Dr.Rachael Gupta MDS PEDODONTICS STUDENT

1. Manipulation of dental amalgam

2. Steps in manipulation of amalgam
1.Selection of alloy
2.Proportioning and dispensing
3.Trituration
4.Mulling
5.Condensation
6.Carving
7.Finishing and polishing

3. 1.Selection of alloy
involves a number of factors, including setting time, particle size & shape & composition, particularly
as it relates to the elimination of the γ2 phase & the presence or absence of zinc.
More than 90% of the dental amalgams currently placed are high copper alloys types
Phillip’s Science of Dental Materials;11th ed
Selection of alloy mainly aims at
High one hour strength
Minimum dimensional change
Lowest creep value
Good condensing property
High corrosion resistance
Good polishing and finishing abilities

4. Mercury/alloy ratio – important variable
• Earlier excess mercury was used to achieve smooth & plastic amalgam mix
• This excess Hg was removed from the amalgam by:
1. Squeezing the excess Hg out by using squeeze cloth before insertion of increments in the prepared cavity
2. Increasing dryness technique
3. Eames minimal mercury technique
Recommended ratio→ 1:1→ 50% Hg
Phillip’s Science of Dental Materials;11th ed

5. 2.Proportioning and dispensing
VARIOUS METHODS –
1.PREWEIGHED TABLET : specific weight of powder with appropriate Hg is dispensed into mixing capsule
• proportion– by wt – not by volume
• %Hg can be adjusted from 48-55%.
2.DISPENSERS : accommodate 2 containers
• 1- having Hg;
• 2 – powder
• specific volume of powder & Hg
-dispensed Into capsule.
• proportion– by volume – not by wt
Phillip’s Science of Dental Materials;11th ed
3.Disposable capsules
4.Reusable capsules
5.Preamalgamated alloys
Sturdevant’s Art & Science of Operative Dentistry;5th ed

6. SIZE OF MIX
Capsules containing 400, 600 or 800 mg of alloy and the appropriate Hg are available
Colour coded for easy identification of capsules.
400mg - single mix.
600mg – single mix.
800mg – double mix
1200mg – for amalgam core
CRAIG’s Restorative Dental Materials;12th e

7. 3.TRITURATION
• Defined as process of grinding powder, esp. within a liquid. In dentistry, the term is used to
describe the process of mixing the amalgam alloy particles with mercury in an amalgamator.
Phillip’s Science of Dental Materials;11th ed
• Objective:
-to wet all the surfaces of the alloy particles with Hg
-for proper wetting, the alloy surface should be clean
-rubbing of the particles mechanically removes the oxide film coating on alloy particles
Phillip’s Science of Dental Materials;11th ed
• Trituration is achieved either by :
A) Hand mixing
B) Mechanical mixing
Phillip’s Science of Dental Materials;11th ed

8. pestlemortar
glass rod with a round
end
Roughened inner
surface, maintained by
carborundum paste
Hand
trituration
Phillip’s Science of Dental Materials;11th ed
• The 3 factors to obtain a well mixed amalgam mass are:
1. Number of rotations
2. Speed of rotation
3. Magnitude of pressure placed on the pestle. Typically a 25-45 seconds period is sufficient
Phillip’s Science of Dental Materials;11th ed

9. Mechanical trituration
• Trituration of alloy & Hg is done with a mechanical mixing device called an “amalgamator or triturator”
• The disposable capsule serves as a mortar
• A cylindrical metal or plastic piston is placed in the capsule which serve as a pestle
Phillip’s Science of Dental Materials;11th ed
AMALGAMATORS FOR MECHANICAL TRITURATION
SPEED TIME
The speed used is recommended by the manufacturer
higher copper alloys require higher mixing speeds

