SILVER AMALGAM

1. SILVER AMALGAM

2. Silver amalgam • Introduction • Classification of amalgam alloy • Composition • Properties of amalgam • Manipulation • Advantages • Disadvantages • Indications • Contraindications • Mercury toxicity

3. INTRODUCTION An amalgam is an alloy of any metal with mercury. Dental amalgam is made by alloying pure mercury with silver-tin-copper

4. G.V.BLACK FATHER OF DENTAL AMALGAM Green Vardiman Black. G.V.BLACK Formulated the alloy in 1896 Born on:1836 Died on :1915 ,Chicago

5. Dental amalgam is a combination of one part liquid mercury with one part of a metallic alloy which mainly contains silver and tin. It has been used for over 150 years to restore decayed teeth, and its use has stirred controversy from the earliest days. To make the amalgam, mercury is mixed with the other metals to form a paste that can be fitted to the tooth cavity. The mixture sets relatively fast to form a hard alloy.

6. At the time of the introduction of amalgam into dentistry, gold could be used in some types of dental restorations, but its cost prohibited widespread use. In the 19th Century, • there were no other synthetic materials that had both the required mechanical properties and the ease of placement. As a metallic alloy, amalgam did not look particularly good, but the increasing prevalence of dental caries at the time meant that this was a minor consideration. • The even more profound increase in caries throughout the twentieth century, through the widespread use of refined sugars in foodstuffs, resulted in the increased use of dental amalgam fillings.

7. Classification of AMALGAM alloy • According to SHAPE • Spherical (spherical in shape) • Lathe cut (irregularly shaped) • Mixed (mixture of lathe cut & spherical) • According to the SIZE • Fine cut (36 microns) • Micro cut (26 microns)

8. Classification of AMALGAM alloy • According to composition • Low copper alloy (< 6%) • High copper alloy (6-30%) • Admixed alloy • Zn containing/non Zn containing • Gallium alloys • According to method of dispensing • Powder and liquid form • Capsule form • As pellets of alloy powder • As pre amalgamated powder

9. Special treatment 1.aged alloys 2.acid washed alloys 3.pre amalgamated alloys

10. LATHE CUT ALLOY The constituents are melted & solidifies as an ingot of suitable dimension-inhomogeneous cored structure. Heated for about 20-24 hours for homogenising. If it is suddenly cooled Ag- Sn i.e. β phase remains with small amount of Ag3Sn i.e. γ phase. If it is cooled very slowly, more γ phase is formed to reach equilibrium ,which influence amalgamation reaction. this ingot is then cut in a lathe by bladed instruments & powdered by milling machine into small particle of size about 15μ-30μm. Aging heat treatment is required for relieving internal stresses induced during this procedure.

11. SPHERICAL ATOMISED PARTICLE The liquid alloy is atomised into a chamber either evacuated/ filled with inert gases. Fine liquid drops solidify into small particles. And subjected to homogenising heat treatment. Controlled cooling to adjust β & γ phases. Low copper & high copper single composition alloy can be prepared. DISPERSE OR ADMIXED ALLOY Is a physical mixture of low copper lathe cut alloy & 30%-55% of Ag-Cu eutectic atomised powder. It have slightly higher strength, lathe cut alloy/ mixtures are preferred as these have better condensing property (good resistance to condensation).

14. High copper admix alloy composition Low copper alloys POWDER Silver 67-70% Tin 26-29% Copper 2-5%,<6% Zinc 1-2% In, Pd , Au in Traces LIQUID Triple distilled arsenic free Mercury POWDER Silver 50-60% Tin 20-25% Copper 13-30% Zinc 1-2%

15. Single composition high copper alloys POWDER Silver 45-60% Tin 15-25% Copper 13-20% Zinc 0% Traces of In , Pt. , Pd

16. PROPERTIES OF AMALGAM Increased mercury leads to increased expansion ,creep & corrosion Compressive strength-Admixed is 430Mpa after 7 days Tensile strength-50Mpa after 24 hours Surface hardness-110KHN Working time 3-8 minute Setting time 5-10 minute Increased expansion is due to increased mercury , short trituration , low condensation pressure & water contamination Creep is associated with : increased or decreased trituration , time lag between trituration & condensation, increased mercury, less condensation force

