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 -4-
Dr. Hazem El Ajrami

3. 5. Carving:
The amalgam should be properly carved to
restore the tooth to its normal masticatory
function. Pre-carve burnishing is first
performed. It is rubbing of the newly condensed
amalgam with a metal instrument having a
broad surface contact. It is done before removal
of the matrix (if placed). The excess amalgam is
forcibly burnished with heavy strokes onto the
surface with a large ball, ovoid or anatomical
burnisher until it touches enamel at a cavo-
surface angle.

5. It aims to:
Eliminate the mercury-rich excess amalgam
on the surface.
Improve the adaptation.
Increase surface density of amalgam at
critical surface and marginal areas.
Help to establish the occlusal anatomy of
amalgam to facilitate carving.

6. Carving is the process of anatomical sculpturing
of the amalgam material. There are several
objectives for this process:
To produce functional, non-interfering
occlusal anatomy.
To produce proper physiological contours.
To produce normal physiological contact area
and compatible embrasures.
To produce a restoration with no under- or
over-hangs.

8. Timing of carving:
The amalgam should not be carved before it
reaches a suitable initial setting stage of hardening
when it acquires a definite resistance to the
carving instruments. Such carvability stage may
be reached immediately after completion of
condensation or a few minutes later, depending on
the setting rate of the alloy used (fast, regular or
slow set). If amalgam is carved earlier than this
stage, over-carving and formation of submargins
are very likely to occur as the soft material will
provide no resistance and will be pushed ahead of
the carving instrument.

9. Carving procedure:
Using a sharp carver is essential to properly
carve rather than burnish the surface. Amalgam
can be carved in any direction except that from the
restoration to the tooth structure because this leads
to submargins and ditch formation. The occlusal
anatomy is reproduced using sharp discoid, cleoid
or Hollenback carver shaving the amalgam in a
direction from the tooth to the restoration. This
direction is useful in removal of amalgam flashes
from the margins. The carver could also be tilted,
so that it is resting on both the tooth and the
restoration, to carve the cuspal inclines and
occlusal anatomy.

10. Carving of occlusal amalgam using discoid
or cleoid carver

11. Hollenback carver

12. • In Class II, a carving explorer is used to trim off
the excess amalgam at the marginal ridge to
establish correct occlusal embrasure and
compatible ridge height and avoid possible
ridge fracture on removal of the matrix. The tip
of the explorer is placed at 45 degree,
contacting the inside of the matrix band, and
moved from the tooth structure towards the
center of the marginal ridge.

14. • The stabilizing compound and wedge are
removed. While loosening and removing the
matrix holder, the band is stabilized by resting
the left index finger on its occlusal end. The
band may be gently pulled in a bucco-occlusal
direction. Carving of the inter-proximal area is
done using inter-proximal explorers or carvers
moved from the tooth structure to restoration
to eliminate marginal overhangs and reproduce
proper embrasures.

15. Post-carve burnishing:
The amalgam is then lightly post-carve
burnished to smoothen the surface using a
suitable small-sized round burnisher and light
pressure to augment occlusal grooves and
fossae and smooth the surface of the
restoration.

16. Checking of occlusion and proximal contact:
When the carving appears to be correct, the
occlusion, contour and proximal contact is
checked. A pressure-sensitive articulating ribbon
is used to check the occlusion for correct
intercuspation. The ribbon will mark the points of
contact when the mandibular and maxillary teeth
are brought together. The amalgam must be carved
until contacts on the restoration occur
simultaneously with other centric contacts on that
tooth and adjacent teeth. This will appear as
homogenous spots on the teeth and restoration.

18. • Any premature contact will appear as darker spot
on the restoration. In this case, there will be no or
lighter spots on the tooth structure. While if there
are homogenous spots on the tooth structure and
no or lighter spots on the amalgam, then the
restoration is under-filled.
• The articulating ribbon should preferably be two-
colored. One color (one side) is used to check the
centric occlusion while the other to check
eccentric occlusion. This will ensure that while
checking and removing any eccentric
interference, the centric holding spots will not be
removed.

19. • The inter-proximal contact in Class II should be
checked for tightness using a waxed dental
floss. A bite-wing radiograph is taken to
confirm freedom from proximal gingival
overhangs and for record purposes. The patient
is then instructed not to use that side for
chewing for the next 8-24 hours to avoid
cracking or fracturing of the restoration. He is
also advised to do regular home care and to
report back in a few days for finishing and
polishing of the restoration.

21. 6. Finishing and polishing:
Finishing of an amalgam restoration
includes evaluating the restoration; ensuring
elimination of marginal flashes and overhangs,
that the contacts, contours and occlusion are
correct and the restoration is smooth.
Polishing provides a lustrous, homogenous
polished layer over the entire surface of the
restoration.

22. • Finishing and polishing of the amalgam
restoration:
Significantly increases its corrosion resistance by
increasing surface homogeneity.
Decreases bacterial plaque retention, thus
rendering the restoration biocompatible with soft
tissues and decreasing caries recurrence.
Minimizes gingival irritation by elimination of
discrepancies at the gingival margin.
Improves its stress response by elimination of
surface roughness which acts as stress
concentrators.
Encourages better home care.

23. • Traditional or conventional amalgams were
not finished and polished before 24-48 hours
after carving to avoid disturbing its
crystallization and activation of mercury at the
surface. Finishing is done using finishing burs
of adaptable form and size to accentuate
occlusal anatomy and eliminate marginal
flashes.