10. • Using a parameter called coherence time (tc), defined as the minimum mixing time required for
an amalgam to form a single coherent pellet, it has been found that the compressive strength,
dimensional change & creep are optimized if mixing is carried out for a time of 5tc.
Phillip’s Science of Dental Materials;11th ed
MIXING TIME –
- spherical alloys usually require less amalgamation time than lathe cut alloys
- a large mix requires slightly longer mixing time than a smaller one
Phillip’s Science of Dental Materials;11th ed
• Advantages of mechanical trituration:
1.Shorter mixing time
2.More standardized procedure
3.Require less mercury when compared to hand mixing technique
Phillip’s Science of Dental Materials;11th ed

11. Undertriturated mix
- is rough & grainy
- mix hardens too rapidly
- excess mercury will remain
- gives a rough surface after carving
- tarnish & corrosion may occur
- less strength.
NORMAL MIX
shiny surface
smooth & soft consistency
warm, when removed from the capsule
best compressive & tensile strength
increased resistance to tarnish & corrosion
Phillip’s Science of Dental Materials;11th ed
Overtriturated mix
Soupy mix
difficult to remove from the capsule
too plastic to manipulate
decreased working time
higher contraction of amalgam
increased creep

12. 4.MULLING
• Continuation of trituration
• Hand mulling
Dry piece of rubber dam or glove
Rubbed between the first finger and thumb
2 to 5 seconds.
• Mechanical mulling mix
-is retriturated in an pestle free capsule for an addtional 2-3 sec

13. 5.CONDENSATION
• The amalgam is placed in the cavity after trituration & the packed (condensed) using suitable
instruments
• Goal of condensation-is to compact the alloy into the prepared cavity so that the greatest possible
density is achieved, with sufficient Hg to ensure complete continuity of the matrix phase(Ag2Hg3) b/w
the remaining alloy
Phillip’s Science of Dental Materials;11th ed
Aims of condensation
1. to secure adaptation of the amalgam to the walls and the margins
2. to get compactness and homogeneity of the amalgam in the restoration with minimal voids
3. Remove the excess mercury
Phillip’s Science of Dental Materials;11th ed

14. Condensers
Are instruments with serrated tips of different shapes & sizes
The shapes are oval, trapezoidal, triangular, circular or square
Condenser type is selected as per the area & shape of the
cavity
Smaller the condenser, greater is the pressure exerted on the
amalgam
Condensation technique
- The field of operation - dry during condensation
-The amalgam should be carried to the cavity with amalgam carrier
incrementally
-Immediate condensation done after each increment with sufficient pressure
(3-4 pounds) in vertical and horizontal direction starting with smaller
condenser
Phillip’s Science of Dental Materials;11th ed

15. GENERAL GUIDELINES
A fresh mix of amalgam should be ready if condensation takes more than 3-4 minutes
After condensation of each increment –remove any excess Hg
15 lbs of pres. of condensation recommended
Avg force used is 3-4 lbs (13.3 – 17.8 N)
-The condensation is started at the center & the condenser point is stepped little by little towards the
cavity walls
-The procedure of adding an increment and condensing it, adding another increment is continued until
the cavity is overfilled (about 1mm) and the filling is over packed with larger condenser

16. CONDENSATION PROCEDURE
Precarving burnishing
• Form of condensation to ensure dense amalgam at the margins & aids in shaping of the
restoration
-Heavy stroke with large burnisher moving from the center of the restoration outwards beyond the
margins
As crystallization of amalgam occurs, it's consistency becomes much stiffer, it is suitable for
carving

17. CARVING OF AMALGAM
Initial carving consist of removal of the bulk excess using a large spoon excavator
OBJECTIVES
no undercuts
proper physiological contours
Functional, non-interfering occlusal anatomy
Compatible marginal ridges
Proper size, location, extent & interrelationship of contact areas
The carving should not be started untill amalgam is hard enough to be carved scrapping or ringing sound
CARVING INSTRUMENTS:
1.Cleoid-Discoid
2.Spoon Excavator
3.Hollenback
4.Wards
5.Diamond shaped

