presentation on direct filling gold.pptx

Direct Filling gold seminar consists of its classification, techniques and various instrument's required to manipulate it.

1. SEMINAR ON Direct Filling Gold Presented By Dr. harshit kothari (P.G. Student) Guided By Dr. N.U. Manwar Dr. Manoj Chandak Prof. & Guide Prof. & H.O.D. Dr. Pradnya Nikhade Dr. Ajay Saxena Asso. Professor Asso. Professor

2. CONTENTS INTRODUCTION HISTORICAL BACK GROUND. PROPERTIES OF DIRECT FILLING GOLD. TYPES OF DIRECT FILLING GOLD. ANNEALING OR DEGASSING. PRINCIPLES OF CONDENSATION. TYPES OF CONDENSERS. CONDENSATION OR COMPACTION. 2

3. METALLURGICAL CONSIDERATIONS. GENERAL STEPS FOR INSERTION OF DIRECT GOLD. INDICATIONS. CONTRA INDICATIONS. LIMITATIONS. ADVANTAGES. DIS ADVANTAGES. 3

4. Gold foil was one of the earliest materials available for restoration of teeth. It is one form of pure gold used for direct restoration . It is undeniably the most permanent restorative modality. This noble metal is a superior restorative material to fill the small cavities. Direct gold are those gold restorative material that are manufactured for compaction directly into prepared cavities. INTRODUCTION 4

5. In 1483 Giovanni d’Arcoli recommended gold leaf filling and he use gold foil for filling diseased tooth . In 1510-1590 the renowned physician Ambroise Pare used lead to fill teeth . In 1700s Pierre Fauchard favored tin foil or lead cylinder . Philips Pfaff ( 1715-1767 ), used gold foil to cap the pulp. HISTORICAL BACK GROUND 5

6. In 1812 Marcus Bull of Harford ,Connecticut, produced beaten gold for dental application. In 1853 sponge gold was introduced in the U.S & England to replace gold leaf . This was followed by Cohesive or adhesive gold , introduced by American dentist Robert Arthur in 1855. Gold leaf as a restorative material become popular in 19 th century. 6

7. INDICATIONS Incipient caries lesion- Pits and small Class I restoration. Class II lesion not subjected to heavy masticatory load. Class V lesion & Class VI lesion. For repair of small defects in casting margins For repair of cement vent holes and perforations in gold crowns. Patients with good oral hygiene, low caries and plaque indices. Lesions with adequate access for detailed preparation and instrumentation.

8. CONTRAINDICATIONS: Young patient- Teeth with large pulp chamber Periodontal weakened teeth High stress bearing areas- Extensive cavities with weakened walls Economy is limiting factor Handicapped patient Root canal treated teeth Hypersensitive cavities Access & Isolation difficulties Lack of skill of operator

9. Pure gold is soft, malleable, and ductile and does not oxidize under the normal atmosphere conditions. It is most ductile and malleable of all metals. 29 gm cylinder to be drawn into a wire of 100km . It can be hammered to a thickness of 0.00013mm, about 1/3 rd of the thinnest gold foil used in dentistry. Properties of gold 9

10. Colour - rich yellow with a strong metallic luster. Fuses at a temperature of 1063 degree C and boils at 2200 degree C . The true density of pure gold -19.0-19.3g/cm3. The measured or apparent density is 14 -15 gm/cm3. Brinell hardness no. of pure gold is 25. Tensile strength during cold working increases from 19,000 psi to 32,000psi. Yield strength increases 0-30,000psi. 10

11. Coefficient of thermal expansion 14.4x10-6 o C which is close to that of that of tooth 11.4x10-6 o C. It has high thermal conductivity 0.710cal/sec/cm2. Noblest of all material . Readily dissolve in aqua regia to from tricholride of gold. 11

12. Most important property of pure gold is the ability to be cold worked and welded at room temperature. Cold welding : If two clean pieces of gold are pressed firmly together and a sufficient force applied, they unite at their point of contact & the gold is welded together without the application of heat. This process is known as cold welding . Gold shows maximum cohesiveness when it is 99.99% fine. 12

13. They are divided into 3 categories . I. FOIL (also know as fibrous gold) a. Sheet Cohesive Non -cohesive b. Ropes c. Cylinders d. Platinized foil e. Laminated foil Forms of direct filling gold 13

