2. Contents
■ Introduction
■ Definition
■ Types of direct gold
■ Properties
■ Manipulation of DFG
Degassing
Compaction
■ Indication
■ Contraindication
■ Conclusion
■ reference
3. Introduction
■ Pure gold has been in used in dentistry for more
than 100 years.
■ It is generally agreed that this noble metal is a
superior restorative material for treatment of
many small lesions and defects in teeth, given
sound pulpal and periodontal health.
■ The longevity of direct gold restorations is a
result of the superb biocompatibility of gold with
the oral environment and its excellent marginal
integrity.
4. Definition
■ Direct gold is a gold restorative material that is
manufactured for compaction directly into
prepared cavities.
6. 1. Gold foil
■ Gold foil is also called fibrous gold . It is
available as sheets, pellets, cylinders, ropes and
pre condensed laminates of varying thickness.
7. ■ A. Gold foil sheets:
■ these are manufactured by beating or rolling pure
gold ingots into thin sheets.
■ Gold foil is cut into 4x4” sheets and sold in books Of
sheet separated by thin paper.
■ The sheet of foil that weighs
4 grain termed as no 4 Foil
3 grain termed as no 3 foil
■ 2grain termed as no 2 Foil
8. ■ B. Gold foil pellets: these may be hand rolled or
commercially produced from a no 4 gold foil sheets
■ Small sections of the gold foil sheets (1/32”, 1/64”,
1/128”) are cut and rolled into pellet form.
9. ■ C. Gold foil cylinders: these may also be hand rolled or
preformed.
■ Usually larger segments of sheet (1/2”,1/4’, 1/8”) are
cut and rolled into cylinders.
10. .
D. Corrugated gold foil:
It was an outcome of Chicago fire in 1871
these are manufactured by placing thin sheets of paper in between the gold foil sheets and igniting
them.
The paper burns and gets charred while the gold foil becomes corrugated.
11. ■ E. Platinized gold foil:
■ this is is a sandwich of gold and platinum with the
platinum content being 15%. It may be manufacture
in one of the following ways.
■ One sheet of pure platinum foil may be sandwich
between 2 sheets of gold. These are then hammered
to form a platinized gold foil.
12. ■ Layers of platinum of gold are rolled over together
to bring about their fusion following which they are
beaten to achieve desired thickness.
■ Addition of platinum increases the strength and
wear resistance of the restoration. Platinized gold
foil may be used for areas of stress concentration
like incisal edges and cusp tips.
13. F. Laminated gold foil: when gold foil is beaten
from an ingot, its crystals are elongated in a
specific direction. A combination of two or three
foils with crystals running in different direction is
called a laminated gold foil.
14. 2. Electrolytic precipitated gold
■ This is a crystalline gold powder formed by
electrolytic precipitation..
■ A.Mat gold: this is a crystalline electrolytically
precipitated gold that is formed into strips. This
form is easy to use for building the internal bulk of
the restoration because of ease of compaction.
15. ■ B. Mat foil:
■ This consists of sandwich of electrolytically
precipitated gold powder between two sheets of
No. 3 gold foil which is sintered and cut into
strips.
■ This purpose of sandwiching mat gold between
foil sheets is to eliminated the need to veneer
the restoration the layer of foil.
16. ■ C. Gold calcium alloy: this the another form of
electrolytically precipitated which is alloyed
with 0.1% calcium.
■ It is commercially available as Electralloy RV.
The addition of calcium produces a stronger
restoration by dispersion strengthening.
■ This is sintered so as to make the gold into strip
form.
17. 3.Powdered gold
Powdered gold is made by a
combination of chemical
precipitation and atomization with
an average particle size of 15 μm.
■ Since powders are difficult to
manipulate the particles are mixed
together in wax and cut in to pieces
and wrapped in gold foils as pellets.
■ This is available as Goldent or
Williams E-Z Gold.
18. Properties of DFG
■ Pure gold is soft, malleable and ductile and does
not oxidize under normal atmospheric conditions.
■ It has a rich yellow color and a strong metallic
luster.
• Gold fusses at 1063° c and boils at 2200° с.
■ The Brinell hardness no. for gold is 25 this makes
it very soft. However during compaction the
hardness increases 258-82 making it a strong
material.
