WO2015155447A1

WO2015155447A1 - Preform made of a cross-linked composite material to be machined in order to form crowns or bridges

Info

Publication number: WO2015155447A1
Application number: PCT/FR2015/050866
Authority: WO
Inventors: Pierre-Luc Reynaud; Manh-Quynh Chu
Original assignee: Societe De Recherches Techniques Dentaires - Rtd
Priority date: 2014-04-07
Filing date: 2015-04-02
Publication date: 2015-10-15
Also published as: EP3128947A1; FR3019461B1; FR3019461A1

Abstract

The invention relates to a preform made of a cross-linked composite material to be machined in order to form crowns or bridges, especially by means of CAD/CAM, comprising an infrastructure formed by laying fibre-based fabrics one on top of the other, the fabrics being impregnated with a resin and being substantially spread over the thickness of said infrastructure, characterised in that it also contains a resin-based suprastructure, said suprastructure being fibre-free and secured to the infrastructure over the entire upper and lower surface thereof.

Description

PREFORMS OF RETICULATED COMPOSITE MATERIAL FOR PROCESSING CROWNS OR BRIDGES

The subject of the invention is a preform made of crosslinked composite material intended for machining crowns or bridges. It also relates to a method of manufacturing said preform.

The machining of dental prostheses, specifically crowns and bridges by CAD / CAM (Computer Aided Manufacturing Design) is well known. This technology has for example been described in EP040165B1. Technology has since evolved in terms of both CAD / CAM hardware and preform composition. Document WO 2010/109496 for example describes a preform made of composite material consisting of a superposition of fibrous webs embedded in a polymeric matrix. The plies are distributed over the entire thickness of the preform and are each connected by transverse threads. The preform is used for making crowns and tenons in particular. According to an essential characteristic, the plies are woven according to the specific patterns, which implies that the proportion of yarns in the weft direction is different from the proportion of yarns in the warp direction. The preform described in this document has several disadvantages. First, the presence of tissue on the surface of the preform causes irritation of the surrounding tissue of the prosthesis, once it is posed. Moreover, the distribution of the son according to predetermined patterns does not ensure satisfactory mechanical strength of the crown over its entire surface.

WO 00/21454 A1 describes a method of applying an splint to a tooth. The method includes disinfecting the tooth, applying an uncharged binder resin to said tooth. A composite resin is then applied to the binder resin. A triaxial material is impregnated separately with the binder resin. The assembly is then applied to the composite resin and polymerized. Finally, a second layer of composite resin is applied which is polymerized.

US 5,816,816 A discloses a method for restoring or stabilizing one or more teeth. To do this, it uses a sheath of woven fibers inside which is cast a self-polymerizable composite. The document WO 02/100355 A1 describes a prepreg (prepreg) composed of a core comprising a resin in which fibers are embedded and whose surface has fibers that are at least partially impregnated. The presence of surface fibers allows the prepreg to be bonded with synthetic or living material.

Document US 2002/086266 A1 describes a reticulated preform intended to be subsequently machined by CAD / CAM. The preform consists of a composite material comprising fibers or fillers embedded in a polymeric matrix. According to this document, the preform consisting of fibers embedded in the composite is machined by CAD / CAM before possibly being associated with a coating or a facet to get as close as possible to the anatomy of the tooth.

US 5,839,900 A describes a dental prosthesis such as a crown, a bridge or an implant. This prosthesis consists of a shell covered by a coating finish. The shell is composed of composite material comprising a fiber reinforcement embedded in a resin matrix. The coating is, for its part, composed of a layer of resin.

In other words, the problem to be solved by the invention is to develop a pre form for machining crowns or bridges by the CADCAM technique, which does not have the disadvantages mentioned above.

Another problem to be solved by the invention is to develop a preform whose appearance (color in particular) is as close as possible to that of the teeth surrounding the tooth to be treated.

To do this, the Applicant had the idea to propose a two-component preform that is to say, a preform consisting of two separate materials respectively, a reinforced fiber-based material and a fiber-free material, the two materials being integral with each other. According to the invention, the suprastructure is free of any fibers, whatever their size. More specifically, the subject of the invention is a cross-linked composite material preform intended for machining crowns or bridges by CAD / CAM comprising an infrastructure composed of the superposition of fiber-based fabrics, the fabrics being impregnated with a resin and being substantially distributed over the entire thickness of said infrastructure.

