EP2640308A1

EP2640308A1 - Method for manufacturing a dental prosthesis

Info

Publication number: EP2640308A1
Application number: EP11796820.6A
Authority: EP
Inventors: Michael Sadoun
Original assignee: Individual
Current assignee: Individual
Priority date: 2010-11-19
Filing date: 2011-11-18
Publication date: 2013-09-25
Also published as: WO2012066507A1; JP2014506139A; CN103313677A; CN103313677B; FR2967568A1; FR2967568B1; US20130277873A1

Abstract

A method for manufacturing a dental prosthesis, this method comprising the following steps: a) preparing a paste by mixing a particulate filler and a resin capable of forming a binding phase by curing; b) curing the paste prepared in step a), optionally after forming, so as to form a solid composite mass; c) optionally, cutting the solid composite mass so as to form at least one composite block; d) optionally, machining the composite block so as to form a dental prosthesis, in which method, in step b), the curing is carried out at a pressure greater than 500 bar, with a return to atmospheric pressure when all of the resin has cured.

Description

METHOD OF MANUFACTURING A DENTAL PROSTHESIS

Technical area

The invention relates to a method for manufacturing a composite block for the manufacture of a dental prosthesis and to a method for manufacturing a dental prosthesis. The invention also relates to a composite block and a dental prosthesis obtained or likely to have been obtained by such methods.

State of the art

Composite blocks made by curing a composite paste, that is to say comprising a particulate filler, conventionally made of ceramic material or glass, and a resin, conventionally a mixture of monomers, are known.

To manufacture such a composite block, this paste is shaped and then cured. After solidification, the resin forms a binder phase, or "matrix", which binds the particles. The composite block obtained is then machined to the shape of the desired prosthesis, conventionally by "computer-aided design and machining" or CAD-CAM (Computer Aided Design - Computer Aided Machining).

The 3M Paradigm M2100 block from 3M is an example of a composite block manufactured in this way.

Composite blocks manufactured according to current methods, however, have a reduced mechanical strength, which limits the life of dental prostheses.

An object of the invention is to provide a novel method for improving the properties of dental prostheses, in particular by increasing their mechanical strength and their chemical stability.

Summary of the invention

According to the invention, this object is achieved by means of a method of manufacturing a dental prosthesis, this method comprising the following steps:

a) preparing a paste by mixing a particulate filler and a resin to form, by curing, a binder phase; b) curing the paste prepared in step a), optionally after shaping, so as to form a solid composite mass; c) optionally, cutting the solid composite mass so as to form at least one composite block;

d) optionally, machining the composite block so as to form a dental prosthesis.

This process is remarkable in that, in step b), the curing is carried out, at least partially, preferably completely, under a pressure greater than 500 bar.

As will be seen in more detail in the following description, a method according to the invention makes it possible to manufacture, in a simple manner, composite blocks having a very high mechanical strength.

Without being bound by this theory, the inventor explains the performance obtained by the fact that the pressure applied in step b) makes it possible to create a stress able to compensate for the shrinkage during the hardening of the resin. This results in a decrease in the number of defects.

The invention also relates to a solid composite mass, a composite block and a dental prosthesis obtained after a step b), a step c) or a step d), respectively, of a method according to invention or may have been manufactured at the end of such steps.

Definitions

By "dental prosthesis" generally means any piece intended to be placed on the teeth of a patient for the purpose of restoring all or part of it in its natural form.

Thus, the dental prostheses manufactured according to the invention may be, for example, peripheral scapes or crowns that are placed on the stump of a natural tooth, or prostheses generally referred to as "inlay" and "onlay" which are intended to reconstruct a partial alteration of a tooth by filling the cavity resulting from the loss of substance of the tooth by a piece of the same shape made by the prosthetist, or even bridges which are prostheses which simultaneously bear on the remaining portions of at least two teeth possibly compensating for one or more of the missing teeth. Unless otherwise indicated, the term "pressure" refers to the high pressure mentioned above and applied to step b). By default, the "pressure" does not refer to "atmospheric pressure".

By "comprising one", it is appropriate to include "comprising at least one". detailed description

A dental prosthesis according to the invention may be manufactured by a process comprising the steps a) to d) above:

In step a), according to well known methods, a paste is prepared by mixing a particulate filler and a resin capable of forming, by curing, a binder phase.

