WO2000074588A1

WO2000074588A1 - Method for moulding dental fillings made of non-metallic compounds and kit for carrying out such method

Info

Publication number: WO2000074588A1
Application number: PCT/IT2000/000224
Authority: WO
Inventors: Fulvio Leni
Original assignee: Fulvio Leni
Priority date: 1999-06-04
Filing date: 2000-06-01
Publication date: 2000-12-14
Also published as: ITFI990136A1; AU5102500A

Abstract

A method for moulding a filling of a relatively small dental caries (2) - the filling being made of a non-metallic setting compound material - in which a predetermined amount (3) of said material sets on the tooth surface (1a) in which the caries (2) is formed, so as to form an individual matrix (6) the shape of which corresponds to the surface (1a). Once removed the individual matrix (6), the dental excavation and, afterwards, the filling of the cavity are carried out. When a surface layer (7c) of the filling is still in a mouldable condition, the individual matrix (6) is placed back on the tooth (1), making it abut on the surface (1a) thereof. The surface layer (7c) of the filling sets in contact with said matrix (6), so that the layer (7c) is moulded by the matrix (6). The matrix (6) is then removed and the filling trimmed.

Description

METHOD FOR MOULDING DENTAL FILLINGS MADE OF NON-METALLIC COMPOUNDS AND KIT FOR CARRYING OUT SUCH METHOD

DESCRIPTION Field of the invention The present invention relates to the field of dentistry, and namely it refers to a method for moulding dental fillings made of non-metallic compounds. Besides, it refers to a kit for carrying out such method. Background of the invention In the dentistry practice, and more specifically when carrying out dental fillings, one of the main problems which the medical operator has to face is that of accomplishing a correct moulding of the surface of the filling. In fact, to succeed in restoring the tooth to its original shape means to fully re-establish all its aesthetic qualities.

The moulding of the surface of the filling is presently carried out by the operator with a free-hand action, using suitable tools, on the material in a mouldable condition. Therefore, the result depends exclusively on the manual skill of the operator and it can be easily appreciated that only a high specialisation allows the accomplishment of a perfect shape restoration of the tooth. Nevertheless, when the area in which the caries to be treated is formed in a proximal (mesial or distal) position, the moulding is more troublesome, because it is difficult to obtain a correct contact point with the proximate tooth, whereby hardly ever the final result is fully satisfactory. In any case, the operation is fairly long and complicated, causing serious troubles to the patient.

Then, the need is deeply felt for filling-shaping techniques which are much less influenced by the manual skill of the particular operator who carries out the procedure and therefore can reduce the uncertainty to which the result can be presently exposed. Such techniques should also allow a shortening of the operation time. Summary of the invention

According to the present invention, such need is satisfied by means of a method for moulding a filling of a relatively small caries - said filling being made of a non- metallic setting compound material - characterised by the following steps :

- let a predetermined amount of said material set on the tooth surface in which the caries is formed, so as to form a individual matrix the shape of which corresponds to said surface; - remove the individual matrix;

- carry out the dental excavation and, afterwards, the filling of the cavity;

- when the surface layer of the filling is still in a mouldable condition, place the individual matrix back on the tooth, making it abut on the surface thereof;

- let the surface layer of the filling set in contact with the matrix, so that it is moulded by the matrix;

- remove the matrix and trim the filling.

If needed, an insulating film is laid over the shaped surface of the matrix before placing it back on the tooth, in order to avoid the joining between the filling material and the matrix, during the setting of the surface layer of the filling.

Advantageously, in order to assist the removal and placing back of the individual matrix, a pin is inserted in the material of the matrix, when it is still in a mouldable condition. According to the invention, a kit is also provided for carrying out the above mentioned method comprising, inside a single package, the setting material for forming at least one individual matrix and at least one pin for assisting the removal and the placing back of the matrix itself. Brief description of the drawings

Further characteristics and advantages of the method for moulding dental fillings made of non-metallic compounds and of the kit for carrying out such method according to the present invention will become apparent in the description which follows of one of its possible embodiments given as an example and not limitative, with reference to the attached drawings in which:

- figures 1 to 11 schematically show subsequent steps of the method for moulding dental fillings according to the invention. Description of a preferred embodiment

The embodiment of the method which will be described hereinafter makes use of a photopolymerisable filling material, of a type which has recently become more and more common for this specific purpose. Beside, reference is specifically made to I and II Black class caries, according to a terminology which will be understood by the person skilled in the art. With reference to the above mentioned figures and especially to figure 1, before starting the filling of a tooth 1 in which a caries 2 is formed, tooth 1 is isolated via a rubber dam or cotton-wool rolls, not shown. In case the caries is formed in a proximal (mesial or distal) position, a tape shaped matrix (made of metal in the rear sectors, transparent in the front ones) is placed. Also such tape matrix, belonging to the prior art, is not shown in the figures. Then, with particular reference to figure 2, a predetermined amount of photopolymerisable compound 3 is arranged over the top surface la of tooth 1. Compound 3 is spread over surface la so as to cover not only the area of caries 2, but the whole area of the dental excavation which will be carried out preliminarily to the filling.

