Most often patients are in need of a crown or replacement when tooth decay has destroyed most of the natural tooth. The crown provides protection for the remainder of the tooth and root structure. Doctors may also recommend the use of a crown after root canal therapy on posterior teeth. Using a crown in these circumstances will help solidify and protect the remaining tooth. Crowns can also be used as a cosmetic option to repair badly chipped and crack teeth or to close space between teeth. Dental crowns for cosmetic purposes are often less expensive than other alternatives.