BDS2: DM > Amalgam > Flashcards

Amalgam Flashcards

(44 cards)

Study These Flashcards
1
Q

What Amalgam contain?

A
  • Silver
  • Tin
  • Copper
  • Zinc
  • Palladium
  • Indium
  • Mercury
    (STiCZPIM)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Definition of Dental Amalgam

A

When Mercury is mixed with silver tin alloy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Low copper Amalgam composition

A
  • 67 -74% Silver
  • 25 -28% Tin
  • 0 - 6% Copper
  • 0 - 2% Zinc
    + Mercury
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

High Copper Amalgam composition

A
  • 40 - 70% Silver
  • 21 - 30% Tin
  • 12 - 30% Copper
  • 0 - 1% Zinc
  • 0 - 0.5% Palladium
  • 0 - 4% Indium
    + Mercury
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Function of Silver in Amalgam

A

Increases

  • Strength
  • Tarnish and Corrosion Resistance
  • Expansion

Decreases

  • Flow and Creep
  • Setting Time
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Definition of Amalgam

A

When mercury is mixed with another metal

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Function of Tin in Amalgam

A

Increases

  • setting time
  • flow and creep

Decreases

  • strength
  • expansion
  • corrosion resistance
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Function of Copper in Amalgam

A

Increases

  • Strength and hardness
  • Tarnish and corrosion resistance
  • expansion

Decreases

  • Flow and Creep
  • Setting Time
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Function of Zinc in Amalgam

A
  • Acts as Scavenger

- Decreases oxidation of other metals

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Function of Mercury in Amalgam

A

Activates the reaction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Function of Palladium in Amalgam

A

Increases

  • Tarnish and Corrosion Resistance
  • Strength
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Function of Indium in Amalgam

A

Increases

  • Strength
  • Expansion
  • Setting time

Decreases

  • Flow and Creep
  • Surface Tension and thus reduces amount of Hg needed
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

How do you form Lathe-cut particles?

A
  • Heat ingot to homogenise (400C for 8hrs)
  • Cut particles from ingot
  • Anneal particles at 100C
  • Treat surface with acid to increase reactivity
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

How do you for Spherical Particles?

A
  • Atomise molten alloy
  • Quench
  • Acid Wash to increase reactivity
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Lathe-cut VS Spherical

A

Spherical

  • Less mercury 40-45%
  • Less mixing time
  • Lower condensation pressures
  • Harden quicker
  • Smoother surface
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What categories can you classify Dental Amalgams based on? 4

A
  • Cu Content
  • Zn Content
  • Alloy
  • Shape
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Conventional Amalgams 2

A
  • Lathe cut Ag3Sn - Spherical Ag3Sn
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

High Cu Amalgams (Admix) 2

Study These Flashcards
A
  • Lathe cut Ag3Sn + spherical Ag-Cu

- Lathe cut Ag3Sn + spherical Ag-Sn-Cu (or Ag-Cu-Pd)

19
Q

High Cu Amalgams (Single shape) 2

Study These Flashcards
A
  • All spherical Ag-Sn-Cu

- Lathe cut Ag-Sn-Cu

20
Q

Quaternary Alloy Amalgam 1

21
Q

Setting Reaction Process

Study These Flashcards
A
  • Mercury initially dissolves the surface of the alloy particles
  • New mercury with alloys is formed
  • Need to condense before crystallisation of new alloys
  • Reaction is never complete
  • Set amalgam contains unreacted Ag3Sn in a matrix of the newly formed alloys
  • A ‘cored structure’
22
Q

Conventional Low Cu Alloys Setting

Study These Flashcards
A
  • Hg dissolves Ag and Sn from alloy
  • New inter-metallic compounds formed
  • Ag2Hg3 – γ1
  • Sn7-8Hg – γ2
23
Q

Gamma Phase (γ) Ag3Sn Properties 3

Study These Flashcards
A
  • Unreacted Alloy
  • Strongest phase and corrodes 2nd least
  • Forms roughly 30% of volume of set amalgam
24
Q

Gamma 1 Phase (γ1) Ag2Hg3 Properties 4

Study These Flashcards
A
  • Matrix for unreacted alloy
  • 2nd Strongest phase and corrodes least
  • Forms roughly 60% of volume
  • Fills gaps between Ag3Sn
25
Gamma 2 Phase (γ2) Sn7-8Hg Properties 4
- Weakest and softest phase - Corrodes fast, voids form - Forms roughly 10% of volume - Volume decreases with time due to corrosion
26
Setting reaction for Admixed high copper alloy
- Hg dissolves Ag from Ag-Cu spherical eutectic particles - Hg dissolves Ag and Sn from Ag3SN particles Reaction - γ + Hg -> γ + γ1 + γ2 - AgCu remains unreacted
27
Final Reaction for Admixed High Copper Alloys
Sn7-8Hg+ Ag-Cu → Cu6Sn5 + Ag2Hg3
28
Single Phase High Copper Setting Reaction
(γ + Cu3Sn) + Hg -> γ + Cu3Sn + γ1 + Cu6Sn5
29
Why does Single phase higher copper alloy corrode the least?
No γ2 in final set product
30
Structure of Single Phase High Copper Alloy
γ with Cu3Sn coating
31
Modern Amalgam Shrinkage process
- Initial shrinkage for roughly 20mins - Expansion from growth of cyrstalline phases - More Mercury = More expansion - Stable after 6-8 hours OVERALL NET SHRINKAGE
32
Reasons for higher shrinkage
- Particle Size Smaller - Higher Hg/Alloy Ratio - Trituration time longer and more rapid - Condensation pressure higher
33
Visual properties of Properly triturated Amalgam
- Shiny | - Separates from capsule in a single mass
34
What is condensation?
Packing incrementally into the cavity
35
3 types of finishing
- Carving - Burnishing - Polishing
36
What Element causes Delayed Expansion?
- Zn Zn + H2O -> ZnO + H2
37
What compound is Tarnish?
Black Silver Sulphide | No long term Problems
38
Order of corrosion in pure phases?
- γ1 - γ - Ag3Cu2 - Cu3Sn - Cu6Sn5 - γ2
39
Types of corrosion in Amalgam 3
- Galvanic Corrosion - Crevice Corrosion - Stress Corrosion
40
Mechanical Properties of Amalgam
- High Compressive Strength - Good Wear Resistance - Mercury content must be < 50% for optimum results
41
Disadvantages of Dental Amalgams
- Non Adhesive (relies on mechanical retention) - Conducts Heat - Corrosion and Tarnish - Poor Aesthetics - Brittle - Viscoelastic (creep)
42
What is marginal breakdown?
Thin layers of amalgam fracture easily as it is brittle Known as 'Ditching'
43
How does the manufacturer affect the quality of Amalgam?
- Alloy Composition - Heat Treatment - Size, Shape and production method of particles - Particle surface treatment - Where it is supplied from - Mercury:Alloy Ratio
44
How does the dentist affect the quality of Amalgam?
- Trituration Procedures - Cavity Design - Condensation Technique - Marginal Integrity - Anatomy
BDS2: DM
flashcards
Decks in class (6)
# Cards
Brainscape helps you reach your goals faster, through stronger study habits.
© 2026 Bold Learning Solutions. Terms and Conditions