18. Carving technique
Create triangular fossae – discoid, cleiod carvers, diamond shaped carver
Define marginal ridges – sharp explorer
Carver moves parallel to the margin
Carver should rest on enamel as well as amalgam
Surface is rendered smooth and free of gross excess material by using a tightly twisted cotton
JPD 1981;VOL46;NO.5
Guidelines for carving
Pulling strokes – mostly
Pushing stroke - developing occlusal anatomy
Occlusal anatomy should be kept reasonably (shallow) to preserve a bulk of amalgam at the
margin
75 – 90 angle at the margin of occlusal amalgam
Mesial and distal pit areas should be carved slightly deeper than the proximal marginal ridge
Undercarving leads to amalgams grown out appearance

19. CARVING PROCEDURE
POSTCARVE BURNISHING
Burnishing of amalgam
• it is a light rubbing of the carved surface with the burnisher to improve smoothness & produce a shiny
appearance & produce a denser amalgam with more compaction , adaptation and sealing of amalgam at the
margins
Burnishing is done with a ball burnisher using light stroke proceeding from the amalgam surface to the tooth
surface
Heavy forces should not be used
Brings excess Hg to surface – discarded
If the temperature rises above 60 ͦC, mercury is released which may cause corrosion & fracture at the
margins
Dental Materials, Volume 3, Issue 3, June 1987, Pages 117-120
Phillip’s Science of Dental Materials;11th ed

20. Articulating paper may be used to check the occlusion
the amalgam is smoothened by a small damp ball of cotton

21. FINISHING & POLISHING
Finishing & Polishing
• they reduce the surface roughness of the restoration with less prone to tarnish and corrosion
AFTER INITIAL SETTING
Prophy cup with pumice provides initial smoothness to restorations
FINAL POLISHING
Done only after amalgam sets, delayed at least 24 hrs following condensation
High Cu single composition spherical alloy: 8 min after trituration
Always - low speed, low pressure --velvet finish
Avoid undue pressure
Use adequate cooling
FINISHING& POLISHING instruments for amalgam
five plain-cut plain steel finishing burs, two mounted stones, three mounted abrasive rubber points from
coarse to fine, and a mounted abrasive rubber cup
Phillip’s Science of Dental Materials;11th ed

22. Finishing Discs
Technique
Use short, overlapping strokes and move diagonally across the margins.
Sequence
Discs are used in a sequence of more abrasive to less abrasive grits.
Embrasures
When using discs in embrasure areas, care must be taken not to damage the contact area or papilla.
Finishing strips
a)Types : fine or medium
b) Placed on both the tooth and the amalgam, and move in a back-and-forth motion.
Phillip’s Science of Dental Materials;11th ed

23. Finishing burs/stones
1. Green stone to remove excess material and irregularities
2. Sequence
largest bur →→ smaller and less abrasive burs
3. Technique
Adapt the side of the bur or stone along the margin, contacting both tooth and amalgam.
4. Direction of stroke
Rotate the bur or stone from the amalgam to the tooth to avoid fracturing the amalgam margins.
5. Direction of work
Always begin at the centre of the restoration and work toward the cavosurface margin

24. REMOVAL OF AMALGAM
Patient is draped with a plastic apron
Rubber dam is customized to fit the existing tooth/teeth
Goggles for the eyes and hair cap are placed
Oxygen is supplied to the patient with a nasal mask and the mercury vapor ionizer is turned on
The operators also protect themselves with a filtered mask, eye and hair protection, and face
A Safe Protocol for AmalgamRemoval Journal of Environmental and Public Health 64 Volume 2012, Article ID 51739

25. New dental bur is used in the handpiece to ensure easy removal
high volume suction and a continual addition of water spray are supplied to the site where the amalgam is
being extracted
if possible, the amalgam restoration is sectioned and then scooped out to eliminate as much mercury vapor
release as possible
oxygen and protective coverings are taken away
immediate inspection under the dental dam
Gauze is then used to inspect the floor of the mouth and tongue to make sure no
particulates seeped under the dam
once all mucosal tissues are fully inspected and cleaned, the mouth is flushed with copious amounts
of water, again to ensure no ingestion or absorption of amalgam particulates

