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If you feel a sharp sensation when you have something cold to eat or drink, you may be suffering from tooth sensitivity.  Tooth sensitivity is usually caused by exposing the inner part of the tooth.  Enamel is the outer layer of tooth structure and is very strong.  The next layer in, dentine, is more porous and allows a direct passageway to the nerves of a tooth.  When the nerves of the tooth are irritated, you get a sharp, sensitive sensation.

There are many reasons for this exposed dentine.  Let’s look at a few common ones:

Gum Recession

Our gums normally cover the roots of our teeth and the jaw bone housing the roots.  When our gums recede, the root surface is exposed and may be sensitive.  Our gums may recede due to trauma or bacterial damage.  Overzealous toothbrushing and flossing is a common example of trauma.  Gum and bone covering our teeth breaking down due to gum disease is an example of bacterial damage.

Tooth Wear

Over time our teeth will wear down.  As the enamel becomes thin and the underlying dentine is exposed, sensitivity may occur.  If you clench or grind your teeth, this tooth wear may happen earlier.  Teeth grinders not only wear away the chewing surfaces of their teeth.  They also break down the necks of their teeth next to the gumline.  This is called abfraction and results in indents at the necks of teeth due to the rocking action of the tooth against the bone when you grind your teeth.  Crack lines can also form in worn teeth that can be sensitive to cold and on being bitten on.

Tooth Decay

An opening in the tooth due to tooth decay may result in sensitivity.  Generally, the larger the cavity, the greater the symptoms.  In deep cavities, the nerves may already be irritated and the large hole provides a direct passageway to the nerves.  A filling that is becoming loose may also cause sensitivity as it no longer seals the tooth properly.