Patents by Inventor Arun Prasad

Arun Prasad has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Patent number: 5423680
    Abstract: A dental alloy is provided which is free of palladium, gallium and copper and which is compatible with a wide variety of composites and porcelain compositions. The alloy has a melting range of between about 870.degree. C. and 1230.degree. C. and a coefficient of thermal expansion of between 15.5.times.10.sup.-6 and 17.5.times.10.sup.-6 in/in/.degree. C. when heated from room temperature to 500.degree. C. The alloy contains between about 40 and 80 percent by weight gold, between 5 and 50 percent by weight of thermal expansion adjuster, between two and 15 percent by weight strengthener and oxide former, up to about 1.5 percent by weight grain refiner, and up to about 0.25 percent by weight deoxidizer.
    Type: Grant
    Filed: November 10, 1993
    Date of Patent: June 13, 1995
    Assignee: Jeneric/Pentron, Incorporated
    Inventor: Arun Prasad
  • Patent number: 5348475
    Abstract: A trimodal method of curing dental composite restorative materials involves the use of visible light illumination for the initial curing of the composite resin and a combination of dry heat and vacuum for the complete cure of the composite restorative materials. More specifically, the method for preparing dental restorative materials includes the steps of forming a dental restoration from a composite resin of a type conventionally employed in the dental profession, in which the composite resin includes a photosensitizing system for initiating polymerization of the composite resin upon exposure to visible light, an initiator for initiating polymerization upon application of heat and at least one filler; exposing the thus prepared restoration to a source of visible light to at least partially cure said composite resin and then subjecting the thus prepared restoration to a combination of heat and vacuum to complete polymerization of said complete resin.
    Type: Grant
    Filed: April 22, 1993
    Date of Patent: September 20, 1994
    Assignee: Jeneric/Pentron Inc.
    Inventors: Samuel Waknine, Arun Prasad, Weitao Jia
  • Patent number: 5314334
    Abstract: Porcelain compositions suitable for layers on metal base dental restorations have fusion temperatures of about 800.degree. C. and lower. The compositions may be employed as coatings on titanium and titanium alloy bases since the compositions have thermal expansion values close to those of titanium and its alloys. A bond layer is also provided to improve bonding between the porcelain layers and the restoration base. A method is also provided for forming dental restorations with relatively inexpensive and biocompatible metal bases and low fusing dental porcelains.
    Type: Grant
    Filed: June 6, 1991
    Date of Patent: May 24, 1994
    Assignee: American Thermocraft Corporation Subsidiary of Jeneric/Pentron Incorporated
    Inventors: Carlino Panzera, Arun Prasad
  • Patent number: 5288232
    Abstract: Porcelain compositions suitable for use as porcelain layers on metal base dental restorations have fusion temperatures of about 800.degree. C. and lower. The compositions may be employed as coatings on titanium and titanium alloy bases since the compositions have thermal expansion values close to those of titanium and its alloys. A method is also provided for forming dental restorations with relatively inexpensive and biocompatible metal bases and low fusing dental porcelains.
    Type: Grant
    Filed: September 23, 1992
    Date of Patent: February 22, 1994
    Assignee: American Thermocraft Corporation Subsidiary of Jeneric/Pentron Incorporated
    Inventors: Carlino Panzera, Arun Prasad
  • Patent number: 5180427
    Abstract: Phosphate-bonded investments and refractory die materials are provided upon which dental porcelains and/or alloy powders can be sintered. Inorganic fillers are mixed with appropriate binders to produce mold materials which exhibit very high thermal expansion properties without exhibiting any large or sudden change in their thermal expansion verse temperature profile. Investments and refractory die materials having thermal expansions of greater than 0.80% in the range of 25.degree.-500.degree. C. are provided by incorporating leucite (KAlSi.sub.2 O.sub.6) or calcium difluoride (CaF.sub.2), or both, as fillers for investments and refractory die materials.
    Type: Grant
    Filed: January 28, 1992
    Date of Patent: January 19, 1993
    Assignee: Jeneric/Pentron, Inc.
    Inventors: Arun Prasad, Carlino Panzera
  • Patent number: 5176747
    Abstract: Porcelain compositions suitable for use as porcelain layers on metal base dental restorations have fusion temperatures of about 800.degree. C. and lower. The compositions may be employed as coatings on titanium and titanium alloy bases since the compositions have thermal expansion values close to those of titanium and its alloys. A method is also provided for forming dental restorations with relatively inexpensive and biocompatible metal bases and low fusing dental porcelains.
