Page 56 - Curriculum Visions Dynamic Book

Another place that ceramics are used is as cements for holding amalgams in place.
Dental cements have to be strong and
not cause problems with the gums. They
also have to be able to bond well with tooth bone. Zinc phosphate is one common cement. Dental cements have the added advantage
that as insulators, they can protect nerves from the highly conductive metal amalgams used in grinding positions. Both can serve as insulating bases to protect tissues from heat or cold. Zinc oxide is also used in a solution of a plastic resin.
Crowns and other artificial dentures are made of porcelain fused to metal. The underlying frame is metal, with the surface layers porcelain, all held in place
by cement. Here is an example of metal being used for its strength and to withstand breaks, while the porcelain is used for its appearance.
Ceramics that resist wear
Many ceramics are used in extremely demanding places
where wear and tear are heavy. If the wrong materials are chosen, rubbing and scuffing can quickly wear out the ceramic part and force an expensive replacement.
Ceramics are used because they are hard and chemically unreactive. But to be really useful, they must also be able to stand up to heat either by swelling and shrinking very little or by being able to transfer away the heat.
The most widely used wear- resistant material is alumina. It has
(Above) These porcelain ceramic tooth caps make beautiful copies of teeth. However, high-tech materials like this are expensive.
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