This document provides information on dental amalgam, including: - A brief history noting amalgam has been used for over 150 years and was originally made by filing silver coins and mixing with mercury. - The components and microstructure of amalgam, including how it is composed of a mixture of silver/tin/copper alloy and mercury that amalgamates during manipulation. - The classification, properties, manipulation techniques, indications and contraindications for amalgam restorations. - Potential failures of amalgam restorations and their causes, as well as precautions needed due to mercury toxicity.

1. AMALGAM
ABDULLA ASSAN ABDULLA
4th batch
R.D.C

2. DEFINITION
 Dental amalgam is a metal like restorative
material composed of a mixture of
silver/tin/copper alloy and mercury.

3. HISTORY
 Amalgam has been primary restorative
material for more than 150 yrs.
 Initially, amalgam restorations were made
by dentists filing silver coins and mixing
the filings with mercury.
 This was made to a putty like mass that
was placed into the defective tooth.

4. USES
 AS CLASS 1,2,5 RESTORATION.
 AS FOUNDATION- IN COMBINATION
WITH RETENTIVE PINS TO RESTORE
CROWN.
 FOR MAKING DIES.
 FOR RETROGRADE ROOT CANAL
FILLING.
 AS CARIES CONTROL RESTORATION.

5. Components of dental amalgam
1)Amalgam alloy
2)Mercury

6. CLASSIFICATION

7. Classification of dental amalgam
alloys
BASED ON Cu CONTENT
HIGH Cu ALLOYS LOW Cu ALLOYS
> 6% Cu < 6% Cu
ADMIXED
REGULAR UNICOMPOSITION
SINGLE COMPOSITION

8. BASED ON Zn CONTENT
Zn CONTAINING Zn FREE ALLOY
> 1% Zn < 1% Zn

9. BASED ON SHAPE OF ALLOY
LATHECUT SPHERICAL ADMIXED

10. BASED ON NUMBER OF ALLOY METAL
BINARY TERTIARY QUATERNARY
Ag,Sn Ag,Sn,Cu Ag,Sn,Cu,Zn

11. BASED ON SIZE OF ALLOY
MICROCUT FINE CUT MACROCUT COURSE CUT

12. MANUFATURE OF ALLOY POWDER
 1)LATHECUT ALLOY POWDER
 2)SPHERICAL ALLOY POWDER

13. COMPARISON OF LATHECUT WITH
ATOMIZED SPHERICAL POWDER
 AMALGAM FROM LATHECUT ADMIXED POWDER,TEND
TO RESIST CONDEN-SATION BETTER THAN AMALGAM
MADE ENTIRELLY FROM SPHERICAL POWDER.
 AMALGAM OF SPHERICAL POWDER ARE VERY PLASTIC-
CANNOT RELY ON PRESSURE OF CONDENSATION TO
ESTABLISH PROXIMAL CONTOUR.
 SPHERICAL ALLOYS REQUIRE < Hg THAN LATHECUT
ALLOY DUE TO SMALL SURFACE AREA PER VOLUME .
 AMALGAM WITH LOW Hg CONTENT –BETTER
PROPERTIES.

16. COMPOSITION

17. COMPOSITION
Low Copper:
Silver - 63-70%
Tin - 26-29%
Copper - 2-5%
Zinc – 0-2%

18. Admixed:
Silver – 40-70%
Tin - 26-30%
Copper-13-30%
Zinc - 0-1%

19. Unicompositional :
Silver- 40-60%
Tin - 22-30%
Copper-13-30%
Zinc -0%

20. FUNCTION OF EACH CONSTITUENT
 SILVER:-
 MAJOR ELEMENT.
 WHITENS ALLOY.
 DECREASES CREEP.
 INCREASES STRENGTH.
 INCREASES EXPANSION ON SETTING.
 INCREASES TARNISHING RESISTANCE IN
RESULTING AMALGAM.

21.  TIN:-
 CONTROLS THE REACTION BETWEEN Ag &
Hg.
 REDUCES STRENGH & HARDNESS.
 REDUCES RESISTANCE TO TARNISH &
CORROSION.
 COPPER:-
 INCREASES HARDNESS & STRENGTH.
 INCRESES SETTING EXPANSION.

22.  ZINC:-
 SMALL AMOUNT –NOT AFFECT SETTING
REACTION PROPERTIES OF AMALGAM.
 ACT AS A SCAVENGER DEOXIDISER.
 WITHOUT Zn ALLOYS ARE MORE BRITTLE &
AMALGAM FORMED LESS PLASTIC.
 CAUSES DELAYED EXPANSION , IF
CONTAMINATED WITH MOISTURE DURING
MANIPULATION.
 BENEFICIAL EFFECT ON CORROSION &
MARGINAL INTEGRATION.

