The term bridges as used in dentistry usually mean a fixed prosthesis, and sometimes are referred to as a fixed partial denture. This is a restoration that is held in place by crowns that are cemented to solid teeth called abutments. They are not removable. The space where a tooth is missing is called a pontic. In cases where implants are not recommended fixed bridges may be the best answer.
Dr. Smith has been making bridges which are still functional after many years. These are made of a variety of materials depending on the cosmetics and usage. Bridges used to be made of metal which was mostly gold and was one of the best materials. Today there are many new materials which are strong and cosmetic.