WO1999022669A1

WO1999022669A1 - Apparatus for continuous cure of dental materials

Info

Publication number: WO1999022669A1
Application number: PCT/US1998/023394
Authority: WO
Inventors: Arun Prasad; Ajit Karnaker; Martin Schulman
Original assignee: Jeneric Pentron Incorporated
Priority date: 1997-11-04
Filing date: 1998-11-03
Publication date: 1999-05-14
Also published as: AU1450899A

Abstract

An apparatus is presented for the rapid curing of resinous materials by application of energy from an external source to excite polymerization in a polymerizable system. The apparatus comprises generally a shape-forming die, a conveyor and at least one inert gas lamp source arranged at a predetermined distance from the shape-forming die to irradiate material being conveyed therethrough. Preferably, the inert gas lamp source is at least one inert gas flash lamp or laser source. In accordance with the present invention, the inert gas flash lamp emits pulse radiation of very high energy and power peaks. Preferably, the spectral output of the inert gas flash lamp is in the range between about 380 nm and about 550 nm. The radiant energy emitted by the present apparatus is diffused or flooded to produce an even distribution of light intensity over the material as it passes through the path of the light. The apparatus of the present invention achieves very fast cure rates, high degree of cure, greater depth of penetration, low heat buildup and instant on-off capability and is particularly suitable for the curing of dental materials comprising filled or unfilled resin(s) having at least one ethylenically unsaturated group, in particular acrylate, methacrylate or vinyl groups.

Description

APPARATUS FOR CONTINUOUS CURE OF DENTAL MATERIALS

Background of the Invention

1. Field of the Invention:

This invention relates generally to an apparatus for the rapid curing of resinous materials by application of energy from an external source to excite polymerization in a polymerizable system. More specifically, this invention relates to an apparatus for the rapid curing of dental materials by using an inert gas lamp source.

2. Brief Description of the Related Art

Curing, as used herein, is the processing of a plastic or resinous material from a fluid or soft and compliant state to a permanent hard, durable and solid state. Conventionally, this is accomplished both by the elimination of solvents and by chemical changes involving interlinking of molecules commonly known as polymerization of the material. Of the two, polymerization is the more advantageous since it does not commonly involve dimensional changes and usually produces a substantial increase in the strength of the material. Polymerization is usually caused by the addition of activating chemicals (activators), by irradiation with some form of wave energy either electric or electromagnetic in nature or by applying heat or by a combination thereof. One of the associated problems with the polymerization of a material is the time involved. For example, when polymerization is caused by the application of heat, the rate of the polymerization is largely determined by the intensity of the heat applied. However, it has been found that the application of high heat may result either in the formation of inferior polymers having less complex molecules, lower density and being weak and relatively fragile, or in the complete destruction of the material. Polymerization by the application of low heat and different forms of wave energy results in a delayed curing process. While the use of chemical activators can increase the polymerization rate, it is extremely inconvenient under some conditions. For the rapid polymerization of a resinous material, the material generally contains passive activators which are then activated by the application of outside energy. Critical factors which affect production costs are the amount of energy required and the time over which it must be applied, and these factors must be accounted to implement an effective system.

Consequently, there is a need for an apparatus that effectively and efficiently can cure a polymerizable resinous material, such as a dental material in a continuous manner.

The present invention is directed to a novel apparatus for the rapid, continuous curing of a polymerizable resinous material, preferably a dental material. The apparatus provides intensive uniform all-round irradiation of the curable resin.

Summary of the Invention The above-described and other problems and deficiencies of the prior art are overcome or alleviated by the curing apparatus of the present invention, wherein a filled or unfilled resin(s) having at least one ethylenically unsaturated group is cured in accordance with the present invention.

The present invention refers to an apparatus suitable for fast curing a pre-formed or extruded shape comprising fibers/particulate in a curable resin matrix. The apparatus uses radiation from an inert gas lamp source. The source in the lamp may be any inert gas, preferably argon, xenon or krypton. The lamp source may be a flash lamp such as a linear (also known as wall-stabilized) or a bulb lamp (also known as probe-stabilized unconfined arc lamp) or it may be a laser source. The high radiant energy emitted from the inert gas lamp source is applied to an uncured preformed substrate immediately after it exits the shape-forming dies. This fast curing allows the shape of the substrate to be retained while being processed on a continuous basis. In accordance with the present invention, the uncured preformed substrate is delivered to the curing apparatus by a conveyor. The conveyor passes the uncured substrate in a continuous manner through the apparatus so that the uncured substrate is sufficiently irradiated by the inert gas lamp source to effectively cure the resin matrix. The inert gas lamp source of the present invention preferably is manipulated in various ways such as (1) a narrow beam of any specific/targeted curing location, (2) an annular ring and (3) a longitudinal tunnel for three dimensional exposure.

