Water fluoridation is the controlled addition of fluoride to a public water supply to reduce tooth decay. Fluoridated water has fluoride at a level that is effective for preventing cavities; this can occur naturally or by adding fluoride. Fluoridated water operates on tooth surfaces: in the mouth it creates low levels of fluoride in saliva, which reduces the rate at which tooth enamel demineralizes and increases the rate at which it remineralizes in the early stages of cavities. Typically a fluoridated compound is added to drinking water, a process that in the U.S. costs an average of about $0.92 per person-year. Defluoridation is needed when the naturally occurring fluoride level exceeds recommended limits. A 1994 World Health Organization expert committee suggested a level of fluoride from 0.5 to 1.0 mg/L (milligrams per liter), depending on climate. Dental cavities remain a major public health concern in most industrialized countries, affecting 60–90% of schoolchildren and the vast majority of adults, and costing society more to treat than any other disease. Water fluoridation prevents cavities in both children and adults, with studies estimating an 18–40% reduction in cavities when water fluoridation is used by children who already have access to toothpaste and other sources of fluoride. There is no clear evidence of other adverse effects. It is controversial, and opposition to it has been based on ethical, legal, safety, and efficacy grounds.

Read the rest of this article: http://en.wikipedia.org/wiki/Water_fluoridation

_______________________________ Today's selected anniversaries:

1398:

The Grand Duke of Lithuania Vytautas the Great and the Grand Master of the Teutonic Knights Konrad von Jungingen signed the Treaty of Salynas, the third attempt after the 1384 Treaty of Königsberg and the 1390 Treaty of Lyck to cede Samogitia to the Knights. http://en.wikipedia.org/wiki/Treaty_of_Salynas

1871:

The Criminal Tribes Act entered into force in British India, giving law enforcement sweeping powers to arrest, control, and monitor the movements of the members of 160 specific ethnic or social communities that were defined as "habitually criminal". http://en.wikipedia.org/wiki/Criminal_Tribes_Act

1915:

A German firing squad executed British nurse Edith Cavell for helping Allied soldiers to escape occupied Belgium. http://en.wikipedia.org/wiki/Edith_Cavell

1928:

An iron lung medical ventilator, designed by Philip Drinker and colleagues at Children's Hospital, Boston, was used for the first time in the treatment of polio victims. http://en.wikipedia.org/wiki/iron_lung

2000:

Two suicide bombers attacked the destroyer USS Cole while it was at anchor in Aden, Yemen, killing 17 of its crew members and injuring 39 others. http://en.wikipedia.org/wiki/USS_Cole

_____________________________ Wiktionary's word of the day:

belligerent (adj): 1. Of or pertaining to war. 2. Engaged in war, warring. 3. Aggressively hostile, eager to fight http://en.wiktionary.org/wiki/belligerent

___________________________ Wikiquote quote of the day:

The concept which assumes that everything in the Church is irrevocably set for all times appears to me to be a false one. It would be naive to disregard that the Church has a history; the Church is a human institution and like all things human, was destined to change and evolve; likewise, its development takes place often in the form of struggles. --Edith Stein http://en.wikiquote.org/wiki/Edith_Stein