The particulate filler preferably represents more than 60%, more than 70%, or even more than 80% and or less than 90% of the mass of the pulp.

Preferably, the resin and the particulate filler together account for more than 90%, more than 95%, more than 98%, more than 99%, even substantially 100% of the mass of the pulp.

Particulate charge

The particulate fillers and resins currently used to make dental prostheses, particularly by injection, can be implemented.

Preferably, the particulate filler comprises, or even consists of, particles made of a material chosen from a metal oxide in the form of glass-ceramic, glass, or crystalline ceramic such as silica, quartz, alumina or mullite, or by a mixture of such particles.

More preferably, the particulate filler comprises, or consists of, particles made of a material chosen from a glass of barium aluminosilicate, a glass containing ytterbium fluoride, albite, a mieatetrafluorosilicate, a lithium disilicate, apatite, quartz, MgAkO-i spinel, mullite and zircon, or by a mixture of such particles.

Particles of the particulate filler may have undergone a silane treatment intended to increase the wettability of their surface by the resin in the liquid state, and in particular to make this surface more hydrophobic. Preferably, this silanation treatment comprises silanization using an alkoxysilane, a halosilane, preferably 3-methacryloxypyropyltrimethoxysilane. After application of the silanating agent, the particles are dried, preferably at a temperature between 100X and 200 ° C, typically for several hours.

The silane treatment may for example be carried out in accordance with the process described in US 5,869,548.

Resin

The nature of the resin is not limiting.

Preferably, the resin is chemo-polymerizable, heat-curing, or thermoplastic.

The resin may in particular be chosen from polymerizable resins, especially those described in US Pat. No. 5,869,548, US Pat. No. 5,843,348 and EP 0 701 808.

Preferably, the resin is chosen from the following list:

a monomer resin that is chemopolymerizable or thermopolymerizable, preferably a vinylester or acrylic resin. The resin may in particular be chosen from the group formed by 2-hydroxyethyl methacrylate, CAS 868-77-9 (HEMA),

Tetraethylene glycol dimethacrylate CAS 109-17-1 (TEGDMA), 2 ₅ 2-bis- (4- (2-hydroxy ~ 3 ~ méÎhacryloyloxy-propoxy) phenyl) propaKe _s CAS 1565-94-2 (BIS GMA), 1, 6-Ws (methacryloxy-2alkyl) xylcarbonylamino) -2,4,4-trimethylhexane urethane, (UDMA) CAS 72869-86-4, ethylene glycol dimethacrylate (EGDMA), diethylene glycol > 1-dimethacrylate (DEGDMA), the

Bisphenol A-dimethacrylate, CAS 109-17-1 (BADMA);

a thermoplastic resin, in particular chosen from saturated polyesters, and in particular polyethylene terephthalate (PET) and poly (1,4-butyiene terephthalate), CAS 24968-12-5 (PBT), Polycarbonates Poly (bisphenol A carbonate) , CAS 25037-45-0 (PC), bisphenol A-carbonate, and polyamides.

In particular for catalyzing the chemopolymerizable resins, it is possible to use peroxides, and in particular Dibenzoylperoxide CAS 94-36-0, Methyl Ethyl Ketone Peroxide, CAS 1338-23-4, Di-tert-amyl peroxide, CAS 10508-09-5, Di-tert.- butylperoxide, CAS 110-Ό5-4, or Cumene Hydroperoxide, CAS 80-15-9. To accelerate the hardening of Dibenzoylperoxydc, CAS 94-36-0, it is possible to use dimethylaniline (DMA), diemylaniline (PEA) or dimethylparallouline (DMPT). To accelerate the hardening of Met yl and yl Ketone Peroxide, CAS 1338-23-4, it is possible to use, especially cobalt (Π) 2-ylhexanoate. The dough may also comprise, in a conventional manner, additives facilitating the control of its curing, for example a catalyst and or an accelerator.

Preferably, the total mass content of additives is less than 2% of the mass of the dough.

Optionally, the dough is shaped, for example in the form of a "brick", a plate, in particular a disk. The maximum thickness of a plate according to the invention is preferably less than 30 mm, preferably less than 20 mm, preferably less than 15 mm, and / or greater than 5 mm, greater than 8 mm.

