EP1406556A1

EP1406556A1 - Dental prosthesis made of composite material and method for making same

Info

Publication number: EP1406556A1
Application number: EP02787159A
Authority: EP
Inventors: Alain Fournet
Original assignee: Individual
Current assignee: Individual
Priority date: 2001-07-18
Filing date: 2002-07-16
Publication date: 2004-04-14
Also published as: US20040197739A1; FR2827501B1; FR2827501A1; US7210934B2; WO2003007837A1

Abstract

The invention concerns dental prostheses. It concerns a method for making a dental prosthesis of composite material by forming an adhesive interface between a metallic support and a cured ceramic material less than 3 mm thick, forming an intermediate interface by treating the surface of a ceramic material with an organic silane, and forming an adhesive interface of the reconstructing mass by treating the silane with an adhesive material compatible with the composite material. The intermediate interface is prepared by an etching operation in conditions liable to form cracks or embrittle the ceramics. The invention is applicable to dental prostheses made of composite material.

Description

The present invention relates to a method for producing a dental prosthesis which comprises a reconstitution mass fixed to a metal support and essentially formed from a composite material containing a polymeric binder in which is dispersed a mineral filler, as well as a dental prosthesis of this type.

Before describing the invention, it is necessary to specify the terminology used in the present specification and which corresponds to that of those skilled in the art.

Teeth care mainly includes the field of restorations and dental restorations, and the field of prosthetic restorations. Restorations designate fillings (classes I to V), inlays and onlays.

Prosthetic reconstructions designate fixed or removable prostheses. Most often, these reconstructions have a metallic part and affect several teeth, although they can also concern only one tooth. They are attached to one or more teeth. They can also be attached to one or more implants. These reconstructions are also called "prostheses" in this memo. The invention relates to prosthetic reconstructions of the fixed type. These reconstructions of the fixed type most often comprise a metal support, produced by casting a metal or an alloy, and a reconstruction mass fixed to the support and which can be formed from different materials. The materials most often used for these fixed reconstructions are ceramic materials and new generation composite materials.

The term “new generation composite material” means a composite material having a flexural strength at least equal to 100 MPa and a Vickers hardness at least equal to 450 N / mm ² , in the form of the polymerized material. Examples include the materials "Columbus" and "Cristobal" from IDR. Prosthetic ceramic restorations have high rigidity and low resistance to bending, and they must be fixed on solidly consolidated teeth. From an implementation point of view, the construction protocols for these ceramic prosthetic reconstructions are simple and well established, and they allow practically all prosthetists to obtain a very high success rate. In terms of clinical results, we find that people who have to wear such large ceramic reconstructions often encounter problems with the periodontium (alveolysis) with possibly thickening of the alveolodentary ligament, and frequently more or less mobility. pronounced teeth as well as fractures. The failure rate due to the above problems is significant.

Prosthetic reconstructions of new generation composite materials pose an opposite problem. From the point of view of clinical results, these prosthetic reconstructions give excellent results, proven by numerous clinical trials. From the point of view of the realization, although we know how to build, as described in the document WO 95/06 453, dental prostheses whose reconstruction mass is essentially made of a new generation composite material, these prosthetic reconstructions pose a problem of realization, because the fixing of the mass of reconstitution to the metallic support is delicate. Indeed, although experienced prosthetists obtain excellent results in a reproducible manner for this fixation, only about a tenth of prosthetists are capable of ensuring with certainty the attachment necessary for the fixation of such prostheses. We can therefore consider that the production of new generation composite materials prostheses has the disadvantage of having to be performed by very experienced prosthetists. The invention relates to the solution of this problem of producing prosthetic reconstructions of new generation composite material. As this problem is posed to prosthetists, the invention therefore relates to prostheses manufactured by prosthetists, that is to say prostheses which can be processed in baking and polymerization ovens, and not mouth work.

More specifically, the invention relates to the provision of means enabling practically all prosthetists to produce prostheses of new generation composite material.

We have already carried out repairs to ceramic prostheses in the mouth with new generation composite materials. We have often obtained good results. However, the prostheses thus repaired do not have the advantages of a prosthesis in which the entire reconstitution mass is formed of a composite material, since the added composite material is fixed to a rigid body constituted by the ceramic material. This ceramic material has a relatively large thickness, of the order of at least a millimeter, the mechanical strength and the rigidity of the prosthesis are given by the ceramic material, and the prosthesis exhibits the same behavior as a ceramic prosthesis in clinical trials. .

During such a repair, the surface of the ceramic part of the prosthesis to be repaired is treated, for example by etching compatible with work in the mouth, so that a silane can then be applied. A bonding layer of composite material is then applied, before several layers of composite material which each undergo a photopolymerization. All these operations are carried out at low temperature, in the patient's mouth.

