WO2005118744A1

WO2005118744A1 - A prepreg containing silicon nanoparticles and its use

Info

Publication number: WO2005118744A1
Application number: PCT/FI2005/000251
Authority: WO
Inventors: Pekka Vallittu; Matti Peltola; Allan Aho; Antti Yli-Urpo; Erkki Hiltunen; Lippo Lassila; Lauri HEIKKILÄ
Original assignee: Pekka Vallittu; Matti Peltola; Allan Aho; Antti Yli-Urpo; Erkki Hiltunen; Lippo Lassila; Heikkilae Lauri
Priority date: 2004-06-01
Filing date: 2005-06-01
Publication date: 2005-12-15
Also published as: FI20040750A0

Abstract

The present invention relates to a prepreg comprising an at least partially uncured matrix, a structural part comprising at least one structural fiber embedded in said matrix, an optical part comprising at least one optical fiber embedded in said matrix, and said at least one optical fiber extending at least from one point on the surface of said prepreg to a distance within said prepreg. The prepreg is characterized in that said structural part further comprises silicon particles having a diameter of up to 5 nm. The invention also relates to a composite and to the use of said prepreg and said composite.

Description

A PREPREG CONTAINING SILICON NANOPARTICLES AND ITS USE

The invention relates to a prepreg comprising an at least partially uncured matrix, a structural part comprising at least one structural fiber embedded in said matrix, and an optical part comprising at least one optical fiber embedded in said matrix, and said at least one optical fiber extending at least from one point on the surface of said prepreg to a distance within said prepreg, The invention also relates to a composite obtainable by curing a prepreg according to the present invention. Furthermore, the invention relates to the use of said prepreg and composite and to various devices prepared from said prepreg.

BACKGROUND OF THE INVENTION

The use of reinforced composites made of particulate fillers or reinforcing fibers has been gaining popularity in dental and medical fields. Recently, several inventions regarding the fiber reinforced composites have been made. The state-of-the-art fiber reinforced composites yield high strength properties and by selecting the multiphase resin matrix for the composite, the handling characteristics of the composite can be considerably improved. These have been described, for example, in the patent applications WO 96/2591 1 and WO 99/45890.

On the other hand, a lot of development has occurred with bioactive materials, namely bioactive glass and sol-gel processed silica. These materials can be used to achieve attachment of e.g. bone to a biomaterial surface after the material has been put in contact with tissue. An additional advantage of bioactive glass is its antimicrobial effect on the microbes existing for instance in sinuses of a bone. These properties have been described in several articles and patent applications, such as WO 96/21628 and Zehnder et al., J Endod 2004 Apr;30(4):220-4.

Attempts to combine the properties of biopolymers, most often resorbable ones, and bioactive substances have been made as disclosed for example in the patent application WO 02/074356. Shortcomings in these approaches have been for instance the coverage of the bioactive substance particles with the polymer that diminishes the bioactivity to a large extent. On the other hand, the thermoplastic composites of polymers and bioactive substance filler particles have not fully filled the clinical requirements when immediate and higher mechanical properties of the composite are required.

From a surgical perspective individual replacement of bone, cartilage and soft tissues are insufficient in tumor, traumatologic and tissue reconstruction surgery despite the increasing advances in biomaterials research and their clinical application methods and tissue engineering. When the tissue engineering procedures with or without biomaterials are used e.g. in calvarial bone defect reconstruction, the surgical methods need patient's bone tissue harvested in a separate operation, the cell culture in laboratory, cartilage tissue harvesting for example from patient's ribs and the application of mixed cultured bone and cartilage tissue to the defect area in a separate operation procedure. In defect reconstruction, as separate template from the defect is needed, commercial alloplastic materials for reconstruction are generally used. These methods are rather complicated and they are also sensible to surgical complications. The experience of clinical usability of these procedures is still unclear and reliable long-term follow-ups do not exist. In addition, the preservation of the clinical outcomes is not reliably documented and not well known.

The need and indications for development of new kinds of materials result from disadvantages of the use of allografts. Risks for transmittable diseases (HIV, Creutzfeld-Jacob^'s disease, etc) are related to allografting. Metals are not bioactive or bone conductive, and their use results in stress shielding phenomena and bone atrophy of the adjacent bone. These main disadvantages are well documented in large clinical series.

A lot of information is available on the use of optical fiber sensors for medical use. They are used for instance in cardiovascular and intensive care, angiology, oncology, ophthalmology, dermatology and dentistry. The use of an optical fiber sensor and monitoring system are based on monitoring devices and they are not currently included to constructions intended to be part of the living body. On the other hand, also piezoelectric particles have been used in medicine, especially in auditory prostheses. Documents US 5,919,044 and US 6,033,223 illustrate different prepreg materials comprising various fibers. In US 6,033,223 for example, the prepreg may also comprise filler material such as silicon dioxide in quartz form. However, as is well known to persons skilled in the art, filler particles are typically of the size of 1 -60 μm.

OBJECTS OF THE INVENTION

An object of the present invention is to provide a biologically compatible material that does not have the above-listed drawbacks. Specifically, an object of the present invention is to provide a material useful for medical, dental and surgical uses, such as for bone grafting and for root canal posts. A further object of the present invention is to provide a prepreg and a composite that allow optimization of photo initiated polymerization in situ and optionally monitoring the biological processes after insertion of the prepreg or composite in tissue, and by the end offering a device for permanent or diagnostic use. A still further object of the present invention is to provide a material suitable for use in the manufacture of implants, by which it is also possible to simulate nerves and detect and transfer signals as well as to function as a position detector.

SUMMARY OF THE INVENTION

The present invention relates to a prepreg comprising - an at least partially uncured matrix, - a structural part comprising at least one structural fiber embedded in said matrix, - an optical part comprising at least one optical fiber embedded in said matrix, and said at least one optical fiber extending at least from one point on the surface of said prepreg to a distance within said prepreg. The prepreg is characterized in that said structural part further comprises silicon particles having a diameter of up to 5 nm.