    Type: Grant
    Filed: July 31, 1991
    Date of Patent: January 5, 1993
    Assignee: American Thermocraft Corporation
    Inventors: Carlino Panzera, Arun Prasad
  • Patent number: 5161600
    Abstract: The system comprises a main casting unit and a glove box unit for reworking cast items. The main casting unit has a frame with a casting chamber, a heating element, a vacuum, a supply of inert gas and a rotatable casting arm for spin casting molten material into a mold. The arm is adapted to removably mount a crucible and mold at one end and, an adjustable counterweight at the other end. The heating element can be moved into and out of the path of the arm and is adapted to heat metallic material in the crucible. The main casting unit also has a driver that projects into the chamber for driving the casting arm with reduced wear on seals between the chamber wall and the driver. A safety bar is provided to prevent the arm from spinning except when desired. The main unit also has electrical and gas conduit connectors for connecting the glove box unit to the main unit.
    Type: Grant
    Filed: November 16, 1990
    Date of Patent: November 10, 1992
    Assignee: Jeneric/Pentron Inc.
    Inventors: Craig Brodersen, Arun Prasad
  • Patent number: 5091148
    Abstract: Improved titanium alloys for dental castings and processes for the preparation thereof, characterized by the incorporation of predetermined small amounts of one or more noble metals, preferably ruthenium, or rhenium, and optional predetermined small amounts of one or more rare earth metals, preferably cerium. The present alloys have improved corrosion and tarnish resistance under the conditions of use, and the preferred compositions including rare earth metals have improved oxidation resistance which improves their receptivity and bonding strength for enamels, porcelain surfacing materials or caps.
    Type: Grant
    Filed: January 2, 1991
    Date of Patent: February 25, 1992
    Assignee: Jeneric/Pentron, Inc.
    Inventor: Arun Prasad
  • Patent number: 4619810
    Abstract: Palladium based dental alloys are provided consisting essentially of, on a weight percent basis:Gold: 8-25Gallium: 0-10Boron: 0.05-0.25Rhenium: 0.1-0.5Indium and/or Tin: 0-20Zinc: 0-4and the balance, palladium--with the proviso that when a mixture of gallium, indium and/or tin are incorporated in the alloy, if gallium is present in amounts less than or equal to about 4% by weight, then the total weight percent of gallium, indium and/or tin ranges from about 12 to 20; whereas, if gallium is present in amounts from greater than about 4% to 10% by weight, then the total weight percent of gallium, indium and/or tin ranges from about 8 to 20; and when a mixture of zinc, indium and/or tin are incorporated in the alloy, zinc is present in an amount less than 4% and is present in the alloy in lieu of gallium, said alloy exhibiting a yield strength greater than 50,000 psi, an ultimate tensile strength of greater than 60,000 psi, an elongation greater than 10%, and a melting point ranging from 2200.degree.-2400.degree.
    Type: Grant
    Filed: October 3, 1985
    Date of Patent: October 28, 1986
    Assignee: Jeneric Industries, Inc.
    Inventor: Arun Prasad
  • Patent number: 4576789
    Abstract: Grain refined palladium-based dental alloys contain about 70-85 weight percent palladium, 7-15 weight percent copper, 2-8 weight percent gallium, 2-15 weight percent indium, 0.2-3.0 weight percent rhenium or ruthenium and an effective amount of boron up to about 0.15% which eliminates the formation of bubbles in porcelain during the porcelain firing process. In addition, there can be an effective amount of zinc up to about 0.5 weight percent. Alternately, in lieu of zinc, the boron is added in the form of calcium boride.
    Type: Grant
    Filed: December 26, 1984
    Date of Patent: March 18, 1986
    Assignee: Jeneric Industries, Inc.
