19 AGO. 2020

19 AGO. 2020 · AMALGAM COMPOSITION Silver, tin, copper, mercury, zinc, palladium, indium MERCURY - Spherical cut – 40-45% – requires less mercury, small surfaces are easier to wet - Lathe cut – 45%-50% - requires more mercury, more difficult to wet SILVER ― 40-70% or 65% content - Increases strength - Increases expansion TIN – 25-27% - Opp to silver - decreases strength - decreses expansion - increases setting time GAMMA PHASES  Alloy containing mercury Ag-Sn + Hg ⟶ AgHg + SnHg Silver Tin + Mercury ⟶ Silver Mercury + Tin Mercury ४ γ1 γ2 (STRONGEST PHASE) (ABUNDANT PHASE) (WEAKEST PHASE)  γ2 - gamma 2 phase - SnHg - Tin Mercury ➢ Disadvantage - Brittle and Corrodes ➢ Advantage - Self Sealing COPPER – 6%, 13% Ag-Sn + Cu + Hg ⟶ AgHg + CuSn ४ γ1 eta η To get eta phase - need 13% Copper ie. high copper amalgam Q. The copper ratio that eliminates gamma phase 2 = 13 %. ZINC – 1% o In Factory, Silver and Tin, they may form oxide o ∴ they add Zinc (used as oxide scavenger) o Provides better clinical performance, less marginal breakdown. o But, In restoration, zinc if contaminated by moisture, it will cause delayed expansionー seen 3-4 days post restoration ー due to release of hydrogen gas. o Moisture contamination of Zn can be caused during aー during trituration. b ー during restoration.

19 AGO. 2020 · PROPERTIES OF AMALGAM RESTORATION Trituration o The longer the trituration the smaller the setting expansion- shiny and wet appearance, strength will be maximal, and will have longer lasting luster after carving o Inadequate trituration will have poor strength and rough surface, will cause corrosion more o Trituration Time – 45-60 seconds P/L ratio o 1:1 by volume (EamesTechnique) o 50% by weight Working/Setting Time ー 3-4 minutes Q. The maximum time elapsed before condensation of amalgam - 3 min Condensing Force ー 3-4 lbs Precarving Burnishing a) to remove excess mercury b) to condense and adapt to lateral walls* Amalgam Cry / Silver Ringing Sound ー Setting Indication Polishing ー After 24 hours* ー In the presence of water.

19 AGO. 2020 · COMPLICATIONS IN AMALGAM 1. MICROLEAKAGE ー sensitivity ● Prevention ー varnish prior to ● Most common problem. ● Causes ○ Not enough bulk restored ○ Lack of adequate condensation ○ Improper manipulation ○ Overcarving bonded

19 AGO. 2020 · 2. ISTHMUS FRACTURE ● Major cause is shallow preparation / inadequate depth of cavity.* ● Other reasons ー too wide cavity preparation, sharp ‘axiopulpal line angle’. So bevel this axiopulpal line angle ● If asked specifically about primary tooth isthmus # - shallow preparation ● If asked specifically about permanent tooth isthmus fracture – sharp axiopulpal line angle . Q. The most common immediate ttt. Reported for fractured teeth was 25%. 3. AMALGAM BLUEING (TOOTH) ● Seepage of amalgam contents upto DEJ causing blue discolouration. ● Management ー prior application of varnish. 4. AMALGAM TATTOO (MUCOSA) ● Seepage of amalgam into the mucus membrane. ● Restoration, also retrograde amalgam restoration after apicoectomy. ● No treatment required.

19 AGO. 2020

19 AGO. 2020 · Gingival discolouration A. Bismuth in blood - Blue-black colour B. Mercury in blood - black C. Lead in blood – red / reddish blue. 5. PAIN ● Within 48 hours ➔ Deep cavity ー patients come with sensitivity to hot and cold food. ➔ Pulp exposed. ➔ Class 2 cases ー pulpal horns exposure. ● Supra occlusion / High point / Defective Occlusion ➔ Within 1 week. ➔ TOP +ve ➔ Sensitivity to hot and cold food ーdue to detachment of CEJ from gums ー thus exposing dentin ∴ Sensitivity. ● If only sensitivity ➔ Dentine cause and not high point

19 AGO. 2020 · 6. Overhanging Restoration ➔ Symptoms ー irritation/ bleeding to interdental papilla. ➔ Happens due to improper or lack of matrix usage ➔ Instrument used to remove.- hoe ➔ It tears the gingiva leading to attachment loss ➔ It can stimulate inflammatory reaction directly ➔ It provides ideal location for plaque accumulation 7. Galvanic shock ➔ Patient shows pain. ➔ Dissimilar metal. ➔ Amalgam vs Gold, ceramic ➔ RX Plan ー no RX required if no galvanic shock. ➔ Change restoration if pain is seen in the one

19 AGO. 2020 · 7. Galvanic shock ➔ Patient shows pain. ➔ Dissimilar metal. ➔ Amalgam vs Gold, ceramic ➔ RX Plan ー no RX required if no galvanic shock. ➔ Change restoration if pain is seen in the one done recently or varnish over restoration. 8. Delayed Expansion ➔ Caused due to insufficient trituration & condensation ➔ Also moisture contamination during either trituration / condensation – it’s the principle cause of amalgam failure. ➔ Careful of moisture contamination. ➔ Zn + H2O = release of hydrogen gas ➔ No particular time period. ➔ Cracks can be seen. ➔ RX ー change restoration.

19 AGO. 2020 · 9. Mercury Toxicity ➔ Daily wear of amalgam seen : 1-3 μgs* (microgram) ➔ Mercury threshold ー 50 μgs or 0.5 mg. ➔ Amalgam waste in special container* with fixer solution or sulphide solution - even for extracted tooth containing amalgam.