Amalgam
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This document provides information on dental amalgam, including: - A brief history noting amalgam has been used for over 150 years and was originally made by filing silver coins and mixing with mercury. - The components and microstructure of amalgam, including how it is composed of a mixture of silver/tin/copper alloy and mercury that amalgamates during manipulation. - The classification, properties, manipulation techniques, indications and contraindications for amalgam restorations. - Potential failures of amalgam restorations and their causes, as well as precautions needed due to mercury toxicity.
Amalgam
- 1. AMALGAM ABDULLA ASSAN ABDULLA 4th batch R.D.C
- 2. DEFINITION Dental amalgam is a metal like restorative material composed of a mixture of silver/tin/copper alloy and mercury.
- 3. HISTORY Amalgam has been primary restorative material for more than 150 yrs. Initially, amalgam restorations were made by dentists filing silver coins and mixing the filings with mercury. This was made to a putty like mass that was placed into the defective tooth.
- 4. USES AS CLASS 1,2,5 RESTORATION. AS FOUNDATION- IN COMBINATION WITH RETENTIVE PINS TO RESTORE CROWN. FOR MAKING DIES. FOR RETROGRADE ROOT CANAL FILLING. AS CARIES CONTROL RESTORATION.
- 5. Components of dental amalgam 1)Amalgam alloy 2)Mercury
- 7. Classification of dental amalgam alloys BASED ON Cu CONTENT HIGH Cu ALLOYS LOW Cu ALLOYS > 6% Cu < 6% Cu ADMIXED REGULAR UNICOMPOSITION SINGLE COMPOSITION
- 8. BASED ON Zn CONTENT Zn CONTAINING Zn FREE ALLOY > 1% Zn < 1% Zn
- 9. BASED ON SHAPE OF ALLOY LATHECUT SPHERICAL ADMIXED
- 10. BASED ON NUMBER OF ALLOY METAL BINARY TERTIARY QUATERNARY Ag,Sn Ag,Sn,Cu Ag,Sn,Cu,Zn
- 11. BASED ON SIZE OF ALLOY MICROCUT FINE CUT MACROCUT COURSE CUT
- 12. MANUFATURE OF ALLOY POWDER 1)LATHECUT ALLOY POWDER 2)SPHERICAL ALLOY POWDER
- 13. COMPARISON OF LATHECUT WITH ATOMIZED SPHERICAL POWDER AMALGAM FROM LATHECUT ADMIXED POWDER,TEND TO RESIST CONDEN-SATION BETTER THAN AMALGAM MADE ENTIRELLY FROM SPHERICAL POWDER. AMALGAM OF SPHERICAL POWDER ARE VERY PLASTIC- CANNOT RELY ON PRESSURE OF CONDENSATION TO ESTABLISH PROXIMAL CONTOUR. SPHERICAL ALLOYS REQUIRE < Hg THAN LATHECUT ALLOY DUE TO SMALL SURFACE AREA PER VOLUME . AMALGAM WITH LOW Hg CONTENT –BETTER PROPERTIES.
- 16. COMPOSITION
- 17. COMPOSITION Low Copper: Silver - 63-70% Tin - 26-29% Copper - 2-5% Zinc – 0-2%
- 18. Admixed: Silver – 40-70% Tin - 26-30% Copper-13-30% Zinc - 0-1%
- 19. Unicompositional : Silver- 40-60% Tin - 22-30% Copper-13-30% Zinc -0%
- 20. FUNCTION OF EACH CONSTITUENT SILVER:- MAJOR ELEMENT. WHITENS ALLOY. DECREASES CREEP. INCREASES STRENGTH. INCREASES EXPANSION ON SETTING. INCREASES TARNISHING RESISTANCE IN RESULTING AMALGAM.
- 21. TIN:- CONTROLS THE REACTION BETWEEN Ag & Hg. REDUCES STRENGH & HARDNESS. REDUCES RESISTANCE TO TARNISH & CORROSION. COPPER:- INCREASES HARDNESS & STRENGTH. INCRESES SETTING EXPANSION.
- 22. ZINC:- SMALL AMOUNT –NOT AFFECT SETTING REACTION PROPERTIES OF AMALGAM. ACT AS A SCAVENGER DEOXIDISER. WITHOUT Zn ALLOYS ARE MORE BRITTLE & AMALGAM FORMED LESS PLASTIC. CAUSES DELAYED EXPANSION , IF CONTAMINATED WITH MOISTURE DURING MANIPULATION. BENEFICIAL EFFECT ON CORROSION & MARGINAL INTEGRATION.