The resin matrix can be one or a combination of several cross-linkable monomers and may further include photo-initiators and accelerators which are known in the dental arts. Suitable resins include filled or unfilled resins having at least one ethylenically unsaturated group, in particular acrylate, methacrylate or vinyl. The curing of the curable resin matrix can be performed either in the presence of air or in an oxygen free atmosphere (aerobic and anaerobic conditions, respectively). The apparatus provides fast cure rates, high degree of polymerization, low heat output and instant on-off capability.

Brief Description of the Drawing For the purpose of illustrating the invention, there are shown in the drawing forms which are presently preferred; it being understood, however that this invention is not limited to the precise arrangements and instrumentalities shown. Referring now to the drawings wherein like elements are numbered alike in the several FIGURES:

FIGURE 1 is a schematic view in cross section of the apparatus of the present invention comprising a longitudinal tunnel for three dimensional exposure to an inert gas lamp source.

FIGURE 2 is a cross section along line I-I of FIGURE I;

FIGURE 3 a schematic view in cross section of the apparatus of the present invention wherein an annular inert gas lamp source is used; FIGURE 4 is a schematic view in cross section of the apparatus of the present invention wherein the inert gas lamp source is a narrow beam of any specific/targeted curing location;

FIGURE 5 is a schematic view in cross section of the optional photocell in accordance with the present invention;

FIGURE 6 is a schematic view of an apparatus of the present invention in combination with a shape-forming die apparatus;

FIGURE 7 is a schematic view of an alternate shape-forming die apparatus; and

FIGURE 8 is a cross-sectional view of FIGURE 6 at line 8-8.

Detailed Description of the Invention

The present invention is directed to a new and improved method for curing a polymerizable resinous material, such as a dental material. U.S. Patent Nos. 5,135,686 and 5,135,685 are directed to methods for the continuous hardening of light-curing resins and are hereby incorporated by reference. The present invention utilizes an inert gas lamp source for providing the additional energy for rapid polymerization. Preferably, the inert gas lamp source used in accordance with the present invention is an inert gas flash lamp or an inert gas laser source. The inert gas source in the lamp or laser may be any inert gas, preferably argon, xenon or krypton. A particularly desirable feature of the inert gas flash lamp is the ability to provide energy pulses with high rise and decay rates. Inert gas flash lamps operate with short, high energy pulses. The pulses are bursts of very high energy and power peaks. An inert gas laser source provides a very intense narrow beam of light of a selected wavelength which is effective in curing the resin matrix. An advantage of utilizing an inert gas laser source in the apparatus is that a specific portion of an uncured pre- formed substrate may be targeted and irradiated with energy to cause curing of the targeted portion. Thus, the use of an inert gas laser source allows more precision in targeting a curing location and it provides the ability to provide a narrow, intense energy beam to effectuate curing.

Thus, the apparatus of the present invention polymerizes thermally sensitive polymerizable resins by exposing the resins to radiation in a predetermined wavelength range. The polymerization of dental materials preferably effectuated by irradiation of a selective wave length range which falls between about 350 nm and 550 nm. Consequently, the spectral output of the inert gas lamp utilized in the present invention is preferably in the range of between about 380 nm to about 550 nm. Preferably, energy is applied in pulses at a rate of 3 to 120 pulses per second, the pulses having a pulse width of lxlO^"3 to lxlO^"6 seconds. When the apparatus comprises at least one inert gas laser source, the wavelength of the radiant energy emitted by the laser is preferably in the range between about 400 nm to about 500 nm.

