Crown covers the tooth and can be made up of porcelain, metal or combination of both the materials. A crown is recommended when the tooth is heavily filled or decayed where just filling will not be supported by remaining tooth structure. Dentist also advises a crown after root canal treatment or if your tooth has got cracks. A bridge replaces the missing tooth and includes crowns on teeth on either side of missing tooth. Properly looked-after crown can last for a long time. You should take care of crown with brushing and flossing.