The preform of the invention is characterized in that it further contains a resin-based suprastructure, said suprastructure being free of fibers and integral with the infrastructure over its entire upper or lower surface. In other words, the invention consists in having coated a preform made of a material reinforced with fibers, a top layer free of fibers making it possible to solve the problem of the irritation of the tissues surrounding the crown or the bridge once posed. In addition, there is no risk of pulling fibers during machining, which avoids the creation of holes forming potential reservoirs of impurities.

Depending on the nature of the constituent resins of the infrastructure and the superstructure, as well as the manufacturing process, the superstructure adheres directly to the surface of the infrastructure or indirectly, through an adhesive interlayer applied between both surfaces.

More precisely, when the resins present at the interface between the infrastructure and the suprastructure are identical or compatible, the suprastructure can adhere directly to the surface of the infrastructure, also according to the manufacturing process. On the contrary, when the resins present at the interface between the infrastructure and the suprastructure are not identical or not compatible, the superstructure adheres to the surface of the infrastructure by means of an adhesive layer applied between the two surfaces. Those skilled in the art will know how to choose the correct dental adhesive. This may include the photo-polymerizable Sealbond Ultima ^® marketed by RTD.

Advantageously, the infrastructure and the suprastructure each contain a single resin or mixture of resins distributed homogeneously over the entire thickness of the infrastructure and the suprastructure. According to another feature, to ensure that no fiber appears on the surface after machining the preform, the thickness of the suprastructure is between 50 and 70% of the thickness of the preform. According to the invention, the preform may be a preform intended for temporary prostheses or a definitive preform depending on the nature of the constituent resin of the suprastructure.

In the case of a preform intended for machining a temporary crown or bridge, the constituent resin of the suprastructure is not loaded. On the contrary, when it comes to machining a final crown or bridge, the constituent resin of the suprastructure is in this case loaded. The infrastructure may possibly contain loads. The charges present in the superstructure and, where appropriate, in the substructure are in particular micron or nanometric charges of silica, quartz, ceramic glass, metal oxide, radiopaque elements (YbF ₃ ), etc., which are well known in the art. the field of dental composites. Advantageously, it is a mixture of silica, borosilicate glass, ceramic glass and glass. Preferably, in this mixture, the ceramic combines silica oxide and strontium oxide.

Of course, the charge rate will be adjusted according to the desired abrasion resistance, without being excessive so as not to cause stress during the machining of the preforms. The level of charges is in practice between 20 and 70% by weight and advantageously 50% and 60% of the suprastructure.

Moreover, to improve the aesthetics, the superstructure contains colored pigments to get closer to the color of the natural tooth and also to hide the infrastructure. The pigments advantageously represent between 0.01% and 0.10% by weight of the suprastructure. These are, for example, white, yellow and red pigment compounds.

The resin present in the preform, whether in the infrastructure or the superstructure, may be a thermosetting resin or a thermoplastic resin. When it is a thermosetting resin, it is advantageously chosen from the group comprising PMMA, TEGDMA, BISGMA, BDMA, HDDMA, UDMA, epoxy and vinylester.

When it is a thermoplastic resin, the preferred material is, for example, PEEK (polyether, ether ketone) or PMMA.

According to an essential characteristic, the infrastructure is composed by the superposition of fiber-based fabrics. These fabrics are advantageously composed of long fibers such as the fibers chosen in particular in the group comprising glass fibers, silica (quartz or polyethylene).

The number of tissues may vary depending on the thickness of the infrastructure. In practice, advantageously the infrastructure contains from 60 to 80 layers of tissue for a thickness of said infrastructure between 19 and 21 mm.

Advantageously, the preform contains exclusively fabrics 100% of the warp fibers are oriented at an angle of 0 ° and 100% of the weft fibers are oriented at an angle of 90 °.

According to another characteristic, all or some of the fabrics also have a distribution of 50% of the fibers in the warp direction and 50% of the fibers oriented in the weft direction. It is said that the fabric is balanced.

In a first embodiment, all tissues are balanced tissues.

In a second embodiment, the preform alternates balanced tissue and unidirectional tissue. A unidirectional fabric is a fabric in almost all fibers are oriented in the warp direction. For example, the preform alternates series 4 balanced fabrics then a unidirectional fabric.