Etching is a chemical surface treatment, and it involves attacking the surface of the ceramic material with solutions of strong acids, for example hydrofluoric. The ceramic material generally comprises a glassy phase which binds a crystalline phase. Etching mainly attacks either the glassy phase or the crystalline phase, and in both cases gives a significant surface irregularity.

It is also generally known that the bonding surface can be increased by a sandblasting operation (unnecessary readable for mouth work). In such sanding, a powder, for example of alumina grains or microbeads, is sprayed onto the surface. This treatment gives surface irregularities. It is sometimes observed that sandblasting causes the creation of cracks on the surface of the ceramic material. Etching, when applied after sanding, has the disadvantage of being able to cause propagation of the cracks initiated during sanding.

Since the ceramic material has a high rigidity, it easily causes crack propagation. Consequently, in the case of repairs of ceramic materials with composite materials, one is limited to conditions which avoid the formation of initial cracks and the propagation of such cracks. For example, the article "La vitrocéramique" by F. Leliêvre, Art and dental technique, vol. 5, n ° 2, April 1994, indicates that "etching is a source of weakening of the ceramic screed". Furthermore, the article by B. Terrié "Ceramics and collage", Art and dental technique, vol. 1, No. 4, August 1990, indicates that the surface irregularities formed by sandblasting "generate cracks which cause rupture by propagation after etching".

As indicated above, experience has shown that the most delicate part to be produced in a prosthesis of a new generation composite material is the attachment interface between the metal support and the reconstitution mass. Given the problems indicated posed by these bonding layers, one could consider applying the teachings of the aforementioned technique of repairing ceramic materials with composite materials for the solution of this problem. Thus, one could consider creating a metal attachment structure formed of a ceramic material, then attaching the reconstitution mass to the ceramic structure by suitable sandblasting and etching operations. However, as indicated in the prior art, it can be predicted that this solution would give cracks in the structure produced. The invention relates to a solution of this type, executed under special conditions such that these problems are solved, or do not even arise anymore.

More specifically, according to the invention, a prosthesis is produced by initial operations for forming a metal bonding interface for a ceramic material fired at high temperature, having in known manner a very good bonding resistance to metal. . According to the invention, the thickness of the ceramic material is very small, between 0.05 and 0.3 mm for example, so that any cracks and crack initiations which could be created have no repercussions on the rest of the prosthesis.

According to the invention, the problem of producing prostheses of composite material, that is to say of the attachment of a composite material to a metal support, is replaced by the problem of the attachment of a material. composite with a thin layer of ceramic material. According to the invention, this attachment can be achieved with a practically maximum success rate by practically all the prosthetists.

Thus, this ceramic-composite material attachment is obtained first by forming an irregular surface of the ceramic material on the side opposite to the interface for attaching the ceramic to the metal, then by forming an intermediate interface with a silane. organic, then by forming an interface for attaching the composite material to the organic silane, allowing the construction of a mass for reconstituting the composite material. The essential characteristics of the invention are therefore on the one hand the formation of an interface for attaching to the metal a very thin ceramic material, with a very irregular surface, then the production of an interface for attaching the reconstruction mass, which does not involve any delicate operation and can therefore be carried out practically by any prosthetist.

More specifically, the invention relates to a method of producing a dental prosthesis of the type which comprises a reconstitution mass attached to a metal support, the reconstitution mass being formed, for the most part at least, of a composite material containing a polymeric binder in which a mineral filler is dispersed; the method is of the type which comprises the formation of an interface for attachment to the metal of the metal support, the formation of an intermediate interface, and the formation of an interface for attachment of the reconstitution mass, and, according to invention, the metal bonding interface is formed by at least one layer of a ceramic material fixed to the metal by firing, the ceramic material of the layer at least having a thickness less than or equal to 0.3 mm, 1 the intermediate interface is formed by treatment of the surface of the ceramic material opposite to the metal with an organic silane, the attachment interface of the reconstitution mass is formed by treatment of the surface of the intermediate interface with a composite material of bonding, and the formation of the intermediate interface comprises, before the treatment with an organic silane, at least one etching operation. The etching operation can be carried out even under conditions liable to form cracks or weaken a ceramic body.

In an advantageous embodiment, before the surface of the ceramic material opposite the metal is treated with an organic silane, the ceramic material undergoes a sandblasting and cleaning operation before etching.

