The Chemistry of Toothpaste - Chemistry Experiments

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toothpastes contain substances such as tetrasodium pyrophosphate to

prevent the build up of tartar. Toothpastes for sensitive teeth generally

contain a desensitizing agent such as strontium chloride, potassium

nitrate, or potassium citrate. Whitening toothpastes contain hydrogen

peroxide or sodium carbonate peroxide to remove stains from the teeth.

Connections

In the early 20th century, scientists found that fluoride had properties

that would prevent tooth decay. This discovery was made based on a

study of children in rural areas of Colorado who had mysterious brown

stains on their teeth but had an amazingly low incidence of cavities. Upon

researching and testing for the cause of the problem, it was concluded

that the brown stains and the lack of tooth decay were due to the

presence of fluoride ions in their drinking water. Scientists concluded that

while large amounts of fluoride could cause stains on the teeth or even

poisoning, small doses of fluoride, about 1 gram (g) per liter (L), added to

drinking water could help to prevent cavities. Fluoride can protect teeth

from decay by strengthening the enamel and preventing acid erosion of

teeth (Figure 3).

In the 1950s many communities began fluoridating municipal water

sources in order to reduce the number of cavities in the community. This

process has been fairly controversial because fluoride can have harmful

effects if not monitored properly. Regardless of the controversy associated

with this practice, around 69 percent of Americans were receiving

fluoridated water in their homes in 2006. The Centers for Disease Control

hopes to increase that number to 75 percent by the end of 2010.

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