Paramita Brahmachari (P.R.C.A)
• Historically the only way to achieve smooth and plastic
amalgam mixes was to use excess of mercury but this was
discarded later considering health hazard.
• for conventional mercury added system two techniques were
used for achieving mercury reduction in final restoration,
initially it is removed with the help of the cloth by squeezing
• Second techqnique- increasing dryness tchnique,during
condensation of each increment a mercury rich soft layer
comes to the surface.
• The most obvious method to reduce mercury content is
minimal mercury technique or eames
technique(mercury:alloy=1:1) ,in which sufficient mercury
should be present to form coherent and plastic mass after
The mercury content of the finished restoration should be
comparable to the original mercury/alloy ratio usually 50 wt%
• The amount of alloy and mercury to be used can be described as
the mercury/alloy ratio which signifies the parts by weight of
mercury and of alloy to be used.
• The recommended mercury/alloy ratio for the lathe cut alloys is
approximately 1:1 or 50% mercury, in case of spherical alloy
mercury should be 42% because spherical particles have lower
• Use of little mercury results in dry mix, impairs the strength of
high copper amalgam and also reduces corrosion resistance.
• Dispenser should be held vertically to ensure consistent spills of
the mercury, tilting the bottle 45-degree results in unreliable
mercury/alloy ratios and the dispenser should be half full when
• The objective of trituration is to provide proper
amalgamation of the mercury and the alloy. The
alloy particles are coated with a film of oxide
which is removed by abrasion when alloy
particles and mercury are triturated
• Types- hand mixing
• A glass mortar and pestle are used.
• The mortar has its inner surface roughened to increase
the friction .
• Usually a period of 25 to 45 second is sufficient for
MORTAR AND PESTLE
The disposable capsule serves as a mortar
and the cylindrical metal placed in the
capsule serves as the pestle.
The alloy and mercury are dispensed into the
capsule ,it is secured in the machine and the
machine is turned on. There is an automatic
timer for controlling the mixing time.
• Mordern amalgamator has two or more
• The mulling process generally causes the
mix to cohere so that it can be readily
removed from the capsule.
• Spherical alloy require less amalgamation
time than lathe-cut alloys, amalgamation
time also depends on the quantity.
• For a given alloy/mercury ratio increased
trituration time and speed shortens the
working and setting time.
UNDER TRITURATED MIX
rough and grainy and may crumble
tarnish and corrosion can occur
strenght is less
mix hardens too rapidly
excess mercury present
Shiny surface,soft and smooth consistency
Warm when removed from capsule
Best compressive and tensile strenght
Has luster after polishing
Increased resistence to tarnish and corrosion
OVER TRITURATED MIX
Soupy mix,difficult to remove from capsule
Working time increased
Higher contraction of amalgam
Creep is increased
• Proper combination of the alloy and mercury is a prime
manipulative consideration, the composition of the final
amalgam is the major determinant of the physical properties.
• Proper mix retains its luster longer after polishing and also
remains warm when it is removed from the capsule.
Mulling is actually a continuation of trituration.
It increases the homogenity of the mass and get a single consistent
The mix is enveloped in dry piece of rubber dam and rubbed
between the first finger and thumb,or the thumb of one hand and the
palm for 2-5 sec.
• The goal of condensation is to compact
the alloy into the prepared cavity so that
the with sufficient mercury present to
ensure complete continuity of the matrix
phase between the remaining alloy
• After the mix is made condensation of
the amalgam should be promplty
initiated, condensation of partially set
material probably fractures and break up
the matrix that has already formed.
• Condensation should be as rapid as
possible and a fresh mix of amalgam
should be made if condensation takes
longer than 3-4 mins.
• The field of operation should be dry
• Once the increment of amalgam is inserted into
the cavity preparation it should be condensed
with pressure to avoid voids and to adapt the
material to the walls, the condenser point is
forced into the amalgam mass under hand
• Condensation is started at the center and then
condenser point is stepped little by little towards
the cavity wall.
• After condensation of the each increment excess
mercury should left over the first increment so
that it can bond with the next increment.
• The procedure of adding an
increment,condensing it,adding another
increment and so forth is continued until the
cavity is overfillled.
• In case the cavity is large well condensed
amalgam restoration can be achieved when the
mix has proper consistency.
• Size of the increments should be small.in larger piece of
increment it is difficult to reduce the voids and to adopt the
alloy to the cavity walls.
• Sufficient condensation force should be used to force the alloy
particles together and to reduce voids,and work mercury to the
surface to achieve bonding between the increments.
When a given force is applied,smaller the condenser greater the pressure
exerted on the amalgam.
. For eg-when a thrust of 40N exerted with the help of the 2mm diameter
results in condensation pressure 13.8MPa, the same thrust produce by
3.5mm in diameter produces 4.6MPa pressure, although forces as great as
66.7N is acceptable.
• Serrated condenser is preferred than round condenser in case of the
corner of the cavity.
• The shape of condenser points should conform to the area under
• eg- a round condenser is ineffection in the corner of the cavity,a
triangular or rectangular is indicated in such areas.
It differs from hand condensation such that it is performed
by an automatic device.
Various mechanics are employed for such instruments-
some provide impact type of force and some use rapid
Less energy is required than hand condensation and the
dentist feels less fatigue.
Carving and finishing
• After amalgam is condensed in cavity it is carved to reproduce
the proper tooth anatomy. It should be started when the
amalgam is hard enough to offer resistance to the carving.
• Burnishing of the occlusal anatomy can be accomplished with
the help of the ball burnisher. A rigid flat-bladed instrument is
best used on the smooth surfaces. Final smoothing can be done
with the help of moist cotton or with the help of prophylaxis
paste. While polishing temp should not raise beyond 60-degree.
• Final finish should be done after the amalgam is fully set,it
should be delayed for at least 24 hr. and a wet prophylaxis
paste should be used .