DIRECT FILLING GOLDSubmitted By: Deepika Bali Direct golds are those gold restorative materials that are manufactured for directly compacting them in to the prepared cavities. This noble metal is a superior restorative material for small defects and lesions in teeth . Pure gold has been a metal of special intrinsic and practical value. In its pure form, gold has unusual ability to cohere to itself at room temperature. Gold is quite soft and in a compressible form, increments can be welded by pressure in to solid metal mass inside a prepared tooth cavity. The metallic bonding between overlapped increments produces the direct gold restoration. It requires care and cleanliness in handling the metal and skill necessary in use , cohesive gold has acquired a reputation as a material that embodies perfection in hands of skillful, well trained operative dentist. Types of Direct Filling Gold 1. Gold foil A. B. C. D. E. F. Sheets Pellets (hand rolled & preformed) Cylinders Corrugated foil Platinized foil Laminated foil Goldent . B.2. Electrolytic precipitated gold A. Powdered gold A. Mat gold Mat foil Gold calcium alloy 2. C. No.since these sheets are too large for restorative purposes. 3 gold foil weighs 3 grains. Gold foil is cut into 4x4µ sheets.Gold Foil Gold foil is also called fibrous gold . the are rolled into pellets or cylinders before insertion into cavity preparation. 2 gold foil weighs 2grains. pellets . Gold foil sheets: these are manufactured by beating sheets: or rolling pure gold ingots into thin sheets.4 gold foil is the standard size and weighs 4 grains.It is available as sheets . No. A. These sheets are seperated by thin paper and bound in books containing 1/10 or 1/20 ounces of gold. ropes and precondensed laminates of varying thickness. . preparation. No. cylinders . 1/128µ) are cut and rolled into pellet form. Usually larger segments of sheet (1/2µ.B. C. Gold foil pellets: these may be hand rolled or pellets: commercially produced from a no. 1/8µ) are cut and rolled into cylinders. Small sections of the gold foil sheets (1/32µ. Gold foil cylinders: these may also be hand cylinders: rolled or preformed. D. 4 gold foil sheets. The paper burns and gets charred while the gold foil becomes corrugated . Corrugated gold foil: these are manufactured by foil: placing thin sheets of paper in between the gold foil sheets and igniting them . . 1/64µ.1/4·. . Platinized gold foil may be used for areas of stress concentration like incisal edges and cusp tips. Addition of platinum increases the strength and wear resistance of the restoration. 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. Layers of platinum of gold are rolled over together to bring about their fusion following which they are beaten to achieve desired thickness .E. Platinized gold foil: this is a sandwich of gold and foil: platinum with the platinum content being 15%. F. A combination of two or three foils with crystals running in different direction is called a laminated gold foil. laminated gold foil are stronger and can be used in stress-bearing areas like cusp tips and stressincisal edges. Laminated gold foil: when gold foil is beaten from an foil: ingot. . Since the crystals run in all direction. its crystals are elongated in a specific direction. Electrolytic precipitated gold This is a crystalline gold powder formed by electrolytic precipitation. A. But mat gold is loosely packed so it shows numerous voids between the particles. This form is easy to use for building the internal bulk of the restoration because of ease of compaction. Mat gold : this is a crystalline electrolytically precipitated gold that is formed into strips. . Hence it is not recommended for the external surface of the restoration as it become pitted. The powder is made into different shapes by sintering at an elevated temperature well below the melting point of gold. Mat foil : this consists of sandwich of electrolytically precipitated gold powder between two sheets of No. The addition of calcium produces a stronger restoration by dispersion strengthening . Gold calcium alloy : this the another form of electrolytically precipitated which is alloyed with 0. .B. This purpose of sandwiching mat gold between foil sheets is to eliminated the need to veneer the restoration the layer of foil. This is sintered so as to make the gold into strip form C. 3 gold foil which is sintered and cut into strips. It is commercially available as Electralloy RV.1% calcium. Powdered gold Powdered gold is made by a combination of chemical precipitation and atomization with an average particle size of 15 m. This is available as Goldent or Williams E-Z Gold. E- . 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. Properties of direct filling gold Pure gold is soft. for gold is 25 this makes it very soft. Gold fusses at 10630 c and boils at 22000 c. It has a rich yellow color and a strong metallic lustre.3g/cm but this is reduce by voids incorporated during restoration to14 -15g/cm3 The brinnell hardness no. However during compaction the hardness increases 258-82 making it a strong material. Density of pure gold is 19 ² 19. malleable and ductile and does not oxidize under normal atmospheric conditions. 2583 . minute amount of calcium. mercury adversely affect the properties of gold. . and platinum can improve the properties of gold.4 x 0 10-6/ C which is close to that of tooth structure(11. The coefficient of thermal expansion of gold is 14. palladium.4 -6/ 0C) x 10 Even small amount of impurities can affect the mechanical properties of gold. Gold exhibits excellent marginal integrity and biocompatibility with the oral tissues. It can be cold welded at room temperature. However. bismuth. Very small amount of lead. Advantages of direct gold 1. Being ductile it can be burnished against the cavity margins to create excellent marginal integrity. The surface of direct gold can be polished well and the smoothness will last indefinitely . When proper case selection is done and the cavity preparation is kept ideal. 