Direct Filling Gold: Degassing, Compaction Methods, and Mechanical Condensation Techniques

Direct Filling Gold

 

Degassing

• The heating process which removes the surface gases and ensures a clean surface is known as degassing or desorbing.
• Degassing removes the surface gases like oxygen, nitrogen, ammonia, moisture or sulfur dioxide which may be present due to improper storage.
• Direct filing gold may be heated by one of two methods as follows:
  • In bulk on a tray, heated by either a gas-flame or electricity
  • Piece by piece in a well–adjusted alcohol flame

“Best Ways To Understand Compaction Methods For Direct Filling Gold”

“Importance Of Degassing In Preparing Direct Filling Gold”

In practice, all but the powder gold may be desorbed, on a tray:

• An electric annealer should be maintained at a temperature between 340°C (650°F) and 370°C (700°F). The time required varies from 5 to 20 minutes depending on the temperature and the quantity of gold on the tray.
• Powder gold must be heated in a flame to ensure the complete burning away of the wax.
• In flame desorption, there is picking up of each piece individually, heating it directly in the open flame, and placing it in the prepared cavity.
• The fuel for the flame may be alcohol or gas, but alcohol is preferred as there is less danger of contamination.
• The alcohol should be pure methanol or ethanol without colorants or other additives.
• Underheating could not adequately remove the impurities and thus results in incomplete cohesion, pitting, and flaking of the surface, while overheating leads to overwintering and possible contamination from the tray, instruments, or flame.
• This results in incomplete cohesion, embrittlement of the portion being heated, and poor compaction characteristics.

“Risk Factors For Improper Compaction Of Direct Filling Gold”

Compaction Methods:

The gold is compacted by following methods, i.e.

1. Hand mallet
2. Condensors
3. Mechanical condensors.

• Hand Mallet: Earlier gold was compacted entirely with a mallet.
  • Starting points are cut in the prepared cavity.
  • The first pieces of foil are wedged into these areas and compacted.
  • The condenser is placed against the foil and struck sharply with a small mallet.
  • Subsequently, additional foil is wedged in the same manner till the cavity is filed.
  • Each increment of gold must be carefully ‘stepped’ by placing the condenser point in successive adjacent positions.
  • This permits each piece to be compacted over its entire surface so that voids are not bridged.

“Early Signs Of Problems With Direct Filling Gold Condensation”

Condensers:

The original foil condensers had a single pyramid-shaped face, but current instruments have a series of small pyramidal ser-rations on the face. These serrations act as swaggers, exerting lateral forces on their inclines in addition to providing direct compressive forces. They also cut through the outer layers to allow air trapped below the surface to escape.

Each increment of gold should be carefully stepped by lacing the condenser point in successive adjacent positions, as the compaction force is applied. The stepping may be more readily accomplished and standardized by mechanical condensers.

• Size of the Condenser Point
  • The diameter of circular points should be 0.5 mm and 1 mm.
  • The size of the condenser point determines the effectiveness of compaction.
  • The force distribution to the gold depends on the area of the point.
  • Small condenser points are indicated in order to get the desired compaction without using forces that might damage oral structures.
• Pressure Application:
  • The pressure was applied by the use of a special mallet. In recent years, there has been a tendency to apply pressure by hand.
  • Compaction with mechanical devices like electromagnetic or spring loading condensers is quite rapid and is accomplished with greater comfort for the patient.

“Can Degassing Improve Direct Filling Gold Quality”

Mechanical Condensers:

Electromagnetic or spring-loaded have provided a mechanical means of applying force. The mechanical devices consist of points activated by comparatively light blows that are repeated with frequencies that range from 360–3600/minute. Vibrations can be produced either pneumatically (air driven) or electrically. They are faster and more comfortable for the patient.