Dental Amalgam
BY UZMA JAN
BDS 1ST
YEAR
Amalgam
 An alloy of mercury with another metal.
Why Amalgam?
 Inexpensive
 Ease of use
 Proven track record
- >100 years
 Familiarity
 Resin-free
- less allergies th...
Composition Of Dental Amalgam
 Traditional or Convential amalgam alloys is based
on Black’s composition.
 63-70% silver
...
Composition Of High Ag-Sn Amalgam
 Ag 40-60%
 Sn 27-30%
 Cu 13-30%
Constituents in Amalgam
 Basic
• Silver
• Tin
• Copper
• Mercury
 Other
• Zinc
• Indium
• Palladium
Basic Constituents
 Silver (Ag)
 Increases strength
 Increases expansion
 Decrease creep
 Whitens the Alloy
 Increas...
Basic Constituents
Copper (Cu)
 Ties up tin
 Reducing gamma-2 formation
 Increases strength & hardness
 Reduces tarnis...
Basic Constituents
Mercury (Hg)
 Activates reaction
 Only pure metal that is liquid
at room temperature
 Spherical allo...
Other Constituents
 Zinc (Zn)
 Used in manufacturing
 Decreases oxidation of other elements
 Sacrificial anode
 Provi...
Other Constituents
 Indium (In)
 Decreases surface tension
 Reduces amount of mercury necessary
 Reduces emitted mercu...
Other Constituents
 Palladium (Pd)
 Reduced corrosion
 Greater luster
 Whitens the Alloy
 Example
 Valiant PhD (Ivoc...
Basic Composition
 A silver-mercury matrix containing filler
particles of silver-tin
 Filler (bricks)
 Ag3Sn called gam...
Basic Setting
Reactions
 Conventional low-copper alloys
 High Cu Alloys
1-Admixed high-copper alloys
2-Single compositio...
Conventional Low-Copper Alloys
 Dissolution and precipitation
 Hg dissolves Ag and Sn
from alloy
 Intermetallic compoun...
Conventional Low-Copper Alloys

Gamma (γ) = Ag3Sn
 Unreacted alloy
 Strongest phase and
corrodes the least
 Forms 30% ...
Conventional Low-Copper Alloys
 Gamma 1 (γ1) = Ag2Hg3
 matrix for unreacted alloy
and 2nd strongest phase
 10 micron gr...
Conventional Low-Copper
Alloys
 Gamma 2 (γ2) = Sn8Hg
 weakest and softest phase
 corrodes fast, voids form
 corrosion ...
Admixed High-Copper
Alloys
 Ag enters Hg from Ag-Cu spherical
eutectic particles
 Eutectic
 An alloy in which the eleme...
Admixed High-Copper Alloys
 Sn diffuses to surface of
Ag-Cu particles
 Reacts with Cu to form
(eta) Cu6Sn5 (η)
Around u...
Admixed High-Copper Alloys
 Gamma 1 (γ1) (Ag2Hg3) surrounds
(η) eta phase (Cu6Sn5) and gamma
(γ) alloy particles (Ag3Sn)
...
Single Composition
High-Copper Alloys

Gamma sphere (γ) (Ag3Sn)
with epsilon coating (ε)
(Cu3Sn)
 Ag and Sn dissolve in ...
Single Composition
High-Copper Alloys
 Gamma 1 (γ1) (Ag2Hg3) crystals
grow binding together partially-
dissolved gamma (γ...
Classifications
 Based on Cu content
 Based on particle shape
 Based on Zn content
 Based on number of alloyed metals
...
Copper Content
 Low-copper alloys
 4 to 6% Cu
 High-copper alloys
 thought that 6% Cu was maximum amount
 due to fear...
Particle Shape
 Lathe cut
 low Cu
 New True
Dentalloy
 high Cu
 ANA 2000
 Admixture
 high Cu
 Dispersalloy, Valian...
Manufacturing Process
 Lathe-cut alloys
 Ag & Sn melted together
 alloy cooled
 phases solidify
 heat treat
 400 ºC ...
Manufacturing Process
 Spherical alloys
 melt alloy
 atomize
 spheres form as particles cool
 sizes range from 5 - 40...
Admixture:
Lathe-cut + Spherical Eutectic (ALE)
 Composition
 2/3 conventional lathe cut (3% Cu)
 1/3 high Cu spherical...
Zn content
 If the Zn content is greater than 0.01% the
amalgam is called a Zn-containing Amalgam.
 If the content is le...
Number of alloyed metals
 Binary alloys : Ag-Sn
 Tertiary Alloys : Ag-Sn-Cu
 Quaternary alloys : Ag-Sn-Cu-In
Size of Alloy
 Micro cut
 Macro cut
THANK YOU
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dental amalgam presentation

