WO1996026237A1

WO1996026237A1 - Improved composite material

Info

Publication number: WO1996026237A1
Application number: PCT/US1996/002062
Authority: WO
Inventors: Paul R. Chalifoux
Original assignee: Wellesley Research Associates, Inc.
Priority date: 1995-02-21
Filing date: 1996-02-15
Publication date: 1996-08-29

Abstract

A crack resistant composite composition is provided comprising a polymeric resin matrix and between 2 and 75 volumetric percent of shaped filler particles based on the volume of the composition (15). The filler particles or fibers are shaped to minimize or prevent cracks from propagating through the resin matrix.

Description

IMPROVED COMPOSITE MATERIAL REFERENCE TO RELATED APPLICATIONS

This application is a contihuation-in-part of co-pending application Serial Number 08/213,938, filed March 16, 1994. BACKGROUND OF THE INVENTION

This invention relates to an improved strength enhancing filler material for use with polymeric material binder in preparing direct and indirect dental, medical, industrial and general commercial composite materials and processes for preparing the same.

Presently, strength enhancing material such as filler or fibers are admixed with a matrix binder such a polymeric or concrete matrix binder to form composite materials having improved strength characteristics as compared to the binder matrix per se. Such composite materials are useful in a wide variety of industrial environments as well as for use in dentistry and in other medical applications.

Present dental composites are based on methylmethacrylate resin systems. Dental systems are primarily based on 2,2 bis[4 - (3 - methacryloxy - 2 - hydroxy - propoxy) - phenyl] - propane (BIS GMA). Unfortunately, a volumetric shrinkage of 21 % for resin during polymerization is unacceptable in use, for example in dentistry, because of precise fits required for restorations. Diluents (Methyl Methacrylate (MMA), Bisphenol A - dimethyl acrylate (BIS-DMA), triethylene glycoldimeth l acrylate (TEGDMA), ethylene glycol dimethyl acrylate (EGDMA) or the like.), prepolymerized particles or organic and inorganic fillers are added to a resin composition in order to minimize shrinkage.

Presently available fillers are produced by grinding, milling, precipitation or by condensation. Present techniques of manufacturing filler particles have not allowed controlling the shape of filler particles and thus the shapes are generally spherical or, in the case of fibers have a regular cross-section such as a circular cross- section. For some dental, medical, industrial and general use applications, translucency is important and therefore only fillers of glass and quartz which have a refractive index similar to a translucent resin composition (1.5) can be used while retaining translucency. Behavior of resin filled composites is dependent on the following characteristics of the filler: particle size and size distribution, particle shape, particle surface, chemical composition, optical properties, radiopacity and proportion of the filler in the composition. Standard classification of dental composites has been based on particle size and is commonly referred to as macrofills (10um or greater) and microfills (1 um or less). Recently, a new category of composite has been introduced which are referred to as hybrids which has 5um particles mixed with smaller than 5um particles which are used to fill space and produce a composite with a lower nonfiller fraction.

Macrofill composites are characterized by good strength. However, the particle size renders the composite unacceptable from an aesthetic point of view and as resin material deteriorates the filler "plucks" out causing rapid wear. Microfill composites produced exceptional aesthetic results but are characterized by poor strength characteristics which has minimized their use. Hybrid composites have become a compromise which are more acceptable than macrofill or microfill composites but they are not completely adequate.

Fracture of a composite composition occurs at the filler/resin interface. For this reason, silanation of the filler surface has been effected to reduce fractures. However these compositions degrade with problems of storage in humid environments and their mechanical properties are reduced after immersion in water. An alternative had been provided which seemed to overcome hydrolytic instability of silanated fillers in dental, medical and general use composites formulated with titanate-coated fillers. Unfortunately, the strength of these composites was reduced by 50-60% by the coating. It has been determined that the bonds were rigid with titanates which caused strength reduction in contrast to the silanates which produced a sliding bond.

Shear and tensile strengths of present dental, medical, industrial and general use composite systems limit usage. Areas where force is applied to composite materials which is not supported by surrounding structure, for example tooth structure for dental fillings, will fracture especially on back teeth. Compressive forces are adequate, improvement in shear and tensile strengths and wear characteristics of filler resin composites would greatly increase usage by minimizing crown, gold inlay and other metal usage.

Fibers having a uniform cross-section, for example, circular, oval, square, rectangular or the like are also commonly used as strength enhancing components with a polymeric matrix to form composite materials having increased strength as compared to the polymeric matrix per se. These fibers can be pulled from a matrix under forces produced during matrix cracking due to their regular cross-section and their being straight along their length.

Medical, dental, industrial and general use composite materials require resistance to compressive, tensile, torsional, shear, wear and abrasive forces. Medical and dental materials require biocompatability of materials in addition to resistance to the aforementioned forces. Precise fits in dentistry also require limiting shrinkage of composite filling materials.

Dental filling materials consisting of cross linking resin binders and finely divided inorganic fillers are well known in the art of dentist y. Since the disclosure of such materials by Bowen in U.S. Patent 3,066,122, variations and improvements thereon have been disclosed by others, e.g. Gander et al. U.S. Patent 3,385,090, Lee et al. U.S. Patent 3,926,906, Waller U.S. Patent 3,709,866, and Erickson U.S. Patent 4, 163,004.

For use as dental, medical, industrial and general use filling materials, the resin binders are mixed with finely divided inorganic filler materials having particle sizes ranging from sub micron to about 85 microns. The fillers are present in excess of about 70% by weight in the composites. The density of the filler materials is greater than 2.5, thus the volume fraction of fillers is usually less than about 50%.

In dental use composites, various inorganic filler materials which have been used, include, titanium, fumed amorphous silica, ground quartz, ground borosilicate glass, ground ceramics, ground aluminum silicates, barium glass, silicon dioxide, trimethylol-propane- trimethacrylate and silicon nitride. The shape of the filler particles are usually round or chunky solids having a randomly shaped surface.

The main wear mechanism in areas where chewing action takes place is abrasive wear. During chewing, dental filling composites experience high stresses at filler-matrix interfaces which may cause filler particles to be loosened. In abrasive wear, the matrix is worn faster than the filler, thus exposing the filler particles which then are plucked out, i.e. separated from the resin, by mechanical action of chewing because they are round or chunky and thus are not shaped well to be anchored down into the matrix. In additron, glass fillers are slightly water soluble. They are attacked in the oral environment which facilitates the plucking out process, and thus contributes to wear and pitting of the composites. Additional functions of fillers in dental, medical, industrial and general use composites are to reduce shrinkage during polymerization and reduce thermal stresses due to the expansion and contraction from temperature changes. Unfortunately, shrinkage of the resin matrix during hardening produces more stress at the critical resin/filler interface.