The invention also relates to a composite obtainable by curing said prepreg. The invention still relates to the use of said prepreg or composite as well as to a prefabricated tooth prosthesis, a prefabricated epithese prosthesis of ear, a prefabricated stent and a prefabricated hip prosthesis.

BRIEF DESCRIPTION OF THE DRAWING

Figure 1 illustrates a prepreg according to a first embodiment of the present invention.

Figure 2 illustrates a use of a prepreg according to a second embodiment of the present invention.

Figure 3 illustrates a use of a prepreg according to a third embodiment of the present invention.

Figure 4 illustrates a use of a prepreg according to a fourth embodiment of the present invention.

Figure 5 illustrates a use of a prepreg according to a fifth embodiment of the present invention.

Figures 6a-6c illustrate a use of a prepreg according to a sixth embodiment of the present invention.

Figure 7 illustrates a use of a prepreg according to a seventh embodiment of the present invention.

Figures 8a and 8b illustrate a use of a prepreg according to an eighth embodiment of the present invention.

Figure 9 illustrates a use of a prepreg according to a ninth embodiment of the present invention.

Figure 10 illustrates a use of a prepreg according to a tenth embodiment of the present invention.

Figures 11a-11 e illustrate schematically a use of a prepreg according to an eleventh, twelfth and thirteenth embodiment of the present invention. Figures 12a-12d illustrate schematically a use of a prepreg according to a fourteenth, fifteenth and sixteenth embodiment of the present invention.

Figures 13a-13d illustrate schematically a use of a prepreg according to a seventeenth, eighteenth and nineteenth embodiment of the present invention.

Figure 14 illustrates schematically a use of a prepreg according to a twentieth embodiment of the present invention.

Figure 15a illustrates schematically a fiber structure according to a twenty-first embodiment of the present invention.

Figure 15b illustrates schematically a use of a prepreg according to a twenty- second embodiment of the present invention.

Figure 16 illustrates schematically a use of a prepreg according to a twenty- third embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The invention is defined in the appended independent claims.

The present invention relates to a prepreg comprising - an at least partially uncured matrix, - a structural part comprising at least one structural fiber embedded in said matrix, - an optical part comprising at least one optical fiber embedded in said matrix, and said at least one optical fiber extending at least from one point on the surface of said prepreg to a distance within said prepreg.

The prepreg is characterized in that said structural part further comprises silicon particles having a diameter of up to 5 nm.

The invention thus relates to a multifunctional fiber reinforced prepreg having both a biomedical load bearing and a tissue replacing functions, as well as light conducting and optionally monitoring functions. The different parts of the prepreg, structural and optical parts, both form integral parts of the composite obtained after the prepreg is cured. The optical part of the prepreg may thus have the functions of transmitting light as well as optical information. Indeed, the curing of the matrix is made through the optical part of the prepreg, by transmitting light into the prepreg. In this context, the optical fibers are used for transmitting light (visible, UV, IR, red light, blue light, etc.) from the surface of the prepreg to the interior of the prepreg. The silicon particles, that may also be called nanoparticles, produce photoluminescence when illuminated or electroluminescence when excited with electrical current.

By using such an optical part, a homogenous curing is thus obtained and the variations in size caused by the curing are minimized. Indeed, the silicon nanoparticles enhance the transmission of light within the prepreg, by scattering, by amplification and/or by generation of longer wavelength light.

In addition, the optical part may further be used for obtaining information on the state of the prepreg or the composite, as will be explained more in detail below.

In this application, by curing it is meant polymerization and/or crosslinking. By matrix, it is understood the continuous phase of the composition and by uncured matrix it is meant a matrix that is in its deformable state but that can be cured, i.e. hardened, to an essentially non-deformable state. The uncured matrix may already comprise some long chains but it is essentially not yet polymerized and/or crosslinked. By prepreg, it is meant a semi-manufactured product, that is, a product that is not or only partly polymerized, but yet still deformable. The polymerization of a prepreg leads to a composite. The terms "composite" and "cured prepreg" may be used interchangeably. By fibers embedded in a matrix it is meant that the matrix essentially covers the fibers and is preferably present also between the fibers. By "silicon" it is meant material that is essentially solely composed of Si-atoms.

The present invention thus fulfils the objects listed above, i.e. it provides a biologically compatible material that is useful for medical, dental and surgical uses, such as for joints, bone grafting and for root canal posts. The prepreg and composite according to the present invention also allow optimization of photo initiated polymerization in situ and optionally monitoring the biological processes after insertion of the prepreg or composite in tissue, and by the end offers a device for permanent or diagnostic use. Indeed, the material according to the present invention may be used for example for filling a hole in the skull of a patient, and the optical fibers may then be used to monitor the healing and the possible reactions under the skull. This then removes the need for using different imaging methods such as RMI and tomography. The materials according to the present invention also make the following up of an operated cancer patient much easier than before.

According to one embodiment of the present invention, said silicon particles are embedded in said matrix. Said silicon particles may also be present in the optical and/or structural fibers, either or both on the surface of the fiber and within the fiber. As an example, it can be mentioned that the particles may be present at those ends of the fibers that are within the prepreg, so as to produce more light within the prepreg. On the other hand, if such nanoparticles are distributed evenly within the optical fibers, infrared light is better transmitted within the said fibers.

When said nanoparticles are used in connection with glass (such as within glass fibers), pure silicon particles can be found useful. On the other hand, according to one embodiment of the present invention, the surface of said silicon particles comprises at least one silicon dioxide layer. The surface may thus comprise one, two, three or more silicon dioxide layers, either on top of each other or separated by other layers such as silicon layers.

For example, it is possible to form an oxide structure on the surface of silicon particles by subjecting said particles to an oxygen treatment. It is also possible to form a silicon dioxide structure directly from gaseous silane and oxygen. The thickness of said structure may be for example from 1 to 2 nm. It is also possible to coat said particles with silicon dioxide. On the other hand, said silicon nanoparticles may also be coated with other materials, as will be explained more in detail below. It is also possible to use thin oxide layers comprising silicon nanoparticles to produce electroluminescence by using electrical tension.