25. • Nowadays, with recent high-copper amalgam
restorations, finishing is usually established at
the placement appointment, but it may be
refined at proceeding appointments. After
carving of the restoration, its surface is rubbed
with a burnisher or with dry or damp cotton
pellet until it is smooth. For amalgam with a
more advanced set, a rubber cup with wet
pumice or a prophylaxis paste may be used to
smooth the restoration.

27. • Polishing of an amalgam restoration should be
accomplished at a succeeding appointment, or
at least several hours after placement of the
restoration. If an amalgam is adequately
smoothed at the placement appointment,
imparting a high luster is usually a very simple
and quick procedure. If the restoration is not
made smooth at placement, more time is
required for polishing.

28. • Polishing could be done using progressively
finer disks or abrasive-impregnated rubber
cups or points, from coarser to finer ones. It is
especially important that rubber polishers and
abrasive disks are used with an abundance of
air coolant and intermittent contact with the
amalgam to prevent excessive generation of
heat which could be injurious to the pulp.

30. Polishing with rubber cups or points

31. Bonded Amalgam:
Adhesive resins might be used to increase the
retention, resistance, and marginal seal of
amalgam restorations. Bonding systems
containing 4-META (4-Methyloxy Ethyl
Trimellitic Anhydride) are used to bond amalgam
to tooth structure or amalgam to other metal
substrates. The primary advantages for amalgam
bonding agents in most clinical situations are the
dentin sealing and improved resistance form, but
the increase in retention form is not significant.

32. • Adhesion of amalgam to tooth structure is not
necessary in clinical circumstances when
satisfactory retention and resistance forms of
tooth preparation already exist. Primary
indication for amalgam bonding is in large,
complex amalgam restorations, especially those
replacing cusps, where bonding might improve
the overall resistance form of the restored tooth.
However, in such cases, amalgam bonding should
be considered as a supplementary mechanical
retentive feature.

33. • Amalgam bonding is also indicated when an
improved initial seal is needed, such as after a
direct or indirect pulp capping in the tooth being
restored. However, dentin sealers or varnishes
might also be used and will serve almost the same
purpose.

34. • Although good bonding occurs to tooth
structure, bonding at the interface of the
amalgam with the bonding system is poor. Since
no chemical bonding occurs at this interface, it is
important to develop micro mechanical bonding
of amalgam to the bonding resin. To accomplish
this, chemical or dual-cured bonding system is
applied in much thicker layers (10 to 50 µm)
than that used with resin composite, and
amalgam is condensed into the uncured resin
adhesive layer.

36. • Dental mercury side effects and hygiene
recommendations:
Presence of mercury in a dental amalgam has
been a subject of controversy ever since its
introduction as a restorative material. No doubt
mercury is poisonous; but its dangers as free
mercury in dental amalgam to the dentist, patient
and the other dental personnel are very remote.
Some of the reported toxic effects of mercury are
contact allergy or hypersensitivity. However,
proper differential diagnosis is mandatory.
Similarly, systemic toxic effects, although very
rare, must be properly evaluated if it occurs.

37. • In addition, the following mercury hygiene
precautions must be followed:
The dental office should be well ventilated with
free circulation of fresh air inside the clinic.
Proper storage of mercury in a container with
tight lid with no possibility of leakage. Even the
squeezed out excess mercury and scrap amalgam
should be stored in a well-sealed container
containing water. If the scrap stored dry,
mercury vapor can escape into room air when the
container is opened. It could also be stored under
radiographic fixer solution. However, special
disposal of the fixer may be necessary.

38. While using disposable capsules, or reusable
capsules, lids of the capsules should be tightly
fitting to avoid any spilling.
If, by any chance, mercury is spilled on the floor,
it should be wiped clean immediately using trap
bottles, tape or freshly mixed amalgam to pick
up the droplets. Commercial cleanup kits could
also be used but a household vacuum cleaner
should never be used.

39. Amalgam mixes should never be touched. If
mercury comes in contact with skin, it must be
washed immediately.
Eye protection, use of disposable face masks and
gloves are mandatory.
Periodic monitoring for the dentist and dental
personnel for mercury level in blood and urine
should be done.
Proper waste disposal methods should be under
taken.

40. Non-mercury containing amalgam:
As a response to environmental issues
connected to amalgam and because of the
increasing patient demand for more esthetic
restorative materials, there has been great pressure
from 1995 to 2000 to provide alternatives to
amalgam. In addition to extensive advances in
esthetic restoratives, two types of metallic
restorative alternatives to amalgam have arisen:
gallium alloy and condensable self-welding metal
alloy powder. The latter consisted of silver
particles that could be cohered together by forceful
condensation, in a process similar to gold foil
restoration. However, it encountered technical
difficulties and was discontinued.

41. Gallium alloy:
These systems make use of the fact that the
melting temperature of gallium can be suppressed
below room temperature with the addition of
appropriate amounts of indium and tin. This liquid
can then be triturated with a silver-tin-copper
alloy powder in the same manner as dental
amalgam. Significant amounts of palladium were
added to the alloy powder to improve corrosion
properties. However, the properties and corrosion
of this restoration were severely affected by
moisture contamination.

42. • For this reason, the cavity preparation should be
properly sealed against dentinal fluid prior to
placement of restoration. It was marketed in the
1990s as a bonded, mercury-free restoration
under the commercial name Galloy. However,
clinical studies have shown poor long-term
performance as a result of corrosion and severe
expansion that often resulted in cuspal fracture
and thus its use was discontinued. However,
recent researches are ongoing for manufacturing
of a more advanced restorative material based on
the gallium alloy.

43. Thank You