Industrial and medical composites can utilize fibers up to several inches in length for large components such as on airplanes, cars, or the like or artificial prosthesis such as an artificial leg in medical use. Long fibers for large components that extend the length of an apparatus such as airplane wings, rockets and the like also are presently utilized.

Accordingly, it would be desirable to provide a resin-filler and/or fiber composite composition having improved mechanical strength, particularly at the resin-filler or fiber interface and which materially reduces separation of filler or fiber from the resin and provides reduced shrinkage.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1. is an isometric view of a filler particle utilized in the composition of this invention shaped as a dumbbell shaped filler. Figure 2 is an isometric view of an alternative filler particle utilized in the composition of invention shaped as a multiple dumbbell shaped filler.

Figure 3 is an isometric view of an alternative filler particle utilized in the composition of invention shaped as a bent dumbbell shaped filler. Figure 4 is an isometric view of an alternative filler particle utilized in the composition of invention shaped as a C shaped filler. Figure 5 is an isometric view of an alternative filler particle utilized in the composition of invention shaped as a S shaped filler. Figure 6 is an isometric view of an alternative filler particle utilized in the composition of invention shaped as a multiple S shaped filler. Figure 7 is an isometric view of an alternative filler particle utilized in the composition of invention shaped as a E shaped filler. Figure 8 is an isometric view of an alternative filler particle utilized in the composition of invention shaped as a multiple E shaped filler. Figure 9 is an isometric view of an alternative filler particle utilized in the composition of invention shaped as a herringbone shaped filler. Figure 10 is an isometric view of an alternative filler particle utilized in the composition of invention shaped as a star shaped filler. Figure 1 1 is an isometric view of an alternative filler particle utilized in the composition of invention shaped as a star shaped dumbbell. Figure 12 is an isometric view of an alternative filler particle utilized in the composition of invention shaped as a three dimensional star shaped filler.

Figure 13 is an isometric view of an alternative filler particle utilized in the composition of invention shaped as a bulb shaped filler. Figure 14 is a cross sectional view of filler materials of present systems.

Figure 15 is a cross sectional view of filler materials utilized in the composition of invention.

Figure 16 is an isometric view of an alternative filler particle utilized in the composition of invention shaped as a L shaped filler.

Figure 17 is an isometric view of an alternative filler of this invention shaped as an irregular dumbbell.

Figure 18 is an isometric view of an alternative filler particle utilized in the composition of invention shaped as an interlocking I shaped filler.

Figure 19 is an isometric view of an alternative filler particle utilized in the composition of invention shaped as a star shaped filler.

Figure 20 is an isometric view of an alternative filler particle utilized in the composition of invention shaped as a loop shaped filler.

Figure 21 is an isometric view of an alternative filler of this invention shaped as a stamped fiber.

Figure 22 is an isometric view of an alternative filler particle utilized in the composition of invention shaped as a dumbbell shaped filler.

Figure 23 is an isometric view of an alternative filler particle utilized in the composition of the invention shaped as multiple branches.

Figure 24 is a cross sectional view of an alternative filler particle utilized in the composition of the invention shaped as five sided C.

Figure 25 is a cross sectional view of an alternative filler particle utilized in the composition of the invention shaped as a hexagon.

Figure 26 is a cross sectional view of an alternative filler particle utilized in the composition of the invention shaped as an eighteen sided polygon.

Figure 27 is a cross sectional view of an alternative filler particle utilized in the composition of the invention shaped as a doughnut.

Figure 28 is a cross sectional view of an alternative filler particle utilized in the composition of the invention shaped as an square with extensions.

Figure 29 is a cross sectional view of an alternative filler particle utilized in the composition of the invention shaped as an A.

Figure 30 is a cross sectional view of an alternative filler particle utilized in the composition of the invention shaped as a B.

Figure 31 is a cross sectional view of an alternative filler particle utilized in the composition of the invention shaped as an oval.

Figure 32 is a cross sectional view of an alternative filler particle utilized in the composition of the invention shaped as a ladder.

Figure 33 is a cross sectional view of an alternative filler particle utilized in the composition of the invention shaped as a mesh.

Figure 34 is a cross sectional view of an alternative filler particle utilized in the composition of the invention shaped as a clover.

Figure 35 is an isometric view of an alternative filler particle utilized in the composition of the invention shaped as a cylinder.

Figure 36 is an isometric view of an alternative filler particle utilized in the composition of the invention shaped as a cylinder.

Figure 37 is an isometric view of an alternative filler particle utilized in the composition of the invention shaped as a hexagonal tube.

Figure 38 is an isometric view of an alternative filler particle utilized in the composition of the invention.

Figure 39 is an isometric view of an alternative filler particle utilized in the composition of the invention.

Figure 40 is a cross sectional view of an alternative cross section througn line L-L of Figure 26.

Figure 41 is a cross sectional view of an alternative cross section through line L-L of Figure 26.

Figure 42 is a cross sectional view of an alternative cross section through line L-L of Figure 26.

Figure 43 is a cross sectional view of an alternative cross section through line L-L of Figure 26.

Figure 44 is a cross sectional view of an alternative cross section through line L-L of Figure 26.

Figure 45 is a cross sectional view of an alternative cross section through line L-L of Figure 26.

Figure 46 is a cross sectional view of an alternative cross section through line L-L of Figure 26.

Figure 47 is an isometric view of an alternative filler of this invention shaped as a spring or spiral.

Figure 48 is an isometric view of an alternative filler of this invention shaped as a crimped fiber.

Figure 49 is an isometric view of an alternative filler of this invention shaped as a fiber.

Figure 50 is an isometric view of an alternative filler of this invention shaped as a fiber.

Figure 51 is an isometric view of an alternative filler of this invention shaped as a fiber.

Figure 52 is an isometric view of an alternative filler of this invention shaped as a stamped fiber.

SUMMARY OF THE INVENTION

It is the object of this invention to provide strength enhancing materials such as filler particles or fibers which permit increased mechanical retention of the filler or fiber in a binder matrix such as a polymeric matrix which fillers or fibers are characterized by undulating or interlocking shapes to afford improved anchoring and interlocking of the filler particles or fibers in the binder matrix of a composite. The filler or fiber shapes of the present invention block fracture lines from extending through the composite composition. In addition, the filler particles or fibers of this invention mechanically hold fractured binder segments together thereby further limiting crack propagation.

It is also an object of this invention to provide filler particles which permit increased mechanical retention, which are essentially insoluble in oral or body fluid environments and which provide improved wear of a composite material against abrasion such as occurs from opposing teeth in dentistry or other moving bodily parts as occurs in artificial joints.

It is a further object of this invention to reduce expansion and contraction of dental composites caused by temperature changes in the oral environment by means by interlocking mechanism of the undulating filler material or fiber.

It is a further object of this invention to provide means for the manufacture of undulating and interlocking filler particles or fibers from sub-micron to about 10 microns in size for dental composites.

