Silver Amalgam Seminar

Introduction
Definition
History
Classification
Composition
Amalgamation
Properties of amalgam
Indications and contraindications.
Advantages and disadvantages
Manipulation
Failure of amalgam restoration.
Amalgam waste management
Repaired amalgam restoration
Recent advances
Conclusion
References

1. AMALGAM 1

2. CONTENTS 2 Introduction Definition History Classification Composition Amalgamation Properties of amalgam Indications and contraindications.

3. 3 Advantages and disadvantages Manipulation Failure of amalgam restoration. Amalgam waste management Repaired amalgam restoration Recent advances Conclusion References

4. INTRODUCTION 4

5. Alloy : A metal made by combining two or more metallic elements, especially to give greater strength or resistance to corrosion. Amalgam: Amalgam is an alloy that contain mercury as on of its constituents . Phillips science of dental materials 11 th edi chp 17 pg no 496 5 INTRODUCTION

6. Mercury : ANSI/ADA specification no. 6 for dental mercury requires that mercury should have clean reflecting surface that is free from surface film when agitated in air. Material used in dentistry, Mahalaxmi chp 12 pg no.195-221. 6 INTRODUCTION

7. Dental Amalgam: Dental amalgam is produced by mixing liquid mercury by solid particles of an alloy containing pre dominantly silver , tin and copper. Phillips science of dental materials 11 th edi chp 17 pg no 496 7

8. HISTORY 8

9. 9

10. 10

11. 11

12. 12

13. 13

14. 14

15. AMALGAM WAR 15

16. In 1845 , A merican society of dental surgeon condemned the use of all filling material other than gold as toxic . The society went further and requested to sign a pledge refusing to use amalgam . However , this policy was reconsidered in 1850 . Material used in dentistry, Mahalaxmi chp 12 pg no.195-221. 16 FIRST AMALGAM WAR

17. The use of amalgam was promoted by work of F.Flagg . Final approval for clinical use came from the work of G.V. Black . Improved handling and performance of amalgam blocked the criticism and inspired the use of amalgam. Material used in dentistry, Mahalaxmi chp 12 pg no.195-221. 17 FIRST AMALGAM WAR

18. German Dentist Professor Alfred Stock claimed to have evidence showing that mercury could be absorbed from dental amalgam , which lead to serious health problems . His writing attracted wide spread attention. Charite Hospital in Berlin appointed a committee to investigate allegation of amalgam toxicity . Material used in dentistry, Mahalaxmi chp 12 pg no.195-221. 18 SECOND AMALGAM WAR

19. An account of committee finding was published in 1930 , declare that there was no reason to condemn newer silver tin amalgam . Material used in dentistry, Mahalaxmi chp 12 pg no.195-221. 19 SECOND AMALGAM WAR

20. War began in 1980 , primarily through writing of Dr. Huggins . He was convinced that mercury released from dental amalgam was responsible for human disease affecting CVS & CNS . Material used in dentistry, Mahalaxmi chp 12 pg no.195-221. 20 THIRD AMALGAM WAR

21. But research ,demonstrated that there was no cause and effect relationship between the dental amalgam restoration and other health problems. Material used in dentistry, Mahalaxmi chp 12 pg no.195-221. 21 THIRD AMALGAM WAR

22. ALLOY COMPOSITION 22

23. ANSI/ADA Specification no. 1 amalgam alloys should contain predominantly silver and tin . The content of the alloy should be at least 65 wt % silver, 29 wt % tin , and less than 6 wt % , copper , a composition close to that recommended by G.V. Black in 1896 . Phillips science of dental material 11th edi chp 17pg no.496-98 23 ALLOY COMPOSITION

24. 1. Powder 2. Liquid Silver Mercury Tin Copper Zinc 24 COMPOSITION

25. Amalgam alloys Classification Particle type Ag Sn Cu Zn Other New true dentalloy Low copper Lathe cut 70.8 25.8 2.4 1 - Dispers alloy High copper Mixed 69.5 17.7 11.9 0.9 - Aristalloy High copper Spherical 58.7 28.4 12.9 - Indiloy High copper Lathe cut 60.5 24 12.1 3.4 (indium) 25 Sturdevant art and science of operative dentistry 6 th edition

26. 26

27. MANUFACTURE OF ALLOY POWDER 27

28. 28 LATHE CUT FILINGS

29. 29

30. 30

31. 31

32. 32 SPHEROIDAL ATOMIZED POWDER

33. 33

34. 34 PARTICLE SIZE

35. 35

36. 36

37. Amalgams made from lathe-cut powders, or admixed powders ( blend of lathe cut and spherical powders). R esist condensation better than amalgams made entirely from spherical powders. Phillips science of dental material 11th edi chp 17pg no.500-502 37 LATHE-CUT POWDER COMPARED WITH ATOMIZED SPHERICAL POWDER

38. Spherical alloys require less mercury than typical lathe-cut alloys Because spherical alloy powder particles have a smaller surface area per volume than do the lathe cut alloy particles. Amalgams with a low mercury content generally have better properties . Phillips science of dental material 11th edi chp 17pg no.500-502 38

39. CLASSIFICATION 39

40. Binary alloy (Ag-Sn) Tertiary alloy (Ag-Sn-Cu) Quaternary alloy(Ag-Sn-Cu-Zn) Sturdevant’s art and science of operative dentistry 5 th edi 40 NUMBER OF ALLOYED METALS:

41. Sturdevant’s art and science of operative dentistry 5 th edi 41 SHAPE OF PARTICLE ADMIXED LATHE-CUT SPHERICAL

42. Conventional/Low copper amalgam ( <0-6%) High copper amalgam (>6-13%) High copper admixed alloy High copper uni - compositional alloy Sturdevant’s art and science of operative dentistry 6 th edi 42 COPPER CONTENT :

43. Zinc containing alloy ( >0.01%) Zinc free alloy(<0.01%) Sturdevant’s art and science of operative dentistry 5 th edi 43 ZINC CONTENT :

44. 1st Gen : 3part silver and 1 part tin . 2nd Gen: 3 parts of Ag ,1 part of Sn, 4% Cu to decrease the plasticity and to increase the hardness and strength and 1 % zinc which act as oxygen scavenger and decreases the brittle ness Sturdevant’s art and science of operative dentistry 5 th edi 44 ADDITION OF GENERATIONS OF AMALGAM:

