Easing the Ouch
Toothpastes with ingredients designed to desensitize teeth are intended for people whose teeth are extremely sensitive to heat and cold and to brushing. As many as 1 in 7 adults develop sensitive teeth, usually after age 45. This typically happens when the gums recede, exposing the sensitive cementum and dentin below the gum line.
Desensitizing toothpastes work differently depending on the desensitizing compounds they contain. Potassium nitrate, strontium chloride, and sodium fluoride are common desensitizing compounds. Fluorides help rebuild a thin layer of cementum on the tooth's exposed root, a process similar to the way in which fluoride remineralizes enamel. Strontium chloride blocks tiny tubules (channels) that lead from root surfaces to the nerves. In doing so, the compound disrupts pathways that help produce pain signals. Although chemists are not completely certain how potassium nitrate works, they believe it also alters chemical signals in the tubules. It and the other desensitizing compounds must be used regularly to be effective.