Crowns are a type of dental restoration which when cemented into place, fully covers that portion of a tooth which lies at and above the gum line. In comparison, composite fillings are dental restorations that are used to fill in or cover over just a portion of a tooth. Since dental crowns encase the entire visible aspect of a tooth, a dental crown in effect becomes the tooth's new outer surface.

Crowns are used to rebuild broken or decayed teeth, to strengthen teeth, and as a means by which to enhance the cosmetic appearance of teeth. Crowns can be made out of porcelain/ceramic, gold alloy, or a combination of both. Dental crowns are often referred to as "dental caps".  They can mask any esthetic concerns and functionally, they act like a helmet for the tooth.  Like a football or hockey helmet which protects your head everytime there is contact, a crown will protect your tooth everytime you eat and chew to prevent fracturing when there is a large restoration.  It is a very effective way to prevent tooth loss due to breakage especially in root canal treated teeth which can be more brittle, especially when a large restoration also exists.