In practice, the fiber content of the preform is between 40 and 80% by weight. Thus conceived, the final prosthesis contains a reinforced infrastructure with fibers distributed homogeneously over the entire height and the entire surface of said infrastructure, giving it optimum mechanical strength. The preform of the invention may be manufactured according to various methods including pultrusion, vacuum molding, infusion, molding RIM (Reaction Injection Molding), compression molding or thermoplastic injection molding. In a first preferred embodiment, the preform is obtained by pultrusion and uses a thermosetting resin.

According to this method,

storing as many reels of fabric as fabrics required to obtain the desired thickness of the infrastructure,

tensioning bobbins of fabrics so that they are superimposed,

we pass the superimposed fabrics in resin,

the resin-impregnated fabrics are polymerized, thus forming the substructure, and then, on the infrastructure, a resin forming the suprastructure is cast,

the suprastructure is polymerized.

In the pultrusion method, it is advantageous to intercalate unidirectional tissues regularly between balanced tissues oriented 0/90 °. The applicant has indeed found that this prevented the formation of bubbles during pultrusion.

In practice, the fabrics are stored in creels. The tissues are unwound and impregnated in a resin tank and then polymerized in a die (semi-open mold). Depending on the chemistry used (nature and amount of catalyst such as peroxide), the temperature, and the time the infrastructure remains in the die, the material is polymerized in whole or in part.

The infrastructure then enters a second die where the resin is cast / injected to form the suprastructure. When the constituent polymer of the resin of the infrastructure is not completely polymerized before passing into the second die and the resin forming the infrastructure is the same as that forming the suprastructure, said supra and infrastructure naturally adhere.

If, on the contrary, the resin of the infrastructure is completely polymerized before passing into the second die, whatever the nature of the constituent resin of the suprastructure, an adhesive layer is applied to the surface of the infrastructure intended to receive the superstructure. According to another embodiment, still in this case, roughness can be created on the surface of the infrastructure intended to receive the suprastructure by employing a shape die.

In a second embodiment, the preform is obtained by compression with two possible alternatives.

According to the first alternative, in a single mold:

each resin fabric is impregnated individually,

the tissues are superimposed until the desired thickness of the infrastructure is obtained, the resin thus constituting the suprastructure is cast onto the infrastructure thus formed,

the whole is compressed while polymerizing the resin.

According to the second alternative:

in a first mold, the infrastructure is formed:

o each resin fabric is impregnated individually,

o the fabrics are superimposed until the desired thickness of the infrastructure is obtained,

o compress the whole while polymerizing the resin,

in a second mold, we form the crosslinked superstructure by resin injection, the infrastructure is secured to the suprastructure.

Bonding may be effected either by means of an adhesive layer, or by means of roughnesses formed on the surface of the infrastructure intended to receive the suprastructure or a combination of both. In the event that a thermoplastic resin is used, it is already crosslinked. Under these conditions, there is no polymerization step as previously indicated. In practice, the resin is melted. Its hardening is obtained by return of the infrastructure and the suprastructure at ambient temperature.

When the preform is made by compression, it is not necessary to insert unidirectional fabrics. Under these conditions, all the tissues are advantageously balanced tissues oriented 0/90 °.

The invention and the advantages resulting therefrom will emerge from the following exemplary embodiments in support of the appended figures.

Figure 1 is a schematic representation of the preform according to the invention.

Figure 2 is an exploded representation of Figure 1. In Figure 1, there is shown a preform of the invention of parallelepiped shape.

This preform (1) consists of two elements respectively an infrastructure (2) and a superstructure (3). The infrastructure (2) itself consists of a series (4) of layers or fabrics superimposed as they appear in Figure (2).

In this example, the preform contains 6 layers or superposed fabrics being specified that this number is not limited and is a function of the thickness of the preform.

The infrastructure is impregnated with a crosslinkable resin, in particular an epoxy, vinyl ester or methacrylic resin.

As shown in FIG. 2, five of the six fabrics (5) are made of warp yarn, 100% of which are oriented at an angle of 0% and weft yarns of which 100% are oriented at an angle of 90. °. Each fabric (5) is a balanced fabric that is to say it contains as many threads in the warp direction as in the weft direction (50/50). In this embodiment, the infrastructure (2) further contains a unidirectional tissue (6) interposed between the first two balanced fabrics. This unidirectional fabric consists in known manner of a majority of fibers oriented at an angle of 0 ° in the warp direction of some son in the weft direction to connect the warp son direction.