17. Physical properties • Bio compatibility : it is biocompatible • Strength : of amalgam takes 24 hours to reach max • Corrosion : amalgam restoration shows corrosion & tarnish over a period of time • Thermal conductivity : it can transmit temp changes to the pulp • Micro leakage : occur when there is 2-20 microns wide gap b/w the amalgam and the tooth structure

18. Dimensional changes : small amount of contraction occurs in the first half an hour after trituration. • Delayed expansion : large setting expansion of about 4% sometimes takes place after few days in case of zinc containing amalgam , if there is moisture trapping or contamination during restoration • Macroscopic expansion : inhomogeneous condensation pressure and wrong burnishing techniques can push mercury rich thin mix to the margins of the cavity. this excess mercury slowly react the alloy and powder more weaker points and large setting expansion at the margins . this can cause marginal breakdown or fracture.

20. INSTRUMENTS

21. Mouth mirror • Explorer • High speed drill: for accessing the decay • Spoon excavator: for scooping out the decay • Dycal instrument: for placing dycal to help build secondary dentin • Tweezers • Cotton pellet

22. 8. Toffelmier retainer with a matrix band 9. Amalgamator: for mixing amalgam 10. Amalgam carrier: for carrying amalgam to the tooth 11. Condenser: for condensing the amalgam into the cavity 12. Carvers( Hollenback , Ward, Diamond): to carve the anatomy of the tooth 13. Ball burnisher : to make the silver shine

23. Manipulation of SILVER AMALGAM

24. Selection of AMALGAM alloy • In wider cavities alloy with low creep value is preferred • Mercury alloy ratio • EAME’s has preferred 1:1 ratio of alloy/mercury for best result

25. Trituration • This is done to remove oxide layers from the alloy particles so as to coat each alloy particle with mercury ,this can be done by hand or mechanical means

27. Mulling • It is done so that all alloy particles are coated with mercury . this can be done manually or mechanically • Continuation of trituration • Done to get homogeneous mix

28. The mix is enveloped in a dry piece of rubber dam and vigorously rubbed between the first finger and thumb; or the thumb of one hand and palm of another hand. This process should not exceed 2 to 5 seconds.

29. Application of matrix band • Placing a matrix for an amalgam restoration allows the dentist to insert restoration without exceeding the limits of normal tooth structure

30. Insertion of amalgam • Pick a small amount of amalgam alloy with the help of amalgam carrier and transfer it to the preparation

31. Condensation • It is the procedure of compacting hg+ alloy mix into the prepared cavity.it reduces the number and size of voids in the restoration. There are 2 methods • Increased dryness technique • EAME’s minimal mercury technique

32. Done to • To adapt mass to cavity wall • To remove excess mercury • To reduce voids and porosities • To increase density of restoration • To attain maximum strength of restoration • To bring reactive phases together

33. 3-5 minutes for condensation • Pressure: 5-6kg • Smaller the size of condenser more will be the pressure • As you come to surface the size of condenser should get bigger • It has been shown that the pressure applied by the condenser nib is inversely proportional to the square of its surface area. Size of condenser: Lathe – cut – smaller Spherical – bigger

34. Burnishing • Pre carve burnishing is the process of rubbing done to make the surface shiny • Post carve burnishing is done after completion of carving with the help of small sized burnishes using light strokes

35. Carving • Objectives of carving are • No over hanging and under hanging restoration • Proper size , location and good inter proximal contraction • Proper contour • Optimal occlusal anatomy

36. Finishing and polishing • Finishing amalgam restoration involves removal of marginal irregularities , retaining contour and smoothening the surface roughness • Polishing is done to achieve a smooth shiny luster on the surface of amalgam • ADVANTAGES • Reduces tarnish and corrosion • Polished surface is plaque resistant • Prevention of recurrent decay • Maintenance of periodontal health

