Classifications

• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C7/00—Alloys based on mercury
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
  • A61K6/00—Preparations for dentistry
  • A61K6/80—Preparations for artificial teeth, for filling teeth or for capping teeth
  • A61K6/84—Preparations for artificial teeth, for filling teeth or for capping teeth comprising metals or alloys
  • A61K6/847—Amalgams
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C30/00—Alloys containing less than 50% by weight of each constituent
  • C22C30/04—Alloys containing less than 50% by weight of each constituent containing tin or lead

Definitions

• This invention relates in general to a dental composition and dental amalgam suitable for use in repairing carious tooth structure. More specifically the invention relates to a .substantially uniform admixture of two powdered alloys in the form of spheroids and irregularly-shaped or cut particles which when amalgamated with mercury exhibit improved handling characteristics.
• U.S. Patent 3,985,558 teaches an improved dental alloy having a relatively low concentration of silver and a critical atomic ratio of silver plus copper to tin which exhibits enhanced mechanical properties and handling characteristics as compared to conventional high silver alloys.
• the alloy is also more economical to use than conventional alloys which require higher silver concentrations.
• Prior art admix compositions generally combine two different alloy compositions for the respective spherical and irregularly- shaped components. This runs the risk that segregation of individual components may result and lead to inconsistent properti in the final amalgamated alloy.
• the alloys Prior to amalgamation, the alloys are annealed by techniques well known in the art to control the work time of the final alloy. The alloys are also cleaned by chemically treating with a dilute acid.
• the alloy of the present invention is composed of an admixture of spherical and irregularly-shaped or "cut" particles.
• the alloy powder has a fine particle size (all about -325 mesh) , of both the spherical and irregular particles which allows the alloy to have the smooth carve associated with all spherical alloys, but with a firmer packing and carving consistency characteristic of conventional alloys.
• the particle size range for both components is from submicron to about 50 microns.
• Both of the particle configurations are made to the same composition: About 24 to 45 weight percent silver, 28 to 42 weight percent copper and 29 to 34 weight percent tin, and where the atomic percentage of the total amount of silver plus copper is about 3 times greater than the atomic percentage of tin.
• a particularly preferred composition comprises about 41% silver, 28% copper and 31 percent tin.
• the powder admixture must be maintained in a weight ratio of about 65 to 85 percent spherical to 15 to 35 percent irregular in order to obtain the enhanced properties described herein. The benefits of this relationship are quite clear; both of the particle configurations participate heavily in the reaction with mercury during amalgamation, therefore enhancing the consistency of the mix and the homogeneity of the amalgam.
• each particle in the alloy of the present invention contains copper, assures that it is distributed fully throughout the amalgam to alloy with tin to prevent formation of the unwanted gamma-2 (tin-mercury) phase.
• This admix alloy produces an amalgam with a smooth carve, but with the body that can be comfortably worked. The amalgam begins to "body-up” upon condensation, which allows for carving to commence almost immediately, with the resistance to carve
• OMP increasing up until the end of working time which can be controlled typically to vary from about 6 1/2 to 11 minutes.
• the alloy composition used was the preferred composition of 41% silver, 28% copper and 31% tin in a weight ratio of 70% spherical to 30 percent irregular particles.
• the concentration of mercury was 48% by weight and the admix alloy constituted 52 weight percent. Both alloy components were of fine particle size of less than 325 mesh.
• the tests were carried out according to ADA speci ication No. 1 for Dental Amalgams.
• the physical properties of the Alloy of the present invention compare favorably to those of other commercial dental alloys.
• spheroidal as used to describe the shape, configuration or form of the first component in the admixture of the present invention means that the individual particles are spheres or shaped like a spheroid.
• the spherical component may be formed by any technique well known to the dental art.
• it may be prepared by first forming a molten alloy in the above concentration ranges and atomizing said alloy at approximately 2,000°F. Atomization is achieved in a conventional manner as described in U.S. Pat. No. 3,305,356 at column 2, lines 9-50, which is incorporated herein by reference. The alloy is then collected and classified using a 325 mesh sieve. The fraction passing through the sieve is retained as the dental alloy product.
• the term "irregularly-shaped" or “cut” as used to described the configuration or form of the second component means that the individual particles are substantially non-equiaxial and are multi-sided and generally angularly shaped or irregular, and usually with rough or otherwise relatively non-smooth surfaces. Typically they are in the form of what is variously referred to in the art as microcut material, lathe-cut material, platelets or filings. Conventional microcutting, lathe cutting or filing techniques, usually from a cast billet of the alloy, can be employed satisfactorily to obtain the irregularly-shaped particles and are well known to those skilled in the art. The irregular particles used in this invention should all be less than 325 mesh in size.
• the dental composition of this invention be in the form of a particulate mixture of the two alloys when used, and may be supplied in such form when supplied, it should be understood that for distribution purposes the two alloys can be in the form of separate powders which can be mixed together by the ultimate user in the required proportions.
• the two admixed alloys in the required proportions can also be pressed into a tablet, used in a capsule form for convenience, or used in bulk powder dispensers.
• the spherical to irregular weight ratio is preferably about 4 to 1; for use in capsule form the preferred ratio is about 7 to 3.

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• Chemical & Material Sciences (AREA)
• Health & Medical Sciences (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Mechanical Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Oral & Maxillofacial Surgery (AREA)
• Plastic & Reconstructive Surgery (AREA)
• Epidemiology (AREA)
• Life Sciences & Earth Sciences (AREA)
• Animal Behavior & Ethology (AREA)
• General Health & Medical Sciences (AREA)
• Public Health (AREA)
• Veterinary Medicine (AREA)
• Dental Preparations (AREA)
• Powder Metallurgy (AREA)

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• 1983
  • 1983-01-17 AU AU11583/83A patent/AU557405B2/en not_active Ceased
  • 1983-01-17 EP EP19830900602 patent/EP0101457A4/fr not_active Withdrawn
  • 1983-01-17 WO PCT/US1983/000063 patent/WO1983002959A1/fr not_active Ceased
  • 1983-01-17 JP JP83500648A patent/JPS59500220A/ja active Pending
  • 1983-02-03 CA CA000420837A patent/CA1222401A/fr not_active Expired
  • 1983-02-10 IT IT47691/83A patent/IT1164867B/it active

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