Porcelain is fused to an underlying metal structure to provide strength to a filling, crown or bridge. Alloy of gold, copper and other metals resulting in a strong, effective filling, crown or bridge. Alloys of non-noble metals with silver appearance resulting in high strength crowns and bridges.orcelain is fused to an underlying metal structure to provide strength to a filling, crown or bridge. Alloy of gold, copper and other metals resulting in a strong, effective filling, crown or bridge. Alloys of non-noble metals with silver appearance resulting in high strength crowns and bridges.
Limit refers principally to the establishment of a maximum beyond which a person or thing cannot or may not go: The Constitution limits the president's term of office to four years. To restrict is to keep within prescribed limits, as of choice or action: The sale of alcohol is restricted to people who are 21 and older.
Noun. 1. boundary-the line or plane indicating the limit or extent of something. bounds, bound. hairline-the natural margin formed by hair on the head. frontier-an international boundary or the area (often fortified) immediately inside the boundary.