    Inventor: Arun Prasad
  • Patent number: 4539177
    Abstract: A dental alloy for use in porcelain-fused-to-metal restorations including palladium, cobalt, gallium, gold, aluminum, copper, zinc and ruthenium or rhenium. The cobalt controls the coefficient of thermal expansion of the alloy to permit the use of the alloy with commercially available porcelains having a variety of thermal coefficients. The zinc serves as a scavenger during formation and casting of the alloy. The aluminum protects the alloy from absorbing gases during torch melting and during the porcelain firing process. The ruthenium or rhenium provides grain refining for the alloy to increase its elongation, tensile strength, and thus toughness. The alloy with ruthenium or rhenium as a grain refining agent must be made in a protective environment to avoid the formation of bubbles in the porcelain during the porcelain firing process.
    Type: Grant
    Filed: January 25, 1984
    Date of Patent: September 3, 1985
    Assignee: Jeneric Industries, Inc.
    Inventor: Arun Prasad
  • Patent number: 4530664
    Abstract: A cobalt-chromium alloy consisting essentially of:______________________________________ Element Weight Percent ______________________________________ Cobalt 50-70 Chromium 25-35 Molybdenum 2-10 Manganese 0-2 Carbon 0-0.1 ______________________________________and(i) from about 1 to about 6% silicon or(ii) from about 2 to about 6% silicon and from about 0.1 to about 1.5% boron with the proviso that the combined amount of silicon and boron is greater than or equal to 3% or(iii) from about 1 to about 6% aluminum or(iv) from about 1 to about 6% silicon and from about 1 to about 6% aluminum with the proviso that the combined amount of silicon and aluminum is less than about 8% or(v) from about 1 to about 6% silicon, from about 0.1 to about 1.5% boron and from about 1 to about 6% aluminum with the proviso that the combined amount of silicon and aluminum is less than about 8%, said alloy constituents totalling 100%.
    Type: Grant
    Filed: March 24, 1983
    Date of Patent: July 23, 1985
    Assignee: Jeneric Industries, Inc.
    Inventors: Arun Prasad, Grant P. Day
  • Patent number: 4526221
    Abstract: A crucible for use with a broken arm-type centrifugal casting machine includes an elongated base section and a top section which is generally in the shape of a half cylinder, a large portion of the top section being removed by a cavity which creates a crucible floor, left and right side walls and a generally funnel-shaped channel which extends to a front surface at the front end of the crucible to provide a discharge opening. The right side wall is always correspondingly higher than the left side wall and both the left side wall and the right side wall increase in height and slope over toward one another as they extend toward the front end of the crucible until they merge at a point on a head portion of the top section which is on the left side of the crucible. The crucible floor includes a portion which narrows in width as it extends toward the front end of the crucible and slopes downwardly from horizontal at an angle of between about 10.degree. and 20.degree.
    Type: Grant
    Filed: January 23, 1984
    Date of Patent: July 2, 1985
    Assignee: Futurdent Industries Inc.
    Inventor: Arun Prasad
  • Patent number: 4518564
    Abstract: A dental alloy for porcelain-fused-to-metal restorations is provided which consists essentially of, on a weight basis, about 60-90% palladium, an effective amount of ruthenium up to about 2% for the purpose of grain-refining the alloy, an effective amount of copper up to about 30% for the purpose of lowering the melting point and raising the thermal expansion, up to about 15% indium, up to about 16% tin, up to about 12% zinc, up to about 5% gold, and from about 0.05 to about 0.25% boron or calcium boride, the total of said constituents being 100%, wherein the sum of the copper, indium, tin and zinc concentrations is greater than about 18%, the sum of the indium, tin and zinc concentrations is greater than about 10%, and the sum of the indium and zinc concentrations is greater than about 5%, such that said alloy exhibits a melting point between about 1100.degree. C. and 1400.degree. C. and a coefficient of thermal expansion of about 0.66 to 0.72 at 500.degree. C.
    Type: Grant
    Filed: May 30, 1984
    Date of Patent: May 21, 1985
    Assignee: Jeneric Industries, Inc.
    Inventor: Arun Prasad
  • Patent number: 4483821
    Abstract: A cobalt-chromium alloy consisting essentially______________________________________ Element Weight Percent ______________________________________ Cobalt 40-60 Chromium 20-35 Tungsten 10-20 Gallium 3-10 Rhenium 0.1-1.0 ______________________________________and from 1 to about 1.75% aluminum, said alloy constituents totalling 100%. These alloys exhibit outstanding physical properties and can be used advantageously as a substitute for precious metals and alloys thereof as well as nickel-chromium-based alloys in the fabrication of porcelain-veneered fixed bridgework and crowns.