19. ■ The coefficient of thermal expansion of gold is
14.4 x 10-6/°C which is close to that of tooth
structure(11.4 x 10-6/°C)
■ It can be cold welded at room temperature
■ Gold doesn’t undergo tarnish and corrosion.
20. Principles of Manipulation of DFG
There are two processes involved;
■ Cohesion and Degassing
■ compaction
21. 1.COHESION AND DEGASSING
■ Direct gold may be either cohesive or non cohesive
COHESIVE GOLD: The gold is considered to be cohesive
in nature when its surface is pure and free of
surface oxides and impurities.
NONCOHESIVE GOLD :it is considered noncohesive in the
presence of surface impurities or wax , which prevents
one increment of gold from cohering to another
22. 1.Degassing ( annealing)
■Degassing is the process of heating direct gold
materials to remove the surface contaminants.
■ It can be achieved by
Heating the gold foil over pure ethanol flame.
Heating in a mica tray mounted over an alcohol
lamp
Heating in a electric annealer.
23.
24. ■ 1. Heating over an open alcohol flame:
■ In this method each piece of direct gold is held
in the middle zone of an alcohol flame for 3-5
sec before inserting into the cavity preparation.
■ 2. Heating in a mica tray over the alcohol
flame:
■ This is a bulk method where several gold pellets
are degassed in a mica tray held over the alcohol
flame. This method tales less time but care
should be taken to prevent the gold pieces from
sticking to each other.
25. ■ 3. Heating in an electric annealer
■ In this the desired amount of gold is placed in the
compartments of the annealer and the lid is closed.
The gold is heated to 850F for ten minutes and then
allowed to cool before it is placed in the cavity.
26. Hazards During degassing :-
1. Overheating – it should be avoided because it may
cause the gold to become brittle or melt and render it
unusable
2. Under heating – it should be avoided because it fails to
render the gold surface pure.
27. 2.Compaction of Direct gold
Two fundamental principles involved in compaction
of cohesive gold are-
i. Weld the gold into a cohesive mass
ii. Wedge as much gold as possible into the tooth
preparation.
28. Direct gold that is in a cohesive state should only be used
⬇️
Direct gold is inserted into tooth preparation and suitable,
biologically compatible compacting force must be delivered
under force
⬇️
Welding occurs because pure gold with an absolutely clean
surface coheres as a result of metallic bonding.
The purpose of the force is to weld the gold into restorations
containing minimal porosity or internal void spaces
⬇️
As the gold is forced and compressed into a tooth preparation,
succeeding increments cohere to those previously placed
29. Methods of compaction
Various methods available are:
1. Compaction with mallet and condensers
i. Hand mallet
ii. Electro-mallet
iii. Pneumatic mallet
2. Compaction with hand condensers: pyramidal
serration on face for additional lateral force along with
direct compressive forces.
30.
31. Condensers for compaction
1. Condensers are designed to deliver forces of compaction
to direct gold.
2. Condensers used in the handpieces of the electromallet or
pneumatic mallet consist of a nib, or working tip, and a short
shank that fits into the malleting handpiece.
3. Condensers used with the hand mallet are longer and have
a blunt ended handle that receives light blows from the hand
mallet.
4. Condenser nibs are available in several shapes and sizes
and have pyramidal serrations on the nib faces to prevent
slipping on the gold.
32. ■ 3. Condensers used with the hand mallet are longer
and have a blunt ended handle that receives light
blows from the hand mallet.
■ 4. Condenser nibs are available in several shapes
and sizes and have pyramidal serrations on the nib
faces to prevent slipping on the gold.
33. Compaction technique for gold Foil
■
■ 1. Stepping motion:
■
■ Compaction begins when a piece of gold is placed in a
tooth preparation.
■ The gold is first pressed into place by hand, then a
condenser of suitable size is used to begin malleting in
the centre of mass.
■ Each succeeding step of the condenser overlaps (by
half) the previous one as the condenser is moved
toward the periphery in an orderly stepping motion.
34. 2.Line of force
■ The line of force is important when any gold is
compacted.
■ The line of force is the direction through which the
force is delivered (i.e. the direction in which condenser
is aimed).
■ Correct hand -malleting technique require a light,
bouncing application of the mallet to the condenser
rather than delivery of heavy blows.
35.