In another advantageous embodiment, the formation of the metal attachment interface comprises the formation of at least two layers of ceramic opaque. Preferably, the ceramic opaque layers comprise at least one aluminosilicate or a glass ceramic. In an advantageous variant, the ceramic material, in at least its surface layer, is formed from a ceramic opaque milk containing mineral particles, for example from a glass. The products from the Dentsply "Opaque Finesse" or "Biopaque" kits from Biodent can be used for this purpose. It is also possible to use 99.7% corundum particles of 50, 125 or 250 μm. Preferably, the thickness of the ceramic material is less than 0.2 mm.

Preferably, the treatment of the surface of the ceramic material opposite the metal with an organic silane is carried out with a methacryloxypropyltri ethoxysilane.

The invention also relates to a prosthesis of the type which comprises a reconstitution mass fixed to a metal support, the reconstruction mass being formed, at least for the most part, of a composite material containing a polymeric binder in which is dispersed mineral filler; the prosthesis comprises an interface for attaching to the metal of the metallic support, an intermediate interface, and an interface for attaching the reconstitution mass which are such that: the interface for attaching to the metal is formed between the metal of the metallic support and a layer of ceramic material fixed by firing and having a thickness less than or equal to 0.3 mm, the intermediate interface is formed between a layer of ceramic material and an organic silane fixed by reaction of a silane group on the surface of the ceramic material opposite to the metal, and the bonding interface of a composite material is formed between organic groups of the organic silane and a material compatible with the composite material.

Preferably, the intermediate interface has an irregularity such that its developed surface is at least equal to 1.4 times its projection in its plane. In an exemplary embodiment, the surface part of the ceramic material on the side opposite to the metal contains particles of a glassy material.

In one embodiment, the ceramic material comprises at least one element chosen from an aluminosilicate and a glass ceramic. Preferably, the thickness of the ceramic material fixed by firing is less than 0.2 mm. Thus, the ceramic material fixed by firing can present cracks, without that these have the slightest importance on the mechanical strength of the prosthesis produced.

The essential advantage of the invention is to allow the production of these prostheses of composite material not by an elite of prosthetists, but practically by the whole profession.

We now consider an exemplary embodiment of a prosthetic reconstruction of composite material according to the invention. In this exemplary embodiment, the first operation is the construction of the metal support which comprises the casting of metal "Esteticor Royal", from Cendres et Métaux, on a wax model, at a temperature of 1345 to 1375 ° C. Then, the metal support undergoes oxidation at 960 ° C for 5 min. Then, the metal support is cleaned with steam or ultrasound. Instead of being cast, the metal support could also be cut from the mass.

The next phase includes the creation of the metal attachment interface for a ceramic material. This embodiment includes for example the application of a first layer of ceramic opaque a few hundredths of a millimeter thick. The first opaque layer may be a De Trey "Biopaque Base" opaque layer, sprinkled with microparticles. These microparticles are formed from a glass of aluminosilicate. The layer is fired, then a second layer of ceramic opaque "Biopaque" by De Trey is applied in a similar manner and sprinkled with microparticles normally intended to give a dispersion of light which has advantageous aesthetic effects. In the context of the invention, the particles have the advantage of increasing the surface irregularity. The second layer is then cooked. The layers of ceramic material are fired at a temperature of the order of 970 to 980 ° C. The operations at high temperature are then terminated, since the rest of the process can be carried out at a temperature close to ambient temperature. Although the particles of the last ceramic opaque layer give a rough surface, it is advantageous to give a greater irregularity to the surface by sandblasting, for example with alumina particles. After cleaning, the irregularity of the surface is increased by etching. This can be carried out, for example, with a 9.5% hydrofluoric acid solution for 4 min or with a 4% hydrofluoric acid solution for 6 min, or by the "Super-Etch" solution from the kit " Porcelain System "from Mirage Dental Products. The surface of the ceramic material is finally treated by rinsing with steam.

The intermediate interface is then produced by applying an organic silane, for example a methacryloxypropyltrimethoxysilane, by application with a brush. After drying, an organic bonding layer compatible with the new generation composite material is applied. For example, two layers of Bisco "One-Step" material can be applied successively, each layer being polymerized for 30 s. Next, an adhesive or bonding liquid normally used with new generation composite materials is applied, for example the "Colombus" adhesive liquid from the company IDR, photopolymerized for 75 s. Then, the reconstitution mass is constructed by applying the necessary number of layers of the composite material, for example "Columbus" material, in accordance with the protocol for this material. More specifically, the construction of the mass for reconstituting the composite material is preferably carried out by photopolymerization, possibly with heating at relatively low temperature, which can reach 60 to 80 ° C.

All the operations used, from the construction of the metal support to the end of the construction of the reconstruction mass, are simple and easy to carry out by all prosthetists. In particular, the formation of the metal bonding interface of the ceramic material is well known, and the entire construction of the ceramic metal bonding structure is to the range of almost any dental technician with a success rate almost equal to 100%.

