The Chemistry of Teeth
Applications of Solubility
Teeth
Why sugar rots your teeth
Sugar does not rot your teeth. Plaque AND sugar work together to rot teeth
Plaque - collection of bacteria that adheres to your teeth
Sugar gives bacteria energy
Lactic acid is a product of sugar breakdown
Lactic acid decreases the pH in your mouth
Low pH causes your tooth enamel to dissolve
Toothy Molecules
Hydroxyapatite
Major component of enamel
Chemical formula :
Ca10 (PO 4 ) 6 (OH)
Is dissolved by acid
Why flourinate water and toothpaste?
Ca5[(PO4)3F] is more chemically stable than Ca5[(PO4)3OH]
The flourinated version dissolves at a pH of 4.5, compared to 5.5 pH for calcium hydroxyapatite.
This is generally believed to lead to fewer cavities, since stronger acids are needed to attack the tooth enamel.
Ksp Values for Calcium Salts
Solubility of Calcium in Flourinated vs. Non Flourinated Teeth
If hydroxyapatite is allowed to reach equilibrium in water, what is the concentration of calcium in solution?
If the flourinated version is allowed to reach equilibrium in water, what is the concentration of the calcium in solution?
Results
Calcium concentration
Analysis of Data
Calcium fluorapatite is about 20% less soluble than hydroxyapatite when the solubilities, measured as the concentration of calcium, are compared.
It would be wrong to use the Ksp values to compare solubility. When this is done the difference is 86% which is misleadingly high.
Because calcium flourapatite is less soluble, florinated teeth will dissolve less easily
