DIRECT FILLING GOLD

Presented by: Dr.Tushar

Moderator: Dr.Aditya chaudhary

Content

• 1. INTRODUCTION
• 2. CLASSIFICATION
• 3. GOLD FOIL
• 4. ELECTROLYTIC PRECIPITATE
• 5. POWDER GOLD
• 6. MANIPULATION OF DIRECT FILLING GOLD
• 7. DESORBING OR DEGASSING
• 8. COMPACTION
• 9. ADVANTAGES & DISADVANTAGES

• Pure gold can be used as an restorative material.

 Most noble metal, rarely tarnishes in oral cavity

 Cold welding property

 Applications

1. Pits and small class I restorations

2. For repair of casting margins

3. For Class II and Class V restorations

4. Repair of cement vent holes in gold crowns

CONTRA-INDICATION

1. Teeth with large pulp chamber
2. severely periodontally weakened teeth
3. Handicapped patient who are unable to sit for the long dental appointment required for the procedure.
4. Root canal filled teeth.

CLASSIFICATION

GOLD- FOIL

•  Oldest
• Manufacture:A cast ingot of 15 mm thickness is beaten to a submicroscopic thickness of 15 or 25 µm
•  Supplied as:FIat square sheets of varying thickness.
•  No. 4 wt. 4 grains (0.259 gram) 0.51 µm thick.
•  No. 3 wt. 3 grains (0.194 gram) 0.38 µm thick.

PREFORMED FOILS & PLATINIZED FOIL

Preformed foils:

 Ropes & cylinders available in preformed shapes.

 Made from No. 4 foil that has been “carbonized” or “corrugated”

Platinized Foil:

 Pure platinum foil sandwiched b/w two sheets of pure gold

 Bonded by cladding process

 Increases hardness

 Available in No. 4 sheet form

Cohesive & Non-Cohesive Gold

 Cohesive: For cold welding gold should have a clean surface

• Gold attracts gases and any absorbed gas film prevents cohesion of individual increments of gold
• Cohesive gold is supplied free of contaminants

 Non-Cohesive:

• Gold is subjected to volatile agent such as ammonia, which is absorbed on surface o Acts as a protective film
• Volatile film readily removed by heating
• Rarely used nowadays

ELECTROLYTIC PRECIPITATE

•  Crystalline gold powder is formed by electrolytic precipitation. Powder is formed into shapes by sintering(heat fusion).
•  Available as: mat, mat foil & alloyed
•  Mat gold: Crystalline  Formed in strips  Easy to build up the internal bulk, more easily compacted & adapted  Results in pitted external surface, so covered with a veneer of foil gold
•  Mat foil:  Sandwich of electrolytic precipitated gold powder b/w sheets of No.3 gold foil

 Alloyed Electrolytic Precipitate:

Newest form is Electralloy RV

 Alloy of gold & calcium (0.1 to 0.5% by wt)

 Calcium produce stronger restoration by dispersion strengthening

 Alloy sandwiched b/w two layers of gold

POWDER GOLD

• Gold powder is enclosed in a No.3 gold foil

Manufacture:

 Fine powder is formed by chemical precipitation or atomizing the metal

 Pellets mixed with soft wax, burned off later & wrapped in gold foil

Available as:

 Foil acts as an effective container and matrix for the powdered metal

 Powdered gold pellet increases cohesion & reduces time required for placing it, because each pellet contain more metal by volume tan same sized pellet of gold foil

 Powdered gold pellets have cylindrical or irregular shape & diameter of 1 – 2mm

 Ratio of gold foil to powder varies from 1 to 3 for small pellets to 1 to 9 for largest

MANIPULATION

• There are two process involved 1. Degassing 2. Compaction

 During storage & packing of cohesive gold, they absorb gasses from atmosphere Prevents it from fusing Removed by heating-

DEGASSING Heating done in two ways

1. In bulk on a tray, by gas-flame or electricity

2. Piece by piece, in a well adjusted alcohol flame

 Totally dry cavity needed to allow complete cohesion

 The gold may be compacted by

1. Hand mallet

2. Pneumatic vibratory condenser

3. Electrically driven condensers

STEP’S INVOLVED

1. Force of condensation must be 45° to the cavity walls and floors,  Bisect the line angle and trisect the point angle (result in maximum adaptation ,minimum irritation to vital pulp and dentin

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2.forces of condensation must be directed at 90degrees to previously condensed gold 3. always start at point angle on one side and proceed to other side. (tie formation)

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 Ensure condenser has covered entire piece of gold

 Condenser has to over lap at least ½ of the previously condensed area64. 4. use minimum thickness of pellet as possible 5 Energy of condensation :

 Less energy is used inside cavity preparation  Gradually increase the energy of condensation as build up proceeds to surface  Maximum energy is used at surface of restoration

6. Condensation can be either from one periphery of the increment to other or preferable from center of the increment to periphery (reduces voids , air entrapment)

PROPERTIES

 Greatest strength-most dense area

 Weakest part- porous area

 In DFG failure occurs from incomplete cohesion, thus transverse strength is a measure of cohesion

 HARDNESS  Indicates overall quality

 Indicates presence of porosity

 DENSITY  Density of pure gold is 19.3gm/cm³

 DFG density less than pure gold because it is not possible to eliminate voids completely during compaction

EFFECT OF VOIDS

 Amount of voids estimated by apparent density of compacted gold

 Voids on surface, increase susceptibility to corrosion and deposition of plaque

 Voids at the restoration-tooth interface cause gross leakage and secondary caries development

TARNISH & CORROSION

 Resistance to tarnish and corrosion is good if compacted well

BIOCOMPATIBILITY

 Pulpal response is minimal if compacted well  This procedure causes a certain amount of trauma to the tooth and supporting structures  Mechanical condensor causes less trauma than the manual technique

Conclusion

The technique skill of the dentist is of paramount importance to the success of the direct gold restorations.