The suprastructure itself comprises a crosslinkable resin identical to that used for the manufacture of the infrastructure. As indicated above, depending on the destination of the preform, namely to perform a definitive or non-definitive prosthesis, the suprastructure may or may not contain charges.

In the present embodiment, the preform has been produced by pultrusion according to the method previously described. The invention and the advantages derived therefrom are apparent from the foregoing description. In particular, there is no irritation of the crown or bridge when placed. The mechanical strength of the prostheses is also reinforced by the choice of the specific tissues constituting the preform.

Claims

1 / preform in crosslinked composite material for machining crowns or bridges by CAD / CAM comprising an infrastructure composed by the superposition of fiber-based fabrics, the fabrics being impregnated with a resin and being substantially distributed over the entire thickness said infrastructure, characterized in that it further contains a resin-based suprastructure, said suprastructure being fiber-free and integral with the infrastructure over its entire upper or lower surface. Preform according to claim 1, characterized in that the resins present at the interface between the infrastructure and the suprastructure are identical or compatible and the suprastructure adheres directly to the surface of the infrastructure.

3 / preform according to claim 1, characterized in that the resins present at the interface between the infrastructure and the superstructure are not identical or not compatible and the superstructure adheres to the surface of the infrastructure through a adhesive layer applied between the two surfaces.

4 / preform according to one of the preceding claims, characterized in that the resin is selected from the group comprising PMMA, TEGDMA, BISGMA, BDMA, HDDMA, UDMA, epoxy and vinylester, PEEK (polyether, ether ketone).

5 / preform according to one of the preceding claims, characterized in that the thickness of the suprastructure is between 50 and 70% of the thickness of the preform.

6 / preform according to one of the preceding claims, characterized in that the superstructure, and where appropriate in the infrastructure comprises charges selected from the group comprising micron or nanometric charges of silica, quartz, ceramic glass, oxide metal, opaque radio elements (YbF3).

7 / preform according to claim 6, characterized in that the charge rate in the suprastructure is between 20 and 70% by weight, preferably between 50%> and 60%> by weight of the suprastructure. 8 / preform according to one of the preceding claims, characterized in that the superstructure contains color pigments advantageously representing between 0.01% and 0, 10%) by weight of the suprastructure. 91 Preform according to one of the preceding claims, characterized in that the fabrics are composed of long fibers such as fibers chosen in particular in the group comprising glass fibers, silica (quartz or polyethylene).

10 / preform according to one of the preceding claims, characterized in that it exclusively contains fabrics 100% of the warp fibers are oriented at an angle of 0 ° and 100% of the weft fibers are oriented at an angle 90 °.

1 / preform according to the preceding claim, characterized in that all or part of the fabrics further having 50%> warp oriented fibers and 50%> of fibers oriented in the weft direction relative to the total number of fibers.

12 / preform according to claim 9, characterized in that all tissues additionally have 50% o fibers oriented in the warp direction and 50%> fibers oriented in the weft direction relative to the total number of fibers.

13 / preform according to claim 9, characterized in that it contains series of tissues alternating 4 fabrics having 50%> warp oriented fibers and 50%> of fibers oriented in the weft direction relative to the total number of fibers, then 1 fabric whose almost all the fibers are oriented in the warp direction.

14 / A process for manufacturing a preform made of crosslinked composite material intended for machining crowns or bridges, in particular using CAD / CAM according to which:

fabric spools are prepared, 100% of which warp fibers are oriented at an angle of 0 ° and 100% of the weft fibers are oriented at an angle of 90 °, the fabrics also having 50% oriented fibers. in the warp direction and 50% of the fibers oriented in the weft direction with respect to the total number of fibers, as many bobbins of fabric as there are layers of fabric necessary to obtain the desired thickness of the infrastructure are stored,

tensioning bobbins of fabrics so that they are superimposed, we pass the superimposed fabrics in resin,

the resin-impregnated fabrics are polymerized, forming the substructure, the substructure is then poured on, a resin forming the suprastructure, and the suprastructure is polymerized.

15 / A method according to claim 14, characterized in that is interposed between the tissues, a fabric which almost all the fibers are oriented in the warp direction.