Crowns - first have a quick look at this Wikipedia page to get some grounding- follow this link to some information on crowns.
Quite good, the Wiki page above!
a crown is a thimble of
some sort of material cemented onto the top of a tooth. They're done to
restore a badly damaged tooth back to shape or sometimes to a new
shape.The point is to make something that's just too difficult to shape
in the mouth. So, they're made using a model of the tooth. The model's
made by taken an impression of the tooth using a silicone material and
then filling this with very hard plaster. There is one technique using
CAD CAM whereby the tooth is scanned to produce a virtual model - see
the section called Cerec.
When we use wooden broom handles, they often have a metal ring around the end to stop them splitting. This ring is called a "ferrule". The crown in this picture has obviously failed the brief!
This is exactly what a crown is designed to do - take a tooth that's weak structurally and strengthen it by wrapping it in strong material.
© Hesslewood Lodge Dental Practice, Nov 16, 2015
Page under construction - this update 11th March 2012