Abstract:
A curing apparatus providing rapid curing by using light, pressure, pressure and light, or purge, pressure and light to cure resinous materials by application of energy from an external source to excite polymerization in a polymerizable system. A curing chamber is provided to house the polymerizable dental material. The apparatus utilizes light emitting diodes (LEDs) to radiate energy to polymerize the dental materials. The LEDs are positioned optimally within the curing apparatus to provide efficient, effective polymerization of the dental materials.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority to Provisional Application No. 60/371,881 filed Apr. 11, 2002 which is hereby incorporated by reference. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates generally to light for a curing unit and more specifically to light for use in a curing unit for dental materials. 
     BACKGROUND OF THE INVENTION 
     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. 
     The use of incandescent lamps such as halogen lamps as light sources for a laboratory curing apparatus generate excessive unwanted heat and also have a short life span, typically 50 hours. The heat may melt the pressure vessel or heat the composite material above recommended temperatures. The incandescent lights are very power inefficient since most of the light is not needed and is the wrong wavelength for the photo-initiators used in the dental composite material. Components to remove the unwanted heat are usually necessary adding to the cost of the device. 
     It would be beneficial to provide a light source that is power efficient and does not overheat the composite material or vessel housing the composite. It would be advantageous to provide a light source that does not require additional components to eliminate unwanted heat such as fans, ducts, vents, thermal sensors and the like. 
     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 rapid curing is provided by using light, pressure, pressure and light, or purge, pressure and light to cure resinous materials by application of energy from an external source to excite polymerization in a polymerizable system. A curing chamber is provided to house the polymerizable dental material. The apparatus utilizes light emitting diodes (LEDs) to radiate energy to polymerize the dental materials. The LEDs are positioned optimally within the curing apparatus to provide efficient, effective polymerization of the dental materials. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Features of the present invention are disclosed in the accompanying drawings, whrerein similar reference characters denote similar elements throughout the several views, and wherein: 
         FIG. 1  is perspective view of a curing apparatus of the present invention; 
         FIG. 2  is a block diagram showing the electrical connections and air line connections of the apparatus of  FIG. 1 ; 
         FIG. 3  a perspective view of the apparatus of  FIG. 1  showing the internal components; 
         FIG. 4  is perspective view of a curing chamber having LEDs positioned in the floor of the chamber; 
         FIG. 5  is a perspective view of an alternate embodiment of a curing chamber having LEDs positioned on the dome cover; 
         FIG. 6  is a perspective view of an alternate embodiment of a curing chamber having LEDs positioned on the dome cover; 
         FIG. 7  is a perspective view of an alternate embodiment of a curing chamber having LEDs positioned along the perimeter of the dome cover; and 
         FIG. 8  is a perspective view of an alternate embodiment of a curing chamber having LEDs rotating about the curing dome. 
     
    
    
     DESCRIPTION OF THE INVENTION 
     As will be appreciated, the present invention provides a new and improved curing apparatus for curing a polymerizable resinous material, such as a dental material. U.S. Pat. Nos. 4,873,446, 4,839,521, 5,040,964, and 4,309,617 are directed to polymerization and/or curing of materials and are hereby incorporated by reference. The dental material may include, but is not limited to at least one filled or unfilled resin having at least one ethylenically unsaturated group. Examples of the ethylenically unsaturated groups include acrylates, methacrylates, vinyl groups and combinations thereof. 
       FIGS. 1 and 3  show a curing apparatus  10  for curing dental materials in a variety of modes including light alone, pressure alone (does not cure, but can be used to reduce porosity), light and pressure in combination, and a purge cycle to be used with light and pressure. 
     Curing apparatus  10  provides a facile method of curing by providing a curing chamber, which is preferably an air-tight chamber,  20 , shown in FIG.  4 . The curing chamber, includes a cover  22 , which is preferably dome-shaped and is located in a cover or top section  32  of the curing apparatus, and a base  24  which is part of the base or bottom section  38  of the curing apparatus. A work piece  25  may be placed on base  24  of bottom section  38  when a curing operation is to be performed. 