23.  PLATINUM:-
 HARDENS THE ALLOY & INCREASES THE RESISTANCE
TO CORROSION.
 PALLADIUM:-
 HARDENS THE ALLOY.
 WHITENS THE ALLOY.
 PRE AMALGAMATED ALLOYS:-
SMALL AMOUNT UPTO 3% OF Hg IS ADDED TO
THE ALLOY BY MANUFACTURER.

24. RECENT DEVELOPMENT OF
D.AMALGAM
 Mercury free direct filling amalgam alloys
 Gallium based alloys
 Low mercury amalgams
 Indium in mercury

25. AMALGAMATION

26. AMALGAMATION AND RESULTING
MICROSTRUCTURE.
 DURING TRITURATION Ag & Sn IN THE OUTER PORTION
OF THE PARTICLES DISSOLVE INTO Hg . Hg DIFFUSES
INTO ALLOY PARTICLES.
 Hg HAS LIMITED SOLUBILITY FOR Ag (.035WT%) & Sn
(.6wt%).
 AMALGAMATION OCCURS WHEN Hg CONTACTS THE
SURFACE OF Ag-Sn ALLOY PARTICLES.
 WHEN THE SOLUBILITY IN Hg EXEEDED- CRYSTALS OF 2
BINARY METTALIC COMPOUND PRECIPITATE INTO Hg.
THESE ARE BCC Ag2Hg3 & HEXAGONAL Sn7-8Hg.

28. Low copper Alloys
 Ag3Sn+Hg > Ag2Hg3 + Sn8Hg + Ag3Sn
(r) (r1) (r2) (unreacted)

29. High Copper Alloys
(1)Admixed alloys
Ag3Sn + Ag-Cu +Hg>Ag2Hg3 + Sn8Hg +
Ag3Sn + AgCu
LATER,
Sn8Hg + AgCu > Cu6Sn5 + Ag2Hg3
(r2) (eutectic) (n) (r1)

30. Single Composition
AgSnCu+ Hg > Cu6Sn5 + Ag2Hg3 +AgSnCu

31. PROPERTIES OF SET AMALGAM.
 MICROLEAKAGE.
 DIMENSIONAL CHANGES.
 STRENGTH.
 CREEP.
 TARNISH & CORROSION.

32. MICROLEAKAGE.
 OCCURS DUE TO PENETRATION OF
FLUIDS OR DEBRIS AROUND THE
MARGINS THAT CAN LEAD TO
SECONDARY CARIES. AMALGAM HAS GOT
A SELF SEALING PROPERTY –
CORROSION PRODUCT WILL FILL THE
TOOTH RESTORATION INTERFACE &
PREVENT MICROLEAKAGE.

33. DIMENSIONAL CHANGES
CONTRACTION EXPANSION
ACCORDING TO ADA SPECIFICATION ,IT SHOULD
NOT EXPAD OR CONTRACT MORE THAN 20ucm AT 37
degree celcious BETWEEN 5min AND 24hrs AFTER
BEGINNING OF TRITURATION.
MODERN AMALGAM ALWAYS SHOWS CONTRACTION.
OLDER AMALGAM SHOWS EXPANSION.

34. CONTRACTION.
 RESULT IN MICROLEAKAGE & SECON –
DARY CARIES.
 FACTORS FAVOURING CONTRACTION
 LONGER TRITURATION TIME.
 HIGHER CONDENSATION PRESSURE.
 SMALL PARTICLE SIZE.
 Hg ALLOY RATIO.

35. EXPANSION.
 IF A Zn CONTAINING LOW Cu HIGH Cu IS
CONTAMINATED DURING TRITURATION
CONDENSATION ,A LARGE EXPANSION TAKE PLACE.IT
USUALLY STARTS FROM 3-5 DAYS AND CONTINUE FOR
MONTHS CREATING VALUES UPTO MORE THAN 400um
– DELAYED EXPANSION.
 H2O + Zn ZnO + H2
 PROTRUSION OF RESTORATION OUT OF CAVITY
 INCREASE CREEP
 INCREASE MICROLEAKAGE
 PITTED SURFACE OF RESTORATION & CORROSION.

