Bonding is a procedure that uses a tooth-colored composite resin (plastic) to repair a tooth. Bonding is typically used for cosmetic purposes to improve the appearance of a discolored or chipped tooth, close spaces between teeth, to make teeth look longer or to change the shape or color of teeth. It is also used as an alternative to amalgam fillings, or to protect a portion of the tooth's root that has been exposed when gums recede.