In step b), the paste prepared in step a) is cured so as to form a solid composite mass.

To control the hardening of the dough, it is possible in a known manner, to act on one or more of the following parameters:

accelerator and / or catalyst concentration in the dough;

the temperature and the holding time at this temperature; the chemical nature of the resin, and in particular monomers.

According to the prior art, the resin is conventionally polymerized at ambient pressure. The retraction resulting from a polymerization at ambient temperature can conventionally lead to a decrease in the volume occupied by the resin of between 6% and 15% of its initial volume. This retraction leads to appearance of defects generally having a size between 35 and 100 microns.

According to the invention, the paste is subjected to a high pressure, greater than 500 bar, at least until a portion, and preferably all, of this paste has hardened. The high pressure makes it possible to compensate, at least partially, the retraction. This results in a very high homogeneity, an increase in density and a reduction in number and size of defects, or even disappearance of defects. The mechanical strength is considerably improved.

In step b), the pressure is preferably greater than 600 bar, preferably greater than 800 bar, greater than 1000 bar, greater than 2000 bar, or even greater than 3000 bar, or even greater than 4000 bar. Preferably, however, the pressure is less than 5000 bar, preferably less than 4000 bar. In a preferred embodiment, the pressure is between 2000 and 3000 bar.

Preferably, the pressure is determined so as to produce a decrease in the volume of the dough greater than or equal to that which, at atmospheric pressure, would result from the shrinkage resulting from the curing of the resin.

As an indication, for the resin, the pressure can be set in the following manner, depending on the shrinkage measured at 20 ° C.

Conventional injection methods are not suited to the application of such high pressures. In addition, the injection under pressure is often used only to improve the filling of the mold.

Preferably, the pressure is exerted isostatically, or "urriaxial". All known methods of pressurization can be used. The pressure must be exerted on the paste while the resin is still at least partly, preferably completely, in the liquid state and until it has at least partially hardened. Preferably, all of the resin is cured, preferably polymerized, to more than 30% by weight, preferably more than 50% by weight, preferably more than 80% by weight, preferably more than 99% by weight. in bulk, preferably substantially 100% by weight, before returning to atmospheric pressure. Preferably, the pressure is kept substantially constant until all of the resin has cured.

The polymerization can be chemical. Preferably, the polymerization is thermal.

Preferably, during step b), a temperature of preferably greater than 60 ° C., or even greater than 80 ° C. or greater than 100 ° C. and / or less than 220 ° C., preferably less than 200 °, is applied. C, preferably below 160 ° C, preferably below 150 ° C.

When a catalyst is added to the dough, the polymerization is preferably carried out at a temperature between 60 and 160 ° C, preferably between 60 and 150 ° C. When no catalyst is added to the dough, the polymerization is preferably carried out at a temperature of between 150 and 220 ° C, preferably between 150 and 200 ° C, preferably between 160 and 200 ° C.

The maintenance of the temperature and / or pressure preferably lasts more than 0.25 hours, preferably more than 0.5 and / or less than 2 hours, preferably less than 0.75 hours. The application of a high pressure at a temperature greater than 150 ° C., preferably greater than 160 ° C. and preferably less than 220 ° C., preferably less than 200 ° C., advantageously makes it possible to open the double bonds. carbon of the monomers of the resin, particularly when the resin is a methacrylate or a polyacrylate, in the liquid state, that is to say without the resin boiling and volatilizing. It is thus possible to polymerize without adding catalyst, which is particularly advantageous, the catalysts are often potentially toxic.

HIP (Hot Isostatic Pressing) mermopolymerization is most preferred. Preferably, during step b), the pressure is kept substantially constant, the pressure variation being preferably less than 20%, preferably less than 10%.

Preferably, the pressure is kept substantially constant until the resin is polymerized to more than 30% by weight, preferably more than 50% by weight, preferably more than 80% by weight, preferably more than 80% by weight. from 99% by weight, preferably to substantially 100% by weight.

Preferably, a single pressurizing operation without return to ambient pressure is carried out to cure the resin.

Preferably, the return to ambient pressure is carried out only after cooling of the cured composite mass, preferably to room temperature.

If appropriate, the solid composite mass may be subjected to a heat treatment suitable for perfecting the polymerization, for example at a temperature between 150 and 180 ° C.