45. 3 rd Gen: First generation + spherical amalgam copper eutectic alloy 4 th Gen: Adding copper up to 29% to original silver and tin powder to form ternary alloy so that tin is bounded to copper Sturdevant’s art and science of operative dentistry 5 th edi 45

46. 5 th Gen : Quaternary alloy that is silver ,tin, copper and indium. 6 th Gen : consisting of eutectic alloy containing silver(62%) , copper (28 %), palladium (10 %) which is lathe cut and blend into 1 st / 2 nd / 3 rd gen amalgam in ratio 1:2 Sturdevant’s art and science of operative dentistry 5 th edi 46

47. AMALGAMATION AND RESULTING MICROSTRUCTURE 47

48. Amalgamation is the process of reaction and setting when mercury is mixed / amalgamated with any alloy. Sturdevant’s art and science of operative dentistry 5 th edi 48 AMALGAMATION REACTION

49. Sturdevant art and science of operative dentistry 6 th edition 49 Silver tin phase γ Ag3Sn Silver mercury phase γ 1 Ag2Hg3 Tin mercury phase γ 2 Sn7-8Hg Copper tin phase ε Cu3Sn Copper tin phase η Cu6Sn5 Phases of Amalgam

50. 50 LOW COPPER CONVENTIONAL AMALGAM ALLOYS

51. 51

52. 52

53. 53

54. Material used in dentistry, Mahalaxmi chp 12 pg no.195-221. 54 Setting reaction Ag 3 Sn + Hg Ag 2 Hg 3 +Sn 7-8 Hg + Ag 3 Sn ( γ ) ( γ 1) ( γ 2) ( γ ) (unreacted)

55. Material used in dentistry, Mahalaxmi chp 12 pg no.195-221. 55 Conventional amalgam contain following component phases Gamma ( γ )phase ( Ag 3 Sn ): strongest phase occupy maximum available space in volume of restoration. Gamma-1 ( γ 1) phase : noblest phase most resistant to tarnish and corrossion .

56. Material used in dentistry, Mahalaxmi chp 12 pg no.195-221. 56 Gamma-2 ( γ 2)phase ( Ag 3 Sn ): weakest phase more prone to tarnish and corrosion. Mercury phase : weakest phase drastic drop in strength occurs if this phases exceeds a certain volume limit .

57. Material used in dentistry, Mahalaxmi chp 12 pg no.195-221. 57 Interphase: interphase between ( γ - γ 1) , ( γ 1- γ 2) , ( γ 2- γ ) The closer and continuous they are in final restoration, the better is the bonding . The resultant mass is more cohorent and more resistant to enviromental variables the restoration is subjected to.

58. In 1963 , Innes & Youdelis added spherical silver copper eutectic alloy These alloys are often called admixed alloys because the final powder is mixture of atleast 2 kinds of particles . Phillips science of dental material 11th edi chp 17 pg no. 505.. 58 HIGH COPPER ADMIXED ALLOY:

59. Amalgam made from this powder is stronger, because of, increase in residual alloy particle, and resultant decrease in matrix . There is elimination of gamma-2 phase , which is the weakest phase . Phillips science of dental material 11th edi chp 17 pg no. 505.. 59

60. Material used in dentistry, Mahalaxmi chp 12 pg no.195-221. 60 Setting reaction : Ag 3 Sn + Hg Ag 2 Hg 3 +Sn 7-8 Hg + Ag 3 Sn   ( γ ) ( γ 1 ) ( γ 2 ) ( γ ) (unreacted) Sn 7-8 Hg +Ag-Cu Cu 6 Sn 5 + Ag 2 Hg 3 + Ag 3 Sn ( γ 2 ) (eutectic) ( η ) ( γ 1 )   ( γ )

61. Material used in dentistry, Mahalaxmi chp 12 pg no.195-221. 61 Thus , in final set amalgam the γ 2 phase is eliminated . The γ 2 phase is replaced by η phase . The total copper content should be at least 12 % for this reaction to occur .

62. Unlike admixed alloy powders, each particle of these alloy has the same chemical composition. ε phase is added to provide additional copper When triturated with mercury , the silver and tin Ag-Sn phases dissolve in mercury whereas copper dissolve in negligible amount. Material used in dentistry, Mahalaxmi chp 12 pg no.195-221. 62 SINGLE- COMPOSITION ALLOY:

63. As γ 1 crystal grows , they form matrix that binds the partially dissolve particle together The ε phase is converted to η phase The reaction occur in a ring around the spherical particles The ring only consist of γ 1 & η The γ and ε remain in center of the ring. Material used in dentistry, Mahalaxmi chp 12 pg no.195-221. 63

64. Material used in dentistry, Mahalaxmi chp 12 pg no.195-221. 64 Setting reaction : Ag-Sn-Cu + Hg Ag 2 Hg 3 + Cu 6 Sn 5 + ( γ 1 ) ( η ) unconsumed alloy particles

65. PROPERTIES OF AMALGAM 65

66. ADA specification no. 1 for amalgam alloy contains certain requirement that aid significantly in controlling the qualities of amalgam. The specification list three physical properties as measure of quality of amalgam Strength Dimensional change Creep and flow Material used in dentistry, Mahalaxmi chp 12 pg no.195-221. 66

67. Stage I : Intial Contraction: Contraction which begins for about 20 minutes after beginning of trituration is called as intial contraction . Occurs as the alloy particles dissolve in mercury and γ 1 phase grow . Material used in dentistry, Mahalaxmi chp 12 pg no.195-221. 67 DIMENSIONAL CHANGE:

68. Stage II : Expansion As γ 1 phase grows – impingement and outward growt h of crystals occur—result expansion . Occurs when there is adequate mercury to provide plastic matrix. Material used in dentistry, Mahalaxmi chp 12 pg no.195-221. 68 DIMENSIONAL CHANGE:

69. Material used in dentistry, Mahalaxmi chp 12 pg no.195-221. 69 DIMENSIONAL CHANGE: Excessive Contraction Excessive Expansion Micro leakage Post operative sensitivity Secondary caries Pressure on pulp Post operative sensitivity Protrusion of restoration

70. ANSI/ADA Specification No 1 requires that amalgam neither to contract nor to expand more than 20 µm/cm , measured at 37°C , between 5 min and 24 hr after the beginning of trituration. Phillips science of dental material 11th edi chp 17 pg no. 508-10. 70