The diameter, i.e. the largest diameter, of the silicon particles used in the present invention is up to 5 nm, i.e. for example 0,1-5 nm. According to some embodiments of the invention, the diameter can be up to 3 nm or up to 1 ,5 nm. For example, when blue light is desired, a diameter of up to 1 ,5 nm is preferred. On the other hand, when visible light is desired, a diameter of up to 3 nm is preferred. Other suitable ranges for the largest diameter are for example 0,1 -1 ,5 nm, 0,5-1 ,5 nm, 0,5-5 nm, 1-1 ,5 nm, 1-5 nm, 1-3 nm, 1 ,5-5 nm, 2-4,5 nm or 2-3,5 nm. As is evident for a person skilled in the art, not all particles have the same diameter and the prepreg may also contain a minimal amount of particles having a smaller diameter than those indicated. Some examples of the photoluminescence are that when illuminated with green light, the particles produce yellow or red light, and when illuminated with blue light, they produce green or yellow light.

The amount of the silicon nanoparticles may be in the range of 1-30 volume-% of the matrix and/or structural and/or optical fibers, where said particles are present. Their amount may also be for example 2-10 volume-%, 5-10 volume- %, 5-15 volume-% or 10-15 volume-%.

According to an embodiment of the invention, the prepreg further comprises a piezoelectric part. The piezoelectric part has a function of producing charge when external force is applied to the prepreg or composite. This charge can be transformed to light, which can in turn be transferred by the optical part (optical fibers or silicon particles) of the prepreg or finished composite.

According to another embodiment, said piezoelectric part is present in the prepreg in a form selected from the group consisting of embedded in the matrix, embedded in at least one optical fiber, embedded in at least one structural fiber, as a coating on at least one optical fiber, as a coating on at least one structural fiber and mixtures thereof. When coating is used, it may cover part or whole of the fiber(s). Some of these forms are explained more in detail in connection with the drawing. By embedded, it is meant here both partial and total embedding.

The piezoelectric materials are biocompatible piezoelectric materials such as Siθ2 in quartz form and/or other piezoelectric materials such as BaTiO3,

PbZrTiOs and LiSO Preferred material is Siθ2 in the form of particles. It is also possible to use partial coatings of Siθ2 or fibers that have piezoelectrical properties per se. It is furthermore possible to use the above-mentioned materials or for example ZnO for coating of the silicon nanoparticles or a Si/Siθ2 nanolayers in order to render them both light producing and piezoelectric. As an example, it can be mentioned that the piezoelectric coefficient of Siθ2 in quartz form is 2,3 pC/N, whereas when a silicon particle is coated with a thin layer of ZnO, a piezoelectric coefficient of 10,6 pC/N can be obtained. The thickness of said coating may be for example in the order of 0,01-100 μm.

By piezoelectric materials it is meant particles, crystals or coatings that acquire a charge when compressed, twisted or distorted. The function of these piezoelectric particles is thus to create a tension as the prepreg is deformed (bent, twist, compressed etc), thus creating a piezoelectric effect. The charge is preferably transformed into light. This light can then be used to simulate nerves. Coating of the fiber can be glass, titanium oxide, Si-sol-gel based, or other minerals. The coating can be on specifically located areas or cover the whole fiber. Between the fibers there can be synthetic polymers or tissues like bone, cartilage, muscle, nervous tissue, epithelial tissue or tissue liquid.

The information transfer may be performed for example in a following manner: a signal is formed in a sensor (piezoelectric particle). Light is formed by an electrical excitation similar to electroluminescence, preferably in a Si/Siθ2 layer structure, or in other structures capable of producing light. The light is then transmitted via optical fibers by using total reflection. This is a transmission without losses. Then the light is transformed back to electrical pulse by a photocathode and the electrical pulse is fed into a computer, another control unit or a nerve.

The nerve-simulation by piezoelectric particles is possible, since the voltage of a nerve impulse is approximatively 100 mV, and the threshold voltage of activation of a nerve is approximatively 7 mV.

The above-mentioned light that may be used to simulate nerves is typically emitted from a very small area, such as couples of micrometers. The signal, i.e. the intensity of light, varies when the environment of the piezoelectric particle varies, for example, when the bioactive glass degrades. In the prepreg according to the present invention, said at least one optical fiber preferably extends at least from one point on the surface of said prepreg to a distance within said prepreg. This means that the optical fiber(s) are present at least on one point on the surface as well as within said prepreg and can thus continue in both directions from said point on the surface, i.e. also outwards from said prepreg, as will be apparent in the description below.

The optical fiber(s) may be used for transferring information from an implant to a nerve, from an implant to a computer, from a computer to an implant, for diagnosing movements as well as for diagnosing and controlling the curing of tissues.

According to another embodiment of the invention, the structural part of the prepreg comprises one or several structural fibers and the optical part of the prepreg comprises one or several optical fibers. In each part, different fibers may have different functions as will be apparent from the description below. The number of said fibers, either structural or optical, may be for example, 1 , 2, 3, 4, 5, 8, 13, 26 or 76.

According to an embodiment of the invention, said at least one optical fiber extends substantially through said prepreg. Said optical fiber or fibers are thus present in essentially whole of the prepreg. According to a preferred embodiment, said fibers are grouped in one point on the surface of a device made of the prepreg according to the present invention, and are positioned on the other parts of the prepreg either as a bundle or at distances from each other. The optical fibers may, for example, be in the form of a fan or a bundle of fibers.

The at least one structural fiber may be any suitable fiber known per se, for example selected from the group consisting of glass fibers, silica fibers, carbon/graphite fibers, ceramic fibers, aramid fibers, zylon fibers, polyethylene fibers, polytetrafluoroethylene fibers, such as Teflon® fibers, poly(p-phenylene- 2,6-benzobisoxazole) fibers, poly(2,6-diimidazo(4,5-b4',5'-e)pyridinylene- 1 ,4(2,5-dihydro)phenylene fibers, polyolefin fibers, fibers prepared from copolymers of olefins, polyester fibers, polyamide fibers and mixtures thereof. Poly(p-phenylene-2,6-benzobisoxazole) fibers and poly(2,6-diimidazo(4,5- b4',5'-e)pyridinylene-1 ,4(2,5-dihydro)phenylene fibers belong to a group called rigid-rod polymer fibers. It is obvious to a person skilled in the art that any other known fibers may be used in the present invention, provided that it is possible to obtain a suitable adhesion between said fibers and matrix, in order to achieve the desired mechanical properties. Preferably, glass fibers are used in dental applications. In applications where load-bearing capacity is needed, continuous biostabile fibers are preferred.