37. STRENGTH.
 AMALGAM IS SRONGEST IN COMPRE-
SSION & MUCH WEAKER IN TENSION &
SHEAR , THE PREPARD CAVITY DESIGN
SHOULD MAXIMIZE THE COMPRESSION
FORCES IN SERVICE & MINIMIZE
TENSION SHEAR FORCES.

38. CREEP.
 DEFINED AS A TIME DEPENDENT PLASTIC
DEFORMATION UNDER CONSTANT STRESS.
 ACCORDING TO ADA SPECIFICATION NO 1
CREEP SHOULD BE BELOW 3%.
 CREEP OF LOW Cu AMALGAM IS 0.8-8% & HIGH
Cu IS 0.4-1%.

41. MANIPULATION

42. MANIPULATION
(1) Selection of materials
(2) Mercury:Alloy ratio
(3) Trituration
(4) Mulling
(5) Condensation
(6) Shaping & finishing

43. SELECTION OF MATERALS
a) ALLOY
b) MERCURY
c) DISPENSORS
d) PRE PROPOTION CAPSULE

47. MERCURY: ALLOY RATIO
(1) Squeezing cloth
(3) Increased dryness technique
(5) EAMES technique

48. TRITURATION
(1)Hand mixing
(2)Mechanical

50. MULLING
 Improve homogenity of mass & get a
single consistent mix

51. CONDENSATION
(1) Hand condensation
(2) Mech.condensation

52. SHAPING & FINISHING.
 CARVING.
 BURNISHING.
 POLISHING.

56. MERCURY TOXICITY.

59. PRECAUTIONS
 Ventilation
 Disposal
 Sealed containers
 Vaccum cleaners

61. INDICATIONS
(1) Moderate to Large Class I & Class II
Restorations
(2) Class V Restorations
(3) Temporary Caries Control Restorations
(4) Foundations

62. CONTRAINDICATIONS
(1)Esthetics
(2)Extensive tooth destruction
(3)Small Class I & II Cavities

63. CAVITY PREPARATIONS
FOR
AMALGAM RESTORATION

64. What is a Cavity Preparation?
It is a mechanical alteration of
a defective, injured, or diseased tooth to
receive a restorative material that re-
establishes a healthy state for the tooth,
including esthetics corrections where
indicated & normal form & function.

65. STEPS IN CAVITY PREPARATION
(1) Initial Cavity preparation
(3) Final Cavity Preparation

66. Initial…
1. Outline form & initial depth
2. Primary Resistance form
3. Primary Retention form
4. Convenience form

67. Final…
1. Removal of any remaining defective
Enamel or Dentin on Pulpal floor
2. Pulp protection
3. Finishing External Walls
4. Final Cleaning & Inspection

69. CLASS I
They are restorations on
occlusal surfaces of premolars & molars,
occlusal 2/3rd of facial & lingual surface of
molars & lingual surface of maxillary
incisors

73. CLASS II
They are reostorations on
the proximal surfaces of posterior teeth-
mesio occlusal , disto occlusal, mesio
occluso distal

77. CLASS III
They are restorations on
the proximal surface of anterior teeth that
that do not involve incisal angle.

78. CLASS V
They are restorations on
gingival 1/3rd of facial & lingual surface of
all teeth.

79. CLASS VI
They are restorations on
incisal edge of anterior teeth or cusp tip
region of posterior teeth.

80. FAILURES OF
AMALGAM
RESTORATIONS

81. Signs of failures :
1. Fracture Lines
2. Marginal Ditching
3. Proximal Overhangs
4. Poor anatomic contours
5. Marginal Ridge incompatibility
6. Improper Proximal Contacts
7. Recurrent Caries
8. Poor occlusal Contacts
9. Amalgam Blues

82. Reasons For Failures:
1. Improper Case Selection
2. Improper Cavity Preparation
3. Faulty Selection & manipulation of
Amalgam
4. Errors in Maricing Procedures
5. Post Operative Factors

88. AMALGAM TATOO
“ Accidental implantation of silver
containing compounds into oral mucosal
tissue”
 O ccur:
3. Removal of old amalgam
4. Broken Pieces-socket-tooth extraction
5. Particles entering surgical wound
6. Amalgam dust in oral fluids- abrasion areas
 Se n as – Grayish black pigmentation
e
 C m Site Gingiva, buccal mucosa, alveolar
o . s-
mucosa

90. CONCLUSION
 Class I & II Restorations are still common
procedures performed by general Dentists.
 Class VI are used infrequently
 It is important for practitioners to understand
the indications, advantages, techniques &
limitations of these restorations.
 When used correctly & properly selected cases,
these restorations have the potential to serve for
many years

91. THANK YOU!!!!