Gold crowns are made from gold alloyed with many other metals. The actual
gold content can range from 90% to as low as 5%. Gold in its pure state is too
soft to withstand the rigors of functioning in the mouth. Platinum or palladium
are frequently added to harden the gold. There are some disadvantages. Both
raise the already high melting point of the alloy. Platinum is expensive,
palladium has been outlawed in some countries because it is toxic, and both turn
the gold color to silver. Copper is added to restore the gold color, but it has
a reddish tint, is toxic, and forms bubbles in the alloy. Silver can be added to
get rid of the red color, and zinc is a toxic metal, but it is in small
quantities and it will eliminate the air bubbles. The latter metals also reduce
the melting temperature.
Crowns replace what is missing from a tooth, and generally cover all of the
crown of the tooth, or that part that is exposed to the mouth. A good crown is
the same size and shape as the original tooth, unless it was malformed or
malaligned, then the final product is better than the original.
Gold crowns are cemented to the teeth, and are not removable by the patient.
They are tough, can withstand chewing without breaking, and usually last from 10
to 20 years. Porcelain or plastic can be attached to the esthetic parts of the
crowns, and they can look quite life-like. Care is the same as for the natural