Page 55 - Curriculum Visions Dynamic Book

See Vol. 1: Plastics for more on resins.
Bioceramics can replace bones. Alumina is often used for hip and knee replacements as well as to stand in for bone pieces (for example, when rebuilding face bone) because it does not corrode, it does not wear out, and it has great strength.
However, it is also possible to use porous ceramics as a kind of scaffolding holding up parts while natural bone growth takes place through the ceramic. Some of these materials become completely reabsorbed into the body when their job is done. They are therefore thought of as temporary ceramics. Some ceramics bond with bones. They are called “bioactive ceramics.” They are used in such non-load-bearing places as implants in the middle ear.
In dentistry ceramics play a major role, mostly in combination with resins. Resins are now being used much more widely as fillings in teeth. They can be coloured to match the existing teeth much more easily than earlier types of fillings.
The binder is a resin, and the filler is pulverized quartz or another hard material.
They are used primarily as fillings on the surfaces of teeth rather than at places where grinding action occurs.
(Above and below) Modern dental fillings use a ceramic powder suspended in a resin matrix. This closely resembles both the natural colour of our teeth and their hardness and brittleness too.
The filling paste is applied to the cavity in a tooth through the nozzle of an applicator (above). Excess is removed, and the filling is smoothed. It is then hardened quickly using white light, as demonstrated below. Seconds later, and the filling is hard and ready to be drilled to make an exact fit for the tooth.
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