Perhaps you've taken a drink of a cold beverage and winced in pain. Or inhaled on a chilly day and felt a jolt when the air hit your teeth. Maybe you found yourself unable to enjoy a cup of hot tea without a sharp ache punctuating each sip. If any of these situations sounds familiar, you probably have sensitive teeth.
The reasons for the discomfort are many. First, the root structure of one or more teeth may have become exposed. Normally covered by gum tissue, this layer just underneath -- called dentin -- contains millions of tiny tubes, each of which is connected to a nerve ending. It's when the tubules are left unprotected by gum recession or enamel erosion that problems arise. Receding gums, tooth grinding, a diet high in acidic beverages, and overaggressive brushing can all leave dentin exposed.
Dentin can also become irritated if you overuse tooth-whitening agents, which contain harsh ingredients to strip away stains. Unfortunately, they can also thin the enamel layer around dentin, exposing the tender tubules.