71. Particle size and shape: Smaller and regular particles – has more smooth surface area– mercury reacts faster – γ 1 phase grows faster— intial contraction (stage I) will occur rapidly and expansion(Stage II) also occur fast to neutralise the initial contraction . Material used in dentistry, Mahalaxmi chp 12 pg no.195-221. 71 FACTOR AFFECTING DIMENSIONAL CHANGE:

72. 2. Mercury: More mercury in amalgam mix– more expansion— stage II expansion prolonged Material used in dentistry, Mahalaxmi chp 12 pg no.195-221. 72 FACTOR AFFECTING DIMENSIONAL CHANGE:

73. 3. Manipulation: During trituration – more energy— particl e will become smalle r –mercury will be pushed between the particles — discouraging the expansion Material used in dentistry, Mahalaxmi chp 12 pg no.195-221. 73 FACTOR AFFECTING DIMENSIONAL CHANGE:

74. 3. Manipulation: More condensation pressure – closer the particle—more mercury is expressed ou t– inducing more contraction . Material used in dentistry, Mahalaxmi chp 12 pg no.195-221. 74 FACTOR AFFECTING DIMENSIONAL CHANGE:

75. 4.Moisture contaimination : Zinc containing low copper/ high copper alloy , which get contaiminated by moisture during manipulation – delayed expansion . Material used in dentistry, Mahalaxmi chp 12 pg no.195-221. 75 FACTOR AFFECTING DIMENSIONAL CHANGE:

76. Zn + H2O---- ZnO+H2 Complication Of Delayed Expansion: Protrusion of restoration out of the cavity Increase in microleakage . Increase in flow and creep Pain due to pressure exerted by expansion of amalgam Material used in dentistry, Mahalaxmi chp 12 pg no.195-221. 76

77. Dental amalgam is strong in compressive strength and weak in tensile strength . . Material used in dentistry, Mahalaxmi chp 12 pg no.195-221. 77 STRENGTH :

78. Hence if the thickness is inadequate , fracturing of this thin amalgam even in small area , especially at margins expedites corrosion, secondary caries, subsequent clinical failure . Material used in dentistry, Mahalaxmi chp 12 pg no.195-221. 78

79. Amalgam Compressive strength(MPa) 1hr 7 days Low copper 145 343 High copper admixed 137 431 High copper uni - compositional 262 510 Material used in dentistry, Mahalaxmi chp 12 pg no.195-221. 79 COMPRESSIVE STRENGTH : 1 hr CS is much less than half the final strength Patients are instructed not to use excessive masticatory forces for at least 6-8 hrs

80. Amalgam Tensile strength in 24 hrs (MPa) Low copper 60 High copper admixed 48 High copper uni - compositional 64 Material used in dentistry, Mahalaxmi chp 12 pg no.195-221. 80 TENSILE STRENGTH : Amalgam is a brittle material It cant undergo deformation or elongation on loading

81. Trituration: Both under trituration and over trituration decreases the compressive strength . Greater trituration energy – even distribution of matrix– results in improved strength of restoration. Material used in dentistry, Mahalaxmi chp 12 pg no.195-221. 81 FACTORS AFFECTING THE STRENGTH :

82. Trituration: If trituration continued even after formation of matrix – lead to crack formation – drop in strength of set amalgam. Material used in dentistry, Mahalaxmi chp 12 pg no.195-221. 82

83. 2. Mercury content : The strength of amalgam depends upon each particles being wetted by mercury. If mercury too less—dry ,granular mix , rough , pitted surface that invites corrosion . Material used in dentistry, Mahalaxmi chp 12 pg no.195-221. 83

84. 2. Mercury content : Any excess mercury - formation of weaker matrix –affect the compressive strength. If mercury content of amalgam mix is more than 53-55% --- drop in compressive strength by 50 % Material used in dentistry, Mahalaxmi chp 12 pg no.195-221. 84

85. 3. Effect of condensation: Condensation pressure and technique – depends on shape of alloy particles. Material used in dentistry, Mahalaxmi chp 12 pg no.195-221. 85

86. 3. Effect of condensation: For lathe cut alloys – more pressure is required to pack compactly -- minimize the porosity—express excess mercury to surface -- higher compressive strength. Material used in dentistry, Mahalaxmi chp 12 pg no.195-221. 86

87. 3. Effect of condensation: For spherical particles much lighter condensation pressure is required– as spherical particles tend to slip under heavy pressure – hence cannot be compacted properly . Material used in dentistry, Mahalaxmi chp 12 pg no.195-221. 87

88. 4. Effect of porosity: Weak areas of restoration –decreases strength of restoration. Porosity facilitates: Stress concentration Propogation of cracks Corrosion Material used in dentistry, Mahalaxmi chp 12 pg no.195-221. 88

89. Porosity can be due to : Under trituration Particle shape(lathe-cut) Insertion of too large increments Inadequate condensation pressure Material used in dentistry, Mahalaxmi chp 12 pg no.195-221. 89

90. 5. Particle size: Smaller particle size – greater will be strength. Material used in dentistry, Mahalaxmi chp 12 pg no.195-221. 90

91. 6. Temperature : Amalgam loses 15% of its strength when temperature is elevated from room temperature to mouth temperature. Loses 50 % of strength when temperature elevates 60 °C . Material used in dentistry, Mahalaxmi chp 12 pg no.195-221. 91

92. Time dependent strain or deformation that is produced by a stress. ANSI/ADA Specification No. 1 specified that creep rate below 3%. Phillips science of dental material 11th edi chp 17 pg no. 515-16. 92 CREEP :

93. Phases of amalgam restoration: High creep rates are associate with γ 2 in low copper alloy and γ 1 in high copper alloy. Material used in dentistry, Mahalaxmi chp 12 pg no.195-221. 93 FACTORS INFLUENCING CREEP Amalgam Creep(%) Low copper 2.0 Admix 0.4 Single composition 0.13

94. CLINICAL SIGNIFICANCE: Reduce creep rate is asociate with : Low mercury: alloy ratio Increased trituration time Greater condensation pressure On non occlusal surface – restoration appear to be extruded – producing esthetic problems /over hangs . Sturdevants art and science of operative dentistry 6 th edi chp 13 pg no.347 94

95. CLINICAL SIGNIFICANCE: On occlusal surface- Occlusal margins become fracture- susceptible Ledges elevates above the natural contour of adjacent enamel. Sturdevants art and science of operative dentistry 6 th edi chp 13 pg no.347 95