14. II . ELECTROLYTE PRECIPITATE(Crystalline Gold) Mat gold Mat foil Gold –calcium alloys III. POWDERED GOLD ( encapsulated gold powder ) 14

15. First introduced in America by Robert W ofendale in 1795. Property of cohesiveness was attributed by Robert Arthur in 1855 Manufacture of gold foil All light weight sheet are formed by beating. Heavy weight sheet are formed by rolling. The pure metal is first melted and formed into ingots of desired size. Rolled by machinery into thin ribbons about 1 inch wide & a little thicker than ordinary paper. GOLD FOIL 15

16. The thickness is regulated by the weight of the foil to be produced . The ribbon is now cut into 1-inch squares, each weighing 3,4,6,or 10 grains. These squares are then laid between sheet of gold beater skins made from intestine of bullocks, or of vellum paper. The pile is now wrapped in the heavy parchment paper &bound so that all edges are well protected. 16

17. The wrapped package is then placed upon a heavy polished stone block, approx 3 feet high by 15 inches squares ,the block resting on the foundation which is set in the ground 3 or 4 feet to give it solidity. With a large, round – faced mallet, the package is then beaten with heavy blows. 17

18. In Rolling process ,gold is passed continuously through the rolling mills until the desired thickness is achieved . During the manufacturing process of gold foil crystals of gold become elongated and assume a fibrous appearance (when view under microscope ). These fibres runs in all direction interlacing with each other. Because of this property fibrous form of gold make a stronger restoration. 18

19. Gold foil sheets are bound in the form of books of 1/10 or 1/20 ounces. One book contains 12 sheets and each sheet commonly has the diamensions of 4”x4”. Standard no.4 gold foil- 4x4 inch sheet. Weigh- 4 grains (259 mg or 0.259 gm) Thickness – 0.51um Standard no.3 gold foil-(used in electrolyte ppt ) Weigh -3 grains (0.194 gms ) Thickness-0.38um Also available no.20, no.40, no.60, no.90 19

20. May be hand rolled or commercially produced An ideal pellet is produced from a no.4 gold foil. Pellet sizes may vary from ½-1/128 which represents the portion of no.4 gold foil used to form a pellet. GOLD FOIL PELLETS 20

21. Manufacture of gold pellet 21

22. This form can both hand rolled and commercially rolled. It is custom made by rolling cut segments of No. 4 gold foil usually ½, ¼ and 1/8 into desired width. GOLD FOIL CYLINDERS 22

23. It is made from no.4 foil that has been carbonized or corrugated This was observed by dental dealer in the great Chicago Fire of 1871 Manufactured by placing the thin sheets of papers in between the gold foil sheet, which are then ignited. The paper burns and get charred. However the foil remains unburned, except that it becomes corrugated because of shriveling of paper PREFORMED GOLD FOILS 23

24. This is sandwich of gold and platinum with the platinum content being 15%. It can be formed in 2 ways . 1.Two sheets of No. 4 pure gold foil & a layer of pure platinum foil sandwich between them can be hammered until the thickness of No. 4 sheet is obtained. 2. Layers of platinum and gold are rolled over together so that fusion occurs before the beating process begun. PLATINISED GOLD FOIL 24

25. Platinum increases hardness & wear resistance of the restoration. This forms can be used in stress concentration areas like incisals and cusps tips. Advantages: 25

26. When a gold foil is beaten from an ingot, its crystals are elongated in a specific direction. A particular directional elongation allows forces to have better resistance in that direction. When two or three foils with crystals running in different directions are combined together, it results in a material that has fibers running in all directions. This makes it more resistance to applied forces. Such a combination of 2-3 foils is called as Laminated Gold Foil . LAMINATED GOLD FOIL 26

27. Dr. Robert Arthur in 1855 announced the method of preparing cohesive gold foil by annealing. The ability of two gold surfaces to cohere by welding at oral temperature is dependent on an anatomically clean surfaces. But gold like other metals ,attract gases to its surfaces ,and any adsorbed gas film prevents the intimate atomic contact required for cold welding Cohesive gold foil 27

28. For this reason ,the manufacturer can supply the foil to the essentially free of surface contaminant and therefore, inherently cohesive . 28

29. Insolubility in the oral fluids . Perfect adaptability to cavity wall, if properly worked. Perfect weld ability in a cold state. Great density, crushing resistance, & edge strength . Advantages of cohesive gold 29

