Transcript AMALGAM - shabeelpn

AMALGAM
Dr shabeel pn
DEFINITION

Dental amalgam is a metal like restorative
material composed of a mixture of
silver/tin/copper alloy and mercury.
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.

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.

Components of dental amalgam
1)Amalgam alloy
2)Mercury
CLASSIFICATION
Classification of dental amalgam
alloys
BASED ON Cu CONTENT
HIGH Cu ALLOYS
> 6% Cu
< 6% Cu
ADMIXED
REGULAR
LOW Cu ALLOYS
UNICOMPOSITION
SINGLE COMPOSITION
BASED ON Zn CONTENT
Zn CONTAINING
Zn FREE ALLOY
> 1% Zn
< 1% Zn
BASED ON SHAPE OF ALLOY
LATHECUT
SPHERICAL
ADMIXED
BASED ON NUMBER OF ALLOY METAL
BINARY
TERTIARY
QUATERNARY
Ag,Sn
Ag,Sn,Cu
Ag,Sn,Cu,Zn
BASED ON SIZE OF ALLOY
MICROCUT \FINE CUT
MACROCUT \COURSE CUT
MANUFATURE OF ALLOY POWDER
1)LATHECUT ALLOY POWDER
 2)SPHERICAL ALLOY POWDER

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 PLASTICCANNOT 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.

COMPOSITION
COMPOSITION
Low Copper:
Silver - 63-70%
Tin
- 26-29%
Copper - 2-5%
Zinc – 0-2%
Admixed:
Silver – 40-70%
Tin - 26-30%
Copper-13-30%
Zinc - 0-1%
Unicompositional :
Silver- 40-60%
Tin - 22-30%
Copper-13-30%
Zinc -0%
FUNCTION OF EACH CONSTITUENT

SILVER:MAJOR ELEMENT.
 WHITENS ALLOY.
 DECREASES CREEP.
 INCREASES STRENGTH.
 INCREASES EXPANSION ON SETTING.
 INCREASES TARNISHING RESISTANCE IN
RESULTING AMALGAM.


TIN:CONTROLS THE REACTION BETWEEN Ag &
Hg.
 REDUCES STRENGH & HARDNESS.
 REDUCES RESISTANCE TO TARNISH &
CORROSION.


COPPER:INCREASES HARDNESS & STRENGTH.
 INCRESES SETTING EXPANSION.


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.


PLATINUM:

PALLADIUM:


HARDENS THE ALLOY & INCREASES THE RESISTANCE
TO CORROSION.
HARDENS THE ALLOY.
WHITENS THE ALLOY.
PRE AMALGAMATED ALLOYS:SMALL AMOUNT UPTO 3% OF Hg IS ADDED TO
THE ALLOY BY MANUFACTURER.
RECENT DEVELOPMENT OF
D.AMALGAM
Mercury free direct filling amalgam alloys
 Gallium based alloys
 Low mercury amalgams
 Indium in mercury

AMALGAMATION
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.
Low copper Alloys

Ag3Sn+Hg > Ag2Hg3 + Sn8Hg + Ag3Sn
(r)
(r1)
(r2)
(unreacted)
High Copper Alloys
Admixed alloys
Ag3Sn + Ag-Cu +Hg>Ag2Hg3 + Sn8Hg +
Ag3Sn + AgCu
(1)
LATER,
Sn8Hg + AgCu > Cu6Sn5 + Ag2Hg3
(r2)
(eutectic) (n)
(r1)
Single Composition
AgSnCu+ Hg > Cu6Sn5 + Ag2Hg3 +AgSnCu
PROPERTIES OF SET AMALGAM.





MICROLEAKAGE.
DIMENSIONAL CHANGES.
STRENGTH.
CREEP.
TARNISH & CORROSION.
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.
DIMENSIONAL CHANGES
CONTRACTION
EXPANSION
ACCORDING TO ADA SPECIFICATION ,IT
SHOULD
NOT EXPAD OR CONTRACT MORE THAN 20u\cm AT 37
degree celcious BETWEEN 5min AND 24hrs AFTER
BEGINNING OF TRITURATION.
MODERN AMALGAM ALWAYS SHOWS CONTRACTION.
OLDER AMALGAM SHOWS EXPANSION.
CONTRACTION.
RESULT IN MICROLEAKAGE & SECON –
DARY CARIES.
 FACTORS FAVOURING CONTRACTION

LONGER TRITURATION TIME.
 HIGHER CONDENSATION PRESSURE.
 SMALL PARTICLE SIZE.
 Hg ALLOY RATIO.