96. INDICATIONS & CONTRA -INDICATIONS OF AMALGAM 96

97. Class I, II, V restoration Caries-control restoration As a foundation for cast-metal, metalceramic , and ceramic restorations, When patient commitment to personal oral hygiene is poor When cost is an overriding patient concern Sturdevants art and science of operative dentistry 6 th edi chp 13 pg no.342-43 97 INDICATIONS OF AMALGAM

98. Sometimes can be used for cuspal restorations (with pins usually). As a core build-up material prior to cast restoration . As a retrograde filling material . As a die material. Sturdevants art and science of operative dentistry 6 th edi chp 13 pg no.342-43 98

99. Pt allergic to alloy component. Esthetic areas of tooth. Class III & IV restorations. Sturdevants art and science of operative dentistry 6 th edi chp 13 pg no.342-43 99 CONTRA -INDICATIONS OF AMALGAM

100. ADVANTAGES & DISADVANTAGES OF AMALGAM 100

101. Restoration is completed within one sitting without requiring much chair time. Well-condensed and triturated amalgams have good compressive strengths . 101 ADVANTAGES OF AMALGAM

102. Least technique sensitive of all restorative material. Good l ong-term clinical performance Ease of manipulation by dentist Economical . 102

103. • Poor esthetic qualities • Long-term corrosion at tooth-restoration interface may result in ditching leading to replacement. • Galvanic response potential exists • Local allergic potential • Concern about possible mercury toxicity • Marginal breakdown 103 DIS-ADVANTAGES OF AMALGAM

104. Metallic taste and Galvanic shock. • Marginal leakage. • Discoloration of the tooth structure. • Lack of chemical or mechanical adhesion to the tooth structure. 104

105. • High rate of secondary caries. • Thermal conductivity. • Promotes plaque adhesion. • Delayed expansion 105

106. MANIPULATION 106

107. Selection of alloys Mode of supply Proportioning of mercury to Alloy Trituration Condensation Pre carve Burnishing Carving the amalgam restoration Post carve Burnishing Finishing Amalgam Restoration Polishing Material used in dentistry, Mahalaxmi chp 12 pg no.195-221. 107 MANIPULATION

108. To enable the clinician to select the appropriate silver amalgam material ,for a particular clinical situation, difference between various silver alloys must be considered. Material used in dentistry, Mahalaxmi chp 12 pg no.195-221. 108 SELECTION OF ALLOY

109. Low copper Amalgamation requires more mercury γ 1 phase is dominant Corrossion due to γ 2 phase Creep value is high(1-8%) Low compressive strength Marked dimensional change High copper Less mercury is required for amalgamation Dominant η phase η phase least corrosion-resistant phase. Very low creep value(0.1-1%) High compressive strength Minimal dimensional change 109

110. Lathe cut Alloy particle have irregular shape Manufactured by lathe cutting a ingot More Hg for mixing Poor mechanical properties Mix is less plastic Heavy condensation pressure is required Spherical Spherical smooth surface Manufactured by process called as atomization Require less mercury Better mechanical properties Mix is more plastic Less condensation pressure 110

111. Admixed Cu: 9-20% WT is longer & sets slow High condensation pressure High Hg content in final set amalgam Low early strength Creep is higher Difficult to finish Spherical Cu : 13-30% WT is less & sets faster Low condensation pressure Low Hg content in final set amalgam High early strength Creep is low Easy to finish 111

112. Alloy powder and mercury Disposable capsule with pre-proportioned alloy powder and mercury Pre-weighted alloy in tube form and mercury in sachets Material used in dentistry, Mahalaxmi chp 12 pg no.195-221. 112 MODE OF SUPPLY

113. Material used in dentistry, Mahalaxmi chp 12 pg no.195-221. 113 PROPORTIONING OF MERCURY TO ALLOY Historical background: Hand trituration using conventional alloys , required a mercury/alloy ratio of 8:5. After trituration the excess mercury was squeezed from mix by hand exposing operator to risk. Increase in proportion of gamma 2 phase producing a weaker restoration that was prone to corrosion .

114. Material used in dentistry, Mahalaxmi chp 12 pg no.195-221. 114 PROPORTIONING OF MERCURY TO ALLOY Current recommendation: Intial mercury content between 50-55 % is still recommended where modern lathe cut alloy is used. Spherical alloy require less mercury for amalgamation as low as 40 %.

115. Material used in dentistry, Mahalaxmi chp 12 pg no.195-221. 115 BY WEIGHT: CRESCENT AND ASH BALANCE BY VOLUME: BAKER PROPORTIONER

116. Material used in dentistry, Mahalaxmi chp 12 pg no.195-221. 116 MODERN ENCAPSULATED ALLOY AND MERCURY WITH PRESS

117. Contain little more mercury than needed for powder. Continue squeezing of mercury is necessary. Each increments dryer than previous one. Equal amount of mercury and alloy powder. Operative Dentistry Modern Theory and Practise . Marzouk chp 4 111-12. 117 PROPORTIONING OF MERCURY TO ALLOY High mercury technique/increasing dryness technique Minimal mercury technique/ E ames technique

118. The purpose of trituration is to mix the amalgam alloy intimately with mercury so as to wet the surface of powder particles to allow reaction between liquid mercury and silver alloy . Operative Dentistry Modern Theory and Practise . Marzouk chp 4 111-12. 118 TRITURATION

119. Objectives of trituration: Workable mass of amalgam Remove oxides from powder particle. To reduce particle size. To dissolve the particles. Operative Dentistry Modern Theory and Practise . Marzouk chp 4 111-12. 119 TRITURATION

120. A Pestle and mortar employed hand trituration. Surface texture of mortar and pestle should be roughened to maximize the friction between amalgam and glass surface. Material used in dentistry, Mahalaxmi chp 12 pg no.195-221. 120 HAND TRITURATION

121. Mechanical trituration of encapsulated alloy and mercury allows a precise , reproducible technique and minimizes a risk of mercury contamination. Three basic movements : Back and forth in straight line . Back and forth in figure 8 . Centrifugal fashion. Operative Dentistry Modern Theory and Practise . Marzouk chp 4 112-13. 121

122. A capsule serves as a mortar. A cylindrical metal or plastic piston of smaller diameter than the capsule is inserted into the capsule, and this serves as the pestle . Silver amalgam in clinical practise 3 rd edition chp 6 pg 105 to 126 122