Preferably, the solid composite mass results from a thermopolymerization under pressure of the paste. Preferably, the solid composite mass obtained at the end of step b), according to the invention, has a hardness greater than 100 Vickers, preferably greater than 120 Vickers, or even greater than 140 Vickers.

Preferably, the solid composite mass obtained at the end of step b) has a Young's elastic modulus greater than 5 GPa, measured according to the ISO 10477 standard and / or a three-point flexural modulus, measured according to the ISO standard. 6,872, greater than 100 MPa, preferably greater than 150 MPa, or even greater than 200 MPa.

In addition, the optical properties of the solid composite mass make it quite suitable for the manufacture of a dental prosthesis,

Preferably, no intermediate step is applied between steps b) and c).

In step c), the solid composite mass is cut to form one or more composite blocks adapted to the machines used for the following steps. The solid composite mass may be in the form of a plate, preferably of substantially constant thickness. Preferably, the solid composite mass is in the form of a rod. The section of this wand may be square, or rectangular, or circular. Preferably, the solid composite mass has at least one planar face. Preferably, the solid composite mass has a convex shape. Preferably, the solid composite mass has at least two parallel faces.

The smallest dimension of the solid composite mass is preferably less than 30 mm, preferably less than 20 mm, preferably less than 15 mm, and / or preferably greater than 5 mm.

The largest dimension, or even each dimension, of the solid composite mass is preferably greater than 15 mm, preferably greater than 50 mm, preferably greater than 100 mm.

The volume of the solid composite mass is preferably greater than 20000 mm ³ , preferably greater than 50000 mm ³ , preferably greater than 100000 mm ³ .

Preferably, the solid composite mass can be cut in a plurality of composite blocks, preferably in at least two composite blocks, into at least three composite blocks, preferably into at least five composite blocks, preferably into at least ten composite blocks. preferably in at least twenty composite blocks. Preferably, all the composite blocks from the same solid composite mass are substantially identical.

Preferably, the solid composite mass results from pressure thermopolymerization of the paste prepared in step a), and is then cut into at least three composite blocks.

Preferably, a composite block has a convex shape. A composite block preferably has at least one planar surface, this surface may for example have streaks resulting from a cutting operation by sawing. Preferably, a composite block does not have the shape of a tooth obtained by molding. A composite block is preferably of parallelepipedal shape, preferably of cubic form. It can be cylindrical or prismatic. Preferably, the smallest dimension, or even each dimension of a composite block is greater than 5 mm, preferably greater than 10 mm, preferably greater than 20 mm, and preferably less than 40 mm, preferably less than 30 mm.

The volume of a composite block is preferably greater than 125 mm ", preferably greater than 1000 mm, preferably greater than 5000 mm ^J, preferably higher than 10000 mm ^3, or and preferably less than 100 000 mm ^3, of Preferably, step c) is carried out in such a way that the composite block or blocks obtained can be machined by a CAD-CAM device, in particular by a machining device such as the CELAY system of the company. Mikrona or CEREC 3 from the company SIRONA If necessary, one or more organs can be integrated in a composite block to maintain it by such devices.

Preferably, the cutting device makes it possible to form a plurality of composite blocks, for example all of identical shape, for example all of the shape of a cube. In one embodiment, it makes it possible to form, for example in several operations, composite blocks of identical shape by cutting a plurality of composite masses of various dimensions.

Preferably, one of the faces of a composite block is bonded to a metal part, this metal part comprising a rod intended to be fixed in a mandrel of the CAD-CAM device, the rod having a flat part for locating and orienting the block composite,

In step d), the composite block is machined so as to form a dental prosthesis. The machining of a dental prosthesis is preferably adapted for the prosthesis to adapt to the tooth or teeth to be treated and or to restore and / or reconstruct a patient The ratio of the amount of material removed from the composite block by machining on that of the composite block before machining, to form a dental prosthesis, is preferably greater than 10%, preferably greater than 30%, preferably greater than 50%, preferably greater than 70%, and / or preferably less than 90%, preferably less than 80%. Depending on the nature of the dental prosthesis manufactured, the composite block according to the invention can be made integral with other parts, for example a metal base. The succession of steps a), b) and c) can be repeated identically, preferably so as to obtain at the end of step c), composite blocks of calibrated dimensions. Steps a), b) and c) can for example be performed in one place, for example in workshops of a factory. One or more composite blocks may be packaged, then routed to a place where it is (are) machined) as described in step d). This place may be for example the workshop of a dental technician with a machining device to perform step d).