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dental amalgam presentation

  1. 1. Dental Amalgam BY UZMA JAN BDS 1ST YEAR
  2. 2. Amalgam  An alloy of mercury with another metal.
  3. 3. Why Amalgam?  Inexpensive  Ease of use  Proven track record - >100 years  Familiarity  Resin-free - less allergies than composite
  4. 4. Composition Of Dental Amalgam  Traditional or Convential amalgam alloys is based on Black’s composition.  63-70% silver  26-28% tin  Less than 6% Cu &  Sometimes 0-2% Zn.
  5. 5. Composition Of High Ag-Sn Amalgam  Ag 40-60%  Sn 27-30%  Cu 13-30%
  6. 6. Constituents in Amalgam  Basic • Silver • Tin • Copper • Mercury  Other • Zinc • Indium • Palladium
  7. 7. Basic Constituents  Silver (Ag)  Increases strength  Increases expansion  Decrease creep  Whitens the Alloy  Increase tarnish resistance  Tin (Sn)  Decreases expansion  Decreased strength  Increases setting time
  8. 8. Basic Constituents Copper (Cu)  Ties up tin  Reducing gamma-2 formation  Increases strength & hardness  Reduces tarnish and corrosion  Reduces creep  Reduces marginal deterioration
  9. 9. Basic Constituents Mercury (Hg)  Activates reaction  Only pure metal that is liquid at room temperature  Spherical alloys  * Require less mercury  - Smaller surface area easier to wet  40 to 45% Hg  Admixed alloys  Require more mercury  lathe-cut particles more difficult to wet  45 to 50% Hg
  10. 10. Other Constituents  Zinc (Zn)  Used in manufacturing  Decreases oxidation of other elements  Sacrificial anode  Provides better clinical performance  less marginal breakdown  Causes delayed expansion with low Cu alloys  If contaminated with moisture during condensation H2O + Zn ZnO + H2⇒⇒
  11. 11. Other Constituents  Indium (In)  Decreases surface tension  Reduces amount of mercury necessary  Reduces emitted mercury vapor  Reduces creep and marginal breakdown  Increases strength  Must be used in admixed alloys  Example  Indisperse (Indisperse Distributing Company)  5% indium
  12. 12. Other Constituents  Palladium (Pd)  Reduced corrosion  Greater luster  Whitens the Alloy  Example  Valiant PhD (Ivoclar Vivadent)  0.5% palladium
  13. 13. Basic Composition  A silver-mercury matrix containing filler particles of silver-tin  Filler (bricks)  Ag3Sn called gamma  can be in various shapes  irregular (lathe-cut), spherical, or a combination  Matrix  Ag2Hg3 called gamma 1  cement  Sn8Hg called gamma 2  voids
  14. 14. Basic Setting Reactions  Conventional low-copper alloys  High Cu Alloys 1-Admixed high-copper alloys 2-Single composition high-copper alloys
  15. 15. Conventional Low-Copper Alloys  Dissolution and precipitation  Hg dissolves Ag and Sn from alloy  Intermetallic compounds formed Ag-Sn Alloy Ag-Sn Alloy Ag-Sn Alloy Mercury (Hg) Ag AgAg Sn Sn Sn Hg Hg AgAg33Sn + HgSn + Hg ⇒⇒ AgAg33Sn + AgSn + Ag22HgHg33 + Sn+ Sn88HgHg γ γ γ1 γ2
  16. 16. Conventional Low-Copper Alloys  Gamma (γ) = Ag3Sn  Unreacted alloy  Strongest phase and corrodes the least  Forms 30% of volume of set amalgam Ag-Sn Alloy Ag-Sn Alloy Ag-Sn Alloy Mercury Ag Ag Ag Sn Sn Sn Hg Hg Hg AgAg33Sn + HgSn + Hg ⇒⇒ AgAg33Sn + AgSn + Ag22HgHg33 + Sn+ Sn88HgHg γ γ γ1 γ2
  17. 17. Conventional Low-Copper Alloys  Gamma 1 (γ1) = Ag2Hg3  matrix for unreacted alloy and 2nd strongest phase  10 micron grains binding gamma (γ)  60% of volume γ1 AgAg33Sn + HgSn + Hg ⇒⇒ AgAg33Sn + AgSn + Ag22HgHg33 + Sn+ Sn88HgHg γ γ γ1 γ2 Ag-Sn Alloy Ag-Sn Alloy Ag-Sn Alloy
  18. 18. Conventional Low-Copper Alloys  Gamma 2 (γ2) = Sn8Hg  weakest and softest phase  corrodes fast, voids form  corrosion yields Hg which reacts with more gamma (γ)  10% of volume  volume decreases with time due to corrosion AgAg33Sn + HgSn + Hg ⇒⇒ AgAg33Sn + AgSn + Ag22HgHg33 + Sn+ Sn88HgHg γ γ γ1 γ2 γ2 Ag-Sn Alloy Ag-Sn Alloy Ag-Sn Alloy
