Dr. lama khaled El Banna Faculty of Oral and Dental Medicine Al – Azhar University operative dentistry part two

2. College of Dentistry
Operative Dentistry II
Amalgam Restorations -3-
Dr. Hazem El Ajrami

3. 4. Condensation:
Condensation is the packing of the freshly
triturated mix of amalgam into the cavity
preparation. It is considered the most important
procedural step in amalgam manipulation. It is
during this step that the final chemical and
physical structure of the restoration is
determined. Condensation produces a limited
degree of reaction with available mercury and
thus new phases are formed. In a sense, it is
considered to be a sort of further trituration.

4. Objectives of condensation:
I. Forceful condensation squeezes un-reacted
mercury out. This brings mercury to the top
which exhibits a binding effect. It enables
cohesion with subsequent increments and
prevents layering. It also facilitates the
blotting of excess mercury which should be
removed from the final increment to
enhance the properties of the final
restoration.

5. II. It increases the adaptation of amalgam to
cavity walls and floor.
III. It decreases the number and size of voids,
thereby increasing the density of the
restoration.
IV. It increases the final strength of restoration
by packing the strong phases together.
V. It starts solid state reaction by getting the
phases closer together.

6. • Delay in condensation:
Condensation should start immediately after
trituration. Only fresh mixes of amalgam should
be condensed and any mix which exceeds the
working time of amalgam must be discarded. As
many multiple mixes as necessary to overfill
extensive cavities can be used in order to avoid
using partially set amalgam which will be dry,
weak, non-coherent, porous, poorly adapted and
corrodible. Using old mixes (partially set)
should be discouraged since:

7. Its decreased plasticity prevents proper
adaptation.
It is impossible to squeeze residual mercury
from it.
Cracks are created in the matrix leading to
fracture, corrosion and leakage.

8. • Methods of condensation:
Amalgam increments are carried into the
cavity using an amalgam carrier. Amalgam is
condensed in small increments for effective
elimination of mercury, and better adaptation and
density. It may be condensed either:
Manually using hand condensers; which is the
most widely used method.
Mechanically using either a vibrator or impact
type mechanical device. Care should be taken if
an impact type condenser is used to avoid
breaking of enamel margins.

10. Ultrasonic condensers are not recommended
since they tend to produce local heating of the
amalgam. This affects mercury vapor release
and the setting reaction.

12. • Technique of condensation:
It is started at the deep and retentive areas, first
at the auxiliary portion against the line angles or
into grooves or slots (if present) up to the level of
the pulpal wall and then proceeds to overfill the
cavity to slight excess. Care should be taken to use
condensers of small size and form that adapts well
to the area being condensed for better
condensation.

13. Condensation of amalgam; A: small condenser in
auxiliary portion, followed by exceedingly larger
condensers (B and C) to over-pack restoration.

14. • The smaller the condenser, the greater will be the
induced pressure and the better the condensation.
The initial condenser should thus be small enough
to condense into line angles, but large enough not
to poke holes into the amalgam mass. Exceedingly
larger condensers are used for over-packing of
amalgam. Each condensation stroke should
overlap the previous one to insure that the entire
mass is well condensed.

15. • The previously mentioned techniques of
proportioning of alloy/mercury will influence the
condensation since they differ in the method by
which excess mercury may be eliminated:
Eames technique, in which equal proportions
of alloy and mercury are used, ensures from the
beginning that the final restoration will never
contain more than 50% mercury. The amalgam
will set faster and exhibit slight insignificant
contraction. This technique requires faster
operators and the use of smaller size
condensers. Still, some mercury can be
removed from this amalgam.

16. • Increased dryness technique, utilized mercury-
rich first increments for claimed better adaptation
followed by increasingly dry increments to a last
over-filling of very dry increments. According to
the advocators of this technique, subsequently
placed dryer increments blot the excess mercury
in the previously condensed mercury-rich
amalgam. However, non homogeneity and
presence of excess mercury are likely to result.

17. • Each amalgam increment should be squeezed
using clean gauze to eliminate excess mercury
before insertion (Squeeze-cloth-technique). This
technique is indicated in very large restorations
which need more than one mix and is retained by
multiple auxiliary means of retention (pins,
grooves or slots) which needs the most plastic
consistency of amalgam.

18. Thank You