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.
STRENGTH.

AMALGAM IS SRONGEST IN COMPRESSION & MUCH WEAKER IN TENSION &
SHEAR , THE PREPARD CAVITY DESIGN
SHOULD MAXIMIZE THE COMPRESSION
FORCES IN SERVICE & MINIMIZE
TENSION \ SHEAR FORCES.
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%.
MANIPULATION
MANIPULATION
(1)
(2)
(3)
(4)
(5)
(6)
Selection of materials
Mercury:Alloy ratio
Trituration
Mulling
Condensation
Shaping & finishing
SELECTION OF MATERALS
a)
b)
c)
d)
ALLOY
MERCURY
DISPENSORS
PRE PROPOTION CAPSULE
MERCURY: ALLOY RATIO
(1)
Squeezing cloth
(2)
Increased dryness technique
(1)
EAMES technique
TRITURATION
(1)Hand mixing
(2)Mechanical
MULLING

Improve homogenity of mass & get a
single consistent mix
CONDENSATION
(1)
(2)
Hand condensation
Mech.condensation
SHAPING & FINISHING.



CARVING.
BURNISHING.
POLISHING.
MERCURY TOXICITY.
PRECAUTIONS
Ventilation
 Disposal
 Sealed containers
 Vaccum cleaners

INDICATIONS
(1)
(2)
(3)
(4)
Moderate to Large Class I & Class II
Restorations
Class V Restorations
Temporary Caries Control Restorations
Foundations
CONTRAINDICATIONS
(1)Esthetics
(2)Extensive tooth destruction
(3)Small Class I & II Cavities
CAVITY PREPARATIONS
FOR
AMALGAM RESTORATION
What is a Cavity Preparation?
It is a mechanical alteration of
a defective, injured, or diseased tooth to
receive a restorative material that reestablishes a healthy state for the tooth,
including esthetics corrections where
indicated & normal form & function.
STEPS IN CAVITY PREPARATION
(1)
Initial Cavity preparation
(2)
Final Cavity Preparation
Initial…
1.
2.
3.
4.
Outline form & initial depth
Primary Resistance form
Primary Retention form
Convenience form
Final…
1.
2.
3.
4.
Removal of any remaining defective
Enamel or Dentin on Pulpal floor
Pulp protection
Finishing External Walls
Final Cleaning & Inspection
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
CLASS II
They are reostorations on
the proximal surfaces of posterior teethmesio occlusal , disto occlusal, mesio
occluso distal
CLASS III
They are restorations on
the proximal surface of anterior teeth that
that do not involve incisal angle.
CLASS V
They are restorations on
gingival 1/3rd of facial & lingual surface of
all teeth.
CLASS VI
They are restorations on
incisal edge of anterior teeth or cusp tip
region of posterior teeth.
FAILURES OF
AMALGAM
RESTORATIONS
Signs of failures :
1.
2.
3.
4.
5.
6.
7.
8.
9.
Fracture Lines
Marginal Ditching
Proximal Overhangs
Poor anatomic contours
Marginal Ridge incompatibility
Improper Proximal Contacts
Recurrent Caries
Poor occlusal Contacts
Amalgam Blues
Reasons For Failures:
1.
2.
3.
4.
5.
Improper Case Selection
Improper Cavity Preparation
Faulty Selection & manipulation of
Amalgam
Errors in Maricing Procedures
Post Operative Factors
AMALGAM TATOO

1.
2.
3.
4.


“ Accidental implantation of silver
containing compounds into oral mucosal
tissue”
Occur:
Removal of old amalgam
Broken Pieces-socket-tooth extraction
Particles entering surgical wound
Amalgam dust in oral fluids- abrasion areas
Seen as – Grayish black pigmentation
Com. Sites- Gingiva, buccal mucosa, alveolar
mucosa
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

THANK YOU!!!!