A dental dam or rubber dam is a thin, rectangular sheet, used in dentistry to isolate the operative site (one or more teeth) from the rest of the mouth. It is used mainly in endodontic, fixed prosthodontic and general restorative treatments such as white dental fillings. Its purpose is both to prevent saliva interfering with dental procedures (e.g. contamination of oral bacteria during root canal therapy, or to keep filling materials such as composite resin dry during placement and curing), and to prevent instruments and materials from being inhaled, swallowed or damaging the mouth. In dentistry, use of a rubber dam is sometimes referred to as isolation.