Referring now to FIGURES 1 and 2, the curing apparatus 10 has a conveyor 12 which is surrounded by an inert gas lamp source 14 which may be a single inert gas flash lamp or a plurality of individually based inert gas flash lamps as illustrated in FIGURES 1 and 2. The conveyor 12 is designed so that it delivers an uncured pre- formed substrate to the curing apparatus immediately after it exits the shape-forming dies. The shape- forming dies may be any known shape useful in the industry such as square, rectangular, triangular, round and the like. The conveyor may be in the form of a conveyor belt or in other forms known in the art which effectively move an object from one location to another such as a strand moving device, pulling device, or a spool or drum for winding material thereon. The individual sockets 16 of each respective individually based inert gas lamp 14 are fastened on a base 18 of a protective chamber 20. The present invention preferably includes chamber 20 to serve as a protective housing for the inert gas lamp source 14; however, the use of chamber 20 is optional. Chamber 20 has openings 22,24 at opposite ends to accommodate conveyor 12 which is disposed within the openings. The openings are of such dimension that a preformed shape can move along while on the conveyor and enter and exit the openings without difficulty. Chamber 20 may optionally include a window for viewing of the curing process and for viewing of the substrate as it moves along while on the conveyor.

The conveyor 12 is arranged in chamber 20 with its support surface 26 above the sockets 16. The walls of chamber 20 preferably have reflective surfaces 28 and may include airways for cooling of the inside of chamber 20. Chamber 20 may be rectangular in shape as illustrated in FIGURES 1 and 2 or it may be in the form of another shape, such as a circle. The conveyor has a power source 29 which allows the speed of the conveyor to be varied and can be set at a predetermined rate so that the residence time of the uncured resin in the apparatus as it moves through the chamber is sufficient to effectively cure the resin. Chamber 20 preferably includes a ceiling 30 of the chamber, to which an optional photocell 32 may be attached. In an alternative embodiment, the ceiling 30 of the chamber comprises a reflective surface and also optionally includes airways for cooling of the chamber.

Photocell 32 is at a first end of a light conduit. Photocell 32 is a hollow cylinder 34 made of quartz glass and screen 36 is fastened to the end of hollow cylinder 34 facing conveyor 12. Screen 36 may have a cylindrical portion 38 which slips into the interior of hollow cylinder 34. On the inner surface of screen 36 and on the end of the hollow cylinder 34, a reflector 40 is arranged whose reflective surface 42 forms a cone with a point. Preferably, reflector 40 is made of a polished metal. By means of this light conduit in the form of a hollow cylinder 34, in conjunction with reflector 40 and screen

36, photocell 32 receives only radiation coming directly from inert gas lamp source 14 and photocell 32 is protected from radiation which reflect from conveyor 12 or object 44 being irradiated (see FIGURE 5) by means of screen 36 which intercepts such reflections.

Furthermore, in order to define the wavelength range required for the polymerization of a dental material, one or more filters 46 are located between photocell 32 and screen 36. Preferably, photocell 32 is located on a first end of a light conduit and screen 36 and /or reflector 40 are located on the remote or opposite end of this light conduit. The light conduit may comprises a bundle of optical fibers in the form of a solid cylinder or a hollow cylinder. The solid cylinder and hollow cylinder preferably comprise a glass material, more preferably quartz glass. The hollow cylinder may further comprise windows or slits associated with the individual inert gas lamp sources in order to let radiation into the cylinder. In this embodiment, the inner surfaces of the cylinder must be mirrored, so that the radiation entering any windows or slits will be reflected to the photocell 32. Inert gas lamp source 14 may comprise a single inert gas flash lamp or it may include a plurality of inert gas flash lamps, as illustrated in FIGURES 1 and 2. The radiant energy produced by inert gas lamp source 14 is diffused or flooded to produce an even distribution of light intensity over the entire conveyor as it moves through the chamber. The inert gas lamp source 14 may be internal or external to chamber 20. When inert gas lamp source 14 is external to chamber 20, then the walls of chamber 20 comprise a transparent material allowing for radiation from inert gas lamp source 14 to freely pass through the walls and irradiate an object on conveyor 12. When inert gas lamp source 14 is a plurality of inert gas lamps, the lamps are connected to a power supply 48 which is capable of providing the desired energy pulses to the inert gas flash lamps. The present invention may further include a trigger generator 50 provides trigger pulses to discharge power supply 48 into the inert gas flash lamps. The discharges are conventionally triggered either by overvoltage of the main discharge or by high voltage triggering from a separate source. When it is provided by the overcharging means, the discharge is usually held off and triggered by a silicon controlled rectifier, hydrogen thyratron or the like while when the discharge is provided by high voltage triggering, the output of a pulse transformer or other low current high voltage source is used to initiate ionization in the inert gas flash lamp.