36. Compaction Technique of E-Z gold
Compaction Technique :
Using a condenser, the first pellet of E-Z gold is
pressed into the depth of the tooth preparation and
tamped into position.
A small condenser is selected to thrust and wedge
the gold into opposing line angles and against
opposing walls, to secure the mass in the
preparation.
Additional pellets are added (one at a time, banking
against the prepared walls) until the entire
preparation is filled.
37. GENERAL PRINCIPLES FOR DIRECT
FILLING GOLD RESTORATION
■ • 1. Build up of restoration.
■ A) Tie formation-
■ this involves connecting two opposing point angles or starting points filled with
gold with a transverse bar of gold. This "tie" forms the foundation for any
restoration in direct gold.
■ B) Banking of the walls:
■ This consists of covering each wall from its floor or axial wall to the
cavosurface margin with the direct gold material. Banking should be done
simultaneously on the surrounding walls of the preparation.
38. ■ C) Shoulder preparation:
■ This consists of connecting two opposing walls with the direct
gold material to completely fill up the restoration.
39. 2) "Paving" of the restoration :
To overfill the preparation every area of the cavosurface margin
should be individually covered with excess cohesive gold foil. This is
condensed with a rectangular "foot" condenser.
3). Surface hardening of the restoration
The rectangular condenser is used with the highest possible
condensation pressure in all directions on the surface of the
restoration to strain harden the surface gold.
40. ■ 4. Burnishing ;
■ This is done with a suitable burnisher moving from the gold to
the tooth surface. This enhances the surface hardening and also
produces good marginal adaptation of the gold.•
■ 5. Margination:
■ This step uses sharp gold knives to remove excess gold from the
surface to the tooth.
41. ■ 6) Burnishing
■ It is important to burnish the surface of the gold restoration after
margination so as to eliminate marginal discrepancies and to
strain harden the surface.
■ 7) Contouring
■ This step uses knives, files or finishing burs to create the proper
occlusal anatomy. Burnishing is done again after contouring.
42. ■ 8) Finishing and polishing
■ Direct gold restorations require very little finishing if the
previous steps are properly done. Finishing can be done using tin
oxide powder on soft bristle brushes or rubber cups.
■ 9) Final burnishing
■ This is done after polishing to make the surface of the
restoration smooth and free from voids.
43. Indication
Class 1 Cavity: Direct gold is indicated for small carious
lesions in pits and fissures of posterior teeth and lingual
surfaces of anterior teeth.
Class 2 cavity: Direct gold is indicated for minimal
proximal caries in posterior teeth especially premolars
when marginal ridges are not subjected Ito to heavy
‘occlusal stresses.
44. ■ Class 3 Cavity: Can be used for small carious defects
in anterior teeth when the defect is only on the
proximal surface and esthetics will not be affected
■ Class 5 cavity: For minimal caries in the Cervical one
third of teeth direct gold can be used. Also for small
abrasion, erosion or abfraction defects on the facial
surfaces of teeth.
■
45. Class 5 cavity: For minimal caries in the Cervical one
third of teeth direct gold can be used. Also for small
abrasion, erosion or abfraction defects on the facial
surfaces of teeth.
Class 6 cavity: For restoration involving incisal edges or
cusp tips direct gold can be used, provided there is no
heavy occlusal stress.
Defective Crown margin: It can be repaired with direct
gold.
46. Contraindication
1. Very large pulp chambers
2. Severely periodontally weakened teeth with
questionable prognosis
3. Patients for whom economics is a severely limiting
factor
4. In handicapped patients who are unable to sit for the
long dental appointments required for this procedure
5. Esthetics: When esthetic is the main concern it is not
recommended.
6. Access and isolation difficulties
47. Conclusion
Direct filling gold still remains one of the most
conservative and long-lasting restorations in
dentistry. Well placed direct gold restorations
provide excellent service to patients for lifetime.
However, the use of this material is on the decline in
the present times because of its high cost, lack of
technical expertise and the ever Increasing demand
for esthetic restorations.
48. Reference
• Sturdivant's art& science Operative Dentistry –
Second South Asia Edition
• Clinical operative dentistry – 2nd Edition Remya
Raghu and Raghu Srinivasan
• Textbook Of Endodontics: Nisha Garg Amit Garg
2nd edition
• Basic dental materials –john j manappallil 4th
edition