123. A continuation of trituration. Improve homogeneity. Assure consistent mix. Achieve a single, consistent coherent mass. Operative Dentistry Modern Theory and Practise . Marzouk chp 4 113. 123 MULLING

124. The mix is placed in a dry piece of rubber dam and vigorously rubbed between first finger and thumb . This process should not exceed 2-5 seconds. Operative Dentistry Modern Theory and Practise . Marzouk chp 4 113. 124

125. After mechanical trituration , the pestle can be removed from capsule and the mix is triturated at low speed for 2-3 sec to achieve mulling This process allows cleaning of capsule Operative Dentistry Modern Theory and Practise . Marzouk chp 4 113. 125

126. Under Triturated: Appears rough, grainy, may crumble easily Outer surface of alloy particles is not completely wetted by mercury. Increases working time More porosity Low strength and corrosion resistance. Operative Dentistry Modern Theory and Practise . Marzouk chp 4 113. 126

127. Normal mix: Appears shiny and has a smooth surface and consistency. Operative Dentistry Modern Theory and Practise . Marzouk chp 4 113. 127

128. Over triturated: Soupy, difficult to remove from capsule & too plastic to manipulate. Decreases working time Higher contraction with trituration Decrease the strength Increases creep. Operative Dentistry Modern Theory and Practise . Marzouk chp 4 113. 128

129. The condensation of amalgam mass into tooth cavity is most important steps in amalgam restoration. Material used in dentistry, Mahalaxmi chp 12 pg no.195-221. 129 CONDENSATION OF AMALGAM

130. To adapt the plastic mix to cavity walls and margins . To squeeze the unreacted mercury out of increments thereby preventing entrapment of mercury. Material used in dentistry, Mahalaxmi chp 12 pg no.195-221. 130 OBJECTIVES OF CONDENSATION:

131. To bring the strongest phase of amalgam close together thereby increasing the final strength of restoration. To reduce the number of voids and keep matrix continuous. Material used in dentistry, Mahalaxmi chp 12 pg no.195-221. 131

132. Careful condensation of amalgam will force alloy particles together, force mercury –rich material to the surface of each increment , facilitated bonding of successive layers and ultimately allow removal of excess mercury. Silver amalgam in clinical practise 3 rd edition chp 6 pg 105 to 126 132

133. Lathe cut alloys require higher mercury content for proper amalgamation Hence , greater forces of condensation is required to remove excess mercury. With spherical alloy, initial mercury is lower, the lower condensation pressure is required Material used in dentistry, Mahalaxmi chp 12 pg no.195-221. 133

134. Rupp , Paffenbarger and Patel (1980 ) Reported “If a delay occurs between condensation and trituration , less mercury can be removed from restoration , strength may be reduced and more creep may result. ” Mosteller (1950) “Set the maximum time limit for safe condensation at 3 mins.” Silver amalgam in clinical practise 3 rd edition chp 6 pg 105 to 126 134

135. Ryge et al (1952) demonstrated that method of mechanical condensation may reduce setting time and increase the compressive strength of restoration. Silver amalgam in clinical practise 3 rd edition chp 6 pg 105 to 126 135

136. Ryge et al (1952) commented that better results will be obtained using either hand or mechanical condensation if multiple small increments are applied . Silver amalgam in clinical practise 3 rd edition chp 6 pg 105 to 126 136

137. Three types: Hand condensation Mechanical condensation Ultrasonic condensation Silver amalgam in clinical practise 3 rd edition chp 6 pg 105 to 126 137

138. Amalgam carrier is use to carry increments of alloy and inserted into cavity. Increment should be as small at a time while condensing , to avoid porous and weak restoration. Material used in dentistry, Mahalaxmi chp 12 pg no.195-221. 138 HAND CONDENSATION

139. Condensing unit is generally contra angled with serrated ends. Most of cavities round condenser is used Parallelogram and oval are more effective in gingival point angles . Material used in dentistry, Mahalaxmi chp 12 pg no.195-221. 139

140. Tip size should be small when lathe cut alloys are condensed . For spherical alloys, larger tipped condensers are used, since smaller tips tend to slip and spherical particles roll over one another. Material used in dentistry, Mahalaxmi chp 12 pg no.195-221. 140

141. SPHEROIDING Ramsay (1941) referred to the spheroiding of amalgam at sharp line angles. To overcome this, line angles be rounded use of small instrument tips of contour suited to the anatomy of line angle is recommended Silver amalgam in clinical practise 3 rd edition chp 6 pg 115

142. The area of the condenser point, or face, and the force exerted on it by the operator govern the condensation pressure (force per unit area ). Forces in the range of 13.3 to 17.8 N (3 to 4 lb ) represent the average force employed. Silver amalgam in clinical practise 3 rd edition chp 6 pg 105 to 126 142

143. To ensure maximum density and adaptation to the cavity walls, the condensation force should be as great as the alloy will allow, consistent with patient comfort. Material used in dentistry, Mahalaxmi chp 12 pg no.195-221. 143

144. Condensation usually starts from the center of cavity and 45° to walls and floor for non spherical amalgam. Subsequently , condensation should be done 90° to displacement of primary increment. The increments are added till the cavity is overfilled. Material used in dentistry, Mahalaxmi chp 12 pg no.195-221. 144

145. After this, the amalgam mix is is condensed heavily using largest condenser possible This is called blotting mix. It serves to blot excess mercury from the margin and surface of restoration and to adapt amalgam more intimately to cavosurface anatomy. Material used in dentistry, Mahalaxmi chp 12 pg no.195-221. 145

146. Mechanical Condensation The procedures and principles of mechanical condensation are the same as those for hand condensation, including the need to use small increments of amalgam The only difference is that the condensation of the amalgam is performed by an automatic device . Some provide an impact type of force , whereas others use rapid vibration . Phillips science of dental material 11 th edi pg no.530. 146

147. Burnishing is defined as plastic deformation of surface due to rubbing / sliding the contact with another object. Material used in dentistry, Mahalaxmi chp 12 pg no.195-221. 147 PRE-CARVE BURNISHING

148. Burnishing the amalgam immediately after condensation has been used in an attempt to increase the packing of particles at surface and reduce the final mercury content of restoration. Restoration with pre carve burnishing were superior to those unburnished in terms of marginal adaptation. Material used in dentistry, Mahalaxmi chp 12 pg no.195-221. 148

