on one side (the upper side as seen in Figure 6) only of said tray 28 and part of it to be pushed through the holes 30 in a web 32 of the tray 28 to the other side (the lower side as seen in Figure 6) of the tray when the tray 28 placed the second time into the mouth to mould the dental impression material 18.

The embodiments described are particularly applicable to moulding the dental impression tray 10, 28 to the teeth in vivo; the temperature to make the tray 10, 28 plastic need not be uncomfortably high.

It will be seen from Figure 1 that the tray 10 is a member of mouldable material 12 of U-shape (like the shape of a normal set of teeth) with a cross-section comprising a square-bottomed U-shape, and from Figure 6 that the tray 28 is of U-shape with a cross-section comprising an H-shape of which the said cross-section square-bottomed U-shape is part. The tray 10, 28 is adapted to be used as a dental impression tray, the adaptation comprising keying means 12, 14, 16, and/or it could comprise adhesive means (which may be provided in situ with a covering that can be peeled off) to retain the dental impression material in the tray 10.

If there is provided a kit of parts, as indicated above, this can include a separate adhesive to be spread inside the tray 10, 28 and/or a tool to provide the keying means, e.g. to roughen the internal surface of the member such as by making the grooves 16, to retain the dental impression material.

The provision of holes 12 for keying means and/or holes 30 for allowing dental impression material 18 to feed through web 32 between the upper and lower sides of the tray will usually be provided by moulding in the course of manufacturing the tray 28, but could be applied after manufacture by cooling the tray 28 until it is rigid and then drilling the necessary holes. As seen in Figure 6, the cross-section comprises an H-shape of which the said cross-section square-bottomed U-shape is part.

According to another aspect of the invention there is provided a thermoplastic material, that can be set. This is not limited to dental uses.

It will be apparent to one skilled in the art, that features of the different embodiments disclosed herein may be omitted, selected, combined or exchanged and the invention is considered to extend to any new and inventive combination thus formed.

Claims

1. A method of producing a dental impression of a set of teeth using a dental impression material in a dental impression tray, characterised in that the tray is formed from mouldable material by being moulded partly to the teeth in vivo.

2. A method of producing a dental impression of a set of teeth using a dental impression material in a dental impression tray, characterised in that the tray is formed from mouldable material having the shape of a dental tray and is moulded partly to the teeth in vivo.

3. A method as claimed in claim 1 or 2, characterised in that the tray is of thermoplastic material and is raised in temperature to make it mouldable in vivo.

4. A method as claimed in any one of claims 1 to 3, characterised in t?at the tray is of rigidly settable material and is set rigid after being moulded to the teeth in vivo.

5. A method as claimed in any one of claims 1 to 4, characterised in that the tray is moulded partly to teeth opposing said set of teeth.

Ci. A method as claimed in any one of claims 1 to 5, characterised in that the dental impression material is moulded also to teeth opposing said set of teeth.

7. A method as claimed in claim 6, characterised in that part of the dental impression material is pushed through holes in the tray to be moulded to the opposing teeth.

8. A method of producing a dental impression of a set of teeth using a dental impression material in a mould able dental impression tray, substantially according to any example hereinbefore described.

9. A method of producing a dental impression of a set of teeth using a dental impression material in a mould able dental impression tray, substantially according to any example hereinbefore described with reference to and illustrated in the accompanying drawings.

10. A dental impression tray, characterised in that it is mouldable to the teeth in vivo.

11. A member of material mouldable to the teeth in vivo, of U-shape with a crosssection comprising a U-shape, characterised in that it is adapted to be used as a dental impression tray.

12. A member as claimed in claim 11, characterised in that the adaptation comprises keying means to retain dental impression material in the tray.

13. A member as claimed in claim 11 or 12, characterised in that the adaptation comprises adhesive means to retain dental impression material in the tray.

14. A mouldable dental impression tray, substantially according to any example hereinbefore described.

15. A mouldable dental impression tray, substantially according to any example hereinbefore described with reference to and illustrated in the accompanying drawings.

16. A kit of parts comprising a member of material mouldable to the teeth in vivo, of U-shape with a cross-section comprising a U-shape, characterised in that the kit further comprises means to adapt the member for use as a dental impression tray.

17. A kit of parts as claimed in claim 16, characterised in that said means comprise adhesive.

18. A kit of parts as claimed in claim 16, characterised in that said means comprise a tool.

19. A member or kit as claimed in any one of claims 11 to 13 or 16 to 18, characterised in that the cross-section comprises an H-shape of which the said crosssection U-shape is part.

20. A dental impression, characterised in that it is produced with the aid of a method, trays member or kit of parts as claimed in any one of claims 1 to 19.

L.--A--kIental impression, substantially according to any example hereinbefore described.

22. A dental impression, substantially according to any example hereinbefore described with reference to and illustrated in the accompanying drawings.

23. A method of producing an article conforming to a set of teeth, characterised in that the article is produced with the aid of a dental impression as claimed in any one of claims 20 to 22.

24J A method as claimed in claim 23, characterised in that the article is produced as a mouth guard.

25 A method as claimed in claim 23, characterised in that the article is produced as a denture.

26 A method of producing an article with the aid of a dental impression, and suhstantially according to any example hereinbefore described.

27. A method of producing an article with the aid of a dental impression, and substantially according to any example hereinbefore described with reference to and illustrated in the accompanying drawings.

28. An article conforming to a set of teeth, characterised in that it is produced by a method as claimed in any one of claims 23 to 27.

29. An article as claimed in claim 28, characterised in that it comprises a mouth guard.

30. An article as claimed in claim 28, characterised in that it comprises a denture.

31. An article conforming to a set of teeth produced with the aid of a mouldable impression tray, and substantially according to any example hereinbefore described.

32. An article conforming to a set of teeth produced with the aid of a mouldable impression tray, and substantially according to any example hereinbefore described with reference to and illustrated in the accompanying drawings.