It is a further object of this invention to produce strong dental, medical, industrial and general use composites free of mercury, in the case of dentistry, for use in fillings on front and back teeth and which are biocompatible for medical use.

It is further the object of this invention to produce strong composites for use in medical prosthesis and use for industrial and consumer products.

It is further the object of this invention to produce composite materials which results in less shrinkage during curing.

The present invention provides a composite composition comprising a matrix binder composition containing filler particles or fibers which are shaped to minimize or prevent crack propagation in the matrix binder. The filler particles or fiber have a cross-section or shape along its length which prevents the filler or fiber from being pulled from the matrix binder under the force of an expanding crack in the matrix. The present invention provides a polymeric matrix binder containing between about 2 and 75 volume percent filler particles or fibers based upon the total volume of the composition for dental applications, between about 2 and 75 volume percent filler particles or fibers for medical applications and between about 2 and 75 volume percent filler particle or fibers for general use applications. The filler particles or fibers have a cross-section comprising at least one central bar and at least one end section having a second cross-section. The end section(s) either (a) extend in a direction different from the direction the central bar extends or (b) has a longest dimension larger than the smallest dimension of the central bar.

In an alternative embodiment of this invention, the filler particles or fibers can include an open volume within a fully closed or partially closed shaped wall which is elongated. A fracture entering the volume is stopped by the wall defining the volume. Generally, the major dimension comprising the length of these particles or fibers can extend the length of the composite particle in which it is incorporated. The wall surrounds at least about 50% of the volume's perimeter defined by an inner surface of the wall up to 100% of the perimeter. Typically, these fibers can have an outer diameter of between about 100 microns and 1 inch. In another alternative of the present invention, the fillers of this invention comprise particles having fiber shape with protrusions along the length of the filber-like filler. The protrusions have a largest cross- sectional diameter between about 2 and 10 times the smallest cross- sectional diameter of the fiber-like filler. The fiber like filler can be of any desired length, usually greater than about 10 centimeters and are formed, for example, by vibrating an extruder nozzle during formation of the fiber like filler by extrusion.

DESCRIPTION OF SPECIFIC EMBODIMENTS Fracture of composite resins occurs at the interface of filler particles and resin matrix. Internal stress is created at this interface when the resin matrix shrinks upon curing or when thermocycling and chewing stresses produces stress as a result of differential in thermal coefficients of expansion. Within a mass of composite, fracture generally starts at a surface area and extends into the composite mass. In the case of a round or otherwise compact filler particle or fiber, the fracture strikes a filler particle and traverses to the other side along the filler/resin interface. It then extends into the resin matrix until it strikes the next filler particle. The lines are relatively straight with no interference to fracture.

In accordance with this invention, it has been found that proper shaping of filler particles or fibers can interrupt fracture extension through the resin matrix. The filler particles utilized in the present invention have a major i.e. largest dimension of between about 1 micron to 10 centimeters. The thickness or minor dimension is controlled so that the ratio of the major dimension to the minor dimension is between about 2 to 1 and 100,000 to 1. The use will define prefsrable size ratio. The filler particles used in dental use composites have a major dimension of between about 1 and 30 microns and a minor dimension of about .01 to 10 microns wherein the ratio between the major dimension to the minor dimension is between about 2 to 1 and 2000 to 1. The filler particles used in medical composites would have a preferable major dimension between about 100-1000 microns and a minor dimension of about .01 -10 microns with the ratio between the major dimensions and the minor dimensions is between about 2 to 1 and 2000 to 1. The fillers for industrial use composites have a major dimension between about 1 micron and 10 centimeters and a minor dimension of .01 -200 microns and can be long non-uniform cross section fibers for pultrusion composite fabrication. By controlling the ratio of filler to resin, fracture lines in the resin component can be effectively interrupted by the filler particles as compared to the lack of effectiveness in this respect of generally spherical particles.

There are many shapes of fillers which can be used to improve shear and tensile strengths of composites including those which block continuation of a fracture line and those which mechanically lock resin into the filler to minimize wear on the surface. For example, dumbbell shapes can be used to interrupt fracture. It should be noted that the demonstration is two dimensional but can be extrapolated to three dimensional models. These fillers can be used alone or combined with other shapes, including present spherical fillers, to fill resin matrix space between shaped fillers.

For example, dumbbell shaped fillers used for dental fillings can have a major dimension between about 1 and 30 microns and a minor dimension which is less than 10 micron diameter. The preferred major dimension is about 1-10 microns and the preferred minor dimension is about .01 to 2 microns. Spherical fillers of 1 micron or less can be used to fill the resin matrix between the dumbbell fillers, if desired.

While fillers which are spherical allow for easy crack propagation because a relatively straight line is formed when the spherical fillers are joined together with a bridge, essentially forming a dumbbell shape, the fracture must brake at the bridge or pass around the perimeter of the filler. Thus potential fracture lines are interrupted by the filler shape.

Much greater force is required for fracture to occur with these shaped fillers in place as compared to spherical fillers. If the fracture line were to extend around the bar of a dumbbell shaped particle to an opposite side, the spheres on either side would still be retained as they can not be pulled out of the particle of the resin matrix. Thus, the filler functions to hold the two fractured resin segments together. If the fracture line were to be directed around all the fillers, effectively not crossing through any bar areas of the dumbbell shaped particle, the fracture line would be much longer and significantly more force would be required to effect fracture. In reality, a fracture line would take a straight line path and could not follow the tortuous path required with dumbbell shaped fillers.

Similar results are achieved by having extensions from a central bar at angles different than the long axis of the central bar. Other extensions can join these extension branching in different directions which result in the same effect as a dumbbell shaped filler previously described. As one example, if one central bar had five extensions each in a row and ended by all joining together, a closed hexagon would be formed. A crack which engaged the central bar would pass through the bar and into the central matrix of resin within the closed hexagon. The extension bars on either side would hold the resin matrix together and help prevent further crack propagation and effectively strengthen the composite material. If the crack were to continue though the central matrix of resin, it would strike the extension bar on an opposing side of the closed hexagon and further stop the crack propagation.

In another embodiment, dumbbell, spiral or other alternative shapes can be formed with spheres or extensions which are made of previously described materials including fiber materials and joined by one or more flexible fibers. Representative suitable fibers materials include graphite fiber, fiber glass, polymeric fibers such as polytetrafluoroethylene (PTFE), polyamide, rayon, polyaramide or the like.