149. Immediately after condensation a large round burnisher is used in light strokes from restoration towards cavosurface margins. Beaver tail burnisher is used in inaccessible areas such as proximal surface of restoration Material used in dentistry, Mahalaxmi chp 12 pg no.195-221. 149

150. Objectives Of Pre Carve Burnishing: To improve marginal adaptation of amalgam To reduce the number of voids present at the surface To bring any further excess mercury on the surface which can be removed during carving. To condition the amalgam surface to the carving procedure. Material used in dentistry, Mahalaxmi chp 12 pg no.195-221. 150

151. The carving procedure should be delayed until the surface offer resistance to instrumentation. A particular “squeaking”(amalgam crying) sound elicited from the surface. A sharp instrument is used to carve along the amalgam/enamel junction. Silver amalgam in clinical practise 3 rd edition chp 6 pg 105 to 126 151 CARVING THE AMALGAM RESTORATION

152. No underhangs Physiologic contour Compatible marginal ridges. Proper contacts Amenable for plaque control Silver amalgam in clinical practise 3 rd edition chp 6 pg 105 to 126 152 OBJECTIVES OF CARVING :

153. 3 stages: Initial carving of accessible areas Second involves occlusal re-assessment and adjustment. Third stage defines the final occlusion form. Silver amalgam in clinical practise 3 rd edition chp 6 pg 105 to 126 153 OCCLUSAL CARVING

154. Incorrect technique-from amalgam to enamel Incorrect technique –from enamel to amalgam Correct technique - blade resting on both enamel and amalgam

155. The main purpose is to render the smooth surface, discourage corrosion. Post carve burnishing may reduce the size of marginal gap around restoration and also reduces the early micro-leakage . (Ben-Amar et al,1987). Silver amalgam in clinical practise 3 rd edition chp 6 pg 105 to 126 155 POST-CARVE BURNISHING

156. The process which continues the carving objectives , remove flash, overhangs, and surface irregularities. Silver amalgam in clinical practise 3 rd edition chp 6 pg 105 to 126 156 FINISHING AMALGAM RESTORATION

157. Polishing is the process that removes the scratches and irregularities from the surface of restoration leaving , smooth high glazed surface that is corrosion resisitant . Silver amalgam in clinical practise 3 rd edition chp 6 pg 105 to 126 157 POLISHING

158. FAILURE OF AMALGAM RESTORATION 158

159. Fracture lines: -Visible on occlusal surface especially in the isthmus region Marginal ditching: -Is the breakdown of the amalgam at the margins due to wear, fracture or improper cavosurface margins

160. Proximal overhangs: -Can be confirmed clinically or radiographically or by tearing of dental floss when passed through interproximal contacts. -Constitute failure as they produce gingival inflammation

161. Poor anatomic contours: -Inadequate embrasure form, flat contours are defects which require replacement Marginal ridge incompatibility: -Results in poor occlusal embrasure form and improper clearance of food leading to food impaction and periodontal disease Improper proximal contacts: -Improper restorations may cause open contact resulting into food impaction and periodontal problems

162. Recurrent caries: -Presence of fractures or marginal gaps indicate recurrent caries -Probing with explorer and radiographic examination helps in diagnosis. Amalgam blues: -Seen as bluish hue through a thin enamel shell -Due to leaching of corrosion products into dentinal tubules

163. Voids: -May be present at the margins due to improper condensation -Possess a risk of secondary caries especially in areas like gingival seat. Bulk fracture of tooth or amalgam: -Bulk fracture of tooth is a sign of lack of resistance form while bulk fracture of amalgam indicates lack of retention form.

164. Poor occlusal contacts: -Lack of occlusal contacts can produce improper occlusal functioning and undesirable tooth movement

165. Improper case selection Improper cavity preparation Inadequate extensions Over extended cavity preparations Shallow cavity preparations Deep cavity preparations Curved pulpal floor 165 REASON FOR FAILURE OF RESTORATION

166. Wide isthmus Narrow isthmus Sharp axiopulpal line angle Lack of butt joint at the cavosurface margins Lack of occlusal convergence Improper convenience form 166

167. Errors in matricing procedures and restoration Unstable matrix Poor contour Absence of wedge 167

168. Postoperative factors Postoperative pain or sensitivity Premature fracture 168

169. POST OPERATIVE PAIN Hyperocclusion leading to inflammation of apical periodontium Cracks in tooth such cracks cause pain during chewing because of expansion or contraction of tooth structure with every bite Galvanism: may be due to dissimilar adjacent metal restoration or poorly condensed amalgam due to variation in silver concentration Delayed expansion

170. Inadequate pulp protection leading to conduction of heat Varnish should be applied under amalgam restoration to avoid leakage around restoration which may lead to post operative sensitivity and amalgam blues due to penetration of corrosion products into dentinal tubules Restoration fracture may occur if patient does not follow instruction properly and bites on restoration before it sets

171. FROM THE MATERIAL SIDE Micro leakage: Percolation of oral fluids Dimensional change Depends on residual mercury contraction and expansion May even cause pain

172. It is the surface discoloration on metallic surface without any loss of structure. In low copper amalgam γ phase is responsible In high copper alloy η phase is responsible Material used in dentistry, Mahalaxmi chp 12 pg no.195-221. 172 TARNISH

173. It is the chemical or electrochemical reaction of metal with its environment and progressive destruction by formation of corrosive byproducts. In low copper alloy : Sn 7-8 Hg +1/2 O2+H2O + Cl --------- Sn4(OH)6Cl2 + Hg (tin oxychloride) Material used in dentistry, Mahalaxmi chp 12 pg no.195-221. 173 CORROSION

174. In high copper alloy : Cu6Sn5+1/2 O2+H2O + Cl ---CuCl2.3Cu(OH)2 + SnO . Material used in dentistry, Mahalaxmi chp 12 pg no.195-221. 174 CORROSION

175. As a result of the corrosion reaction , mercury is released. This released mercury then reacts with unreacted γ particles and produce additional γ 1 & γ 2 phases , resulting in expansion This results in porosity and reduction in strength of restoration . Material used in dentistry, Mahalaxmi chp 12 pg no.195-221. 175 MERCUROSCOPIC EXPANSION

176. . Sturdevants art and science of operative dentistry 6 th edi chp 13 pg no.346 176 ELECTROCHEMICAL CORROSION