30. Low tendency to molecular change, since it is free from objectionable shrinkage or expansion . Capability of receiving and maintaining high polish. DISADVANTAGE OF COHESIVE GOLD Inharmonious Colour High conductivity Difficulty in manipulation 30

31. It is the one in which the cohesive property of the foil is not developed to its full extent. Most gold sheet are provided with an adsorbed protective gas film, such as ammonia by manufacture . SEMI-COHESIVE GOLD FOIL 31

32. In this type of gold certain non volatile contaminants like iron, sulphur or phosphorus are permanently deposited onto the surface . The cannot be driven away by heat and the gold therefore loses its cohesive property Advantage Can work easily as compared to cohesive form. Disadvantage Not have sufficient strength and hardness. Non cohesive form of gold 32

33. It was introduced in dentistry in 1853.it is also k/as sponge gold. This consists of a crystalline gold powder formed by electrolyte precipitation. The powder is formed into different shapes by heating at a temperature well below the melting point of gold. Diffusion of the particles occurs below the melting point of contact so that the particles coalesce and grow. ELECTROLYTE PRECIPITED GOLD 33

34. Rule, in 1937, referred to crystal gold in his analysis of gold foil. It is crystalline, electrolytically precipitate gold form that is formed into strips. These strips are cuts by the dentists into desired size. MAT GOLD/ Crystal Gold 34

35. This is a sandwich of electrolyte precipitated gold powder between sheets of No. 3/No.4 gold foil. The sandwich is sintered and cut into strips of different widths. The purpose of sandwiching of mat gold between foil sheets was to try to eliminate the need to veneer the restoration with the layer of foil. MAT FOIL: 35

36. It is the newest form of electrolyte precipitate. This is an alloy of electrolytic gold and calcium. The Calcium content is usually 0.1 – 0.5 % by weight. Its purpose is to produce stronger restoration by dispersion strengthening. ALLOYED ELECTROLYTE PRECIPITATE (ELECTRALLOY RV) 36

37. Powdered gold is in the form of minute particles . It can be obtained by atomization from a molten state or by chemical precipitation . In latter process, gold is dissolved in aqua regia and precipitated by oxalic acid sulphurdioxide or sodium nitrate. Average particle size 15ums Maximum 74ums (atomized) POWDERED GOLD: 37

38. As the powder is impractical to manipulate so is gathered into conglomerate mass having a diameter of 1-3mm . These mass are either sintered or lightly precondensed to facilitate slight adhesion between the particles and ease handling. However these masses tend to fall apart. Because the powdered gold produces a less porous surface compared to mat gold, veneering with a gold foil is not very much necessary. 38

39. Goldent - This form was introduced in 1962 by Lloyd Baum . commercially available pellet of powdered gold wrapped in a gold foil are k/as goldent . Powdered gold and gold foil combination 39

40. The powdered particle are mixed with a soft wax and held in no.3 foil . gold foil act as container for powdered particle and facilitated their condensation. Each pellet contain approximately 10 times more gold than pellet of comparable size. Hand method is used for compaction of powdered gold . The ratio is 95% powder and 5% foil. 40

41. Cleansing of the gold surface by heating is referred to as annealing. Annealing removes all the volatile contaminants ,there by restoring the cohesive characteristics of gold. Temperature in the range of 650– 700 o C. Removal of surface impurities: (Annealing or Degassing) 41

42. To drive off impurities from the surface , thus making the surface ready for cohesion. To keep the surface devoid of impurities until complete cohesion occurs during compaction. AIMS AND OBJECTIVES OF ANNEALING 42

43. UNDER ANNEALING Leaves impurities prevents thorough condensation thus cause the restoration to pit and flake. 43

44. OVER-ANNEALING 44

45. Two methods can be used for degassing: Piece annealing Bulk annealing Alcohol flame Alcohol Electric flame annealer 45

46. single piece is annealed at one time ADVANTAGES: Lack of wastage. Ability to select a piece of desired size. Elimination of chances of contamination between annealing and use. DIS ADVANTAGES: Might require chair side assistant. Time taken is more. PIECE METHOD 46

47. absolute 90% ethyl /methyl alcohol is used. It is important to use its middle zone for heating ALCOHOL FLAME 47