Representative suitable polymer matrix materials include: acrylonitrile butadiene styrene copolymers, polytetrafluorethylene (PTFE), polyesters, i.e., polybutylene terephthalate, polyetheramide, polyethersulfone, polyethylene, polyethylene copolymers, polyimides, polyphenylene oxide, polyphenylene sulfide, polyphthalamide, polypropylene and polypropylene copolymers, polystyrene and styrene copolymers, polyurethane, silicone polymers, sulfone polymers, e.g., polysulfone, polyarylsulfone or polyethersulfone, thermoplastic elastomers such as aromatic polyether urethane, vinyl polymers and copolymers such as polyvinylchloride, polyacrylics, polyacrylonitrile, cellulose acetate, epoxides, polyfuran, fluoroplastics, ionomers, polyaryl ether ketone , polyether ketone, melamine formaldehyde polymers, melamine phenolic polymers, phenolics, phenol formaldehyde, polyamides or the like.

Any solid material which can be shaped in accordance with this invention and which is compatible with the polymeric matrix can be utilized in this invention. Representative suitable fillers include ceramics, glass, minerals, metallic and polymeric fillers such as polyaramid, barium, calcium carbonate, calcium sulfate, clays, hydrated alumina, magnesium, perlite, mica, quartz, silane treated silicates, silica, talc, wallastonite, stainless steel fibers, aluminum flakes, carbon fibers, graphite, alpha cellulose, cork, wood flour or the like.

The filler material for dental and medical application is formed of a physiologically acceptable ceramic such as silica, alumina or the like, prepolymerized resins, acrylics or the like, or a physiologically acceptable metal or metal oxide such as silver, gold, titanium, tung¬ sten or the like. Representative suitable physiologically acceptable resins include methyl methacrylate, polymethyl methacrylate and poly ethyl methacrylate or the like. The filler particles generally comprise between about 2% to 75% by volume, preferably between about 25 and 70% by volume of the composite. In a specific composite composition for dental use, comprising a polymeric resin composition containing between about 2 and 70 volume percent of filler particles based upon the total volume of the composition, the filler particles having a major dimension between about 1 and 30 microns and a minor dimension between about .01 and 10 microns and wherein the ratio of the major dimension to the minor dimension is between about 2 to 1 and about 2000 to 1 is made. A preferable major dimension of 5-10 microns, a minor dimension of .01-1 micron and a ratio of 2-1 to 100,000-1. Alternatively, long fibers with undulating or interlocking segments of 1-1000 microns in cross section can be made for pultrusion manufacture of large composite shapes.

In an alternative composite composition for industrial and commercial use, a polymeric resin composition containing between about 2 and 75 volume percent of filler particles based upon the total volume of the composition is provided. The filler particles have a major dimension between about 1 micron and 10 centimeters and a minor dimension between about .01 and 200 microns and wherein the ratio of the major dimension to the minor dimension is between about 2 to 1 and about 100,000 to 1 is made. A preferable major dimension of 5-10 centimeters, a minor dimension of 1-200 microns and a ratio of 20-1 to 20,000-1.

In an alternative composite composition for medical use, a polymeric resin composition containing between about 2 and 75 volume percent of filler particles based upon the total volume of the composition is provided. These compositions can be used to form artificial limbs, knee joints, artificial heart valves, prosthesis or the like. The filler particles have a major dimension between about .1 and 100,000 microns and a minor dimension between about .01 and 200 microns and wherein the ratio of the major dimension to the minor dimension is between about 2 to 1 and about 2000 to 1 is made. A preferable major dimension of 100-1000 microns, a minor dimension of 1 -10 microns and a ratio of 2-1 to 500-1.

Production of filler materials can be effected by alternative methods. One method which can be used to create small structures comprises the use of a light sensitive ceramic which is acid etched after exposure to light. Binary optics and electron beams are presently used to produce patterns whose dimensions are as small as half a micron. Thus binary optical and electron beam techniques can be used with current semiconductor manufacturing techniques to fabricate small undulating shaped fillers from submicron to 10 microns in size and larger if necessary. Optical and laser techniques can be used with current semiconductor manufacturing techniques to fabricate undulating shaped fillers from micron to 10 microns in size and larger if necessary.

In addition, conventional masking etching techniques utilizing optical, electron beam, laser, binary optics or the like can be used to fabricate dumbbell and other undulating shaped fillers of less than 10 micron size of almost any etchable material or laser ablatable material.

The following examples illustrate the present invention and are not intended to limit the same.

The fibers useful in the present invention can be formed by extrusion or by causing movement of the fiber material under an electromotive force under conditions wherein a fluctuating force is applied such as vibration, variance in pressure, variance in electromotive force, stamping or the like to form fibers having a nonuniform cross-section or having an undulating shape along its length. The fibers of this invention therefore, like the fillers of this invention prevent separation thereof from the polymer matrix since they cannot be pulled therefrom along a uniform path. In addition, the fibers of this invention provide enhanced strength to the composite material utilizing the fiber.

EXAMPLE I

A substrate comprising a continuous plastic film support is first coated with a thin layer of a soluble substance such as polyvinyl alcohol after which it is coated such as by vacuum evaporation, plasma deposition, sputtering, or plating techniques, or the like with a layer of filler material less than 10 micron thick. The resultant multilayer composite structure is then overcoated with a thin layer of a photoresist. The photoresist is exposed via optical, electron beam, laser, binary optical techniques or the like to the desired filler pattern to be produced. The coating is passed through the photoresist etching and filler material etching process to produce the shaped filler particles. The underlying soluble coating under the filler particles releases the shaped filler particles into the solution. The particles then are collected by settling, filtration, centrifugation or the like. The remaining photoresist is removed with an appropriate solvent. The filler is washed and dried to produce the desired filler particle for the preparation of dental, medical and general use composite materials.

Any etchable material that can be deposited as a thin layer by vacuum or plasma deposition or plating can be made into undulating dental, medical and general use fillers; for example silica, silver, gold, aluminum, copper, or the like.

EXAMPLE II

A thin coating of photoresist is coated on a substrate, which is an inflexible solid substrate or flexible substrate such as a plastic film. The photoresist is exposed via optical, laser, electron beam, binary optical or like techniques to form a pattern that will, after etching of the photoresist, provide a longitudinal undulating surface that provides discontinuous undulating shapes.

A thin layer of a soluble substance is deposited such as polyvinyl alcohol or other soluble polymer on the undulating surface. This is followed by vacuum evaporation.

The vacuum deposited filler particles are lifted off the substrate by passing the film through a solution that dissolves the soluble substrate. The filler particles are collected by filtration or centrifugation. After washing and drying, the filler particles may be processed further for dental, medical and general use filling composite use by being mixed with a resin composition. By controlling etching depths of the hilly patterns, extremely small undulating filler particles are formed.

EXAMPLE III

Fotoceram, derived from a specially formulated photosensitive glass which can be chemically etched to extremely close tolerances is available from Corning, a New York company, is differentially etchable after photo exposure.

