Week 4 PP Flashcards
What is an Alloy?
Fusion of two or more metals
What is Amalgam?
Silver tooth filling material made from an alloy, with one of the elements being mercury
What is Trituration (amalgamation)?
The process where the mercury and the alloy are mixed together to form amalgam
What is Condensation?
Amalgam is placed into the prepared tooth in increments. The material is condensed using a condenser to pack the amalgam tightly into all areas of the cavity preparation.W
What is Tarnish?
Surface discoloration will occur in older amalgam fillings. Can be polished away
Thermal change for amalgam
Expansion and contraction when the amalgam is exposed to heat or cold
What is micro-leakage?
Due to temperature changes a dental material can contract and expand. Significant changes in the degree of contraction and expansion can cause a dental material t opull away from the tooth structure.
What is Percolation?
A microscopic space between the tooth and the restorative material where bacteria and oral fluids can pass. This is referred to as percolation
What is Ductility & Malleability?
capacity of a metal to be stretched out without fracturing and malleability is the capacity of a metal to be extended in all directions by a compressive force
Carving and Finishing of Amalgam
Using hand carving instruments, amalgam is carved to recreate the tooth’s normal anatomy
Summary of Amalgam
- Technical name for silver fillings
- Amalgam consists of several different metals, with
silver being the predominant metal ◦ Metals are in a powder form and then mixed with
mercury to form a soft, pliable mixture
◦ When placed into a prepared tooth, condensed, carved,
and allowed to harden, the mixture becomes a
permanent amalgam restoration - Amalgam is a safe, affordable, and durable
material used predominantly to restore premolars
and molars
Composition of Dental Amalgam? ** KNOW THIS FOR TEST **
Amalgam is the end result of mixing almost equal part of mercury and an amalgam alloy powder
Mercury - 43-54%
Alloy (46-57%) .. which consists of..
-Sliver - strength
-Tin - Workability & Strength
-Copper - Strength & corrosion resistance
-Zinc - Suppress Oxidation
What is the Eames Technique?
Amalgam alloy powder is mixed with mercury in a 1:1 ratio (1 portion mercury to 1 portion alloy)
What are High Copper Alloys?
Frequently used in dentistry, and classified according to their particle shape (Spherical, Irregular, Admixed)
Properties of Spherical (round particle) Amalgam?
◦ Require less mercury for amalgamation and less pressure during
condensation. Resulting in a more compact and strong restoration.
Also adapts easily to small discrepancies and undercuts
Properties of Irregular (rough, lathe-cut particles) amalgam?
Condenses well interproximally, creates a nicec tight contact
Properties of admixed amalgam?
Mixture of irregular and spherical alloys combining the strength of each
Properties of Amalgam?
- Strength is not adequate to withstand occlusal forces alone; so the preparation is designed so that surrounding tooth structure sustains the forces to the amalgam
- Proper manipulation is important in overall strength and success of the restoration
- Subject to dimensional change (expansion and contraction). This is controlled by the alloy composition. * Ability to “creep” (change in material when it’s under a constant load)
Are Amalgam Restorations subject to corrosion and tarnish?
YES!
Tarnish is the discoloration of the surface
Corrosion is the deterioration of the surface
What can be an issue for amalgam restorations?
Thermal and electrical conductivity can be an issue
What happens if amalgam restorations breaks?
It usually needs to be replaced as it is not easily repaired
Indications for Using Dental Amalgam?
- Long success record
-Can be used on primary & permanent teeth
-When moisture control is problematic
-Less technique sensitive
-As a foundation for cast-metal, metal ceramic, and ceramic restorations
-When a patient’s commitment to personal oral hygiene is poor
-Less expensive restorative material
What are contraindications for Using Dental Amalgam?
-Poor Esthetics (silver material)
-Used only on posterior teeth (anterior are contraindicated)
-Allergy to mercury or alloy components
-Can be discoloration at the margins of the restoration
What is the controversy with Mercury?
- Harm to patients from the mercury in the amalgam placed in their mouths
- The toxicity level of mercury vapor dental personnel are exposed to over time
When mercury is combined with other materials in dental amalgam, the chemical nature changes and is relatively harmless
Amount released in the mouth with chewing and griding is very small and shouldn’t cause alarm
Amount of mercury given off of restorations is less than what patients are exposed to in food, air and water
Whose health is more at risk re. Mercury?
The health risk for dental personnel is greateer than that for a patient.
◦ Precapsulated amalgam has decreased the risk, but care should still be maintained.
◦ The dentist and assistant who are exposed to mercury vapors daily should be aware of their toxic effects
◦ Increase in exposure can result in tremors, kidney dysfunction, depression, and central nervous system disorders
Mercury Hygiene Guidelines
-Wear PPE when handling amalgam (gloves, mask, safety glasses)
-Use pre-measured capsules
-Use an amalgamator with a protective cover
-Store amalgam scraps in a capped wide mouth jar containing x-ray fixer, glycerin, or mineral oil
-Use water spray and HVE when cutting and removing old amalgams or polishing new restorations
- Change chairside traps by placing in a sealed baggie and placing in a biohazard container for pick up
-Keep a mercury spill kit
-Ensure proper ventilation in the dental office
-Avoid using mercury or amalgam near a heat source
What is the Dental Amalgam Capsule?
Amalgam is supplied in a sealed single use capsule with the proper ratio of alloy powder on one side and mercury in the other side. It is separated by a thin membrane
What is a “Spill”?
Amount of mercury dispensed by volume
Capsules are supplied in 3 sizes:
1 spill - for class 1 conservative restoration
2 spill - class 2 conservative restoration
3 spill - multi-surface restoration
if more is required then additional capsules are placed in the set up and triturated as required
What is Trituration / amalgamation?
-Process which mixes the alloy & mercury together to form the mass of amalgam to fill the cavity prepartion
- Capsule is placed in the amalgamator, lid is closed
and capsule is mixed for the appropriate time
(based on MFIU)
1 spill = 7 seconds
2 spill = 9 seconds
What is a pestle?
Maybe contained within the capsule to help with the mixing process (think the little ball in a protein shaker)
How to tell if Amalgam is properly mixed together?
If mixed properly, the mass of amalgam is free of dry alloy particles and stays together
