A crown is a restoration that encompasses all surfaces of your tooth and is designed to bind the remaining tooth structure together.
The treatment for a crown traditionally involves two appointments. The first appointment is normally quite long. Any old fillings in the tooth are replaced at this appointment, and then the tooth is reshaped to a particular design, depending on the type of crown being fitted. A silicon rubber impression is taken of the prepared tooth, and then a temporary crown is fabricated and cemented with temporary cement.
At the second appointment the temporary crown is removed and the final crown tried in for fit, appearance and occlusion (fitting into the bite). Finally, it is cemented into place.
However, most crowns in the back of the mouth are now fabricated using CAD/CAM technology (CEREC) and the treatment is completed in a single unit.