A layer of Fotoceram of less than 10 microns thick is exposed via optical, binary optical or like techniques to a pattern that will after processing and etching with hydrofluoric acid, produce filler particles having the desired undulating patterns. Thus, the Fotoceram is exposed, processed, and etched to produce the shaped filler directly out of the Fotoceram material. By manipulating binary photo exposure patterns, even three dimensionally shaped Fotoceram fillers, such as the star patterns can be made.

The surface of the fotoceram and other silicate fillers can be further silanated or titanated prior to use as fillers in dental, medical and general use composites by conventional techniques.

EXAMPLE IV

Ceramic spheres or particles of different melting points can be mixed such that there is a predominance of spheres which melt at a higher temperature. The mixture of spheres are heated to the temperature of the melting point or above of the lowest melting point spheres but below the higher melting point spheres. The melted spheres will join to adjacent spheres. The mixture is then cooled to effect fusion of a plurality of the higher melting spheres with solidified lower melting point ceramic. The resulting joined spheres are separated by sedimentation, filtration, centrifugation or the like. Alternatively, metal, resin, ceramic, silica, glass spheres or other inorganic particles are bonded by using lower and higher melting temperature materials which can be done with like materials such as ceramic to ceramic or unlike materials such as metal to glass. In addition, materials like organic polymers are used for spheres. In addition, spheres are coated with a different material such as silicoating onto titanium particles to allow bonding with silinated spheres of ceramic. In addition, coatings, including techniques such as electroplating, dipping, spraying, or the like, are applied to particles and the coatings melted to join particles.

EXAMPLE V

In an alternative method, thin sheets of various filler materials can be exposed to laser energy and through micron size pixels ablation will occur resulting in shaped filler particles of dimensions described previously.

EXAMPLE VI

In an alternative method, carbon fiber can be manufactured to have crimps or enlarged areas. Organic fiber polymer such as rayon is reduced to carbon fiber by heat and reduced atmosphere. To form notches, the organic fiber is crimped by machine and converted to carbon fiber. Other shapes can be formed along a fibers length by stamping during the formative stage and. or by using heat stamps on heat sensitive material such as fiber glass. To form enlarged areas, the machine which stretches or extrudes the organic polymer to form fibers is vibrated which results in thick and thin areas. Controlling of vibrations speed and intensity will vary the size and shape of enlarged areas in various fibers. To form spirals, the machine is spun during the stretching process and. or the fiber is produced in an oval cross- section which induces spiraling.

EXAMPLE VII In an alternative method, metallic fillers or fillers with metal coatings are magnetized to attract each other and form described shapes of this invention.

Alignment of shaped fillers described in this invention can further be accomplished by magnetizing particles or using ultrasound to align particles through settling.

Referring to Figure 1 , filler particle 2 has a major dimension L and a minor dimension W and has central bar 6 which joins spheres 4 and 8. The spheres 4 and 8 are used for the purpose of demonstration and these areas can be of various shapes such as round, oval, triangular, square, rectangular, hexagonal, T shaped, L shaped, rounded T shaped, solid or hollow, or the like. Filler particle 2 is completely surrounded by a resin matrix. When sphere 8 is exposed to the surface of the composite mass as the resin matrix deteriorates, it is held in the composite by the junction to central bar 6 to sphere 4 which is still embedded in the resin matrix. This process reduces normal plucking of filler spheres and results in great reduction in surface wear of a filling.

Referring to Figure 2, an alternative shaped filler particle 16 has a major dimension L and a minor dimension W and has central bars 20 and 24 which join spheres 18, 22, and 26 in a straight alignment. Referring to Figure 3, an alternative shaped filler particle 30 has a major dimension L and a minor dimension W and has central bars 34 and 38 which join spheres 32, 36 and 40 in a non straight undulating alignment.

Referring to Figure 4, an alternative shaped filler particle 40 has a major dimension L and a minor dimension W and has end sections 42 and 46 joined by central bar 44 shaped in a C shape to form central space 48 which is filled with resin matrix. Central space 48 is filled with resin matrix which is connected to surrounding matrix material through opening 49 resulting in filler particle 40 being better retained into the composite mass at the surface thereby reducing plucking and wear.

Referring to Figure 5, an alternative shaped filler particle 50 has a major dimension L and a minor dimension W and has an S shape with ends 52 and 60 being joined by curved central bar 56 which results in central spaces 54 and 58 for fill with resin matrix and better retention.

Referring to Figure 6, an alternative shaped filler particle 70 has a major dimension L and a minor dimension W and has a W shape with ends 72 and 80 being joined together by curved central bar 76 to form central spaces 74, 78 and 82 filled with resin matrix for better retention of filler particle 70 in the composite mass.

Referring to Figure 7, an alternative shaped filler particle 90 has a major dimension L and a minor dimension W and has an E shape with ends 92, 96 and 100 being joined by central bar 102 forming central spaces 94 and 98 which fills with resin matrix.

Referring to Figure 8, an alternative shaped filler particle 1 10 has a major dimension L and a minor dimension W and has end sections 1 12, 1 16, 120, 124 and 128 joined by central bar 125 to form central spaces 1 14, 1 18, 122, and 126 which fills with resin matrix. Referring to Figure 9 an alternative shaped filler particle 130 has a major dimension L and a minor dimension W and has end sections 132, 136, 140, 144, 146, 148, 150 and 152 which form central areas 134, 138, 142, 154, 156 and 158 with resin matrix.

Referring to Figure 10, an alternative shaped filler particle 160 has a major dimension L and a minor dimension W and has an X shape with end sections 162, 164, 166, and 168 being joined at central bar area 170.

Referring to Figure 1 1 , an alternative shaped filler particle 172 has a major dimension L and a minor dimension W and has spheres 174, 178, 182 and 188 joined by central bars 176, 180, 184 and 186 at central area 190.

Referring to Figure 12, an alternative shaped filler particle 192 has a major dimension L and a minor dimension W and has end sections 196, 198, 200, 202, and 204 extending in three dimensional planes joined at central area 194.

Referring to Figure 13, an alternative shaped filler particle 264 has a major dimension L and a minor dimension W and with a central bar 262 joined to an end section 260.

Referring to Figure 14, an arrangement of sphere shaped fillers 220 which is surrounded by resin matrix 222 which occurs in present composite systems is shown. Fracture line A-A shows the easy, relatively straight fracture line which occurs. At worst, a fracture line engages filler 220 and has to work around 180 degrees to continue the fracture line.

Referring to Figure 15, an arrangement of dumbbell shaped filler particles 230 in resin matrix 233 is shown. Filler particles 239 are spherical fillers seen in present composite systems used in this composite to fill the resin matrix 233 between filler particles 230, 242, 250 and the like. Filler particles 230 has spheres 232, 236 and 238 joined by central bars 234 and 240 of the same material or different. Fracture line B-B engages filler particle 230 at bar 234 and continues through to the other side and on into the resin matrix. The resin matrix above fracture line B-B is retained by sphere 232 and resin matrix below fracture line B-B is retained by spheres 236 and 238 because central bars 234 and 240 hold them together. The result is the resin matrix does not separate at fracture line B-B. Fracture line B-B further engages filler particle 260 which stops propagation of the fracture line B-B.