The structural fibers may be in the form of continuous fibers, fiber fabrics, fiber weaves, fiber mats, short fibers and mixtures thereof, and they may be oriented in one direction, two directions, three directions, four directions, randomly or mixtures thereof. This part gives the prepreg its load-bearing capacity after the matrix has been cured.

The matrix may comprise monomers selected from the group consisting of methyl acrylate, ethyl acrylate, propyl acrylate, isopropyl acrylate, n-hexyl acrylate, styryl acrylate, allyl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, 2-ethylhexyl methacrylate, cyclohexyl methacrylate, isobornyl methacrylate, tetrahydrofurfuryl methacrylate, benzyl methacrylate, morpholinoethyl methacrylate, diurethane dimethacrylate, acetoacetoxy ethyl methacrylate (AAEM), methacrylate functionalized dendrimers, other methacrylated hyperbranched oligomers, hydroxymethyl methacrylate, hydroxymethyl acrylate, hydroxyethyl methacrylate, hydroxyethyl acrylate, hydroxypropyl methacrylate, hydroxypropyl acrylate, tetrahydrofurfuryl methacrylate, tetrahydrofurfuryl acrylate, glycidyl methacrylate, glycidyl acrylate, triethylene glycol diacrylate, tetraethylene glycol dimethacrylate, tetraethylene glycol diacrylate, trimethylolethane trimethacrylate, trimethylolpropane trimethacrylate, pentaerythritol trimethacrylate, trimethylolethane triacrylate, trimethylolpropane triacrylate, pentaerythritol triacrylate, pentaerythritol tetramethacrylate, pentaerythritol tetra-acrylate, ethylene dimethacrylate, ethylene diacrylate, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate (TEGDMA), ethylene glycol diacrylate, diethyleneglycol diacrylate, butylene glycol dimethacrylate, butylene glycol diacrylate, neopentyl glycol dimethacrylate, neopentyl glycol diacrylate, 1 ,3-butanediol dimethacrylate, 1 ,3-butanediol diacrylate, 1 ,4-butanediol dimethacrylate, 1 ,4-butanediol diacrylate, 1 ,6- hexanediol dimethacrylate, 1 ,6-hexanediol diacrylate, di-2-methacryloxyethyl- hexametylene dicarbamate, di-2-methacryloxyethyl-trimethylhexametylene dicarbamate, di-2-methacryloxyethyl-dimethylbenzene dicarbamate, di-2- methacryloxyethyl-dimethylcyclohexane dicarbamate, methylene-bis-2- methacryloxyethyl-4-cyclohexyl carbamate, di-1 -methyl-2-methacryloxyethyl- hexamethylene dicarbamate, di-1-methyl-2-methacryloxyethyl- trimethylhexamethylene dicarbamate, di-1 -methyl-2-methacryloxyethyl- dimethylbenzene dicarbamate, di-1-methyl-2-methacryloxyethyl- dimethylcyclohexane dicarbamate, methylene-bis-1-methyl-2- methacryloxyethyl-4-cyclohexyl carbamate, di-1-chloromethyl-2- methacryloxyethyl-hexamethylene dicarbamate, di-1 -chloromethyl-2- methacryloxyethyl-trimethylhexamethylene dicarbamate, di-1 -chloromethyl-2- methacryloxyethyl-dimethylbenzene dicarbamate, di-1-chloromethyl-2- methacryloxyethyl-dimethylcyclohexane dicarbamate, methylene-bis-2- methacryloxyethyl-4-cyclohexyl carbamate, di-1 -methyl-2-methacryloxyethyl- hexamethylene dicarbamate, di-1-methyl-2-methacryloxyethyl- trimethylhexamethylene dicarbamate, di-1 -methyl-2-methacryloxyethyl- dimethylbenzene dicarbamate, di-1-methyl-2-methacryloxyethyl- dimethylcyclohexane dicarbamate, methylene-bis-1-methyl-2- methacryloxyethyl-4-cyclohexyl carbamate, di-1-chloromethyl-2- methacryloxyethyl-trimethylhexamethylene dicarbamate, di-1 -chloromethyl-2- methacryloxyethyl-dimethylbenzene dicarbamate, di-1 -chloromethyl-2- methacryloxyethyl-dimethylcyclohexane dicarbamate, methylene-bis-1 - chloromethyl-2-methacryloxyethyl-4-cyclohexyl carbamate, 2,2-bis(4-(2- hydroxy-3-methacryloxy)phenyl)propane (BisGMA), 2,2^*-bis(4- methacryloxyphenyl)propane, 2,2'-bis(4-acryloxyphenyl)propane, 2,2'-bis[4(2- hydroxy-3-acryloxyphenyl)propane, 2,2'-bis(4- methacryloxyethoxyphenyl)propane, 2,2'-bis(4-acryloxyethoxyphenyl)-propane, 2,2'-bis(4-methacryloxypropoxyphenyl)propane, 2,2'-bis(4-acryloxy- propoxyphenyl)propane, 2,2'-bis(4-methacryloxydiethoxyphenyl)-propane, 2,2'- bis(4-acryloxydiethoxyphenyl)propane, 2,2'-bis[3(4-phenoxy)-2- hydroxypropane-1-methacrylate]propane, 2,2'-bis[3(4-phenoxy)-2- hydroxypropane-1-acrylate]propane and mixtures thereof. The matrix may also be made of crosslinkable monomers or polymers such as ε-caprolactone, polycaprolactone, polylactides, polyhydroxyproline, and other biopolymers as well as polyamides, polyurethane, polyethylene, polypropylene, other polyolefins, polyvinyl chloride, polyester, polyether, polyethyleneglycol, polysaccharide, polyacrylonitrile, poly(methyl methacrylate), phenol- formaldehyde, melamine-formaldehyde, and urea-formaldehyde. The matrix may naturally also consist of a mixture of a monomer(s) and a polymer(s).