Trigger generator 50 may be a separate unit as depicted in FIGURE 1 or it may be part of the power supply 48. The trigger generator 50 has a trigger rate, which may be fixed or it may be a variable rate in a range sufficient to provide triggering pulses effective to cure the polymerizable resinous material. The range of the trigger rate may be empirically determined and should be such that the time for polymerization begins to approach the same time that would be required if the energy used was averaged over and applied continuously at an average rate. The shape of each pulse and the amount of energy in each pulse are determined by the parameters of the inert gas flash lamp system. Trigger generator 50 and power supple 48 are such that the apparatus of the present invention has instant on-off capability. The energy in the form of pulses used to irradiate the polymerizable resinous material may be controlled by the power supply 48 and trigger generator 50 so that radiation in a desired wavelength sufficient to effectively cure the irradiated object 44 is directed at the object for a predetermined period of time with a predetermined pulse rate.

Now turning to FIGURE 3 illustrating a second embodiment 11 wherein conveyor 12 is surrounded by at least one inert gas lamp in the form of an annular ring 52. To effectively cure a curable resin matrix, a plurality of annular inert gas rings may be disposed in succession surrounding the conveyor which passes through the circular opening in the center of the annular inert gas rings. The conveyor is designed so that it delivers an uncured pre-formed substrate to the curing apparatus immediately after it exits the shape forming dies. The conveyor may be in the form of a conveyor belt or in other forms known in the art which effectively move an object from one location to another.

Preferably the annular inert gas rings are disposed within a chamber 20 which serves as a protective housing. The annular inert gas rings may be fastened to a base 54 of the chamber. Chamber 20 has openings 22,24 at opposite ends to accommodate conveyor 12 which is disposed within the openings. The openings are of such dimension that a preformed substrate can move along while on the conveyor and enter and exit the openings without difficulty. Chamber 20 may optionally include a window for viewing of the curing process and for viewing of the substrate as it moves along while on the conveyor. The conveyor 12 is arranged in chamber 20 with its support surface 26 above the sockets 16. The walls of chamber 20 preferably have reflective surfaces 28 and may include airways for cooling of the inside of chamber 20. Chamber 20 may be rectangular in shape as illustrated in FIGURES 1 and 2 or it may be in the form of another shape, such as a circle. The conveyor has a power source 29 which allows the speed of the conveyor to be varied and can be set at a predetermined rate so that the residence time of the uncured resin in the apparatus as it moves through the chamber is sufficient to effectively cure the resin. Chamber 20 preferably includes a ceiling 30 of the chamber, to which an optional photocell 32 may be attached. The use of a photocell has been previously described herein. In addition, the apparatus 11 may further include power supply 48 and trigger generator 50, both of which have been previously described herein. Now turning to FIGURE 4 illustrating a third embodiment 13 wherein a curable resin is cured by radiant energy from at least one inert gas laser source 56. The inert gas laser source provides a very intense narrow beam of light of a selected wavelength which is effective in curing the resin matrix. The beam from the inert gas laser source is positioned so that it directs radiant energy at a target location as an uncured pre-formed substrate passes through the target location while being moved along by the conveyor. Preferably, the inert gas laser source comprises at least one inert gas laser disposed within chamber 20 which serves as a protective housing. Chamber 20 has openings 22,24 at opposite ends to accommodate conveyor 12 which is disposed within the openings. The openings are of such dimension that a typical replicate model of a human jaw or hand can move along while on the conveyor and enter and exit the openings without difficulty. Chamber 20 may optionally include a window for protective viewing of the curing process and for viewing of the substrate as it moves along while on the conveyor. The conveyor 12 is arranged in chamber 20 with its support surface 26 directly below the inert gas laser source 56. The walls of chamber 20 preferably have reflective surfaces 28 and may include airways for cooling of the inside of chamber 20. Chamber 20 may be rectangular in shape as illustrated in FIGURES 4 or it may be in the form of another shape, such as a circle. The conveyor has a power source 29 which allows the speed of the conveyor to be varied and can be set at a predetermined rate so that the residence time of the uncured resin in the apparatus as it moves through the chamber is sufficient to effectively cure the resin.