Fracture line C-C encounters filler particle 242 and fracture line D-D encounters filler particle 250 which stops further propagation of the fracture, therefore, shear and tensile strength of the composite is dramatically improved. If fracture line E-E were to occur without encountering a filler particle bar it would require a longer path than spherical fillers as seen by line A-A on Figure 14. and therefore, require increased force to produce composite fracture.

Referring to Figure 16, an alternative shaped filler particle 268 has a major dimension L and a minor dimension W and with a central bar 270 and an end section 272.

Referring to Figure 17, an alternative filler 770 has irregular central bar 774 and irregular spheres 772 and 776. Rough surfaces which can be formed by etching, machining or other common process further aids in retention of the filler in a polymeric matrix.

Referring to Figure 18, alternative shaped filler particles 290, 292 and 294 which has a major dimension L and a minor dimension W and which consist of central bars 326, 296 and 314 and end sections 318, 320 and 310, 300, and 298, 316 respectively. The end sections can interlock to further prevent composite fracture. For example, end section 320 of filler 290 is interlocking with end section 310 of filler 292. Referring to Figure 19, an alternative shaped filler particle 300 which has a major dimension L and a minor dimension W and which consists of central bar 333 has attached central sphere 332 to which is further attached bars 334.

Referring to Figure 20, an alternative shaped filler particle 340 which has a major dimension L and a minor dimension W and which consists of central bar 342 to which is attached an open sphere 344 with central hole 346 and open sphere 348 with central hole 350. Resin material fills central holes 346 and 350 to provide improved retention of filler particle 340.

Referring to Figure 21 , an alternative filler 760 has square enlargements 764 and T shaped areas 766 which provides further interlocking into a polymeric matrix.

Referring to Figure 22, an alternative shaped filler particle 360 has a major dimension L and a minor dimension W and which consists of central bar 362 and attached hexagonal end sections 364 and 366.

Referring to Figure 23, an alternative shaped filler particle 400 has a major dimension L and a minor dimension W and which consists of central bar 402 and extensions 404, 406, 408, 416, 418, and 420. Extensions 408, and 420 have extensions 410, 412 and 414 and 422 and 424 which further respectfully extend off them. The increase number of extensions further minimizes crack propagation.

Referring to Figure 24, an alternative shaped filler particle 430 has a major dimension L and a minor dimension W and which consists of central bar 432 with extension 438 which has extension 440 off it and with extension 434 which has extension 436 off it and forms central resin volume 437. A propagating crack entering volume 437 is trapped by extensions 432, 434, 436, 438 and 440.

Referring to Figure 25, an alternative shaped filler particle 451 has a major dimension L and a minor dimension W and which consists of central bar 454 which has extension 444 off it which further has extension 446 off it. Central bar 434 has extension 452 extending off it which further has extension 450 off it which further has extension 448 off it. Extension 446 and extension 448 meet at their far end. The result is a central bar 454 and its extensions 444, 446, 452, 450, and 448 which form a hexagon. The hexagon reduces crack propagation as seen by demonstration crack as shown by line K- K. When crack K-K strikes extension 452 it can be stopped at that point. If the crack continues through the bar and into the central resin matrix 449, it will be further blocked by extension 446. If the crack K-K continues through to the other side, the top part of the resin matrix (that which is above the crack K-K) will be held in place by central bar 454 and extension 444 while lower section of the resin matrix (that which is below the crack K-K) will be held in place by extensions 450 and 448 effectively reducing further crack propagation and stop segments above and below the crack from separating. An additional benefit will be reduced shrinkage of the composite mass as the central resin matrix 449 will not effect resin material outside the hexagon as it is complete surrounded by filler material.

Wear will also be reduced by filler particle 451. As resin matrix is worn around the filler particle 451 , extension 444, for example, will be exposed, however, the extension cannot disengage the resin matrix because it is being held in position by the attached extension 446 and 454 which are further held in the resin matrix by extensions 452, 450 and 448.

Referring to Figure 26, an alternative shaped filler particle 460 has a major dimension L and a minor dimension W and which consists of central bar 462 which has extensions 464, 466, 468, 470, 472, 474, 476, 478, 480, 482, 484, 486, 488, 490, 492, 494, 496 attached in sequence to each other with extension 496 attaching to central bar 462 resulting in an eighteen sided polygon. Filler particle 460 minimizes crack propagation and composite surface wear in the same manner as the filler particle 451 in Figure 25.

Referring to Figure 27, an alternative shaped filler particle 500 has a major dimension L and a minor dimension W and which consists of central bar 504 which is very small. Extensions which are attached around a central bar can be numbered from two to infinity in a system which is closed such as a triangle, square or other polygon. Polygon 506 is a circle formed by one central bar and an infinity of extensions and central space 510. The result is a circular filler particle 500 which minimizes crack propagation and composite surface wear in the same manner as filler particles in Figure 25 and 26.

Referring to Figure 28, an alternative shaped filler particle 512 has a major dimension L and a minor dimension W and which consists of central bar 514 and extensions 516, 518 and 520 joined to form a square. Extension 524 is attached to extension 520 and extends into central resin matrix 526. Extension 522 is attached to extension 520 and extends into the surrounding resin matrix.

Referring to Figure 29, an alternative shaped filler particle 530 has a major dimension L and a minor dimension W and which consists of central bar 534 and extensions 536 and 532 which form central resin matrix 538.

Referring to Figure 30, an alternative shaped filler particle 540 has a major dimension L and a minor dimension W and which consists of central bar 542 which has curved extensions 544 and 546 which form central resin matrixes 549 and 548 respectfully.

Referring to Figure 31 , an alternative shaped filler particle 550 has a major dimension L and a minor dimension W and which consists of curved central bar 554 and curve extension 552 which join together on both ends to form oval filler particle 550 with central resin matrix 556.

Referring to Figure 32, an alternative shaped filler particle 560 has a major dimension L and a minor dimension W and which consists of central bar 562 and extensions 568, 560, 562, 564, 566 and 569 which join together to form central resin matrixes 563, 565, 561 and 567.

Referring to Figure 33, an alternative shaped filler particle 570 has a major dimension L and a minor dimension W and which consists of central bar 574 and series of extension such as extension 572 which combine to form a mesh with central resin matrixes like central resin matrix 576.

Referring to Figure 34, an alternative shaped filler particle 580 has a major dimension L and a minor dimension W and which consists of a circular central bar 585 with central hole 586 and attached round extensions such as extensions 585 and 582 which form central resin matrix 587 and 584.

