In general, stainless steel crowns are used for children's teeth because they don't require multiple dental visits to put in place and so are more cost- effective than custom-made crowns and prophylactic dental care needed to protect a tooth without a crown.
Phosphorus comes from many places. You might think that the biggest sources of phosphorus are the obvious onesâsewage treatment plants, chemical factories, and the like. But in fact, identifiable sources such as these contribute less than 20% of the phosphorus in the river.
Overview. Phosphorus is found in Group 15 (VA) of the periodic table. The periodic table is a chart that that shows how chemical elements are related to each other. Phosphorus is part of the nitrogen family along with nitrogen, arsenic, antimony, and bismuth. Phosphorus was first discovered in 1669 by German physician Hennig Brand (ca. 1630-92). Brand is somewhat famous in chemistry.