177. Galvanic corrosion: Dental amalgam is in direct contact with an adjacent metallic restoration such as gold crown As a result of large difference in electromotive forces (EMF) of two materials . The corrosion process can liberate free mercury, which can contaminate and weaken gold restoration . Phillips science of dental material 11th edi chp 17 pg no. 517-19.. 177 TYPES OF CORROSION:

178. Crevice Corrosion: Local electrochemical cells may arise whenever a portion of amalgam is covered by plaque on soft tissue . The covered area has a lower oxygen and higher hydrogen ion concentration making it behave anodically and corrode . Phillips science of dental material 11th edi chp 17 pg no. 517-19.. 178

179. Stress Corrosion: Regions within the dental amalgam that are under stress display a greater probability for corrosion, thus resulting in stress corrosion. For occlusal dental amalgam greatest combination of stress and corrosion occurs along the margins. . Phillips science of dental material 11th edi chp 17 pg no. 517-19.. 179

180. CLINICAL SIGNIFICANCE: Amalgam has linear co efficient of thermal expansion 2.5 times greater than tooth structure. During expansion and contraction percolation occurs along the external walls Sturdevants art and science of operative dentistry 6 th edi chp 13 pg no.346 180

181. Percolation owes to difference intra oral temperature changes . Sturdevants art and science of operative dentistry 6 th edi chp 13 pg no.346 181

182. SIDE EFFECTS OF MERCURY 182

183. The amalgam restorations possible only because of the unique characteristics of mercury. The use of mercury in the oral environment has raised concerns regarding safety for more than 170 yrs. To understand the possible side effects of dental amalgam, the differences between allergy and toxicity must be discussed. Material used in dentistry, Mahalaxmi chp 12 pg no.195-221. 183 SIDE – EFFECT OF MERCURY

184. Typically , allergic responses represent an antigen-antibody reaction marked by Itching Rashes Swelling Phillips science of dental material 11th edi chp 17 pg no. 535-40.. 184 ALLERGY

185. Contact dermatitis or Coombs Type IV hypersensitivity reactions represent the most likely physiologic side effect to dental amalgam, but these reactions are experienced by less than 1 % of the treated population. Phillips science of dental material 11th edi chp 17 pg no. 535-40.. 185 ALLERGY

186. Normal daily intake of mercury is 15µg fro m food 1µg from air 0.4 µg from water . Maximum allowable limit of mercury in blood is 3µg Material used in dentistry, Mahalaxmi chp 12 pg no.195-221. 186 TOXICITY

187. Mercury from dental amalgam is released in the form of vapors and ions Mercuric ions are released from corrosion. Material used in dentistry, Mahalaxmi chp 12 pg no.195-221. 187 MERCURY EXPOSURE IN DENTISTRY

188. The amalgam restoration may release mercury in range 1-3µg/day. The released mercury is greater for low copper amalgam than high copper amalgam Material used in dentistry, Mahalaxmi chp 12 pg no.195-221. 188 MERCURY EXPOSURE IN DENTISTRY

189. Minamata disease is methylmercury ( MeHg ) poisoning that occurred in humans who ingested fish and shellfish contaminated by MeHg discharged in waste wat er from a chemical plant . . Minamata disease: methylmercury poisoning in Japan caused by environmental pollution. Crit Rev Toxicol . 1995;25(1):1-24 189 MINAMATA DISEASE:

190. Symptoms : Sensory disturbances (glove and stocking type), ataxia, dysarthria, constriction of the visual field, auditory disturbances and tremor were also seen. . Minamata disease: methylmercury poisoning in Japan caused by environmental pollution. Crit Rev Toxicol . 1995;25(1):1-24 190

191. Urinary mercury levels (µg) Symptoms Up to 25 No side effects 100 Decrease brain activity with verbal skills 500 Irritability, depression, memory loss,early symptom ofdisturbed kidney function. 1000 Kidney inflammation. Swollen gums, excessive tremors 2000 Joint pain 4000 Hearing loss and death. . Minamata disease: methylmercury poisoning in Japan caused by environmental pollution. Crit Rev Toxicol . 1995;25(1):1-24 191

192. 192 AMALGAM WASTE MANAGEMENT

193. Current limit of mercury vapor established by OSHA is 50µg/m 3 in any 8 hour work shift over 40 – hours work week . Material used in dentistry, Mahalaxmi chp 12 pg no.195-221. 193 AMALGAM WASTE MANAGEMENT

194. Well ventilated. Well-sealed containers. Proper disposal through reputable dental vendors is mandatory to prevent environmental pollution . Phillips science of dental material 11th edi chp 17 pg no. 535-40.. 194 AMALGAM WASTE MANAGEMENT

195. Increasing legal attention is being focused on correct disposal of potentially hazardous waste materials, including dental amalgams and mercury. Amalgam scrap and materials contaminated with mercury or amalgam should no t be incinerated or subjected to heat sterilization . Phillips science of dental material 11th edi chp 17 pg no. 535-40.. 195

196. If mercury is spilled, it must be cleaned up as soon as possible. Mercury suppressant powders are helpful, but these should be considered temporary measures . Phillips science of dental material 11th edi chp 17 pg no. 535-40.. 196

197. REPAIRED AMALGAM RESTORATIONS 197

198. Occasionally, when an amalgam restoration fails, as from marginal fracture , it is repaired. A new mix of amalgam is condensed against the remaining part of the existing restoration. Phillips science of dental material 11th edi chp 17 pg no. 540 .. 198 REPAIRED AMALGAM RESTORATIONS

199. Thus the strength of the bond between the new and the old amalgam is important . The strength of repaired amalgam is less than 50% of that of unrepaired amalgam . Phillips science of dental material 11th edi chp 17 pg no. 540 .. 199

200. The bond is a source of weakness . Factors such as corrosion and saliva contamination at the interface present formidable barriers that interfere with bonding of the old and new ,amalgam. Phillips science of dental material 11th edi chp 17 pg no. 540 .. 200

201. Another repair option for areas that exhibit minor marginal breakdown (i.e., gaps that are 250 µm in width) is to etch the enamel adjacent to the restoration and, after rinsing and drying the marginal gap area, sealing the gap with a dentin bonding adhesive . However , minimal scientific evidence is available to prove that this procedure can prevent secondary caries . Phillips science of dental material 11th edi chp 17 pg no. 5 40 .. 201

