A temporary crown is designed to protect the tooth, prevent tooth sensitivity, allow you to function and eat normally, be able to continue good oral hygiene, and provide adequate esthetics. Normally the permanent crown is placed in approximately 2 to 3 weeks, but this time period may vary greatly depending on many other factors. These factors may include such things as complicated laboratory procedures, the need to delay the final crown until after orthodontics or other dental procedures. In our office we like to replace the temporary crown with a permanent one as soon as possible, but under certain circumstances there can be as long as a year before the final crown is placed. In these situations the final impression for the crown is not taken until we can place the final crown in less than a month. Temporary crowns should not fall off by themselves. If this happens it usually indicates that the preparation for the permanent crown does not have adequate retention form. The problem with having a temporary crown in your mouth for more than a month is that these crowns may wear significantly and this may result in a shift in the tooth position and the bite.