- 23. PLATINUM:- HARDENS THE ALLOY & INCREASES THE RESISTANCE TO CORROSION. PALLADIUM:- HARDENS THE ALLOY. WHITENS THE ALLOY. PRE AMALGAMATED ALLOYS:- SMALL AMOUNT UPTO 3% OF Hg IS ADDED TO THE ALLOY BY MANUFACTURER.
- 24. RECENT DEVELOPMENT OF D.AMALGAM Mercury free direct filling amalgam alloys Gallium based alloys Low mercury amalgams Indium in mercury
- 25. AMALGAMATION
- 26. AMALGAMATION AND RESULTING MICROSTRUCTURE. DURING TRITURATION Ag & Sn IN THE OUTER PORTION OF THE PARTICLES DISSOLVE INTO Hg . Hg DIFFUSES INTO ALLOY PARTICLES. Hg HAS LIMITED SOLUBILITY FOR Ag (.035WT%) & Sn (.6wt%). AMALGAMATION OCCURS WHEN Hg CONTACTS THE SURFACE OF Ag-Sn ALLOY PARTICLES. WHEN THE SOLUBILITY IN Hg EXEEDED- CRYSTALS OF 2 BINARY METTALIC COMPOUND PRECIPITATE INTO Hg. THESE ARE BCC Ag2Hg3 & HEXAGONAL Sn7-8Hg.
- 28. Low copper Alloys Ag3Sn+Hg > Ag2Hg3 + Sn8Hg + Ag3Sn (r) (r1) (r2) (unreacted)
- 29. High Copper Alloys (1)Admixed alloys Ag3Sn + Ag-Cu +Hg>Ag2Hg3 + Sn8Hg + Ag3Sn + AgCu LATER, Sn8Hg + AgCu > Cu6Sn5 + Ag2Hg3 (r2) (eutectic) (n) (r1)
- 30. Single Composition AgSnCu+ Hg > Cu6Sn5 + Ag2Hg3 +AgSnCu
- 31. PROPERTIES OF SET AMALGAM. MICROLEAKAGE. DIMENSIONAL CHANGES. STRENGTH. CREEP. TARNISH & CORROSION.
- 32. MICROLEAKAGE. OCCURS DUE TO PENETRATION OF FLUIDS OR DEBRIS AROUND THE MARGINS THAT CAN LEAD TO SECONDARY CARIES. AMALGAM HAS GOT A SELF SEALING PROPERTY – CORROSION PRODUCT WILL FILL THE TOOTH RESTORATION INTERFACE & PREVENT MICROLEAKAGE.
- 33. DIMENSIONAL CHANGES CONTRACTION EXPANSION ACCORDING TO ADA SPECIFICATION ,IT SHOULD NOT EXPAD OR CONTRACT MORE THAN 20ucm AT 37 degree celcious BETWEEN 5min AND 24hrs AFTER BEGINNING OF TRITURATION. MODERN AMALGAM ALWAYS SHOWS CONTRACTION. OLDER AMALGAM SHOWS EXPANSION.
- 34. CONTRACTION. RESULT IN MICROLEAKAGE & SECON – DARY CARIES. FACTORS FAVOURING CONTRACTION LONGER TRITURATION TIME. HIGHER CONDENSATION PRESSURE. SMALL PARTICLE SIZE. Hg ALLOY RATIO.
- 35. EXPANSION. IF A Zn CONTAINING LOW Cu HIGH Cu IS CONTAMINATED DURING TRITURATION CONDENSATION ,A LARGE EXPANSION TAKE PLACE.IT USUALLY STARTS FROM 3-5 DAYS AND CONTINUE FOR MONTHS CREATING VALUES UPTO MORE THAN 400um – DELAYED EXPANSION. H2O + Zn ZnO + H2 PROTRUSION OF RESTORATION OUT OF CAVITY INCREASE CREEP INCREASE MICROLEAKAGE PITTED SURFACE OF RESTORATION & CORROSION.
