They form precipitates in exposed dentinal tubules, thereby blocking
them and alleviating sensitivity. There is a wide range of
anti-sensitivity products, from toothpastes to gels to mouthwashes.
They work better for some people than others. Some cases may have to be
treated by a dentist. Reccurrence is common if you stop using them, but
these toothpastes are as good as regular ones so there's not really any
reason to stop using them.

Regards,
George

    Good question.
    The working hypothesis of how these work is that the active incredient
(usually potassium nitrate; original Sensodyne IIRC had strontium
chloride) causes a precipitation of mineral crystals in the dentinal
tubules.  Dentinal sensitivity is thought to be largely a hydrodynamic
effect--in English, this means that disturbing the surface of the
dentine can cause transmission of pressure through these tubules into
the pulp.  The tubules, once clogged with mineral deposits do not
transmit the pressure as effectively to the pulp.
    Generally it takes a few weeks to build up maximum protection.  From
personal experience I can say that it works; both for sensitivity to
touch and to cold.  How long the effect lasts after discontinuing the
toothpaste I imagine depends upon diet and other factors that may
dissolve the minerals.  My brother for example likes green seedless
grapes; they have a relatively acid content and tend to make his teeth
sensitive.  He frequently uses desensitizing toothpastes in the summer
when these grapes are in season--he usually doesn't need them in the
winter.  I've seen different patterns of use, and some people respond
better than others--but generally speaking they are effective.
    If further measures are necessary, most dentists will have more potent
desensitizing agents for topical application in the office.

Steve

If a tooth or teeth are sensitive, is that a forerunner for decay?  Is it
better to stay away from the foods that cause the sensitivity (which can be
many) or equally good to use the Sensodyne toothpaste.    And if ordinary
toothpaste is used, is that more of a jeopardy to the teeth.
Gail

yip they d

--
Joel34