Cast gold – more similar to tooth enamel than you might think
Hard tooth structure has been described as a composite material made up
of enamel, mantle dentin, and the Dentino-Enamel Junction (DEJ). The
surface hardness of enamel protects the tooth as it strikes against the
opposing one, and guards the softer underlying DEJ and dentin. As it
turns out, though, recent evidence suggests that enamel is not the
inherently brittle material it was once believed to be.
Ceramics, such as those used for dental crowns, have a strong
inter-atomic bond causing them to be brittle. Failure of brittle
materials occurs because they have only limited ability to deform or
“give” under pressure.
Natural dental enamel is composed of mineral crystals and protein.
This composition enables the enamel to retain its structural integrity
under bite force.
But the protein layers in the enamel give it a most interesting
shearing characteristic, similar to that of metals – the atoms slip over
one another when stress is applied. This enables the enamel to absorb a
significant amount of pressure before it cracks. Since this physical
property of gold mimics the natural characteristic (bio-mimetic) of
dental enamel with regard to wear and fatigue, it is a superior choice
for restoration compared to brittle materials such as ceramic or
tooth-colored composites.
Additionally, it has been proven that dental ceramics, because of
their inherent hardness, cause more wear on the antagonist dentition
(the tooth opposite the ceramic crown) than does gold alloy. Dental
materials with stress-strain responses more similar to those of natural
enamel are less abrasiveness and better protect the opposing dentition.
There is less stress concentrated at points where the teeth meet. Gold
alloys possess these biomechanical characteristics as well as the
ability to maintain their form long-term, more than any other material
currently used in dentistry. Therefore, gold alloys function
harmoniously with a patient’s own dentition.
Build up of tooth with composite base prior to preparation
