A. To differentiate between amalgam alloy and dental amalgam. B. To learn the manipulation of dental amalgam.
C. To explain the trituration and setting processes.
Amalgam alloy, mercury, proportioner , mortar and pestle, squeeze cloth, rubber dam, class I prepared cavities, amalgam carrier, cotton plier, amalgam plugger, carver, burnisher.
III. General consideration:
Amalgam is a metal alloy the components of which are predominantly silver (Ag), and tin (Sn), other components are copper (Cu), and zinc (Zn). Dental amalgam is made by mixing equal parts (by weight) of powdered metal alloy with the liquid mercury (Hg). The mixing process of the alloy with the liquid mercury is called trituration.
Amalgam is one of dentistry’s main therapeutic agents for restoring defective teeth. It is a very old but it is still a widely used restorative material. The oldest written record of the use of amalgam in dentistry is a complication in 1528. Amalgam is plastic at temperature of the body for a few minute and then hardens. During hardening little change in volume in occurs. Properly condensed amalgam exhibit compressive strength as high as some cast irons. The amalgam can withstand the corrosive mouth environment, and are bland to the host. The combination of all these properties makes amalgam the most universally used restorative material.
The revised specifications for dental amalgam took effectively on June 1970. The major difference in the presence specifications is the inclusion of a diametric tensile test and the adjustment in setting change in flow requirements, due to changes in test procedure. Whereas in the past, hand trituration and condensing are utilized, the revision includes mechanical mixing with an amalgamator and condensation. As a result the specification limits for setting changes during hardening have been increased and now allow either a small contraction...