Chamber 20 preferably includes a ceiling 30 of the chamber, to which an optional photocell 32 may be attached. In an alternative embodiment, the ceiling 30 of the chamber comprises a reflective surface and also optionally includes airways for cooling of the chamber. The use of a photocell has been previously described herein. In addition, the apparatus 11 may further include control unit 49 which includes a power supply. Control unit 49 allows the user of the apparatus to operate the inert gas laser source in instant on-off capability. An advantage of utilizing an inert gas laser source in the apparatus is that a specific portion of an uncured pre-formed substrate may be targeted and irradiated with energy to cause curing of the targeted portion. Thus, the use of an inert gas laser source allows more precision in targeting a curing location and it provides the ability to provide a narrow, intense energy beam to effectuate curing. The wavelength of the radiant energy emitted by the laser is preferably in the range between about 400 nm to about 500 nm. The apparatus according to the present invention provides rapid curing of a polymerizable resinous material. The present invention is particularly suited for curing unfilled or filled polymerizable dental resins having at least one ethlenically unsaturated group. Generally, dental materials contain a polymeric matrix and may contain a filler component. Preferred polymerizable dental resins are unsaturated resins containing acrylate, methacrylate or vinyl groups. Particularly preferred dental resins include those based on acrylic and methacrylic monomers, for example those disclosed in U.S. Patent No. 3,066,112, No. 3,179,623, and No. 3,194,784 to Bowen; U.S. Patent No. 3,751,399 and No. 3,926,906 to Lee et al.; and commonly assigned U.S. Patent No. 5,276,068 to Waknine, all of which are herein incorporated by reference in their entirety. Filled dental resins can, in general, include any suitable filler which is capable of being covalently bonded to the polymeric matrix itself. Example of suitable filling materials include but are not limited to, silica, silicate glass, quartz, barium silicate, strontium silicate, barium borosilicate, strontium borosilicate, borosilicate, lithium silicate, amorphous silica, ammoniated or dea moniated calcium phosphate and alumina zirconia, tin oxide and titania. The polymerizable dental resin may further include photo- initiators and accelerators which are known in the dental arts.

Preferably a fibrous material is impregnated with the polymeric matrix discussed above to provide reinforcement and strength to the resultant product. The reinforcing fiber element of the composite preferably comprises glass, carbon, graphite, polyaramid, or other fibers known in the art, such as polyesters, polyamides, and other natural and synthetic materials compatible with the polymeric matrix. Some of the aforementioned fibrous materials are disclosed in commonly assigned copending U.S. Patent Application Nos. 08/907,177, 09/059,492, 60/055,590, 08/951,414 and U.S. Patent Nos. 4,717,341 and 4,894,012 all which are incorporated herein by reference. The fibers may further be treated, for example chemically or mechanically abraded or etched and or silanized, to enhance the bond between the fibers and the polymeric matrix. The fibers preferably take the form of long, continuous filaments, although the filaments may be as short as 3 to 4 millimeters. Shorter fibers of uniform or random length might also be employed. Preferably, the fibers are at least partially aligned and oriented along the longitudinal dimensions of the wire. However, depending on the end use of the composite material, the fibers may also be otherwise oriented, including being normal or perpendicular to that dimension.

Fabric may also be combined with the fiber-reinforced composite material to produce a high strength appliance. Fabric may be of the woven or non- woven type and is preferably preimpregnated with a polymeric material. Examples of suitable woven fabric materials include but are not limited to those known in the art such as E glass and S glass fabrics and reinforcement fabrics sold by NFGS inc. of New Hampshire under the style numbers 6522 and 7581. One preferred non-woven fabric material is available under the name Glass Tissue (20103 A) from Technical Fibre Products Ltd. of Slate Hill, NY. Suitable polymeric materials are those listed above as polymeric matrix materials. FIGURES 6 through 8 depict a curing apparatus 60 in combination with a shape- forming die 62. The curing apparatus comprises an inert gas flash lamp or laser source for curing material after it exits shape-forming die 62. A fibrous material 61 shown being unwound on spool apparatus 66 is passed through a resin bath 63 of an uncured polymerizable resinous material 64. The impregnated fibrous material 69 is pulled through shape-forming die 62 and formed into a preferred shape 65 and immediately partially cured by curing unit 60. As shown the shape is of circular cross-section and the long circular shaped rod will ultimately be cut after full curing into short sections for use as posts in the formation of dental restorations. This partial cure is used to maintain the shape of the material prior to fully curing same. Thereafter, the partially cured shaped material 67 is further cured by curing apparatus 68. Curing apparatus 68 comprises an inert gas flash lamp or laser source for further curing the material. Alternately, curing apparatus 68 is located proximate shape-forming die 62 and replaces curing apparatus 60 to fully cure the shaped material 65 immediately upon exiting shape-forming die 62. FIGURE 7 shows an alternate shape-forming die 70 comprising a plurality of sections 72 coaxilly aligned proximate one another for shaping the impregnated fibrous material 64. FIGURE 8 is a sectional view of curing apparatus 68 and shows an inert gas source 80 irradiating impregnated fibrous material 65 or 67, depending on the location of unit 68.

