Your tooth is complex
A tooth consists of a crown and a root. The root is attached to the surrounding bone by thin threads. The gum surrounds the lower part of the crown, covers the bone and functions as a protective barrier against bacteria in the mouth.

Tooth sensitivity can be caused by many things like, caries, overload, inflammation, infections. A common cause is that the gum recedes and exposes the root surface. Inside the root is the pulp tissue and it consists of nerves and blood vessels. The outer surface of the crown is protected by enamel, but there is no enamel protecting the root surface.

With age the gum recedes, but behaviour like teeth clenching or periodontitis and even the wrong cleaning technique can make it worse.

Sensitivity is annoying but mostly harmful
If we magnify (below) the exposed root surface we can see it consists of small canals. The canals are narrow and filled with liquid. If the root is exposed to heat, cold, sweet, dryness, the liquid will move. This causes the nerve to react which manifests as a sharp, icy sensation. It can be painful, but is not harmful. In some rare cases, a root canal might be necessary to treat the pain.

The root surface consists of millions of microscopic canals. The canals are filled with liquid that stimulates the nerve when there is a change on the surface (heat or cold). Caries builds easier on the softer root surface than the enamel covered crown.

Bone recession
When the root surface is exposed it is because the bone underneath has receded. The bone can recede for various reasons. The most common ones are:

• Load: Overload, caused by teeth grinding at night may result in bone recession.
• Oral hygiene: If cleaning – especially in the area between the teeth – is compromised, the gums respond with inflammation, swelling and/or bleeding . This may cause the bone to recede. In some cases, the bacteria build-up may lead further bone loss and eventually tooth mobility and tooth loss (periodontitis). This can be prevented by practising proper oral hygiene.
• Old fillings and crowns: Fillings and crowns with bad fits can cause bacteria to accumulate and initiate the reaction described above (oral hygiene).

What to do about tooth sensitivity
In some cases, the icy sensation can be a sign of possible tooth damage. You dentist will look for signs of damage, but if the condition worsens, your dentist might ask you to visit the clinic again and prescribe a topical fluoride treatment. Certain toothpastes, like Sensodyne and Zendium, might be effective at closing the canals on the root surfaces so that the nerve is not stimulated. In most cases the pain from tooth sensitivity gradually disappears. If it persists, please contact your dentist.

If the symptoms are not severe and the dentist does not find a reason, it is not harmful to wait. Occasionally the reason surfaces later, but in most cases it is just a temporary sensitivity that gradually diminishes. However, if it worsens, do contact the dentist.

A root canal treatment will remove the icy pain, but the modern approach to dentistry is to keep the teeth alive as long as possible.