As it will be made clearer hereinafter, the amount of material 3 has to be about 1 mm thick, in order to assure a suitable mechanical strength. Besides, the material used must necessarily be transparent - at least to a certain extent - to the radiation employed for the photopolymerisation. A material which is especially suitable is the Z100 ϊncisal produced by the company 3M. It is a restoration material having BISGMA (bisphenolglycidil metacrylate) and TEGDMA (triethylenglycol dimetacrylate) resins as organic base.

After that, a transparent plastic pin 4 is inserted in the material 3 (figure 3) , still in a mouldable condition, and the photopolymerisation is carried out, using a radiant device 5 of a known type. The transparency of the material assists the penetration of the radiation thereinside, allowing the photopolymerisation, i. e. the setting, also of the area contacting tooth 1. Therefore, the amount of material 3, once set, becomes in this way a individual matrix the shape of which corresponds, as a negative mould, to that of the covered area of surface la.

Advantageously pin 4, which can be formed for instance using a Hawe-Neos cervical matrix, can have a slightly enlarged base, in order to assist its fixing to material 3. Thus, exerting a traction on pin 4, individual matrix 6 and, if present, also the tape shaped matrix, can be easily removed by means of common tweezers. The adequate thickness of the amount of material 3 makes individual matrix 6 suitably strong. Therefore, matrix 6 can be kept intact during both removal and the following steps. The removal of individual matrix 6 from tooth 1 can be made easier if an insulating cavity liner or primer is spread over surface la, e.g. by means of a cotton-wool pallet, before applying material 3.

The conventional dental excavation is then accomplished, according to the techniques that are known to the experts in the field. Therefore, caries 2 is eradicated, forming in tooth 1 a larger and deeper cavity 9

(figure 4) and, once the metal or transparent tape-shaped matrix - if necessary - is placed back, the operator mordants the cavity and arranges the adhesive. As shown in figures 5 and 6, the filling of cavity 9 is carried out with the so-called incremental technique, i. e. depositing a number of superimposed layers one after the other.

In the depicted reference example, layers 7a, 7b of the same materials used for forming the individual matrix 6 are deposited within cavity 9 and photopolymerised successively. During this step, particular care has to be taken in order to prevent particles of the filling material from setting beyond the edge of the cavity. In fact, such particles could hinder a correct placing back of individual matrix 6 in the following step.

Referring to figure 7, before completing the filling of cavity 9, a lubricating film is spread over the shaped surface 6a of individual matrix 6, typically via a brush 8. A vaseline oil or an equivalent liquid insulating substance can be used as a lubricant. As an alternative, surface 6a can be simply moistened. Said surface is then polymerised again, so as to wipe out the free radicals that might be present thereon and could assist its chemical bond with the filling material.

Afterwards, the filling of cavity 9 is completed (see figure 8) with a surface layer 7c, the filling material being deposited slightly in excess. Then matrix 6 is placed back on the tooth, gradually pushing it until shaped surface 6a abuts on top surface la, as shown in figure 9.

Excess material is taken away from layer 7c and tooth 1 is radiated again (figure 10) , in order to photopolymerise such surface layer 7c of the filling. In this step individual matrix 6 is kept into contact with tooth 1, so that surface layer 7c can set in a shape which is obliged by matrix 6 itself. The radiation has to pass through matrix 6, and it is clear that the transparency of the material of which such matrix is made allows a correct accomplishment of this step too.

Once the surface of layer 7c is set enough, individual matrix 6 is pulled out, by means of tweezers or the assistance of a sealer. The removal is relatively easy, the lubricating and insulating action provided by the vaseline oil film preventing particles of layer 7c from being torn away by matrix 6. A last photopolymerisation (figure 11) completes the setting of layer 7c. Finally, the operator trims the filling, such operation being simple and quick owing to the fact that the surface of the filling already corresponds to the original shape of the tooth.

It will be easily appreciated that with the above described method the original shape of tooth 1 can be perfectly restored. Carrying out the method is easy and quick, and above all does not rely on the manual skill of the operator. Besides, in case of caries formed in a proximal (mesial or distal) position, it is easy to obtain an excellent contact point with the proximate tooth. The method can be profitably employed for any kind of direct filling, both in front sectors and in rear ones, and also for moulding compound inlays. The only essential condition for utilising the method is that the carious teeth have substantially integral external surfaces, i. e. that the caries are relatively small . By the way, the treatment of such caries is very frequent in dentistry practice.

Preferably, the photopolymerisable material which matrix 6 is made of, besides being transparent, has a colour which contrasts with the white of the tooth (e.g. green or blue) and can be easily abraded by means of rotating tools. In this way the trimming operation are even simpler, since it is easy to distinguish and remove possible residues on the tooth surface.