    Type: Grant
    Filed: December 27, 1982
    Date of Patent: November 20, 1984
    Assignee: Jeneric Industries, Inc.
    Inventor: Arun Prasad
  • Patent number: 4459263
    Abstract: A cobalt-chromium dental alloy for use in porcelain-fused-to-metal restorations consisting essentially of about:______________________________________ Element Weight Percent ______________________________________ Cobalt 40-60 Chromium 20-30 Ruthenium 5-15 Aluminum 1-4 Yttrium 0-0.15 Tungsten 0-15 Molybdenum 0-6.5 Niobium 0-3.0 Zirconium 0-0.25 Manganese 0-1.5 ______________________________________wherein the sum of the constituents equal 100% and the sum of the tungsten and molybdenum constituents minus the sum of the ruthenium, niobium and zirconium constituents is less than about 5%. These alloys exhibit outstanding physical and chemical properties, including the formation of a tenacious bond with porcelain without the need for a separate bonding agent, and can be used advantageously as a substitute for alloys having a high proportion of precious metals as well as for nickel-chromium-based alloys in the fabrication of porcelain-veneered fixed bridgework and crowns.
    Type: Grant
    Filed: September 8, 1982
    Date of Patent: July 10, 1984
    Assignee: Jeneric Industries, Inc.
    Inventor: Arun Prasad
  • Patent number: 4451639
    Abstract: A dental alloy for use in porcelain-fused-to-metal restorations including palladium, cobalt, gallium, gold, aluminum, copper, zinc and ruthenium or rhenium. The cobalt controls the coefficient of thermal expansion of the alloy to permit the use of the alloy with commercially available porcelains having a variety of thermal coefficients. The zinc serves as a scavenger during formation and casting of the alloy. The aluminum protects the alloy from absorbing gases during torch melting and during the porcelain firing process. The ruthenium or rhenium provides grain refining for the alloy to increase its elongation, tensile strength, and thus toughness. The alloy with ruthenium or rhenium as a grain refining agent must be made in a protective environment to avoid the formation of bubbles in the procelain during the procelain firing process.
    Type: Grant
    Filed: August 31, 1983
    Date of Patent: May 29, 1984
    Assignee: Jeneric Industries, Inc.
    Inventor: Arun Prasad
  • Patent number: 4450958
    Abstract: A self-actuated dental capsule is provided which includes a three-part container for holding the liquid component of an amalgam. One part of the container holds the liquid; a second part is used to attach the container along an inner side wall of the capsule so that the container is not repeatedly pounded by the amalgam during the vibratory process; and the third part allows the liquid to achieve sufficient momentum when the capsule is vibrated in a dental amalgamator to rupture the container.
    Type: Grant
    Filed: January 18, 1983
    Date of Patent: May 29, 1984
    Assignee: Jeneric Industries, Inc.
    Inventor: Arun Prasad
  • Patent number: 4419325
    Abstract: A dental alloy for use in porcelain-fused-to-metal restorations including palladium, cobalt, gallium, gold, aluminum, copper and ruthenium or rhenium. The cobalt controls the coefficient of thermal expansion of the alloy to permit the use of the alloy with commercially available porcelains having a variety of thermal coefficients. The ruthenium of rhenium provides grain refining for the alloy to increase its elongation, tensile strength, and thus toughness. The alloy with ruthenium or rhenium as a grain refining agent must be made under vacuum or in an inert atmosphere to avoid the formation of bubbles in the porcelain during the porcelain firing process.
    Type: Grant
    Filed: July 21, 1982
    Date of Patent: December 6, 1983
    Assignee: Jeneric Industries, Inc.
    Inventor: Arun Prasad
  • Patent number: 4412970
    Abstract: A dental alloy for use in porcelain-fused-to-metal restorations including palladium, cobalt, indium, tin, aluminum and rhenium. The aluminum protects the alloy during torch melting and during the porcelain firing process through the formation of a protective oxide. The rhenium provides grain refining for the alloy to increase its elongation, tensile strength, and thus toughness. The alloy must be made under vacuum or in an inert atmosphere to avoid the formation of bubbles in the porcelain during the porcelain firing process.
    Type: Grant
    Filed: December 6, 1982
    Date of Patent: November 1, 1983
    Assignee: Jeneric Industries, Inc.
    Inventor: Arun Prasad