Although the use of an adhesive liquid has been described, it is understood that, when the organic patterns of the silane are directly compatible with the composite material used, this composite material can be directly applied to the organic silane.

Attempts have been made to determine the bond strength of various layers with different materials, under comparable conditions so that the results are comparable.

The bonding resistance obtained between a new generation composite material ("Columbus") and a metal support, produced by an experienced prosthetist according to established protocols, commonly exceeds 20 MPa. However, it is frequent that the value obtained by an inexperienced dental technician is less than 5 MPa, this value being very insufficient. The connection obtained with the "Silicoater-Rocatec" technique does not exceed 7.5 MPa. The bonding resistance obtained between a metal and an opaque ceramic material ("Biopaque") has a value of at least 40 MPa.

According to the invention, the bonding resistance between a composite reconstitution mass ("Columbus") and a ceramic material ("Biopaque") reproducibly exceeds 35 MPa.

As a reminder, the value of the composite-composite link is 40 to 50 MPa.

It is thus noted that, without any difficulty, a prosthetist, implementing operations which he routinely practices and with well-known protocols, can easily obtain a bond resistance always greater than

20 MPa, at all interfaces of the prosthesis.

We know that, in the 1970s, only an elite of prosthetists was able to produce suitable ceramic prostheses. It took a few decades for the evolution of techniques to allow all prosthetists successfully complete all ceramic prostheses.

The current situation of composite prostheses is similar to that of ceramic prostheses in the 1970s. The techniques of the invention make it possible to avoid such a period of evolution of a few tens of years, so that all of the prosthetists can now succeed all prostheses of composite materials. Industrial application possibilities

The method according to the invention is suitable for making dental prostheses in the workshops of prosthetists.

Claims

1. A method of producing a dental prosthesis of the type which comprises a reconstitution mass fixed to a metal support, the reconstruction mass being formed, at least for the most part, of a composite material containing a polymeric binder in which a mineral filler is dispersed, the method being of the type which comprises: the formation of an interface for attachment to the metal of the metal support, the formation of an intermediate interface, and the formation of an interface for attachment of the mass reconstitution, the method being characterized in that: the metal bonding interface is formed by at least one layer of a ceramic material fixed to the metal by firing, the ceramic material of the layer at least having a lower thickness or equal to 0.3 mm, the intermediate interface is formed by treating the surface of the ceramic material opposite the metal with an organic silane, the interface for hooking the m The reconstitution layer is formed by treatment of the surface of the intermediate interface with a bonding composite material, and the formation of the intermediate interface comprises, before treatment with an organic silane, at least one etching operation.

2. Method according to claim 1, characterized in that the formation of the metal attachment interface comprises the formation of at least two layers of ceramic opaque.

3. Method according to claim 2, characterized in that the ceramic material forming the metal bonding interface is obtained by using, at least on the side opposite to the metal bonding interface, a milk of opaque ceramic containing particles of a glass.

4. Method according to any one of the preceding claims, characterized in that the formation of the intermediate interface comprises, before etching, at least one sandblasting and cleaning operation.

5. Method according to any one of the preceding claims, characterized in that the treatment of the surface of the ceramic material opposite the metal with an organic silane is carried out with a methacryloxypropyltrimethoxy-silane.

6. Prosthesis of the type which comprises a reconstitution mass fixed to a metal support, the reconstruction mass being formed, for the most part at least, of a composite material containing a polymeric binder in which a mineral filler is dispersed , and which comprises: an interface for attaching to the metal of the metal support, an intermediate interface, and an interface for attaching the reconstitution mass, characterized in that: the interface for attaching to metal is formed between the metal of the metal support and a layer of a ceramic material fixed by firing and having a thickness less than or equal to 0.3 mm, the intermediate interface is formed between a layer of a ceramic material and an organic silane fixed by reaction of a silane group on the surface of the ceramic material opposite the metal, the bonding interface of a composite material is formed between organic groups of an organic silane and a material compatible with the composite material.

7. Prosthesis according to claim 6, characterized in that the thickness of the layer of a ceramic material fixed by firing is less than 0.2 mm.

8. Prosthesis according to one of claims 6 and 7, characterized in that the intermediate interface has an irregularity such that its developed surface is at least equal to 1.4 times its projection in its plane.

9. Prosthesis according to any one of claims 6 to 8, characterized in that the surface part of the ceramic material on the side opposite the metal contains particles of a glassy material.

10. Prosthesis according to any one of claims 6 to 9, characterized in that the ceramic material comprises at least one element chosen from an aluminosilicate, and a glass ceramic.