Amalgam - Dental Materials Lecture Note

Mercury+silver alloy= Dental amalgam

Amalgam restoration limited to the replacement of the tooth tissue in posterior teeth and are recognized by silver gray metallic appearance.

Mercury –dense liquid metal that is high toxic.

Silver alloys for dental amalgams:

Low cooper alloys : silver-65-72%,tin 26-29%,cooper 2-4%, Zinc up to 2%

High cooper alloys : silver-40-60,tin 27-30%,cooper 13-30%

Amalgamation –reaction that occurs b/n mercury and amalgam alloy.

2 types of amalgam alloy compositions are:

1. Silver-Tin alloys w/significant amount of Cooper.

2. Silver-Tin alloys without significant amount of Cooper.

The rardering of amalgam is the result of 2 phenomena:

1. Solutoin

2. Crystalization.

Properties:

1. Dimension change when amalgam hardness , it can be expansion or contraction

2. Strength.

If an amalgam restoration is subjected to the forces of mastication too soon after insertion, it may be seriously damaged by being sufficiency overloaded to cause fraction of the amalgam mass.

Creep of  amalgam is a dimension change that occurs under load as a result of the viscoelastic properties of amalgam.

Tarnish   and corrosion –discoloration and or failing by mechanical properties.

• Proportion of mercury and alloy is 1:1. The mercury must wet the alloy particles before the 2 components can react.
• Moisture contamination of the amalgam must be prevented before and during condensation of the mass into the cavity.

Key Words : fillings dental fillings amalgam fillings mercury free fillings tooth fillings temporary fillings composite fillings teeth fillings tooth colored fillings