Dendrimers having 5 to 35 functional groups (or more) such as methacrylate or acrylate groups may also be used. Multifunctionality forms highly cross-linked matrix and decreases the creep of the polymer in the long-term use. Examples of suitable dendrimers are given for example in US 5,834,118 (incorporated herein by reference). Dendrimers may particularly be starburst or hyperbranched methacrylated polyesters.

According to one embodiment of the present invention, the matrix of the prepreg can be made of monomer systems of mono-, bi, or multifunctional acrylates, epoxies, dendrimers, hyper branched reactive polymers, their combinations, or the like. The matrix of said structural part may, for example, be selected from the group consisting of mono-, di-, and multifunctional acrylates, mono-, di-, and multifunctional methacrylates, epoxies, starburst methacrylated polyesters, hyperbranched methacrylated polyesters and mixtures thereof. Optionally, polymers of polymethyl methacrylate, polyvinyl chloride, polyetherketone, polylactides, epsiloncaprolactone or their combinations, or the like may be used. Combinations of monomers and polymers are also suitable to be used in the prepregs. In dental applications, it is preferred, for the moment, to use dimethacrylates in combination with polymethyl methacrylate as a matrix, because it forms a gel like matrix before polymerization. The matrix can be dense or contain pores and holes in the structure depending up to clinical needs. The optimal pore size for endosseus applications is 100 to 500 micrometers when bone ingrowth is considered, but the composite can optionally contain also holes up to 5 millimeters in diameter.

The fibers for the optical part are selected according to the function of transmitting polymerization initiation light to the prepreg, and/or of functioning as a conductor for optical information. In the light transmitting function the required wavelength of the light sets limitations for the selection of suitable fiber material. The importance of optical fiber(s) for photo polymerization is especially highlighted when the light cannot penetrate into the material otherwise, e.g. through the matrix. The at least one optical fiber may, for example, be selected from the group consisting of monophasic quartz fibers, polymethylmethacrylate fibers, multiphasic optical fibers and mixtures thereof. In the following, the optical part may be divided into two systems, the curing system and the monitoring system. The fibers in the two systems may be identical or different. The wavelengths used may be for example 400-520 nm, such as 430-490 nm and the diameters used are typically in the range of 20-50 μm.

In some occasions, when the thickness of the multifunctional prepreg/composite is limited (1 - 3 mm) and the operation area is visible, the photo polymerization may occur also through the light penetration of the matrix. As an example, when the intention of the optical fibers is to initiate polymerization of acrylates and methacrylates by camphorquinone - amine initiator system, the required wavelength is 476 nm. For transmitting light of this wavelength, quartz fibers or polymethyl methacrylate fibers are preferred. On the other hand, when the intention of the optical fibers is to provide a conductor for optical information to and from tissues, the fibers are preferably selected from the group of layered optical fibers of e.g. germania doped silica core and cladding of silica.

The fibers of the optical fiber system can be cut after photo polymerization or they can remain for further monitoring use. In this application, the light radiation is made after some period time and the transmittance of light from polymerization initiation fibers to the monitoring fibers is used as indicator for the internal integrity of the multifunctional composite. If the interface between the fibers and the matrix is deteriorated e.g. by mechanical fatigue or degradation, the light transmittance is lowered. The optical fiber parts may thus function as a microscope to view the inside the body.

When the prepreg is used, the matrix is still in essentially non-cured form. This enables contouring and placing the prepreg according to the anatomy of the tissue to be replaced. Transmitting light to the prepreg through the optical fibers starts the polymerization of the composite, for example blue light through quartz fibers. This polymerizes the prepreg into a composite. The existence of optical communication fiber system in the composite becomes a part of the composite in polymerization and the fiber system can be used for monitoring the healing process of tissues around the composite material. Also, either or both of the optical fiber systems can be used for transmitting the light required to activate locally applied photosensitive drugs. It is also possible to add sensors to the optical fiber systems to monitor non-destructively the structure of implants of for example dental prostheses.

The prepreg according to the present invention may further comprise particulate filler material, such as inert glass, bioactive glass, metal oxides, ceramics, polymers and mixtures thereof. Metal oxides may for example be used as radio or X-ray opaque materials or as coloring materials. It is for example possible to make the prepreg such that it is not further necessary to coat it with another material to make the final outer surface of the finished device.

The prepreg according to the present invention may further comprise a bioactive substance that may be in the form of particulate fillers or fibers. It is preferred to use particulate fillers in dental applications. The bioactive material can be selected from bioactive glasses, silica gel, silica xerogels, silica aerogel, natrium silica glass, titanium gels, bioactive glass ionomer, hydroxyapatite, Ca/P-doped silica gel or the like. Any combination of said materials may naturally also be used. When rapid mineralization is needed, it is preferred to have bioactive glass with sol-gel processed silica particles on the surface of the prepreg.

The invention further relates to a composite obtainable by curing the prepreg according to the present invention. The invention thus relates to a composite comprising a matrix, structural part comprising at least one structural fiber embedded in said matrix, an optical part comprising at least one optical fiber embedded in said matrix. Said composite is characterized in that said optical part further comprises silicon particles having a diameter of up to 5 nm. The materials as well as the filler particles that may be used in the composite are the same as disclosed above in connection with the prepreg. The invention still relates to different devices made of a prepreg or a composite according to the present invention.

The invention thus relates to a prefabricated tooth prosthesis consisting essentially of a prepreg according to the present invention, wherein said optical part consists of at least two optical fibers, said fibers forming a bundle on one point on the surface of said prefabricated tooth and said fibers being positioned at a distance from each other on other parts of said prefabricated tooth.

The invention also relates to a prefabricated epithese prosthesis of ear consisting essentially of a prepreg according to the present invention, wherein said optical part consists of at least two optical fibers, said fibers forming a bundle on one point on the surface of said prefabricated epithese prostheses of ear. The prepreg/composite according to the present invention may also be used for manufacturing implants for auditory ossicles or veins, for example.

