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These are lectures of The Gulfie Dentist Online Coaching
19 AUG 2020
19 AUG 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 AUG 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 AUG 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 AUG 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 AUG 2020
19 AUG 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 AUG 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 AUG 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 AUG 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.
These are lectures of The Gulfie Dentist Online Coaching
Information
| Author | Dr.Mayakha Mariam |
| Organization | Dr.Mayakha Mariam |
| Categories | Courses |
| Website | - |
| thegulfiedentist@gmail.com |
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