The apparatus according to the present invention achieves very fast cure rates, high degree of cure, greater depth of penetration, low heat buildup and instant on-off capability. In addition to delivering more energy faster, the high peak pulses and broad wavelengths have advantage in penetrating and speeding up the cure of thick and translucent dental materials. The apparatus of the present invention also has low heat buildup. The lower heat associated with pulsed inert gas flash lamps is an important advantage in curing heat sensitive dental devices. The lower heat associated with this apparatus is attributed to four characteristics of the present apparatus: (1) narrow pulses, (2) a cooling zone between the pulses, (3) conversion to useful radiation without heating to vapor levels, as required with mercury lamps, (4) and minimum infrared generation. As previously mentioned, chamber 20 may include cooling devices to cool the air around the inert gas lamp to a lower temperature without affecting radiation efficiency.

While preferred embodiments have been shown and described, various modifications and substitutions may be made thereto without departing from the spirit and scope of the invention. Accordingly, it is understood that the present invention has been described by way of illustration and not limitation.

Claims

What is claimed is:

1. An apparatus for curing a polymerizable resinous dental material, comprising: a shape-forming die for foming a shape for use in a dental restoration; a conveyor for conveying a polymerizable resinous material through the shape- forming die; and at least one inert gas lamp source arranged at a predetermined distance from the plane of the conveyor and proximate the shape-forming die to irradiate the polymeriable resinous material exiting the shape-forming die.

2. The apparatus of claim 1 wherein at least one inert gas lamp source is at least one inert gas flash lamp and/or an inert gas laser.

3. The apparatus of claim 2 or wherein the inert gas flash lamp has a spectral output in the range between about 350 nm to about 550 nm, and perferably in the range between about 400 nm to about 500 nm.

4. The apparatus of claim 2 wherein the inert gas flash lamp emits pulsed radiant energy.

5. The apparatus of claims 1-4 wherein the polymerizable resinous dental material comprises at least one filled or unfilled resin having at least one ethylenically unsaturated group.

6. The apparatus of claims 1-5 wherein the polymerizable resinous dental material comprises a fibrous material.

7. The apparatus of claims 1-6 wherein the shape is a post.

8. The apparatus of claims 1 -7 wherein the conveyor is a conveyor belt on a series of rolls, or a a spool, the spool comprising a plurality of impregnated fibers wound thereon which are pulled through the shape- forming die.

9. The apparatus of claim 1-7 further comprising a resin bath, wherein the conveyer conveys material into and out of the bath pror to conveying the material into the shape- forming die.

10. A method for curing a polymerizable resinous material comprising: conveying a polymerizable resinous material through a shape-forming die to shape the material into a shape suitable for use in a dental restoration; passing the shaped material within the path of at least one inert gas lamp source; radiating the energy from the inert gas lamp source onto the shaped material to at least partially or fully cure the shaped material.

11. The method of claim 10 further comprising passing the partially cured shaped material within the path of a second inert gas lamp source.

12. The method of claims 10 or 11 wherein the inert gas lamp source comprises at least one inert gas flash lamp or at least one inert gas laser source.

13. The method of claim 12 wherein the inert gas flash lamp has a spectral output in the range between about 350 nm and about 550 nm, and preferably i in the range between about 400 nm to about 500 nm.

14. The method of claims 12 or 13 wherein the inert gas flash lamp emits pulsed radiant energy.

15. The method of claims 10-14 wherein the polymerizable resinous material comprises at least one filled or unfilled resin having at least one ethylenically unsaturated group.

16. The method of claims 10-15 wherein the shape is a post.

17. The method of claims 10-16 wherein the polymerizable resinous material is impregnated into fibers prior to conveying the polymerizable resinous material through the shape-forming die.