2. INTRODUCTION
• Among all Restorative materials , Direct Filling Gold is the oldest
filling material used in restorative dentistry.
• The vision to utilize the noble metals for the replacement of lost
tooth structure steamed from perfect harmony of its biological &
mechanical properties.
3. • Most of the metals can be welded & alloyed at a temperature above the
room temperature but, the pure gold can be cold welded & made to adhere
to each other at room temperature.
• Direct gold restorations are highly durable if proper case selection , cavity
preparation & careful manipulation of the material are done.
• Direct Gold Restorations exhibit Excellent marginal integrity &
Biocompatibility in oral environment.
4. PROPERTIES OF GOLD
• Gold (au)
• Atomic No : 79
• Atomic weight: 196.96 amu
• Melting Point : 1064.43˚c
• Boiling Point : 2807˚c
• Brinell`s Hardness no. : 25
• Malleability : malleabilityof goldis thehighestof all metals
• Ductility : Goldisextremelyductile.
5. TYPES OF GOLD FILLING
• Many categories of DFG are available & is based on its physical form &
manufacturing process.
6. CLASSIFICATION
ACCORDING TO PHILLIP`S SCIENCE OF DENTAL MATERIAL
1. Foil ( Fibrous Gold )
A. Sheet
i.. Cohesive
ii.. Non-cohesive
B. Pellets
C. Cylinders
D. Laminated Foil
E. Platinised Foil
F. Corrugated Foil
7. II. Electrolytic Precipitate / Crystalline Gold
A. Mat Gold ( sponge or Crystalline )
B. Mat Foil
C. Electro-alloy
III. Powdered Gold / Gold-dent / Granular Gold.
8. GOLD FOIL / FIBROUS GOLD
• Gold Foil is oldest of all foil described .
• Manufactured by beating gold into Sheets.
• SUPPLIED AS :
Flat square sheets (of varying thickness ) in booklet form , 12 sheets per booklet
(10cm × 10cm ).
No. 4 wt. 4 grains (0.259grams) 0.51um thick.
No.3 wt. 3 grains(0.194grams)0.38um thick.
9. • The no. denotes the weight of the gold. Other no. sheets are also available are
Nos.20,40,60 & 90.
• No. 3 Foil is used to manufacture electrolytic & powder gold.
• These sheets may be cut & then rolled & compressed into pellets or cylinders in
dental office.
• Foils available commercially as Preformed cylinders & Ropes.
10. FORMS OF GOLD
• Ideally , manufacturer should supply gold foil free from surface contaminant to
place it in preparation.
• But, it`s difficult to maintain .
11. COHESIVE GOLD
• Also known as `Sticky Gold`. It is a gold Foil which is Free from impurities.
• It was introduced in 1854 by Dr. Robert Arthur. – in his paper on sticky
gold (cohesive gold) “A new method of using Gold Foil”.
• For cold welding ( at room temperature) – Gold should be clean i.e free
from impurity.
• It`s difficult to maintain cohesive form because gases like Carbonic acid,
Phosphoric acid & Hydrogen sulfide get accomodated on surface during
storage .
12. • This contamination of gold interferes with Cohesive nature of gold.
• This cohesive nature of gold can be maintained by proper storage or by process of heating
before insertion into cavity.
• Gold attracts gases like Oxygen & Nitrogen to it`s surface - Due to which it looses it`s cohesive
property – So Degassing is necessary.
• So, manufacturer supplies the gold essentially free of surface contaminants. This type of Gold
is known as `Cohesive Gold Foil`.
13. • These gold foils is coated with protective layer like Ammonia gas which :
1. Can be easily removed by Degassing.
2. Minimizes the adsorption of other gases.
But, before placing gold in preparation, degassing is done to make it free from any surface
contaminants..
14. NON-COHESIVE FORM
• Form of gold which loose its cohesive property because of adsorption of
contaminants like Sulphur, Phosphorous & Iron on surface which can not be
removed by heating.
• Non-cohesive form have lesser strength & hardness as compared to cohesive
form.
• Ammonia-treated foil is called non cohesive foil.
• Non-cohesive gold is rarely used in nowadays.
15. TYPES OF COHESIVE GOLD FOIL
• SOFT TYPE Cohesive foil : is annealed before trimming & is treated in Ammonia
Fumes to reduce cohesion.
• DEAD-SOFT type foil : it is soft due to the fact that it has not been annealed. It is
softer & much less cohesive than the soft type.
• SPECIAL-SOFT foil : has been alloyed with trace of silver to limit its
cohesiveness.