5. Direct gold exhibits good adaptation to the cavity walls. direct gold is the most durable restorative material. 3. They are insoluble in the oral fluids and exhibit thermal expansion similar to that of dentin. The density and hardness of compacted gold provide adequate compressive strength. 2. As pure gold is a noble metal. . 4. When properly placed. it does not undergo tarnish or corrosion in the oral cavity. 7. 6. it is atraumatic to the dental pulp and supporting structures. .Disadvantages of direct gold 1. Expensive material. The manipulation of gold is very exacting and difficult to master. So pulp protection is necessary under gold restoration. 5. 4. Thermal conductivity of gold is high. It is time consuming. 3. The yellow colour of pure gold is not esthetically acceptable to most of the patients. 2. 2. 6. 5. 3. 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 5 Cavity : For minimal caries in the Cervical one third of teeth direct gold can be used. Defective Crown margin : It can be repaired with direct gold.Indications 1. provided there is no heavy occlusal stress. Also for small abrasion. 4. 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. 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 2 cavity : Direct gold is indicated for minimal proximal caries in posterior teeth especially premolars when marginal ridges are not subjected to heavy occlusal stresses. Young Patients : Because of presence of large pulp chambers it is contraindicated as the malleting forces of direct gold may not be tolerated by the pulp. 7.Contraindications 1. 6. Access and isolation difficulties. 2. difficulties. . Esthetics : When esthetic is the main concern it is not recommended. 5. Heavy occlusal stresses : For moderate to large carious defects direct gold is not used as it can not withstand heavy occlusal forces. direct gold is not employed because of questionable prognosis. 4. Poor periodontal status : In periodontally weakened teeth. Handicapped Patients : It is contraindicated as long appointments are necessary. Economics : It is not indicated when cost is the limiting factor. 3. Degassing compaction .Manipulation of direct filling gold There are two processes involved. 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. annealer. . Heating in a mica tray mounted over an alcohol lamp Heating in a electric annealer. 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. 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. 3. 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 3the cavity preparation. The gold is heated to 850 0 F for ten minutes and then allowed to cool before it is placed in the cavity. 2. .1. excessive sintering and contamination from the tray. This results in recrystallization and grain growth. Underheating ² If the gold is not heated adequately it results in incomplete removal of surface impurities. Overheating ² If the gold is heated for prolonged periods of time or to high temperatures. . instrument or flame can occur.Hazards during degassing. 2. decrease plasticity of the material and improper compaction of the gold. This leads to poor cohesion between the gold pieces on condensation causing pitting and porosity in the final restoration. 1. During these movements. then back to the original side on a different straight line. 3. the condenser should overlap at least half of the previously condensed area. This ensures maximum adaptations of the gold to the cavity walls and also cold welds. 2.Certain Principles to be followed for compaction of direct gold 1. This process is called ´steppingµ. 4. always start at a point on one side and proceed in a straight line to another point on the opposite side. This produces maximum adaptation of the gold into all details of cavity preparation. 0 The force of condensation must be at 90 to previously condensed gold to prevent displacement of the already condensed pieces of gold. The force of condensation should be at 45 to the cavity walls and floors. Minimally sized increments of gold should be used. Whenever condensing a piece of direct gold. 0 . Each increment of gold thus reducing the voids. . and a frequency of 360 to 3600 cycles per minute.The energy condensationproduced by this method is not sufficient to fulfill the objective of condensation.It requires a trained malletassistant to apply the condensation energy with a mallet. .Modes of condensation: 1. it can be used only as a first step in a two step condensation process. However. 2. Electronic condensation. Hand condenser and mallet.This is the most efficient condensationand controlled way of condensing materials the vibrating condenser heads can have an intensity or amplitude from 2 oz. to 15 lbs. Hand instrument condensation.This involves the use of condensationvibrating condensers energized by compressed air. 4. simply to effect the initial confinement of the material within the cavity preparation. This in turn must be in coordination with locating the hand condensers by the operator to the inside of the cavity preparation. 3. Pneumatic condensation. The width of the cavity should be minimal. The depth of the cavity should be 0. Retention form : Is achieved by parallel or slight occlusal convergence of the facial and lingual walls. 3. . 2.General principles of cavity preparations for direct gold restorations 1. Resistance form : Is achieved by creating flat pulpal floors perpendicular to occlusal forces. The walls must be smooth and flat.5 mm into dentin. Enamel walls must be supported by sound dentin the cavity width must be minimal while providing adequate convenience form. The outline form : Should include all structural defects and margins must be placed on sound tooth structure. The outline should be smooth and designed to be esthetically pleasing. Sharp internal line and point angles in dentin serve as convenient ´startingµ points for compaction of direct gold. The presence of sharp internal line angles resist the movement of the restorations. Convenience Form : Requires suitable access and a dry field. 