If a tooth with a gold crown breaks, it is generally because the underlying tooth structure has fractured or decayed. Gold crowns are not immune to becoming loose, especially if you are eating foods and candy that are harmful to crowns and bridges. Gold crowns also cause the least wear on the opposing tooth.
Making the world better, one answer at a time. An artificial boundary is a boundary made by humans, examples include dams, the fence at the border between the U.S and Mexico. A natural boundary is a boundary made by nature, a boundary that happens naturally, examples include rivers, mountains and such.
Natural boundaries. GOVERNMENTS USE physical features as boundaries of political units: boundaries of countries, states, counties, cities, and so forth. (Not all political boundaries follow natural features. A boundary can be geometric, meaning it is be composed of straight-line segments and arcs. There is a cultural type of boundary, as well. This boundary usually separates different ethnic groupings.