Referring to Figure 35, an alternative shaped filler particle 600 has a major dimension L and a minor dimension W and third dimension H which consists of central bar 602 with central resin matrix 604.

Referring to Figure 36, an alternative shaped filler particle 610 has a major dimension L and a minor dimension W and third dimension H which consists of central bar 614 with central resin matrix 616. Cut away section from a full cylinder results in wall 613 and slot 621 which extends the full length of the cylinder.

Referring to Figure 37, an alternative shaped filler particle 630 has a major dimension L and a minor dimension W and third dimension H which consists of central bar 632 and extensions 634, 636, 638, 639 and 640 with central resin matrix 634. Slot 645 results in wall 646 extending the full length of filler particle 630.

Referring to Figure 38, an alternative shaped filler particle 650 has a major dimension L and a minor dimension W and third dimension H which consists of central bar 654 and round cylinder extensions 652 and 656. Central bar 654 has central hole 660 which is filler with resin and cut out section 658.

Referring to Figure 39, an alternative shaped filler particle 670 has a major dimension L and a minor dimension W and third dimension H which consists of central bar 672 and extensions 674, 676, 678, 680 and 682 which form a hexagon with central resin matrix 684. Filler particle 670 is smaller at end section 673 and progressively larger toward end section 683.

Referring to Figure 40, an alternative triangular cross section through the central bar or extensions is shown as would be represented by line L-L of Figure 26.

Referring to Figure 41 , an alternative hexagonal cross section through the central bar or extensions is shown as would be represented by line L-L of Figure 26.

Referring to Figure 42, an alternative square cross section through the central bar or extensions is shown as would be represented by line L-L of Figure 26.

Referring to Figure 43, an alternative round cross section through the central bar or extensions is shown as would be represented by line L-L of Figure 26.

Referring to Figure 44, an alternative oval cross section through the central bar or extensions is shown as would be represented by line L-L of Figure 26.

Referring to Figure 45, an alternative showing a long thin rectangular area cross section through the central bar or extensions is shown as would be represented by line L-L of Figure 26 which would result in a cylinder being formed.

Referring to Figure 46, an alternative cross section through the central bar or extensions is shown as would be represented by line L-L of Figure 26 forming a cylinder with a raised area in the center and the outside.

Referring to Figure 47, an alternative spiral shaped filler 690 of this invention has a width W, a length L and a height H and consists of round spiral central bar 692 which forms a central resin matrix 694.

Referring to Figure 48, an alternative shaped filler 700 of this invention has a width W and a length L and consists of a central bar 702 and crimped areas 704, 706 and 708. In an alternative method, the machinery producing a fiber can be vibrated in a side to side or up and down movement or combinations there of to form an irregular pattern.

Referring to Figure 49, an alternative shaped filler 720 is formed of fiber materials such as aramid, carbon fiber, glass fiber or the like which is has central bar fiber 721 and enlarged areas 723 which can be formed by vibration in a back and forward motion of the machinery producing the fiber. The forward and back motion can be combined with other motions such as side to side, up and down or the like to form alternative patterns.

Referring to Figure 50, an alternative shaped filler fiber 728 has central bar 730 with enlarged areas 723 which are formed in irregular shapes by controlling the speed of forward and back vibration for example, the machine producing fiber can be vibrated forward at a faster rate than the backward rate.

Referring to Figure 51 , an alternative shaped filler fiber 738 has central bar 740 with enlarged areas 742 which are formed by vibration of machinery which forms fiber fillers at a fast rate.

Referring to Figure 52, an alternative shaped filler fiber 752 has crimped bulge 754, enlarged round area 756 and triangular area 758 which is formed by stamping fibers while still soft and formable as they exit machinery which forms fibers. In thermoplastic materials the stamping equipment can be heated to post form shapes.

Claims

1. A crack resistant composite composition comprising a polymeric resin composition containing between about 2 and 75 volume percent of filler particles based upon the total volume of said composition, said filler particles having a shape which minimizes or prevents a crack within said resin composition and which contacts one of said filler particles from by-passing said one of said filler particles.

2. A crack resistant composite composition comprising a polymeric resin composition containing between about 2 and 75 volume percent of fibers based upon the total volume of said composition, said fibers particles having a cross-section and or having a shape along the length of said fibers which minimizes or prevents a crack from within said resin composition and which contacts one of said fibers from by-passing said one of said fibers.

3. A crack resistant composite composition comprising a polymeric resin composition containing between about 2 and 75 volume percent of filler particles and fibers based upon the total volume of said composition, said filler particles having a shape which minimizes or prevents a crack within said resin composition and which contacts one of said filler particles from by-passing said one of said filler particles, and said fibers having a cross-section and/or having a shape along the length of said fibers which minimizes or prevents a crack from within said resin composition and which contacts one of said fibers from by-passing said one of said fibers.

4. A method for improving crack resistance of a polymeric resin composition which comprises incorporating into said polymeric composition between about 2 and 75 volume percent of filler particles and fibers based upon the total volume of said composition, said filler particles having a shape which minimizes or prevents a crack within said resin composition and which contacts one of said filler particles from by-passing said one of said filler particles.

5. A method for improving crack resistance of a polymeric resin composition which comprises incorporating into said polymeric composition between about 2 and 75 volume percent of fibers based upon the total volume of said composition, said fibers particles having a cross-section and/or having a shape along the length of said fibers which minimizes or prevents a crack from within said resin composition and which contacts one of said fibers from by-passing said one of said fibers.

6. A method for improving crack resistance of a polymeric resin composition which comprises incorporating into said polymeric composition a polymeric resin composition between about 2 and 75 volume percent of filler particles and fibers based upon the total volume of said composition, said filler particles having a shape which minimizes or prevents a crack within said resin composition and which contact one of said filler particles from by-passing said one of said filler particles and said fibers having a cross-section and/or having a shape along the length of said fibers which minimizes or prevents a crack from within said resin composition and which contacts one of said fibers from by-passing said one of said fibers.

7. A composite composition comprising a polymeric resin composition containing between about 2 and 75 volume percent of filler particles based upon the total volume of the composition, said filler particles having a cross section comprising at least one central bar and at least one end section having a second cross section, said end section either (a) extending in a direction different from a direction said central bar extends or (b) having a largest dimension larger than a smallest dimension of said central bar, and said filler particles having a major dimension between about 1 and 2000 microns and a minor dimension between about .01 and 200 microns and wherein the ratio of the major dimension to the minor dimension is between about 2 to 1 and about 2000 to 1 long fibers with protrusions between 2 to 1 to 10 to 1 ratio of protrusion to smallest cross section.

8. The composition of Claim 7 wherein said cross-section comprises a central bar having two end sections having a larger dimension larger than the smallest dimension of said central bar.