4. The preparation is done with a no. oblong. .Class 1:Cavity preparations for direct gold restorations The outline form is kept as small as possible while providing convenience for instrumentation and restoration. It is extended slightly beyond the lesion and it may be a simple circular design. The walls are extended minimally. This allows a 40-45 40degree metal margin that can be burnished well against the tooth.2mm in width using a small finishing bur or a flame shaped white stone. 330 bur.5mm in to dentin. Retentive undercuts are placed in dentin using a no. 331/2 Bur at a slow speed or using angle formers. Occlusal cavosurface margin is slightly beveled not more than 0. or triangular for a pit. The pulpal depth is . Outline form for a class 1 pit cavity in a mandibular premolar . . . 3. Gingival margins should just clear the contact area and not extend subgingivally. 5. The proximal box is also prepared same as that of amalgam cavity preparation except it is more conservative. All walls of the proximal box are extended minimally into the respective embrasures.Class 2:Cavity preparation 1. 7. 330 bur(pear shaped). 8. All line angles except axiopulpal line angle are kept very sharp. 10. Facial and lingual walls of the proximal box should only extend into the contact area. Cavosurface margins are beveled at 45 degree to the enamel walls. 2. 9. Breaking the contact is not necessary. 6. The outline includes entire defect and should be in the form of straight lines and definite curves. The cavity width is kept very narrow not exceeding 1/5 the intercuspal distance. The preparation is done with a no. 4. A reverse bevel is placed on the gingival floor towards the axial wall. . Gingival floor showing reverse bevel . This design is indicated for small carious lesions on proximal surfaces when thick labial.25mm ² 0. .Class 3:Cavity preparations FERRIER DESIGN Before commencing the cavity preparation minimal tooth separation (0.50mm) is necessary for good access.1 round bur. the facial wall follows the facial contour of the tooth and meets the gingival margin in a slight obtuse angle The gingival margin is kept just apical to the crest of the free gingiva. When viewed from the proximal aspect. This is done with a ferrier separator. lingual and incisal walls remains. A no. The lingual wall is straight gingivally and curves abruptly in the incisal 1/3rd to meet the incisal angle. It meets the facial wall in a sharply defined obtuse angle. It is straight faciolingually.331/2 inverted cone bur extends the outline form. Access is done from the facial approach using a no. and the lingual wall in a sharply defined acute angle. . . A bibeveled hatchet establishes the incisal retention point. Finally the wedlestaedt chisel is used to bevel the cavo surface margins. To provide enough resistance form.5mm into dentin. This creates maximum convenience form. The axial wall is located 0.The incisal margin extends just incisal to the contact area and meets the facial and lingual walls in a smooth curve. Small angle formers are then used to accentuate the point angles and the axiogingival angle. removes any unsupported enamel and allows esthetic blending of the gold restorations . the internal aspect of the preparation are precisely instrumented . . The dentinal portion of the wall planed using a hoe and angle former. The gingival wall is shorter than the occlusal due to narrowing of tooth gingivally. 2. Proper isolation is necessary. 212 clamp is modified before placement to allow proper access and isolation of the class 5 lesion. 5. 3. . 4. It trapezoidal in shape.75mm deep gingivally. The no. The axial wall is located in dentin and is 1mm deep occlusally and 0. This parallels the occlusal wall. 6.Class 5 : Cavity preparation 1. The occlusal wall is longer and straight. The mesial and distal walls parallel the proximal line angle of the tooth and diverge facially meeting the occlusal and gingival margins in sharp angles. . Class 5 cavity preparation done using a no. 331/2 inverted cone bur . A slight cavosurface bevel is placed on all enamel margins using the wedelstaedt chisel. 8. 9. The entire preparation is done using a 331/2 inverted cone bur. A hoe or a monangle chisel may be used to established an acute axiogingival line angle. This provides major retention form. .7. Sharp line and point angle also provide retention. . . . General steps for direct gold restorations 1. This tie forms the foundation for any restoration in direct gold. Build up of the restoration 1. Tie formation: This involves connecting two opposing point formation: angles or starting points filled with gold with a transverse bar of gold. . 2. . It should be done simultaneously on the surrounding walls of the preparations. Banking of the walls : Consist of converging each wall from its floor or axial wall to cavo surface margin with a direct gold material. . Shoulder formation : This consist of connecting two opposing walls with the direct gold material to completely fill the restorations.3. 4. Burnishing This is done with suitable burnisher moving from the gold to the tooth surface. This enhances the surface hardening and also produces good marginal adaptation of the gold. Paving of the restorations To overfill the preparation every area of the cavosurface margins should be indivisually covered with excess cohesive gold foil. 5. Margination This step uses gold knives to remove excess gold from the gold surface to the tooth surface. 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. This is condensed with a ´footµ condenser 3.2. . create proper occlusal anatomy. or finishing burs to knives.files. 9. Contouring This step uses knives. Finishing and polishing Can be done using tin oxide powder on soft bristle or rubber cups. Final burnishing This is done after polishing to make surface of restoration smooth and free from voids. 7. . 8.6. Burnishing is done again after contouring. Burnishing It helps to eliminate marginal discrepancies and to strain harden the surface.files. BIBLIOGRAPHY Baum Charbeanu Sikri Marzouk Ramya Raghu .