Crowns usually require two separate visits.  During the first appointment, the dentist will examine the tooth, take x-rays to check for cavities and the structure of the tooth root.  Following that, the tooth is prepared for the crown by filing down and reshaping the tooth.  Local anesthetics are given during this portion of treatment.  Then, the dentist will take impressions of the tooth which are then sent off to the dental laboratory, where the crowns are custom-crafted. 

In most cases, the lab work can be done for a crown in about 5-7 days and then you would return to have the crown fitted.  During this time you would have a temporary crown fitted.

After the lab has crafted the crowns, you would return for the second visit dental crown.   The dentist will check the color and fit of the crown, make sure that it lines up correctly with your bite, and then if all is in order, permanently cement the crown into place.