Some applications for the multifunctional composite in contact to soft tissues are stents, catheters and prostheses to assure patency of contracted lumens. The invention thus also relates to a prefabricated stent consisting essentially of a prepreg according to the present invention. Such a prefabricated stent may be used for example in blood vessels, guts, esophagus, gastrointestinal tract, lymph vessels, urinary tract, respiratory tract and nervous system. The invention still relates to a prefabricated hip prosthesis consisting essentially of a prepreg according to the present invention.

The prepreg/composite according to the present invention may thus be used to manufacture any kind of device, and the manufacturing process is evident for a person skilled in the art. The device may be either made of a prepreg, i.e. still deformable, or it may also be made of a composite, i.e. already cured and essentially not deformable, according to the intended use. The size of the device may vary from micrometer range (such as for auditory ossicle implants) to large pieces of tissue. The prepreg/composite according to the present invention may thus be used for manufacturing "spare parts" such as ears, noses and eyes. The advantage of the present materials for ears and noses is, for example, that the optical fibers may be positioned in such a way that the implant follows the coloring of the surrounding skin, for example when the person blushes.

Furthermore, the present materials may be used for manufacturing of nose or facial soft tissues, knee or shoulder prosthesis, as well as stress level and position detectors.

The invention yet still relates to the use of a prepreg or of a composite according to the present invention in different applications. The present invention also relates to the use of a prepreg or of a composite according to the present invention for the manufacture of devices and/or materials for use in different applications.

Some examples of applications are the use as a load bearing structural biomaterial, for replacement and repair of tissue, bones and skeleton, for monitoring the biological processes in the tissue, for retaining soft and cartilage tissues in desired form, for activating the locally applied photosensitive agents, such as initiators of polymerization reactions and drugs in tissue, for monitoring structural changes of composite structure under function, for estimating nondestructively the life span of a composite device in situ, for cell and tissue engineering and testing, for process and tissue technology control in vitro, for monitoring the biting habits of a patient, for disinfection, for positioning detector or for stress-level sensor in a biomaterial-living tissue system.

In dental prostheses and restorations, the monitoring function can be focused on biological processes around root, biting force monitoring to evaluate and diagnose bruxism or other parafunctional habits that could cause damage to the dentition. It is also possible to use the optical part as non-destructive, in situ method to estimate and evaluate the life span of fiber-reinforced composite in medical and dental restorations.

The multifunctional prepreg/composite as structural biomaterial can also be used in long bone replacement, individually formed root canal posts of teeth, dental implants, replacement of vertebra, pelvis, and reconstruction of other skeletal parts such as in repair and replacement of auditory ossicles. The multifunctional prepreg/composite can also be used as replacing material for e.g. tumor-invaded tissues. By means of the optical part, the composite can be used to monitor physiological and pathological processes adjacent to the composite material. It is also within the use of the composite material to activate photosensitive drugs by the optical fiber system if relapses of e.g. cancer treatment occur. In this case, it is also possible to use optical fibers that are able to transmit laser irradiation, so that for example laser irradiation may be used at a later stage to destroy a metastasis.

In plastic surgery, the multifunctional prepreg/composite can be used to retain soft or cartilage tissue in the position where they give the optimal and desired support for the tissues with regard to the esthetics and cosmetics of a human body.

Furthermore, the prepreg/composite according to the present invention may be used for enhancing tissue culture by providing light into the culture in a more homogeneous way than by normal lightning.

The prepreg and composite according to the present invention may be used in both humans and animals. They may be used also for manufacturing prostheses, clothes and appliances such as combinations of a nose prostheses and eye glasses.

The specific embodiments and details listed above in connection with the prepreg also apply for the composite and devices according to the present invention.

DETAILED DESCRIPTION OF THE DRAWING

Figure 1 illustrates a prepreg according to a first embodiment of the present invention. The Figure illustrates the structure of a prepreg according to a first embodiment of the present invention, made of continuous unidirectional fibers 1 and matrix 2. The prepreg consists of fibers of the structural fiber system 1 and fibers of the optical fiber system 3 that transduce and scatter the light required to photopolymerize the matrix of the prepreg by light irradiation 4. There is also a fiber 5 of the optical fiber system allowing monitoring the integrity of the composite system after the prepreg has been polymerized and the composite used. Furthermore, the matrix comprises silicon particles 2', optionally comprising a layer of Siθ2- These particles are here largely oversized for illustration purposes and are not shown in the other Figures. The monitoring is made through determining the light transmittance from the structural fiber system to the optical fiber system via the interface of the fiber 5 and matrix 2. In the case of good internal integrity of the composite after being used for a period of time, the light transmittance remains at the same level as immediately after insertion. If damage of the internal integrity of the composite has occurred, the light transmittance is lowered.

Figure 2 illustrates a use of a prepreg according to a second embodiment of the present invention, i.e. the use of a prepreg as individually formed and in situ polymerizable dental implant. After extraction of a left mandibular central incisor, the prepreg consisting of continuous unidirectional fibers 6 as structural fiber system is placed into the extraction socket 7. The non- or only partially polymerized matrix of the prepreg adapts the form of the walls of the extraction socket. The fiber 8 of the optical fiber system transduces and scatters the light needed for photopolymerization of the matrix of the prepreg after being irradiated with light 4. After polymerization, the composite implant is covered with a suprastructure known per se (not shown). It is evident for a person skilled in the art that an implant of this type may also be inserted into a drilled hole.

Figure 3 illustrates a use of a prepreg according to a third embodiment of the present invention. The Figure illustrates the use of a prepreg as internal fixation device of a fractured long bone 9. A hole 10 is drilled to the cortex and medullae of the bone. Prepreg containing fibers of the structural fiber system 11 is inserted into the bone and polymerized through the fiber of the optical fiber system 12, extending through the prepreg, by light irradiation 4. After photopolymerization, the device is a solid fiber-reinforced composite and supports the fragments of bone.

