Re: How does potassium nitrate in Sensodyne toothpaste reduce tooth sensitivity

Andrew,

That's a very interesting series of questions, and I hope I can help you out a bit with them. I've had sensitive-tooth troubles in the past, too, and welcomed the chance to read up a little on the subject again.

Taking everything in order:

A. No one is really sure just how potassium nitrate makes teeth less sensitive. The Journal of Orofacial Pain says that the most common explanation is that the potassium nitrate releases potassium ions into solution and the ions migrate along the porosities in the tooth dentin, eventually reaching the nerves and blocking some of the action of the nerve to stimulation. This ion migration has been observed in extracted teeth, but hasn't been proved to happen in live ones. An abstract of an article about sentitive-tooth dentifrices is at http://www.tmjpain.org/mai n_m/w_n_57.htm.

It's interesting to note that oral fluoride treatments also tend to reduce tooth sensitivity and, in fact, that's how my dentist chose to treat mine. Sensitive-tooth toothpastes also usually use milder abrasives than other formulations and dentists usually recommend using soft toothbrushes to reduce irritation of the tooth and gums.

B. Potassium Nitrate is an oxidizer for gunpowder and some low explosives-- it supplies oxygen to feed the chemical reaction that makes the explosion. While it promotes combustion, it doesn't of itself do much. Its other uses, according to the World Health Organization, includes use as an anti-microbial preservative for food. In fact, several familiar foods might contain saltpeter -- salami, sausages, pepperoni, corned beef, and hot dogs have all been made with it as an ingredient.

C. Going back to my file and pulling the Material Safety Data Sheets I have for potassium nitrate, I find that, overall, it's considered pretty innocuous except as an oxygen source for combustion. There is a note that some people with sensitivity to nitrates could suffer from ill effects with long-term high exposure, and some people believe it can be converted to free radicals that attack the kidneys and other organs. Gastritis seems to be limited to acute exposure (large quantities taken in very quickly) and to people who have a sensitivity to nitrates. I cannot find any hard numbers that give the demarcation between a small and large dosage of saltpeter, which is another indication that it is generally considered pretty harmless.

Unless you're one of a small percentage of people who are sensitive to nitrates, the fluoride compounds used in toothpastes are actually higher in toxicity than the potassium nitrate added to help reduce the sensitivity of your teeth.

If you would like to do a little more checking, you can check the Academy of General dentistry at http://www.agd.org and the American Dental Association at http://www.ada.org

I hope this helps!

Kevin