9. The composition of Claim 1 wherein said cross section comprises two intersecting central bars each connected to two end sections having a larger dimension larger than a smallest dimension of said central bar.

10. The composition of any one of claims 7, 8 or 9 wherein said filler particles are formed of ceramic.

1 1. The composition of any one of claims 7, 8 or 9 wherein said filler particles are formed of silver.

12. The composition of any one of claims 7, 8 or 9 wherein said filler particles are formed of gold. 13. The composition of any one of claims 7, 8 or 9 wherein said filler particles are formed of titanium.

i 4. The composition of any one of claims 7, 8 or 9 wherein said cross-section is E shaped.

15. The composition of claim 9 wherein said filler particles have two central bars each extending in a direction different than an other of said central bars.

16. The composition of Claim 7 wherein said filler particles comprise two central bars each connected to a common end and to a non-common end section, each of said end sections having a largest dimension larger than a smallest dimension of said central bars.

17. The composition of Claim 7 wherein said filler particles have end sections extend in a common direction.

18. The composition of Claim 7 wherein said filler particles have a central bar from which said end sections extend in different directions.

19. The composition of any one of claims 7, 8 or 9 wherein said filler particles are formed of a polymeric material.

20. The composition of any of claims 7, 8 or 9 wherein said filler particles are formed of glass.

21. A composite composition comprising a polymeric resin composition containing between about 2 and 75 volume percent of fibers based upon the total volume of the composition, said fibers (a) having a cross section including an open volume, (b) a change of direction along fiber length, (c) a change in cross-sectional area along fiber length or (d) a combination of at least two of (a), (b) and (c).

22. The composition of claim 21 wherein said fibers are formed of carbon fiber.

23. The composition of claim 21 wherein said fibers are formed of glass fiber.

24. The composition of claim 21 wherein said fibers are formed of aramid fibers.

25. The composition of any one of claims 1 , 2, 3 or 7 wherein said (a) polymeric resin composition and (b) said filler particles, and/or fibers are physiologically acceptable.

AMENDED CLAIMS

[received by the International Bureau on 12 August 1996 (12.08.96); original claims 1-25 replaced by amended claims 1-23 (4 pages)]

1. A crack resistant composite composition comprising a polymeric resin composition containing between about 2 and 75 volume percent of fibers based upon the total volume of said composition, said fibers having a spiral shape and/or having a varying cross-section area along the length of said fibers which minimizes or prevents a crack within said resin composition from by-passing one of said fibers by said crack contacting one of said fibers.

2. A crack resistant composite composition compnsirtg a polymβ ric resin composition containing between about 2 and 75 volume percent of rionfibrous filler particles and fibers based upon the total volume of said composition, said filler particles having a cross section comprising at least one central bar and at least one end section having a second cross section, said end section either (a) extending in a direction different from a direction said central bar extends or (b) having a largest dimension larger than a smallest dimension of said central bar. and said fibers laving a spiral shape and/or having a varying cross-section area along the length of said fibers which minimizes or prevents a crack from within said resin composition from by-passing one of said fibers by said crack contacting one of said fibers

3. A method for improving crack resistance of a polymeric resin composition which comprises incorporating into said polymenc composition between about 2 and 75 volume percent of nonfibrous filler particles based upon the total vol jme of said composition, said filler particles having a shape which minimizes or prevents a crack within said resin composition from by-passing said one of said filler particles by said crack contacting a filler particle.

4. A method for improving crack resistance of a polymeric resin composition which comprises incorpoiating into said polymeric composition between about 2 and 75 volume peroent of fibers based upon the total volume of said composition, said fibers having a spiral shape and/or having a varying cross-section area along the length of said fibers which minimizes or prevents a crack within said resin composition from by¬ passing said one of said fibers by said crack contacting one of said fibers.

5. A method of improving crack resistance of a polymeric resin composition which comprises incorporating into said polymeric composition a polymeric rosin composition between about 2 and 75 volume percent of nonfibrous filler particles and fibers based upon the total volume of said composition, said filler particles having a (I) having a cross section comprising at least one central bar and at least one end section having a second cross section, said end section either (a) extending in a direction different from a direction said central bar extends or (b) having a largest dimension arger than a smallest dimension of said central bar, (II) having a spiral shape and/or (III) having a varying cross-section area along the length of said fibers which rninirrizes or prevents a crack from within said resin composition from by-passing one of said ϊbers by said crack-contacting said fibers.

6. A composite composition comprising a polymeric resin compo ition containing between about 2 and 75 volume percent of nonfibrous filler particles and/or fibers based upon the total volume of the composition, said filler particles having a cross section comprising at least one centra! bar and at least one end sect on having a second cross section, said end section either (a) extending in a direction different from a direction said central bar extends or (b) having a largest dimensior larger than a smallest dimension of said central bar. said filler particles having a ratio of a largest dimension to the smallest dimension is between about 2 to 1 and about 2000 to 1 , said fibers having protrusions wherein the ratio of protrusion diameter to smallest diameter is between 2 to 1 and 10 to 1.

7. The composition of Claim 6 wherein said cross-section composes a central bar having two end section having a dimension larger than the smallest dimension of said central bar. 8. The composition of Claim 2 wherein said cross section comprises two intersecting central bars each connected to two end section having s larger dimension larger than a smallest dimension of said central bar.

9. The composition of anyone of claim 6, 7 or 8 wherein said fille- particles are formed of ceramic.

10 The composition of any one of claims 6, 7 or 8 wherein said filer particles are formed of silver.

11. The composition of any one of claims 6, 7 or 8 wherein said filler particles are formed of gold.

12. The composition of any one of claims 6, 7 or 8 wherein said filer particles are formed of titanium.

13. The composition of any one of claims 6. 7 or 8 wherein said cross-section is E shaped.

14. The composition of claim 8 wherein said filler particles have Iwo central bars each extending in a direction different than an other of said central bars.

15. The composition of Claim 6 wherein said filler particles comp rise two central bars each connected to a common end and to a non-common end section, each of said end sections having a largest dimension larger than a smallest dimension of said central bars.

16. The composition of Claim 6 wherein said filler particles have end section extend in a common direction. 17. The composition of claim 6 wherein said filler particles have a central bar from which said end sections extend in different directions.

18. The composition of any one of claims 6, 7 or 8 wherein said filter particles are formed of a polymeric material.

19. The composition of any one claims 6, 7 or 8 wherein said filler particles are formed of glass.

20. The composition of claim 1 wherein said fibers are formed of carbon fibers.

21. The composition of claim 1 wherein said fibers are formed of glass fibers

22. The composition of claim 1 wherein said fibers are formed of ε ramid fibers.

23. The composition of any one of claims 1 , 2 or 6 wherein (a) sai 1 polymeric resin composition and (b) said filler particles, and/or fibers are physiologically acceptable.