• PLATINISED SOFT gold foil : has been alloyed with platinum, usually by placing
a layer of platinum foil between two sheets of gold foil,& then malleting again
until its original thickness is established.
16. ELECTROLYTIC PRECIPITATED GOLD
• Sponge gold / Crystalline gold is a powder form - Introduced in Dentistry
in 1853.
• Manufactured by - amalgamating the gold with mercury & then driving
of the mercury by heat .
• Available as :
1. Mat Gold.
2. Mat Foil.
3. Electralloy.
17. • MAT GOLD :
Electrolytically precipitated type of gold i.e produced by electrodeposition.
For its preparation-
Pure gold sintered in oven , this hold the crystalline gold together.
Then gold is heated slightly below the melting point so that partial fusion occurs, resulting in
spongy structure of loosely aligned crystals.
These crystals are about 0.1mm long dendritic or fern like in shape.
Crystals adapt very nicely to prepared wall.
Mat gold can be used plain/sandwiched in gold foil to make it easier to handle.
It is mainly used for building of internal restoration because it can be easily compacted
&adapted to internal walls of the preparations.
18. MAT FOIL :
It is formed by placing the mat gold between No.3 & No.4 gold foil & then sintering just
below the melting point of gold.
It is then cut into strips of different sizes.
Advantage of using gold sheets is that gold sheets hold the crystalline gold together when
it is placed & compacted into prepared tooth.
19. • ELECTRALLOY:
It is the newest form of Direct Filling Gold. & produced by Electrolytic Precipitation Method.
Then this crystalline structure is sandwiched between two gold foils to improve the
properties.
In this calcium (0.1%) is added to increase hardness &strength of gold.
Electralloy on compaction produces the hardest Direct Filling Gold surface.
20. POWDERED GOLD
• Also known as Granular Gold / Gold Dent /E-Z gold.
• It is a blend of atomized & chemically precipitated powder. Embedded in wax like
organic matrix.
• Available in pellets of various sizes which are enclosed in gold foil wrappers &
packed for use.
• Prior to its condensation, the matrix is burned away leaving only pure gold to be
packed in the cavity.
21. • GOLDENT:
Is a combination of powdered gold & gold foil
The ratio is 95% powder to 5% foil. Provided in cohesive form.
23. • Degassing / Annealing :
During storage & packaging Gold foil adsorbs gases from
Adsorbed gases prevent gold from fusion.
Specially done for non-cohesive gold in which ammonia layer is
as a protective coating.
So, dentist needs to heat the foil / palate immediately before placing
in the cavity. This removes surface gases ( O2, N, NH3, or Moisture)
ensures the clean surface called as “ Annealing / Degassing. “
24. • Compaction :
The gold may be compacted by-
Hand Mallet
Pneumatic Vibratory Condenser.
Electrically driven Condenser.
25. INDICATIONS
• Gold is the material of preference in all class 1 cavities, where sufficient access is
obtainable.
• Ideal material in class V cavities with easy access & where it will not be exposed
to view.
• Class III direct gold restorations.
• Class II direct gold restoration.
• Class V direct gold restorations may be used on incisal edges or cusp tips.
• A defective margin of an otherwise acceptable cast gold restoration also may be
repaired with direct gold.
26. CONTRAINDICATIONS
• It is strictly contraindicated if opposite tooth has amalgam restoration as it causes
galvanic current which causes shocking pain in patients mouth.
• Teeth with very large pulp chambers.
• Severely Periodontally weakened teeth.
• Handicapped patients who are unable to sit for the long dental appointments
required for the procedure.
27. • Root canal filled teeth because these teeth are brittle.
• When economics is a limiting factor.
• It is usually not indicated in disto-occlusal cavities in molars , where it is difficult to apply correct
angles of force in adapting it to cavity walls.
28. ADVANTAGES
• Insoluble in the oral fluids.
• Perfect adaptability to cavity walls , if properly worked.
• Perfect weld ability in a cold state.
• High density, crushing resistance & edge strength.
• Low tendency to molecular change, since it is free from objectionable shrinkage
or expansion.
29. • Capability of receiving & maintaining a high polish.
• No intercementing substance necessary.
• Being noble metal, it do not under go Tarnish & Corrosion.
• Good Biocompatibility.
30. DISADVANTAGES
• Inharmonious color.
• Because of High conductivity of gold, large restoration can increase sensitivity.
• Difficulty in manipulation.
• Poor Esthetics.
• Gold is indicated only when lesion is small in size & present in non stress bearing
area.