       FIG. 2  is provided to show the electrical connections and air or gas line layout. The front panel  40  is the control panel that is operatively associated with a processing device located internally. The control panel receives input from an operator relating to the light source and the gas source. The processing device is operatively associated with the light source and the gas source for controlling curing of the dental material by light and pressure within the air-tight chamber. The processing device may include, but is not limited to, a microprocessor, a microcontroller, a microcomputer, a controller, a digital signal processor, a central processing unit (CPU), or an application specific integrated circuit (ASIC). The processing device may be configured to cause gas to supply gas under pressure to the air-tight chamber prior to the time the light source supplies light to the chamber. It may be further configured to cause gas pressure to be maintained in the chamber at a constant level during the time the light source supplies light to the chamber. The processing device may be configured to cause the gas pressure to be initially supplied and subsequently released at least twice in succession, followed by application of pressure, whereby gas pressure is maintained at a constant level with in the chamber during the time the light source supplies light to the chamber. 
       FIG. 3  shows a light source comprising two lamps  39  arranged above cover  22 , which cover may be transparent, positioned over base  24  of bottom section  38 , which can create air-tight chamber  20  when in closed position. The lamps may comprise light emitting diodes, tungsten, halogen, mercury vapor, short arc xenon, or a metal halide source. The light source may comprise one or a plurality of lamps directed at base  24 . Preferably, the spectral output of the lamp utilized herein is in the range of between about 380 nm to about 550 nm. Most preferably, the lamps comprise light emitting diodes. The LEDs may be positioned in a variety of ways to provide optimal curing of dental components 
     The operation and the components of this curing apparatus are set forth in U.S. patent application Ser. No. 10/120,934, filed Apr. 11, 2002, which is hereby incorporated by reference. 
     In accordance with one embodiment herein,  FIG. 4  shows the LEDs  26  positioned on base  24 . Polymerizable material  25  is placed on base  24  and dome cover  22  is positioned thereon. LEDs  26  located on base  24  may be covered by a protective transparent cover  28  to prevent any seepage of polymeric material onto the LEDs. LEDs  26  are optimally located on base  24  to provide direct application of light to the polymerizable material. Dome cover  22  may be transparent or opaque and may be covered with a reflective coating on the internal side to reflect any upwardly emitted light, down toward the polymerizable material. Base  24  acts as a heat sink for the power created by the LED semiconductor junction, reducing the need for cooling aids, such as fans. 
     In accordance with another embodiment,  FIG. 5  shows a dome cover  50  with LEDs  52  mounted in cover  24  so that light is transmitted directly from the LEDs to the material being cured. LEDs may be mounted in a continuous pattern over the surface of cover  50 . The LEDs may be mounted continuously as shown or in a variety of different patterns, as desired.  FIG. 6  shows an alternate embodiment of a dome cover  50  having LEDS  62  mounted to cover  64  in a series of locations on the surface of cover  34 . The LEDs  62  are shown mounted on a substrate  66  and substrates  66  may be mounted continuously along the lower surface as shown or in a variety of different patterns, as desired. In the embodiments shown in  FIGS. 5 and 6 , covers  50  and  64  may include a reflective internal surface on the areas where the LEDS are not located to provide reflectance of light to the material being cured. 
     In yet another embodiment herein,  FIG. 7  shows dome cover  70  having LEDs  72  mounted along the perimeter of cover  70 , so that light is transmitted through cover  70 . LEDs  72  may be connected to cover  70  or may be independently located proximate cover  70 . Cover  70  may be completely transparent or transparent only in those locations where the light is directed. 
       FIG. 8  shows yet another embodiment of dome cover  80  having LEDs  82  located above cover  80  and rotatable around cover  80  to provide even and continuous light to the dental material being cured. 
     The wavelength of the LEDs used herein are in the wavelength range from about 380 to about 550 nanometers. Commercially available LEDs useful herein include Luxeon Star Power Light Source LEDs from Lumileds in San Jose, Calif. and Shark High Flux LED Illuminators from Opto Technology Inc. in Wheeling, Ill. The dome described herein in combination with the LEDs is used in a light curing apparatus or in a light and pressure curing apparatus. The dome is preferably used in a light curing apparatus or in a light and pressure curing apparatus such as that described in copending application Ser. No. 10/120,934, filed Apr. 11, 2002 entitled Curing Unit For Dental Materials, naming one common inventor, and is hereby incorporated by reference. 
     While various descriptions of the present invention are described above, it should be understood that the various features can be used singly or in any combination thereof. Therefore, this invention is not to be limited to only the specifically preferred embodiments depicted herein. 
     Further, it should be understood that variations and modifications within the spirit and scope of the invention may occur to those skilled in the art to which the invention pertains. Accordingly, all expedient modifications readily attainable by one versed in the art from the disclosure set forth herein that are within the scope and spirit of the present invention are to be included as further embodiments of the present invention. The scope of the present invention is accordingly defined as set forth in the appended claims.