Even if, as an example, reference has been made to an embodiment in which photopolymerisable materials are used both for manufacturing individual matrix 6 and for accomplishing the filling, the method according to the invention can be carried out even with different materials, of which the use will require adaptations and modifications to one or more of the above described steps, as it is obvious to the skilled person.

Namely, the filling can be executed with different compound materials, e. g. self-polymerising ones. Also the matrix can be made of a self-polymerising material, a thermoplastic one, or a compound having a polycarbonate or a urethanic resin as a base, all these materials having low adhesion properties with respect to BISGMA and TEGDMA based filling materials. Any other setting material having suitable properties for the specific purpose - in terms of quality, accuracy and quickness of the surface setting and of mechanical strength - can be used. In this respect, it has to be stressed that if the matrix material and the filling one are chemically inert each other, the spreading of an insulating film can be unessential. Finally, the insulating film can be formed with techniques and substances different from the above described one.

Advantageously, what is necessary for the carrying out of the method according to the invention can be made available in a kit, in order to assist and speed up the work of the medical operator. The kit will comprise the setting material for a matrix 6 and the relevant pin 4, housed in a single package allowing a suitable preservation and a quick use. Preferably, the kit will also comprise a certain amount of the insulating liquid - or equivalent substance - as well as disposable tools for the spreading thereof, e.g. the brush 8, and for applying the setting material 3 on tooth 1. Multiple kits can be provided, that is to say kits for carrying out a pre-determined number of moulding operations. In that case the setting material can be boxed up in a single multi-dose container or pre-divided in single doses of various amounts, to be chosen according to the type of work which is taking place, and namely to the size of caries 2. Pins 4, inside the kit and in general for carrying out the method, can have various shapes and sizes according to the specific needs.

Variations and/or modifications can be brought to the method for moulding dental fillings made of non-metallic compounds and kit for carrying out such method according to the present invention without departing from the scope of the invention itself as set forth in the appended claims.

Claims

1. A method for moulding a filling of a relatively small dental caries (2) - said filling being made of a non- metallic setting compound material - characterised by the following steps:

- let a predetermined amount (3) of said material set on the tooth surface (la) in which said caries (2) is formed, so as to form a individual matrix (6) the shape of which corresponds to said surface (la) ; - remove said individual matrix (6) ;

- carry out the dental excavation and, afterwards, the filling of the cavity;

- when a surface layer (7c) of the filling is still in a mouldable condition, place said individual matrix (6) back on said tooth (1) , making it abut on the surface (la) thereof;

- let said surface layer (7c) of the filling set in contact with said matrix (6) , so that the layer (7c) is moulded by the matrix (6) ; - remove said matrix (6) and trim the filling.

2. The method according to claim 1, wherein an insulating film is laid over the shaped surface of said matrix (6) before placing it back on the tooth, in order to avoid the joining between the filling material and said matrix (6) during the setting of said surface layer (7c) of the filling.

3. The method according to claim 1 or 2, wherein, in order to assist the removal and placing back of said individual matrix (6) , a pin (4) is inserted in the material (3) of said matrix (6) , when it is still in a mouldable condition.

4. The method according to claim 3, wherein a pin (4) is used having an enlarged base so as to assist its fixing to material (3) .

5. The method according to one or more of the previous claims, wherein a photopolymerisable material is used for forming said matrix (6) .

6. The method according to one or more of the previous claims, wherein a photopolymerisable material is used for carrying out the filling.

7. The method according to claim 5 or 6, wherein said setting material of said matrix is a restoration material having a BISGMA or TEGDMA resin as a base.

8. The method according to one or more of claims from 5 to

7. wherein said pin (4) is made of a material which is transparent to the radiation used for the photopolymerisation.

9. The method according to one or more of the previous claims, wherein, in order to assist the removal of said individual matrix (6) from said tooth (1) , an insulating primer is spread over said surface (la) in which the caries (2) is formed, before applying said amount of setting material (3) .

10. The method according to one or more of the previous claims, wherein said setting material of said matrix (6) has a colour contrasting that of the tooth, in order to assist the removal of possible residues during the trimming step.

11. The method according to one or more of claims 2 to 10, wherein said insulating film is obtained by spreading a liquid lubricant over the shaped surface of said matrix (6) .

12. A kit for carrying out the method according to the previous claims, characterised in that it comprises the setting material for forming one or more individual matrixes (6) , and a corresponding number of pins (4) for assisting the removal and the placing back of respective matrixes (6) , all housed in a single package allowing a suitable preservation and a quick use.

13. A kit according to claim 12, wherein said setting material for forming said individual matrixes (6) is pre- divided in single doses of various amounts, each for forming one matrix (6) .

14. A kit according to claim 12 or 13, comprising the substance for forming said insulating film, alone or in combination with disposable tools for the application thereof .

15. A kit according to one or more of claims from 12 to 14, comprising disposable tools for the arrangement of said amount of setting material (3) of said matrix (6) over the tooth.