48. METHOD OF DEGASSING BY ALCOHOL FLAME: Select desired size. the gold is carried & held with a suitable instrument usually a nichrome wire Regular cohesive gold is held only momentarily for few seconds in the flame . Powdered gold must be held in flame until all wax is burnt out and the pellet reaches a dull red glow. It takes 15-20 seconds for complete degassing of the powdered gold pellet. 48

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50. Under Annealing by Alcohol flame: Partial cohesiveness Subsequent peeling away of adjacent segment or layer OVER-ANNEALING scorches the Foil, shriveling the fine edges. Renders the foil harsh and unworkable. scorched Foil will not burnish properly. 50

51. It is degassing of several gold pellets at same time. Advantages: Less time is taken in the whole process. Convenient method when one is working alone. Dis Advantages: Inability to select a piece of desired size. Wastage of material is more. BULK ANNEALING 51

52. BULK ANNEALING BY ALCOHOL FLAME Usually takes 5 min for the process . Mica trays are used to hold the gold over the flame. 52

53. BULK ANNEALING BY ALCOHOL FLAME Advantages: Less time is taken in the whole process. Dis Advantages: Inability to select a piece of desired size. Wastage of material is more. Gold pellets may stick to each other if the trey is accidentally moved. 53

54. Most controlled and standard way of degassing gold. Heated compartment is made of Aluminium . Temperature required is between 340 to 370 c or 800 F for 5 to 20 min BULK ANNEALING BY ELECTRIC ANNEALER 54

55. Problems with Electric Degassing Pellets may stick together. Air currents may effect the uniformity of heating. Difficult to desorb appropriate amount of gold. Greater exposure to contamination. Size selection of desorbed gold pieces is limited. 55

56. The objectives of condensation of cohesive gold are to weld together the pieces of gold adapt the gold intimately to walls and margins of the prepared cavity gain a uniform compactness and drive out all air between the pieces of gold cold work and thus harden the mass, and develop strength within the restoration Condensation 56

57. Condenser is instrument used to deliver the forces of compaction to the underlying restorative material. There are several different methods for the application of forces: Hand pressure Hand malleting Automatic hand malleting Electric malleting Pneumatic malleting CONDENSERS 57

58. Use of this method is contraindicated alone except in a few situation like adapting the first piece of gold to the convenience or point angles &where the line of force will not permit use of other methods Powdered gold is better condensed by this method Hand pressure 58

59. Small point condenser of 0.5mm in diameter are generally recommended as they do not require very high forces for their manipulation. 59

60. Hand malleting for percussion was originally introduced by Dr. E. Merritt of Pittsburgh's in 1838. Then it was later introduced by Dr.W.H . Atkinson in 1861 Hand malleting 60

61. Condensation by hand malleting is a team work in which the operator directs the condenser & moves it over the surface, while the assistant provides rhythmic blow from mallet . Long handled condensers & leather face mallet (50 gms in wt) are used for this purpose. 61

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63. c. Automatic hand malleting This method utilizes a spring loaded instrument that delivers the desired force once the spiral spring is released. Disadvantage is that the blow descends very rapidly even before full pressure has been exerted on the condenser point. 63

64. d. Electric malleting ( McShirely electro mallet): This instrument accommodates various shapes of condenser points & has a mallet in the handle itself which remains dormant until wish by the operator to function. The intensity or amplitude generated can vary from 0.2ounces -15 pounds & the frequency can range from 360-3600 cycles /min. 64

65. Pneumatic malleting (Hollenbeck condenser) This is the most recent & satisfactory method developed by Dr. George M Hollenback . A pneumatic mallet consists of vibrating condenser & detachable tips run by compressed air. The air is carried through thin rubber tubing attached to the hand piece. 65

66. Controlling the air pressure by a rheostat allow adjusting the frequency & amplitude of condensation strokes. The construction of the handpiece is such that the blow does not fall until pressure is placed on the condenser point .then it continues until released. 66

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68. GOLD CONDENSERS Hand condenser has a long handle, approximately 6” in length & a blunt end to receive blows from the mallet. On the other hand, ones which are to be inserted into the hand pieces for mechanical malleting have a short shanks of 1” in length 68

69. Condenser shank may be straight, monoangle , or offset .nibs of the plugger can be of various shapes like round, rectangular & parallelogram shaped. Pyramid /wedge like serrations are present on the face of the condenser nib 69