26. Recent advances in amalgam
Gallium based alloys
Consolidated silver alloy system
Indium containing alloy powder & binary Hg-Indium liquid alloy
Fluoride containing amalgam
Low mercury amalgam
Bonded amalgam
Essentials of operative dentistry; 67 I Anand Sherwood

27. Side effects of mercury
1.ALLERGY
• Allergic responses represent an antigen-antibody reaction marked by itching, rashes, sneezing, difficulty in
breathing, swelling , or other symptoms
• Contact dermatitis or type IV hypersensitivity reactions represent the most likely physiologic side effect to dental
amalgam
Immediate hypersensitivity reaction associated with the mercury component of amalgam restorations- a
case report*
• The release of mercury induced an acute reaction which resulted in erythematous lesions, severe
burning and itchy sensation and difficulty in breathing
• Skin patch test results indicated a very strong positive reaction to mercury
• Amalgam restorations were replaced with composite filling material
* Br Dent J. 2008 Nov 22;205(10):547-550 92

28. Three Types of Mercury:
1. Elemental Hg - Is Used in Dental Amalgam
• Heavy, odorless, silver-colored liquid
• Inhalation is the main source of toxicity .
• Well absorbed by lungs.
• Need long-term exposure or one large exposure
2.Inorganic Hg
• Known as mercuric salts…i.e. mercuric chloride, mercuric iodide
• Found in many medicine
• Corrosive and can damage the kidneys
• Long-term exposure can cause skin irritation, staining, and nerve damage
3. Organic Mercury = Methylmercury
• More potent and more bioaccumulative than other forms of mercury
• Form to which humans are primarily exposed
CRAIG’s Restorative Dental Materials;12th ed

29. Sources of mercury
• Exposure to mercury can occur from many different sources, including diet, water, air &
occupational exposure
• WHO has estimated that eating seafood once a week raises urine Hg levels to 5-20 µg/L, 2-8
times the level of exposure from amalgam
• Mercury blood levels that were measured in one study indicated that the average level in patients with
amalgam was 0.7ng/ml compared with a value of 0.3ng/ml for subjects with no amalgam. This difference
was found to be statistically significant (P=0.01)
• However, a study in Sweden demonstrated that one saltwater seafood meal per week raised avg blood
levels of mercury from 2.3 to 5.1 ng/ml , a seven fold increase compared with that associated with
amalgam restorations(0.3 ng/ml)
PHILLIPS’ Science of Dental Materials;11th ed

30. The normal daily intake of mercury is:
15µg from food,
1µg from air,
0.4µg from water
PHILLIPS’ Science of Dental Materials;11th ed
THRESHOLD LIMIT VALUE(TLV): Allowable exposure level to mercury vapor,
8hrs/day, 40hrs/wk
OSHA RECOMMENDED - TLV=0.05 mg/m³
Normal Mercury Level in Urine=0-0.02mg/lt
Allowable max. limit in urine=0.15mg/lt
Allowable max. limit in blood=3µg/lt
Most dental office mercury vapor levels lie below 0.05
mg/m³
The mercury enigma in dentistry; JADA,VOL.92,June
1976
PHILLIPS’ Science of Dental Materials;11th ed

31. • In one study, patients with amalgam restorations were monitored with mercury vapor detectors over
a 24 hr period & the amount of vapor inhaled was calculated to be 1.7 µg/day
• 3 other studies have confirmed that the magnitude of vapor exposure for a patient with 8-10
amalgam restorations is in the range of 1.1-4.4µg/day
PHILLIPS’ Science of Dental Materials;11th ed

32. TOXIC REACTIONS
3 -7µg/kg body weight
500µg/kg body weight
1000µg/kg body weight
2000µg/kg body weight
4000µg/kg body weight 103
LOWEST DOSE TO ELLICIT TOXIC REACTIONS
Paresthesia
Ataxia
Joint pain
Hearing loss DEATH
CRAIG’s Restorative Dental Materials;12th ed