Examples

The following examples are provided for illustrative and non-limiting purposes.

Example 1

The particulate filler is a mixture consisting, for 80% by weight, of a barium aluminosilicate glass powder having a particle size of between 0.1 and 5 microns, the 100% complement being a silica powder. colloidal whose particle size is between 20 and 50 rianometers.

This particular load has been successively

a silanation treatment with a solution having the following composition, in percentages by weight:

methoxypropanol: 93.8%

water: 5%

acetic acid: 0.2%

silane: 1%

drying at 150 ° C. for 4 hours.

The resin has the following composition, in percentages by weight

UDMÀ: 80%

TEGDMA: 19.2%

Benzoyl peroxide: 0.8%.

The paste is obtained by mixing 75% by weight of the particulate filler and 25% by weight of the resin.

The paste thus obtained is then cured under a pressure of 500 bar, by polymerization at 100 ° C for one hour. Example 2

The particulate filler is a mixture consisting, for 70% by weight, of a quartz powder 3ί¾ whose particle size is between 0.1 and 2 microns, the 100% complement being a colloidal silica powder whose size particles is between 5 and 75 nanometers.

This particulate filler was subjected to a silane treatment identical to that of Example 1. The resin has the following composition, in percentages by weight:

BIS-GMA: 40%

UDMA: 28%

TEGDMA 30%

MEKP: 2%

The paste is obtained by mixing 80% by weight of the particulate filler and 20% by weight of the resin.

The paste thus obtained is then cured under a pressure of 1000 bar, by thermopolymerization at 80 ° C for two hours.

Example 3

The particulate filler is a mixture consisting, for 50% by weight, of an albite glass ceramic powder NaAISsOg, the particle size of which is approximately 10 μm, for 20% by weight, of a glass powder of barium akuninosilicate having a particle size of between 0.4 and 1 μπι, the 100% complement being a colloidal silica powder having a particle size of between 50 and 100 nanometers.

This particulate filler was subjected to silanation treatment identical to that of Example 1.

The resin has the following composition, in percentages by weight:

EBADMA 99.68%

Benzoyl peroxide: 0.3%

DMPT: 0.02%

The paste is obtained by mixing 70% by weight of the particulate filler and 30% by weight of the resin. The paste thus obtained is then cured under a pressure of 2000 bar, by thermopolymerization at 130 ° C for 0.5 hour.

Example 4

The particulate filler is a mixture consisting, for 70 by weight, of a glass powder of barium duminosilicate having a particle size of about 1 μm, for 10% by weight, of a fluoride powder. Ytterbium YDF3, whose particle size is about 3 microns, the 100% complement being a colloidal silica powder whose particle size is between 20 and 50 nanometers.

The resin has the following composition, in percentages by weight:

BIS-GMA: 50%

DEGDM 50%

The paste is obtained by mixing 60% by weight of the particulate filler and 40% by weight of the resin.

The paste thus obtained is then cured under a pressure of 3000 bar, by mermopolymensation at 180 ° C. for 1.5 hours.

Example 5

The particulate filler is a mixture consisting, for 80% by weight, of an alumina powder whose particle size is between 0.3 and 5 μm, the 100% complement being a colloidal silica powder whose size particles is between

50 and 100 nanometers.

This particulate filler was subjected to a silanation treatment identical to that of Example 1. The resin is a UDMA resin,

The paste is obtained by mixing 90% by weight of the particulate filler and 10% by weight of the resin.

The paste thus obtained is then cured under a pressure of 4000 bar, by thermopolymerization at 200 ° C for 0.5 hours. Example 6

The particulate filler is a mixture consisting, for 60% by weight, of a mullite powder whose particle size is between 1 and 10 μm, for 20% by weight, of a silica powder whose particle size is between 0.1 and 1 μm, the 100% complement being a colloidal silica powder whose particle size is between 20 and 50 nanometers.