37. Advantages of amalgam • Adequate mechanical properties • Sufficient long service time • Can retain the anatomic forms • Not expensive

38. Disadvantages • Poor corrosion resistant • Poor esthetics • Ditched amalgam • Poor marginal adaptation • Mercury contamination • Allergic to few patients

39. Indications • Moderate to large class I preparation • Class II preparation , in which there is heavy occlusion and problem of isolation • Class IV preparation • Used as post orthodontic restoration

40. Contraindications • Small to moderate class I and class II preparation should be restored with composite rather than amalgam is former results in more conservative tooth preparation • Amalgam should avoid in area where aesthetic is of important

41. Mercurytoxicity

42. Mercury can enter into the body respiratory and circulatory system by ingestion through skin or as vapors into the respiratory system and through food diet in circulatory system. In dentistry mercury is released during abrasion of amalgam restoration or trapped in the restoration which can migrate easily to body system • In addition mercury vapors are inhaled during the time in dentistry, only very small amount of mercury is excreted but large amount is accumulated in the body.

43. Causes Damage to Brain in Children Amalgam Fillings Linked to Neurological Problems, Gastrointestinal Problems Mercury / Alzheimer's Disease Connection Found Amalgam Fillings Release Highly Toxic Elemental Mercury Gold Crowns, Gum, Bruxism, Computer Monitors Increase Release of Mercury Significantly Cumulative Poison and Builds Up in Organs

44. Potential Contributory Factor in Other Diseases like allergy Mercury Build Up in Brain, Organs and Breast Milk of Foetuses of Mothers With Amalgam Fillings Proper Removal of Fillings Produces Eventual Health Improvement World-renowned Experts Agree About Potential Danger Birth defect may be due to brief exposure during critical periods of fetal development

45. Precautions • Keep the mercury always in air tight bottles • Do not touch mercury directly without gloves • Do not spill the mercury on the floor or carpet • Do not open the capsules immediately after trituration • Do not use ultrasonic amalgamators • Collect all waste under water or sodium thiosulfate solution • Waste should be disposed by burying at larger depth • Keep the clinics well ventilated

46. The Mine Safety and Health Administration (MSHA), National Institute for Occupational Safety and Health (NIOSH), and the World Health Organization (WHO) have established an exposure limit of 0.050 mg Mercury Vapour Detector

47. Amalgam Tattoo An Amalgam Tattoo (also called a focal argyrosis) is the most common pigmentation of the oral cavity. It is an area of permanent bluish-grey pigmentation resulting from amalgam (silver) filling particles falling into small, open wounds created during dental treatment or by trauma shortly after a dental treatment, when small, fresh amalgam particles still cling to the mucosa.

48. The amalgam tattoo presents as a soft, painless, non- • ulcerated, blue / grey / black macule (a small, flat, • distinct, coloured area of skin that is ≤ 10 mm in • diameter and does not include a change in skin texture or • thickness) with no surrounding reddening • They are more common in the lower jaw than the upper, typically in the bicuspid-molar region. The tattoo is found more frequently in women than in men, perhaps because women more frequently seek dental care. It is also seen more frequently with advancing patient age, presumably because of increased exposure to dental procedures over time.

49. Recent modification Bowen’s hybrid composite resin Modified visible light cure Bowen's hybrid composite resin have desirable property to Replace the silver amalgam

50. Gallium alloy(model) Gallium is a greyish metal of low density, and melting point 29.8 degree Celsius, which can be used instead of mercury. Gallium alloy with indium and tin is a liquid at room temperature. Powder contains silver ,tin ,copper , and palladium. Liquid has gallium ,tin ,indium . When triturated, palladium alloys of Ag, Cu ,In are formed with unreacted phases. Indium alloys Alloy containing higher percentage of indium has been tried. Powder has silver ,copper and indium (4 to 30%). Indium replaces some amount of mercury and decreases health hazards by mercury vapour pollution. It has adequate mechanical properties strength at I hour 240MPa ,low creep-0.8%Several composition, low and high Indium-alloys are under research-investigations.