Dental bridges are natural-looking dental appliances that can replace a section of missing teeth. Because they are custom-made, bridges are barely noticeable and can restore the natural contour of teeth as well as the proper bite relationship between upper and lower teeth. Bridges are sometimes referred to as fixed partial dentures because they are semi-permanent and are bonded to existing teeth or dental implants. Some bridges are removable and can be cleaned by the wearer; others need to be removed by a dentist. Porcelain, gold alloys or combinations of materials are usually used to make bridge appliances. Appliances called implant bridges are attached to an area below the gum tissue or to the bone.