Manipulation of Dental Amalgam

1. MANIPULATION OF
AMALGAM
YARTI LONGKUMER
2ND YEAR BDS
REGIONAL DENTAL COLLEGE & HOSPITAL, GUWAHATI

2. CONTENT
• ALLOY SELECTION
• POWDER AND LIQUID PROPORTIONING
• TRITURATION
• Hand Trituration
• Mechanical Trituration
• Trituration Consistency
• MULLING
• CONDENSATION
• SPEEED OF PLACEMENT
• PRE- BURNISHING
• CARVING
• POST-BURNISHING
• FINISHING AND POLISHING

3. ALLOY SELECTION
• ACCORDING TO COPPER CONTENT:
High-Cu Unicomposition , High-Cu Admixed , Low-Cu
  
• ACCORDING TO ZINC CONTENT:
Zn containing , Zn-free

• ACCORDING TO PARTICLE SIZE:
Lathe-cut , Sphereical , Spheroidal
  

4. SUPPLIED AS:
DISPENSERS TABLETS PREPROPORTIONED
CAPSULES

5. PROPORTIONING
• EAMES TECHNIQUE (Mercury: Alloy - 1:1)
• However, it is still necessary to squeeze mercury out of the mix using the increasing
50% or less mercury will be in the final restoration, with obvious advantages.
• Mercury alloy ratios ranges from 43 to 54%. In pre-proportioned capsule the
is usually less than 50%.

6. ADVANTAGE OF EAMES TECHNIQUE:
High strength
Needs no squeezing of excess
mercury
Greater plasticity and adapts well to
cavity walls

7. TRITURATION
Trituration is the process by which mercury is allowed to react with the alloy powder. This procedure allows the rubbing of the
surface oxide on amalgam particles, exposing an active surface to react with mercury.
OBJECTIVE:
To provide proper amalgamation of the mercury and Alloy
TRITURATION
HAND TRITURATION
MECHANICAL TRITURATION

8. TRITURATION
HAND TRITURATION
• A glass mortar and pestle is used.
• The mortar has its inner surface roughened to increase the friction between
amalgam and glass surface with carborundum paste.
• A pressure of 2-3 psi should be applied

9. TRITURATION
MECHANICAL TRITURATION:
• The disposable capsule serves as a mortar. Some capsules have a cylindrical
metal or plastic piece in the capsule which serves as the pestle.
• Reusable capsules are available with friction fit or screw – type lids.
• Amalgamators have automatic timer and speed control device.
• The speed ranges from 3200 to 4400 cycles per minute.
• High copper alloys require higher mixing speed.

10. EFFECT OF DIFFERENT TRITURATION
CONSISTENCY
UNDER TRITURATED
1. Grainy appearance
2. Restoration will be weak
3. It gives a rough surfaces after carving and
tarnish and corrosion.
4. Strength is less
5. Mix hardens too rapidly and excess mercury
OVER TRITURATED
1. Shiny and soupy appearance.
2. Working time is decreased.
3. Results in higher conc. of Amalgam.
4. Strength increases from lathe cut
decreases in high copper alloys.
5. Creep is increased.
NORMAL TRITURATED
1. Shiny Surface and smooth and soft consistency.
2. It has the best compressive and tensile strength.
3. Carved surfaces retains its lustre after polishing. Hence increase resistance to tarnish and
4. It may be warm when removed from the capsule

12. MULLING
• Mulling is actually a continuation of trituration. It is done to improve the homogeneity of the mass and
get a single consistent mix. It can be accomplished in two ways:
The mix is enveloped in a dry piece of rubber dam and vigorously rubbed between the first
finger and thumb, or the thumb of one hand and palm of man other hand for 2-5 seconds.
After trituration the pestle is removed and the mix is triturated in the pestle-free capsule for 2-3
seconds.
• Mulling is not necessary for mechanical triturated amalgams.