202. AMALGAM TATTOO 202

203. Amalgam tattoo is an iatrogenic lesion caused by traumatic implantation of dental amalgam into soft tissue. . Amalgam tattoo of the oral mucosa: clinical manifestations, diagnosis and treatment . Refuat Hapeh Vehashinayim ( 1993 ) 2004 Apr;21(2):19-22, 96. 203 AMALGAM TATTOO

204. Amalgam tattoo is the most common localized pigmented lesion in the mouth . Clinically , amalgam tattoo presents as a dark gray or blue , flat macule located adjacent to a restored tooth . . Amalgam tattoo of the oral mucosa: clinical manifestations, diagnosis and treatment . Refuat Hapeh Vehashinayim ( 1993 ) 2004 Apr;21(2):19-22, 96. 204 AMALGAM TATTOO

205. Most are located on the gingiva and alveolar mucosa followed by the buccal mucosa and the floor of the mouth. Microscopic examination reveals that amalgam is present in the tissues in two forms : A s irregular dark, solid fragments of metal or as numerous, discrete fine, brown or black granules dispersed along collagen bundles and around small blood vessels and nerves. . Amalgam tattoo of the oral mucosa: clinical manifestations, diagnosis and treatment . Refuat Hapeh Vehashinayim ( 1993 ) 2004 Apr;21(2):19-22, 96. 205

206. RECENT ADVANCES 206

207. Gallium based alloy Consolidated silver alloy system Indium containing alloy powder Fluoride containing amalgam Bonded amalgam Cermet Miracle mixture 207 RECENT ADVANCES

208. As early as 1956, Smith and coworkers claimed that a gallium based alloy could serve as a possible alternative to dental amalgam . They found that mixing gallium with either nickel or copper and tin produced a pliable mass that could be condensed into a prepared cavity, which, after setting , had physical properties suitable for a restorative material. Dental amalgam: An update J Conserv Dent. 2010 Oct-Dec13(4): 204–208. 208 GALLIUM BASED ALLOY:

209. It uses a fluoro boric acid solution to keep the surface of the silver alloy particles clean . The alloy, in a spherical form, is condensed into a prepared cavity in a manner similar to that for placing compacted gold. Dental amalgam: An update J Conserv Dent. 2010 Oct-Dec 13(4): 204–208. 209 CONSOLIDATED SILVER ALLOY SYSTEM

210. One problem associated with the insertion of this material is that the alloy strain hardens , so it is difficult to compact it adequately to eliminate internal voids and to achieve good adaptation to the cavity without using excessive force Dental amalgam: An update J Conserv Dent. 2010 Oct-Dec 13(4): 204–208. 210

211. Powel et al (1989) added indium powder into dispersed phase of high copper alloy and triturate with mercury. They found significant difference in mercury evaporation from amalgam. These were marketed as “ Indisperse ” & “ Indiloy ” 211 INDIUM CONTAINING ALLOY POWDER Dental amalgam: An update J Conserv Dent. 2010 Oct-Dec 13(4): 204–208.

212. Fluoride, being cariostatic , has been included in amalgam to deal with the problem of recurrent caries associated with amalgam restorations . Several studies concluded that a fluoride containing amalgam may release fluoride for several weeks after insertion of the material in mouth. Dental amalgam: An update J Conserv Dent. 2010 Oct-Dec 13(4): 204–208. 212 FLUORIDE CONTAINING AMALGAM

213. As an increase of up to 10–20fold in the fluoride content of whole saliva could be measured,the fluoride release from this amalgam seems to be considerable during the first week. Dental amalgam: An update J Conserv Dent. 2010 Oct-Dec 13(4): 204–208. 213

214. An anti-cariogenic action of fluoride amalgam could be explained by its ability to deposit fluoride in the hard tissues around the fillings and to increase the fluoride content of plaque and saliva, subsequently affecting remineralization. Dental amalgam: An update J Conserv Dent. 2010 Oct-Dec 13(4): 204–208. 214

215. In recent times, adhesive resins have been employed to bond amalgam restorations to tooth surface The objective is to cause Intermingling of amalgam and bonding resin BONDED AMALGAM RESTORATIONS

216. Indications: Extensive caries in posterior teeth when cast restorations cannot be done Teeth with short clinical crown height when inlays or onlays or pin retained amalgam restorations are not possible Foundations for full crown restorations

217. MECHANISM OF BONDING: In bonded amalgam restorations, the bonding interface consists of tooth-adhesive resin-amalgam The mode of retention is by micromechanical means due to microscopic projections of the resin into the amalgam

218. ADVANTAGES: Allows conservative tooth preparation Reinforces the remaining tooth structure Better marginal seal More cost effective DISADVANTAGES: Technique sensitive Incorporation of resin into amalgam can lower down its mechanical properties Long term durability of the bond between amalgam and tooth is not well known

219. This system consists of - physically blending of silver alloy powder with the glass powder in the ratio of 1:7 - Glass ionomer liquid ADVANTAGES: - Increase in strength - Increase in abrasion resistance SILVER ALLOY ADMIX GLASS IONOMER CEMENT

220. A glass ionomer cement that has been reinforced with filler particle prepared by fusing silver particle to glass. Radiopaque and grayish in color Used as an alternative to amalgam and composite for posterior restoration. Dental amalgam: An update J Conserv Dent. 2010 Oct-Dec 13(4): 204–208. 220 CERMET

221. CONCLUSION 221

222. Amalgam restorations have served the profession well and will continue to do so in the years to come. In terms of longevity , they are probably superior to composite resins, especially when used for large restorations and cusp capping . The new high copper single composition alloys offer superior properties. 222

223. The use of amalgam can be continued as a material of choice if esthetics is not a concern. 223

224. Phillips science of dental material 11th edi chp 17 . Silver amalgam in clinical practise 3 rd edition chp 6 Sturdevants art and science of operative dentistry 6 th edi chp 13 Craig’s restorative dental materials 13 th edi.chp10 224 REFERENCES

225. Material used in dentistry, Mahalaxmi chp 6, 12 ,13 . Operative dentistry modern theory and practise 1 st edi chapter 4. Bharti R, Wadhwani KK, Tikku A, Chandra A.Dental amalgam: An update J Conserv Dent. 2010 Oct-Dec;13(4): 204–208 . . Amalgam tattoo of the oral mucosa: clinical manifestations, diagnosis and treatment. Refuat Hapeh Vehashinayim (1993) 2004 Apr;21(2):19-22, 96 . 225

226. 226 THANK YOU