Figure 4 illustrates a use of a prepreg according to a fourth embodiment of the present invention. The Figure illustrates the use of a prepreg as a segment fractured long bone. For supporting the pieces of bone 13, the prepreg material is inserted into the medullae of the pieces of long bone. The fibers of the structural 14 and optical 15 fiber systems are penetrated into the bone and the fibers of the optical fiber system 15 allow photopolymerization of the matrix of the prepreg by light irradiation 4. Additional fibers of the structural fiber system 5 form the outermost part of the segment of long bone.

Figure 5 illustrates a use of a prepreg according to a fifth embodiment of the present invention. The Figure illustrates the use of a prepreg in hip prostheses. The prostheses contains fibers of the structural fiber system 16 that gives the load bearing capacity for the implant and the retaining surface for the artificial joint material 17. The fibers of the optical fiber system 18 allow photopolymerization of the prefabricated implant in situ by light radiation 4, transmittance and scattering. Another fiber 19 of the optical fiber system 18 is used for monitoring the internal integrity of the composite material by determining the light 20 coming back from the composite once it has been irradiated through fibers 18.

Figures 6a-6c illustrate a use of a prepreg according to a sixth embodiment of the present invention. The Figures illustrate the use of a prepreg in replacement of bones or pieces of bones of human skull. Lined areas represent the prepreg or resulting composite material in Figure 6a as a lateral, in Figure 6b as a frontal and in Figure 6c as a caudal view of the human skull. There are short chopped fibers 21 forming the structural part of the composite and continuous fibers of the optical fiber system 22 to ensure photopolymerization of the matrix by light radiation 4. The prepreg is formed to correspond to the anatomical requirements before polymerization.

Figure 7 illustrates a use of a prepreg according to a seventh embodiment of the present invention. The Figure illustrates the use of a prepreg as an epithese prosthesis of ear 23. The optical fibers 24 of the prepreg extend to different distances from their starting point. The prepreg is again polymerized by light irradiation 4.

Figures 8a and 8b illustrate a use of a prepreg according to an eighth embodiment of the present invention. The Figure 8a illustrates a blood vessel

25 with stenosis 26 requiring enlargement of the lumen, in the direction of the arrows 27 with a stent 28. The stent made of a prepreg according to the present invention is placed into the vessel by catheter 29. The stent is shown more in detail in Figure 8b. When the partially polymerized resin matrix of the stent 28 is enlarged in the vessel, in the direction of arrows 30, by pressing air into the catheter 29, the lumen of the vessel is also enlarged. The enlarged stent 28 is polymerized to the desired magnitude of enlargement by the optical fiber system 31 of the stent 28 and light irradiation 4. The operation is made under visual control 32 of the operator via the catheter 29.

Figure 9 illustrates a use of a prepreg according to a ninth embodiment of the present invention. The Figure illustrates the knee joint 33 having an arthrotic region 34 needing operation. The arthrotic region 34 is reshaped with endoscopical surgical procedure and the remaining cavity of the knee joint 33 is filled with a prepreg 35 according to the present invention. The prepreg 35 is polymerized into the desired surface contour by the optical fiber system 36 which transduces the polymerization initiation light 4 into the prepreg 35. After polymerization, the optical fibers 36 are cut endoscopically and removed.

Figure 10 illustrates a use of a prepreg according to a tenth embodiment of the present invention. The Figure illustrates a tooth implant prepared from a prepreg according to the present invention, said implant containing an artificial root 37 and a crown 38. The structural fibers 39 between the matrix 40 are combined with the optical fibers 41 that form a window to the buccal or lingual surface of tooth. Light initiated curing of the matrix is done through the optical fiber system 41. The optical fiber system 41 may also be used for detecting the impulse as explained more in detail below.

Figures 11a-11e illustrate schematically a use of a prepreg according to an eleventh, twelfth and thirteenth embodiment of the present invention. In these embodiments, the optical fibers are present as in the previous embodiments, but for reasons of simplicity, they are not represented. In Figure 11a, a urinary tract 42 is represented, wherein at a prepreg according to the present invention is used at two locations, A and B. Figure 11 b represents one possible use of a prepreg, the eleventh embodiment. In this embodiment, a stent 43 made of a prepreg according to the present invention is positioned inside the urinary tract. Figure 11 c represents the twelfth embodiment of the invention, i.e. the use of a prosthesis 44 made of a prepreg according to the present invention in the urinary tract. Figures 11 d and 11e represent, in cross-sectional view and in perspective view respectively, the thirteenth embodiment of the invention, i.e. a stent or tube 45 made of the prepreg according to the present invention and positioned over the urinary tract.

Figures 12a-12d illustrate schematically a use of a prepreg according to a fourteenth, fifteenth and sixteenth embodiment of the present invention. In these embodiments, the optical fibers are present as in the previous embodiments, but for reasons of simplicity, they are not represented. Figure 12a shows a respiratory tract, wherein a stent 48 manufactured from the prepreg according to the present invention is positioned inside the tranchea 47. Devices 48, 50 made of said prepreg may also be used in the larynx. Figure 12b shows the part C of Figure 12a in more detail, and corresponds to the fourteenth embodiment of the invention. The fifteenth embodiment of the present invention is illustrated in Figure 12c, wherein a stent 51 is positioned over the tranchea. Figure 12d represents the sixteenth embodiment of the present invention, i.e. a prosthesis 52 made of a prepreg according to the invention.

Figures 13a-13d illustrate schematically a use of a prepreg according to a seventeenth, eighteenth and nineteenth embodiment of the present invention. Figure 13a shows schematically and in a cross-sectional view a part of a nervous system 53, wherein a tube 54 is positioned over a nerve as shown in the section D and more in detail in Figure 13b, corresponding to the seventeenth embodiment of the invention. In Figure 13d, the section E of Figure 13a is shown in more detail and it schematically illustrates a prosthesis 55 made of a prepreg according to the invention, as a nineteenth embodiment of the invention. In these two embodiments, the optical fibers are present as in the previous embodiments, but for reasons of simplicity, they are not represented.