70. ROUND CONDENSER Used mainly to start the direct gold restoration & to establish ties in the inner parts of the restoration. Diameter – 0.4 to 0.55mm. PARALLELOGRAM & HATCHET CONDENSER Used for preliminary condensation & to form bulk of the restoration. Diameter– 0.5 to 1 mm. 70

71. VARNEY FOOT CONDENSER— Has a rectangular face Diameter – 1 to 1.3 mm. Used mainly for surface condensation & surface hardening & bulk build up. 71

72. Condenser shanks may be straight , angled or offset& their nib faces may be perpendicular to the long axis of the handle or perpendicular to the end portion of the shank. The smaller the nib face size, the greater the pounds per square inch delivered . For most gold 0.4 to 0.55 mm diameter nibs are suitable. Smaller condensers tend to punch the gold, where as larger ones are less effective in forcing the gold into angles in the tooth preparation. 72

73. PRINCIPLES OF CONDENSATION 1). Forces of condensation must be 45 degree to the cavity wall& floor 73

74. 2). Forces of condensation must be directed at 90 degree to previously condensed gold. PRINCIPLES OF CONDENSATION 74

75. 3). Uniform stepping of the condenser point is important to ensure hardening & welding of the entire restoration without leaving behind any voids. Stepping is overlapping of the previous area of condensers stroke by half or one fourth both in individual steps and in lines of steps. PRINCIPLES OF CONDENSATION 75

76. Stepping process PRINCIPLES OF CONDENSATION 76

77. Stepping process can proceed in two ways 1. Moving parallel to the wall and wedging the final row between the already condensed mass of gold and cavity wall. 77

78. Moving perpendicular to the wall . In these method, the final row of steps wedges the gold between that wall & the mass of the gold already being condensed. This stepping Process likened to cause shingling Because of overlapping 78

79. 4).Use minimal thickness of pellet possible provided that the condensers will not penetrate it. 79

80. 5). Energy of condensation should only be dissipated in fulfilling the objectives of the condensation. It is more effective to utilize lesser amount of energy inside the cavity preparation & to increase energy of condensation gradually as the step- by- step build up proceeds to the surface. PRINCIPLES OF CONDENSATION 80

81. The average force required to condense gold with a condenser point of 1mm diameter is 15 pounds . Force is applied through mallet is recommended because it is rapid, easier and less strenuous .Blow should not be too strong nor too light. 81

82. Stronger blow deliver heavier forces which could perforate the gold and damage pulp and supporting structures . With lighter blows inadequate force is applied which could results in inadequate compaction, poor adaptation to cavity walls and a restoration full of voids. 82

83. Forces required for 3.75 pound are recommended for condenser nibs of 0.5 mm diameter , 8.43 pound for 0.75mm diameter 15 pound for 1mm diameter nibs It can be noted here that when the diameter of instrument is doubled, forces required are increased 4 times . 83

84. Single most important item in the energy dissipation & tissue reaction towards it is the nature of the resistance to that energy. Such resistance is effected by many variables. A). Tone of the periodontal ligament. B).Volume of the tooth being condensed. C).The modulus of resilience of tooth. D).Design factors. PRINCIPLES OF CONDENSATION 84

85. E). Operator variables. F).Increment size. G).Technique variables. 6).When inserting pieces of direct gold materials condensation can be either from one periphery of the increment to the other or preferably from the center of the increment to the peripheries. PRINCIPLES OF CONDENSATION 85

86. 7). The condensation of precipitated type of direct gold materials should be started by hand, in rocking motion , preferably from the center to peripheries PRINCIPLES OF CONDENSATION 86

87. 8).Control of line of force i.e. the direction through which the force is delivered. The line of force is determined principally by the axis of the shaft or handle of the condenser. PRINCIPLES OF CONDENSATION 87

88. Force applied to the condenser is parallel to the long axis of instrument shaft regardless of the angle of the working point while compacting in the center of the cavity; forces are usually directed at 90 degree to the pulpal floor. 88

89. First is to select a suitable size of piece of gold. Gold is first pressed into place by hand, then a condenser of suitable size is used to begin malleting in the center of the mass. A)Three step build up for the restoration: 1)Tie formation: Connecting two apposing point angles or starting points filled with a transverse bar of gold. GENERAL STEPS FOR INSERTION OF DIRECT GOLD RESTORATION IN PREPARATION 89