33. Mercury poisoning
Mercury toxicity in the dental office: a
neglected problem 105 JADA,Vol.92,June
1976

34. Minamata disease
• Came into existance after the Minimata Bay incident in Japan in 1952
• A local chemical plant (Chisso Corporation) disposed of its methylmercury waste into the
nearby bay, contaminating the shellfish & causing toxic levels of mercury in the fish eaten by the
local population
• Symptoms were:
1.Ataxic gait
2.Convulsions
3.Numbness in mouth & limbs
4.Constriction in the visual field
5.Difficulty in speaking
Sturdevant’s Art & Science of Operative Dentistry; 5th ed

35. Amount of mercury released during manipulation of amalgam
Br Dent J 1997;182;293-297
• Trituration=1-2µg
• Condensation=6-8µg
• Dry polishing=44µg
• Wet polishing=2-4µg
• Removal of amalgam restoration underwater spray & high volume suction=15-20µg
• Additional evacuation for 1 min to remove residual amalgam dust=1.5-2µg

36. Risks to dentists & office personnel
Store mercury in unbreakable, tightly sealed containers
Clean up any spilled mercury immediately
Storage locations should be near an exhaust vent that carries air out of the building
Use tightly closed capsules during amalgamation
Reusable capsule with a mechanical amalgamator should have a tightly fitting cap to avoid mercury leakage
All amalgam scrap , store it under water that contains sodium thiosulfate (photographic fixer is convinient)
,water, glycerine
Use conventional dental amalgam condensing procedures, manual & mechanical, but do not use ultrasonic
amalgam condensers
Work in well ventilated spaces
Avoid carpeting dental operatories; decontamination of carpeting is very difficult
If mercury comes in contact with skin, the skin should be washed with soap & water immediately

37. Adequate water spray & suction should be used during amalgam polishing & removal
During the intra oral placement & condensation procedures, rubber dam & high volume evacuation should be
used
CRAIG’s Restorative Dental Materials;12th ed
Spent capsules & mercury contaminated cotton rolls or paper napkins should not be thrown out with regular
trash, rather they should be stored in a tightly capped plastic container or closed plastic bag for separate
disposal
Determine mercury vapors levels in operatories periodically
Alert all personnel who handle mercury, especially during training of the potential hazard of mercury vapors &
the necessity for observing good mercury & amalgam practices
Sturdevant’s Art & Science of Operative Dentistry; 5th ed

38. Amalgam waste management

39. REFERENCES
5th
• PHILLIPS’ Science of Dental Materials;11th ed Kenneth J.
Anusavice
• CRAIG’s Restorative Dental Materials;12th ed John M.
Powers, Ronald L. Sakaguchi
• Materials science for dentistry;9th ed B.W.Darvell
• Sturdevant’s Art & Science of Operative Dentistry; ed; Roberson,
Heymann, Swift
• fundamentals of operative dentistry, a contemporary approach; 3rd
ed
Summitt, Robbins, Hilton, Schwartz
• Essentials of operative dentistry; I Anand
Sherwood

40. • Dental amalgam: An update
J Conserv Dent. 2010 Oct-Dec; 13(4): 204–208
• The amalgam controversy-an evidence based analysis ;
JADA,Vol.132,march 2001
• Effect of admixed indium on the clinical success of amalgam restorations
. operative dentistry journal1992 Sep-Oct;17(5):196-202
• American Dental Association (ADA) Council on Scientific Affairs, “Statement on dental amalgam,”
2011,
• Dental Materials Volume 15, Issue 6, November 1999, Pages 382-389
• Biomaterials, Volume 18, Issue 13, July 1997, Pages 939-946
• Journal of Endodontics
Volume 9, Issue 12 , Pages 551-553, December 1983
• Corrosion sealing of amalgam restorations -in vitro study Oper Dent.
2009 May-Jun;34(3):312-20.