- 37. STRENGTH. AMALGAM IS SRONGEST IN COMPRE- SSION & MUCH WEAKER IN TENSION & SHEAR , THE PREPARD CAVITY DESIGN SHOULD MAXIMIZE THE COMPRESSION FORCES IN SERVICE & MINIMIZE TENSION SHEAR FORCES.
- 38. CREEP. DEFINED AS A TIME DEPENDENT PLASTIC DEFORMATION UNDER CONSTANT STRESS. ACCORDING TO ADA SPECIFICATION NO 1 CREEP SHOULD BE BELOW 3%. CREEP OF LOW Cu AMALGAM IS 0.8-8% & HIGH Cu IS 0.4-1%.
- 41. MANIPULATION
- 42. MANIPULATION (1) Selection of materials (2) Mercury:Alloy ratio (3) Trituration (4) Mulling (5) Condensation (6) Shaping & finishing
- 43. SELECTION OF MATERALS a) ALLOY b) MERCURY c) DISPENSORS d) PRE PROPOTION CAPSULE
- 47. MERCURY: ALLOY RATIO (1) Squeezing cloth (3) Increased dryness technique (5) EAMES technique
- 50. MULLING Improve homogenity of mass & get a single consistent mix
- 51. CONDENSATION (1) Hand condensation (2) Mech.condensation
- 52. SHAPING & FINISHING. CARVING. BURNISHING. POLISHING.
- 59. PRECAUTIONS Ventilation Disposal Sealed containers Vaccum cleaners
- 61. INDICATIONS (1) Moderate to Large Class I & Class II Restorations (2) Class V Restorations (3) Temporary Caries Control Restorations (4) Foundations
- 62. CONTRAINDICATIONS (1)Esthetics (2)Extensive tooth destruction (3)Small Class I & II Cavities
- 63. CAVITY PREPARATIONS FOR AMALGAM RESTORATION
- 64. What is a Cavity Preparation? It is a mechanical alteration of a defective, injured, or diseased tooth to receive a restorative material that re- establishes a healthy state for the tooth, including esthetics corrections where indicated & normal form & function.
- 65. STEPS IN CAVITY PREPARATION (1) Initial Cavity preparation (3) Final Cavity Preparation
- 66. Initial… 1. Outline form & initial depth 2. Primary Resistance form 3. Primary Retention form 4. Convenience form
- 67. Final… 1. Removal of any remaining defective Enamel or Dentin on Pulpal floor 2. Pulp protection 3. Finishing External Walls 4. Final Cleaning & Inspection
- 69. CLASS I They are restorations on occlusal surfaces of premolars & molars, occlusal 2/3rd of facial & lingual surface of molars & lingual surface of maxillary incisors
- 73. CLASS II They are reostorations on the proximal surfaces of posterior teeth- mesio occlusal , disto occlusal, mesio occluso distal
- 77. CLASS III They are restorations on the proximal surface of anterior teeth that that do not involve incisal angle.
- 78. CLASS V They are restorations on gingival 1/3rd of facial & lingual surface of all teeth.
- 79. CLASS VI They are restorations on incisal edge of anterior teeth or cusp tip region of posterior teeth.
- 80. FAILURES OF AMALGAM RESTORATIONS
- 81. Signs of failures : 1. Fracture Lines 2. Marginal Ditching 3. Proximal Overhangs 4. Poor anatomic contours 5. Marginal Ridge incompatibility 6. Improper Proximal Contacts 7. Recurrent Caries 8. Poor occlusal Contacts 9. Amalgam Blues
- 82. Reasons For Failures: 1. Improper Case Selection 2. Improper Cavity Preparation 3. Faulty Selection & manipulation of Amalgam 4. Errors in Maricing Procedures 5. Post Operative Factors
- 88. AMALGAM TATOO “ Accidental implantation of silver containing compounds into oral mucosal tissue” O ccur: 3. Removal of old amalgam 4. Broken Pieces-socket-tooth extraction 5. Particles entering surgical wound 6. Amalgam dust in oral fluids- abrasion areas Se n as – Grayish black pigmentation e C m Site Gingiva, buccal mucosa, alveolar o . s- mucosa
- 90. CONCLUSION Class I & II Restorations are still common procedures performed by general Dentists. Class VI are used infrequently It is important for practitioners to understand the indications, advantages, techniques & limitations of these restorations. When used correctly & properly selected cases, these restorations have the potential to serve for many years
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