13. CONDENSATION
• The amalgam is placed in the cavity after trituration, and condensed using suitable
instrument.
• Proper condensation increase the strength and decrease the creep of the amalgam.
Condensation must always be done within the four walls and floor.
• If one or more walls of the cavity are missing, a steel matrix may be used to compensate
for it.
• INSTRUMENTS USED:
• Amalgam Carrier
• Round Condenser

14. 1. To
adapt it
to the
cavity
2.
Remove
excess
Hg
AIM
3. Reduce
voids
CONDENSATION
MANUAL CONDENSATION
MECHANICAL CONDENSATION

15. MANUAL CONDENSATION
The mixed material is condensed in increments. Each increment is carried to the prepared
cavity by means of a small forceps or an amalgam carrier.
Once inserted, it should be condensed immediately with sufficient pressure
(approximately 3 to 4 psi).

16. MECHANICAL CONDENSATION
Mechanical condensers provide vibration or impact type of force to
pack the amalgam mix. Less effort is needed than for hand
condensation.

17. SPEED OF PLACEMENT
• Once amalgam is triturated, phase formation commences and the setting reaction is underway.
• Amalgam must be placed in a plastic state
• No amalgam should be placed more than 3 minutes after the start of mixing.
• Attempting to condense a partly set amalgam into a cavity will result in
• Poor adaptation,
• Reduced marginal seal and
• A weak restoration.

18. PRE-CARVE BURNISHING
Carried out using a large burnisher for 15 seconds
Use light force and move from the center of the restoration outwards to the
margins.

19. OBJECTIVES OF PRECARVE
BURNISHING
Continuation of condensation, further reduce
the size and number of voids on the critical
surface and marginal area of the amalgam.
Brings any excess mercury to the surface,
to be discarded during carving.
Adapt the amalgam further to cavosurface
anatomy.

20. CARVING
Using remaining enamel as a guide, carve gently from enamel towards the center and
recreate the lost anatomy of the tooth.
Amalgam should be hard enough to offer resistance to carving instrument
A scraping or "ringing" (amalgam crying) should he heard.
If carving is started too soon, amalgam will pull away from margins.

21. OBJECTIVES OF CARVING:
TO PRODUCE :
A restoration with no under-
hangs.
A restoration with the proper
physiological contours.
A restoration with adequate,
compatible marginal ridges.
A restoration with minimal flash
A restoration with proper size, location,
extend and interrelationship of contact
areas.

22. FINAL BURNISH
(POST CARVE BURNISHING)
Following carving, check the occlusion and carry out a brief final burnish.
Use a smaller-end of the burnisher at a low load and burnish outwards towards
the margins
Improves smoothness
Heat generation should be avoided
If temp raises above 60°C, causes release of mercury accelerates corrosion &
fracture at margins

23. FINISHING & POLISHING
FINISHING can be defined as the process, which continues the carving objectives,
removes flash and overhangs and corrects minimal enamel underhangs.
POLISHING is the process which creates a corrosion resistant layer by removing
scratches and irregularities from the surface.
Can be done using descending grade abrasive, eg. rubber mounted stone or rubber
cups.
A metallic lusture, is always done with a polishing agent (precipitated chalk, tin or
zinc oxide).

24. CONTOUR
• GREEN STONE,ABRASIVE DISKS OR BURS
MARGIN
FINISH
• GREEN STONE,ABRASIVE DISKS OR BURS
SMOOTH
ALLOY
SURFACE
• RUBBER ABRASIVE POINTS AND BURS
RUBBER ABRASIVE POINTS AND FINE ABRASIVE PASTE
ADD
LUSTRE

25. Minimizes fatigue failure of
the amalgam under the
cyclic loading of mastication
Minimizes concentration cell
corrosion which could begin
in the surface irregularities
Prevents the adherence of
plaque
Removal of superficial scratches and
irregularities

26. BIBLIOGRAPHY
• STURDEVANT’S ART AND SCIENCE OF OPERATIVE DENTISTRY
• PRE- CLINICAL MANUAL OF CONSERVATIVE DENTISTRY ANF ENDODONTICS – V Gopikrishna

27. THANK
YOU