  19. 19. Admixed High-Copper Alloys  Ag enters Hg from Ag-Cu spherical eutectic particles  Eutectic  An alloy in which the elements are completely soluble in liquid solution but separate into distinct areas upon solidification  Both Ag and Sn enter Hg from Ag3Sn particles AgAg33Sn + Ag-Cu + HgSn + Ag-Cu + Hg ⇒⇒ AgAg33Sn + Ag-Cu + AgSn + Ag-Cu + Ag22HgHg33 + Cu+ Cu66SnSn55 γ γ γ1 η Ag-Sn Alloy Ag-Sn Alloy Mercury Ag AgAg Sn Sn Ag-Cu Alloy Ag HgHg
  20. 20. Admixed High-Copper Alloys  Sn diffuses to surface of Ag-Cu particles  Reacts with Cu to form (eta) Cu6Sn5 (η) Around unconsumed Ag-Cu particles Ag-Sn Alloy Ag-Cu Alloyη Ag-Sn Alloy AgAg33Sn + Ag-Cu + HgSn + Ag-Cu + Hg ⇒⇒ AgAg33Sn + Ag-Cu + AgSn + Ag-Cu + Ag22HgHg33 + Cu+ Cu66SnSn55 γ γ γ1 η
  21. 21. Admixed High-Copper Alloys  Gamma 1 (γ1) (Ag2Hg3) surrounds (η) eta phase (Cu6Sn5) and gamma (γ) alloy particles (Ag3Sn) Ag-Sn Alloy γ1 Ag-Cu Alloyη Ag-Sn Alloy AgAg33Sn + Ag-Cu + HgSn + Ag-Cu + Hg ⇒⇒ AgAg33Sn + Ag-Cu + AgSn + Ag-Cu + Ag22HgHg33 + Cu+ Cu66SnSn55 γ γ γ1 η
  22. 22. Single Composition High-Copper Alloys  Gamma sphere (γ) (Ag3Sn) with epsilon coating (ε) (Cu3Sn)  Ag and Sn dissolve in Hg Ag-Sn Alloy Ag-Sn Alloy Ag-Sn Alloy Mercury (Hg) ε Ag Sn Ag Sn AgAg33Sn + CuSn + Cu33Sn + HgSn + Hg ⇒⇒ AgAg33Sn + CuSn + Cu33Sn + AgSn + Ag22HgHg33 + Cu+ Cu66SnSn55 γ γ γ1 ηε ε
  23. 23. Single Composition High-Copper Alloys  Gamma 1 (γ1) (Ag2Hg3) crystals grow binding together partially- dissolved gamma (γ) alloy particles (Ag3Sn)  Epsilon (ε) (Cu3Sn) develops crystals on surface of gamma particle (Ag3Sn) in the form of eta (η) (Cu6Sn5)  Reduces creep  Prevents gamma-2 formation Ag-Sn Alloy Ag-Sn Alloy Ag-Sn Alloy γ1 η AgAg33Sn + CuSn + Cu33Sn + HgSn + Hg ⇒⇒ AgAg33Sn + CuSn + Cu33Sn + AgSn + Ag22HgHg33 + Cu+ Cu66SnSn55 γ γ γ1 ηε ε
  24. 24. Classifications  Based on Cu content  Based on particle shape  Based on Zn content  Based on number of alloyed metals  Based on size of alloy
  25. 25. Copper Content  Low-copper alloys  4 to 6% Cu  High-copper alloys  thought that 6% Cu was maximum amount  due to fear of excessive corrosion and expansion  Now contain 9 to 30% Cu  at expense of Ag
  26. 26. Particle Shape  Lathe cut  low Cu  New True Dentalloy  high Cu  ANA 2000  Admixture  high Cu  Dispersalloy, Valiant PhD  Spherical  low Cu  Cavex SF  high Cu  Tytin, Valiant
  27. 27. Manufacturing Process  Lathe-cut alloys  Ag & Sn melted together  alloy cooled  phases solidify  heat treat  400 ºC for 8 hours  grind, then mill to 25 - 50 microns  heat treat to release stresses of grinding  More Hg needed – high force needed due to irregular form
  28. 28. Manufacturing Process  Spherical alloys  melt alloy  atomize  spheres form as particles cool  sizes range from 5 - 40 microns  variety improves condensability Spherical particles wet easier ( less Hg is required)
  29. 29. Admixture: Lathe-cut + Spherical Eutectic (ALE)  Composition  2/3 conventional lathe cut (3% Cu)  1/3 high Cu spherical eutectic (28% Cu)  overall 12% Cu, 1% Zn  Example  Dispersalloy (Caulk)
  30. 30. Zn content  If the Zn content is greater than 0.01% the amalgam is called a Zn-containing Amalgam.  If the content is less, then Amalgam is Non-Zn Amalgam.
  31. 31. Number of alloyed metals  Binary alloys : Ag-Sn  Tertiary Alloys : Ag-Sn-Cu  Quaternary alloys : Ag-Sn-Cu-In
  32. 32. Size of Alloy  Micro cut  Macro cut
  33. 33. THANK YOU

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