A removable partial denture or bridge usually consists of replacement teeth attached to a pink or gum-colored plastic base, which is sometimes connected by metal framework that holds the denture in place in the mouth. Partial dentures are used when one or more natural teeth remain in the upper or lower jaw. A fixed bridge replaces one or more teeth by placing crowns on the teeth on either side of the space and attaching artificial teeth to them. This "bridge" is then cemented into place. Not only does a partial denture fill in the spaces created by missing teeth, it prevents other teeth from changing position. A precision partial denture is removable and has internal attachments rather than clasps that attach to the adjacent crowns. This is a more natural-looking appliance.