EBADMÀ EGDMA:

Benzoyl peroxide

D FF:

The paste thus obtained is then cured under a pressure of 3000 bar, by thermopolymerization at 60 ° C for 2 hours.

Example 7

The particulate filler is a mixture consisting, for 60% by weight, of a powder of vitroceramic particles of fluoro tetra mica silicate, the particle size of which is between 1 and 5 μm, and for 20% by weight of a powder. of zentonium silicate whose particle size is between 0.1 and 0.5 μιη, the 100% complement being a colloidal silica powder.

The resin has the following composition, in percentages by weight:

UDMA: 69%

EGDMA 30%

ME P: 1% The paste is obtained by mixing 70% by weight of the particulate filler and 30% by weight of the resin.

The paste thus obtained is then cured under a pressure of 2500 bar, by thermopolymerization at 90 ° C for 1 hour.

For the following examples, products were made from commercially available pastes using a process according to the invention (pressure of 2500 bar in step b) and following a conventional process (pressure of 1 bar). The properties of the composite masses obtained were compared.

The following tables illustrate the remarkable efficiency of a process according to the invention, whatever the pulp considered.

Example 8

Starting paste: "Grandio" light-curing dental composite marketed by VOCO GmbH (Cuxahaven, Germany)

Example 9

Starting paste: "Gradia" light cured dental composite marketed by GC CORPORATION (Tokio, Japan)

Example 10

Starting paste: "Z100" photopolymerizable dental composite sold by the company 3M ESPE (St Paul, MN, USA)

As is now clear, the invention provides a method for making composite blocks and mechanically strong prostheses. These composite blocks are also very chemically stable, have improved optical properties and are easier to machine than prior composite blocks.

Of course, the invention is not limited to the embodiments described.

In particular, the invention is not limited by the chemical nature of the dough or by the shape of the solid mass.

Claims

1. A method of manufacturing a dental prosthesis, this method comprising the following steps:

a) preparing a paste by mixing a particulate filler and a resin capable of forming, by curing, a binder phase;

b) curing the paste prepared in step a), optionally after shaping, so as to form a solid composite mass;

c) optionally, cutting the solid composite mass so as to form at least one composite block;

d) optionally, machining the composite block so as to form a dental prosthesis,

in which, in step b), the curing is carried out at a pressure greater than 500 bar, and is returned to atmospheric pressure when all the resin has <

2. Method according to the preceding claim, wherein said pressure is greater than

3. Method according to the preceding claim, wherein said pressure is greater than

2000 bar.

A method according to any one of the preceding claims, wherein the largest dimension of the solid composite mass is greater than 15 mm, and the smallest dimension of the solid composite mass is less than 30 mm.

5. Method according to any one of the preceding claims, wherein is applied, during step b), a temperature greater than 60 ° C.

6. Method according to the preceding claim, wherein is applied, during step b), a temperature above 150 ° C.

7. Process according to any one of the preceding claims, in which, during step b), a temperature of less than 220 ° C. is applied.

The process according to any one of the preceding claims, wherein in step a) no catalyst is added to the dough and wherein during step b) a temperature of between 150 and 220 ° C.

The process according to any one of claims 1 to 7, wherein in step a) a catalyst is added to the dough and in which a temperature of between 60 and 60 is applied during step b). 150 ° C.

The process according to any one of the preceding claims, wherein in step b), it returns to atmospheric pressure when all of the resin has hardened.

11. Method according to any one of the preceding claims, wherein the parucular charge has, prior to step a), undergone a silanation treatment.

12. A method according to any one of the preceding claims, comprising a step d) machining by a computer-aided design and machining device.

13. A method according to any one of the preceding claims, wherein the solid composite mass results from a pressurized memopolymerization of the dough prepared in step a), and is then cut into at least three composite blocks in step c. ).

The method of any one of the preceding claims, wherein in step a) the resin is chemopolymerizable, thermopolymerizable or thermoplastic.

The method of any one of the preceding claims, wherein in step a)

the particulate filler comprises particles made of a material chosen from silica, a barium aluminosilicate glass, a glass containing ytterbium fluoride, a pallite, a micatetrafluorosilicate, a lithium disilicate, apatite, quartz, MgAlaO ₄ spinel, mullite and zircon, and / or

the resin is a vinylester, acrylic or methacrylic monomer resin.