Figure 13a further illustrates a use of a prepreg according to an eighteenth embodiment of the invention, i.e. for use for modifying the functioning of the nerve. This is again shown in more detail in Figure 13c, wherein the optical fibers 56 of the prepreg are illustrated. These fibers can be made to enter inside the nerve at one or more locations and are used for enhancing, reducing or replacing the electrical or impulse transferring function of the nerve.

Figure 14 illustrates schematically a use of a prepreg according to a twentieth embodiment of the present invention. In this embodiment, the prepreg is used for a positioning detector system for a knee, made of a piezoelectric fibers system comprising a fiber 57 and a partial piezoelectric coating 58. The charge that is formed in the movement of the knee in the piezoelectric system provides information on the position of the knee.

Figure 15a illustrates schematically a fiber structure according to a twenty-first embodiment of the present invention. In this embodiment, the fiber structure is composed of a structural fiber 59, an optical fiber 60, a piezoelectric coating 61 or a dual-layered piezoelectric coating 62. The silicon particles are comprised in the structural fiber 59 and/or the optical fiber 60. By twisting or compressing the fibers a piezoelectric effect and charge is acquired and transformed into light.

Figure 15b illustrates schematically a use of a prepreg according to a twenty- second embodiment of the present invention. This embodiment shows the use of the prepreg in an artificial tooth. In this embodiment, a fiber structure illustrated in Figure 15a is used. When the tooth is loaded in the direction of the arrow 63, the stress is transferred to a detector layer 64 and transferred further to the root causing bending. In the bending, the piezoelectric fiber system acquires charge and/or light emission which is transferred by the optical fibers.

Figure 16 illustrates schematically a use of a prepreg according to a twenty- third embodiment of the present invention. In this embodiment, the prepreg is used in a crown of a tooth. The fiber system 65 is positioned on the crown. When the tooth is loaded in the direction of the arrow 66, the optical and/or piezoelectric fiber system is activated and it detects the stress level of the tooth.

In this specification, except where the context requires otherwise, the words "comprise", "comprises" and "comprising" mean "include", "includes" and

"including", respectively. That is, when the invention is described or defined as comprising specified features, various embodiments of the same invention may also include additional features.

Claims

1. A prepreg comprising - an at least partially uncured matrix, - a structural part comprising at least one structural fiber embedded in said matrix, - an optical part comprising at least one optical fiber embedded in said matrix, and said at least one optical fiber extending at least from one point on the surface of said prepreg to a distance within said prepreg, characterized in that said optical part further comprises silicon particles having a diameter of up to 5 nm.

2. Prepreg according to claim 1 , characterized in that said silicon particles are embedded in said matrix.

3. Prepreg according to claim 1 or 2, characterized in that the surface of said silicon particles comprise at least one silicon dioxide layer.

4. Prepreg according to any of the preceding claims, characterized in that it further comprises a piezoelectric part.

5. Prepreg according to claim 4, characterized in that said piezoelectric part is present in the prepreg in a form selected from the group consisting of embedded in the matrix, embedded in at least one optical fiber, embedded in at least one structural fiber, as a coating on at least one optical fiber, as a coating on at least one structural fiber and mixtures thereof.

6. Prepreg according to any of the preceding claims, characterized in that said at least one optical fiber extends substantially through said prepreg.

7. The prepreg according to any of the preceding claims, characterized in that the at least one structural fiber is selected from the group consisting of glass, silica, carbon/graphite, aramid, polyethylene, poly(p-phenylene-2,6- benzobisoxazole) fibers, poly(2,6-diimidazo(4,5-b4',5'-e)pyridinylene-1 ,4(2,5- dihydro)phenylene fibers and mixtures thereof.

8. Prepreg according to any of the preceding claims, characterized in that the at least one optical fiber is selected from the group consisting of monophasic quartz fibers, polymethylmethacrylate fibers, multiphasic optical fibers and mixtures thereof.

9. Prepreg according to any of the preceding claims, characterized in that the matrix of said structural part is selected from the group consisting of mono-, di-, and multifunctional acrylates, mono-, di-, and multifunctional methacrylates, epoxies, starburst methacrylated polyesters, hyperbranched methacrylated polyesters and mixtures thereof.

10. A composite obtainable by curing the prepreg according to any of the claims 1 to 9.

11. A composite comprising a matrix, structural part comprising at least one structural fiber embedded in said matrix, an optical part comprising at least one optical fiber embedded in said matrixcharacterized in that said optical part further comprises silicon particles having a diameter of up to 5 nm.

12. A prefabricated stent consisting essentially of a prepreg according to any of the claims 1 -9 or of a composite according to claim 10 or 11.

13. A prefabricated prosthesis consisting essentially of a prepreg according to any of the claims 1-9 or of a composite according to claim 10 or 11.

14. A prefabricated tooth prosthesis consisting essentially of a prepreg according to any of the claims 1-9 or of a composite according to claim 10 or 11 , wherein said optical part consists of at least two optical fibers, said fibers forming a bundle on one point on the surface of said prefabricated tooth and said fibers being positioned at a distance from each other on other parts of said prefabricated tooth.

15. A prefabricated epithese prosthesis of ear consisting essentially of a prepreg according to any of the claims 1-9 or of a composite according to claim

10 or 11 , wherein said optical part consists of at least two optical fibers, said fibers forming a bundle on one point on the surface of said prefabricated epithese prostheses of ear.

16. A prefabricated hip prosthesis consisting essentially of a prepreg according to any of the claims 1-9 or of a composite according to claim 10 or 11.

17. Use of a prepreg according to any of the claims 1-9 or of a composite according to claims 10 or 11 in manufacture of devices and/or materials for replacement and repair of bones and skeleton, for monitoring the biological processes in the tissue, for retaining soft and cartilage tissues in desired form, for activating the locally applied photosensitive drugs, for monitoring structural changes of composite structure under function, for estimating nondestructively the life span of a composite device in situ, for cell and tissue engineering and testing, for process and tissue technology control in vitro, for monitoring the biting habits of a patient, for disinfection, for positioning detector or for stress- level sensor in a biomaterial-living tissue system.