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91. GENERAL STEPS FOR INSERTION OF DIRECT GOLD RESTORATION IN PREPARATION 2). Banking of Walls: Covering each wall from its floor or axial wall to the cavosurface margin. A wall should be banked in a way that will not obstruct tie formation. 91

92. 3).Shoulder formation: Connecting two opposing walls with the direct gold material. These 3 steps should completely fill up the cavity preparation. GENERAL STEPS FOR INSERTION OF DIRECT GOLD RESTORATION IN PREPARATION 92

93. B. Paving of the Restoration: Every area of cavo surface margin portion should be individually covered with excessive cohesive gold foil. GENERAL STEPS FOR INSERTION OF DIRECT GOLD RESTORATION IN PREPARATION 93

94. C. Surface hardening of the Restoration: Utilizing the highest condensation energy go over the surface of the restoration ,as to strain harden the surface gold. GENERAL STEPS FOR INSERTION OF DIRECT GOLD RESTORATION IN PREPARATION 94

95. D).Burnishing: Moving from gold to tooth surface. Enhances surface hardening. Adapts the material more the margins. Eliminates surface & marginal voids. E). Margination : Using sharp instruments.( eg-knives&files ). GENERAL STEPS FOR INSERTION OF DIRECT GOLD RESTORATION IN PREPARATION 95

96. F). Burnishing: Follows margination as a means of closing marginal discrepancies. G).Contouring: To create proper anatomy of the Restoration. Done by using knives,files or finishing burs. H).Additional burnishing. GENERAL STEPS FOR INSERTION OF DIRECT GOLD RESTORATION IN PREPARATION 96

97. I). Finishing & Polishing: Done by using precipitated chalk or tin oxide powder on soft bristle brushes or rubber cups. J).Final burnishing: Done to ensure closure of marginal voids. GENERAL STEPS FOR INSERTION OF DIRECT GOLD RESTORATION IN PREPARATION 97

98. Cohesive gold foil restorations: Superficial 400 to 600 microns– solid gold. Deepest 200 microns - solid gold with minimal voids. METALLURGICAL CONSIDERATIONS . 98

99. Mat Gold Restorations: No areas of solid gold i.e. voids spread through out the restoration METALLURGICAL CONSIDERATIONS 99

100. Powered Gold Restorations: Full of voids. Only scattered thin areas of solid gold will be found within the restoration corresponding to the gold foil encapsulatig sheets. METALLURGICAL CONSIDERATIONS 100

101. EFFECT OF DIRECT GOLD AT DIFFERENT EFFECTIVE DEPTHS At 3 mm– normal pulp will undergo healthy reparative reaction. At 1-2 mm– unhealthy reparative reaction. Less than 1 mm– destruction in pulp- dentin organ. The initial sign is cracking in the pulpal or axial wall. 101

102. Effective Thickness of dentin: 3mm or more --- no intermediary base 2mm or more --- cavity varnish. 1-2mm --- sub base of calcium hydroxide or ZnoE & base of Zinc phosphate or Zinc polycarboxylate Less than 1 mm-- Direct Gold Restoration contraindicated. 102

103. INDICATIONS FOR DIRECT FILLING GOLD Lesions with limited dimensions & extent. Lesions with cavity margins on sound enamel surface. Lesions in patients with good oral hygiene. Lesions with adequate access Lesions in vital teeth. Lesions in which esthetics is not a primary concern. 103

104. CONTRAINDICATIONS FOR DIRECT FILLING GOLD Teeth with large pulp chamber Severely periodontally weakened teeth. Large carious lesion. Handicapped,elderly patients who cannot give very long sitting. Inaccessible areas. Area of undesirable occlusal stresses. Patients with high caries index. 104

105. Limitations There is something about manipulation of gold foil that brings out expertness , as does no other operation of dentistry. Gold foil demands cleanliness , exactness , precision and concentration. 105

106. ADVANTAGES Permanent method for repairing teeth Does not tarnish and corrode in oral cavity. Tooth discoloration does not occur around margin. No cementing medium is required. Chances of plaque accumulation is very less. Most efficiently sealing material. 106

107. DISADVANTAGES Unesthetic . High cost. Thermal conductivity. Difficulty in manipulation. Long chair side time. High condensation forces may injure the tooth and supporting structure. Use limited to conservative cavities. 107