Dentistry (metals)
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Dentistry (metals)

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Dentistry (metals) Dentistry (metals) Presentation Transcript

  • Metallic RestorationsStudent: Alonso Martinez TapiaDr. Alfredo Nevarez Rascon
  • METALS
  • DEFINITION“Chemical substance that is a good electrical and thermal conductor, when is polished is a good reflector “
  • FEATURES SHINE RESISTANCE TO CORROSION THERMAL AND ELECTRICALCONDUCTOR STRENGTH AND RIGIDITY DRIVE RESISTANCE
  •  ALLOY : This are unions of 2 or more metallic elements.
  • In Dentistry, alloys are use except for:• pure gold laminated• commercial pure titanium• Silver points for endodontic
  • CHANGES IN THE METAL STRUCTURE lackluster : Loss of gloss or sheen in a alloy or metal surface. Pigmentation : Partial impariment on metal surface, or color change. CORROSION : Actual deterioration on metal surface.
  • • FACTORS CAUSING CORROSION– pH of the saliva.– Wrong adapted prosthesis.– Poor dental position.– Deposits of food.– Poor hygiene.– Food that release certain chemical components.– Drugs.– Fluctuations in temperature.
  • ALLOYS USED IN DENTISTRY Highly noble alloys (precious) Alloys of noble metals Predominantly base alloys
  • PRECIOUS METALSCorrosion resistance in the oral cavity:Gold, Platinum, Palladium, Rhodium,Ruthenium, Iridium, Osmium and Silver.There are four main metals: Gold,Palladium, Platinum and Silver.
  • Cast Metal Or DrainProcess for the constuction of a restoration or appliance out for the previously made a mouth waxed or pattern.
  • CAST ALLOYS FOR HIGHLY NOBLEComposition:2. Gold: malleability, resistance to corrosion.3. Silver: Hardness4. Zinc: decreases T fusion5. Platinum or Palladium: Hardness6. Copper: resistance and bactericidalNota: the white gold casting whit less gold and copper are not.
  • TIPOS DE OROS PARA COLADOSType I (SOFT GOLD)For the construction of scale in class III y V Type II (MEDIUM GOLD)For all types of deposits, plus ¾ cr owns and complete Type III (HARD GOLD)For small fixed bridges and removable Type IV ( GOLD EXTRA HARD)For large fixed bridges and removable palatal bars and lingual
  • NOBLE METAL ALLOYS (Semiprecious) 25% of noble metals, does not require gold: Silver - Palladium Palladium - Silver Silver - Tin
  • SILVER-PALLADIUM ALLOYS (Ag-Pd)
  •  Developed as an alternative to those based on gold. There are two varieties: Silver 60-70% Palladium 25-30% Note: Some containe 10% copper. Palladium 60% Silver 30% Note: El 10% of other metals to failitate bonding with porcelain.
  • CHEMICAL PROPERTIES Pigmentation and resistance to corrosion properly handled. Note: It is possible to achieve adequate accuracy casting and a good polishing and acceptable welds.
  • CLINICAL APPLICATION Scale Crowns Fixed partialDentureEndopostes
  • PALLADIUM-SILVER ALLOY (Pd-Ag)
  • They are an alternative to gold alloy for ceramics.
  • This are alloys of high melting point and which support thefiring of ceramics of porcelain. (1400°C)
  • ADVANTAGES Good physical properties and bonding with ceramics. Biocompatible
  • DISADVANTAGESThe likely change in color of porcelain baked.Expensive
  • SILVER-TIN ALLOY (Ag-Sn)
  • These alloys have been used for decades in dentistry to make deposits, not being suitable for prosthetic purposes. INDICATIONS: Temporary inlays.
  • ADVANTAGESCheapEasy handlingPoor precision casting
  • DISADVANTAGES Fragile marginal edges Pigmentation Can not be welded Slight corrosion resistance After a short clinical use and even before cemented in the mouth have lost shine and later changed to dark
  • BASE METALS These are noble elements. Is the so called because it reacts with the environment and are use to protect an alloy against corrosion by passivity.
  • COBALT-CHROMIUM ALLOYS (Co-Cr)
  • FEATURESHigh hardenessGood glossMechanical strengthResistance to corrosiony corrosiónCheap
  • CLINICAL APPLICATION Development ofbases in removabledentures. Basis of dentures
  • PRESENTATION Form of granules IngotsTRADE NAMES Vitalium (Co-Cr) Ticonium (Ni-Cr) Dentillium (Fe-Cr)
  • ADVANTAGESCheapVery lightMore durable adjusting hooks.
  • DISADVANTAGES• Excessive hardness• Minor casting accuracy• Complicated heat treatment
  • Welds
  • Welds WELDING : Intermediate element that is used to join metallic surfaces each other. It’s a technique for join 2Or more metal elements,Rebuild or repair a metal surface.
  • REQUIREMENTS Free toxic substance Resistant Flow Similar color Lower temperature of• fusion Corrosion resitant
  • TECNICAS PARA SOLDARTECHNICAL COMM : Requires the useof an intermediate (welding).WELD TECHNICAL : Application of heatto melt the two metal surfaces.ELECTRICAL TECHNICAL : Applicationof electric current-tap to join metallicsurfaces.
  • FLUX Facilitate the flow of welding,Eliminating impurities. They come in powder and paste Composition of flux for alloys with chromium :pottasium fluoride, boric acid, borax glass, and sodium carbonate or silica. And for gold alloys: Borax powder, boric acid and silica.