Cold Sensitivity in Teeth

Living in Ottawa, the world capital apparently with the most extreme temperatures over the course of a year, (-40 to 104 / -40c -40c), the issue of teeth sensitivity to cold stimulus is common. In some cases where a tooth is dying the first sign is often cold sensitivity. But, in many instances patients report a short duration pain when drinking a cold liquid or when breathing cold air. This is not an indicator of possible root canal treatment. But, to some this can be extremely debilitating.

At one time it was surmised that root exposure was caused by overly aggressive tooth brushing. In recent years research has shown that some people clench and grind their teeth, often not perceived by the patient. A laser was used to measure the effect on the tooth and it was found that there is a slight bending at the root/ crown level. The result is that over time some of the ligament structure, that holds the gums to the roots is detached. This results in a loss of gun structure and an exposure of the root. This in itself is not a major concern;but, if it persists there can be a loss of cementum., the structure that covers the roots.

This in turn exposes the underlying dentin layer of teeth. In some cases this can progress to where there is a visible groove in the root. This condition is common, it is called an abfraction, from the Latin 'breaking away from'.

Many abfractions are not sensitive; but, those that are, can be attributed to the fact that as surface dentin is fractured from the tooth minute small 'tunnels' called tubules, are exposed. These can number up to 20,000 per square millimeter. The tubules contain a gel and they lead to the nerve area of the tooth in the root. There nerve cells are sensitive to movement in the gel of the tubules. Cold will cause a contraction of the gel which in turn stimulates the nerve cells, this can send a strong painful signal which many patients report.

The tubules, if exposed, are also sensitive to brushing and sweet stimulus from sugars. The brushing effect causes tubule gel movement and the sugars cause a transfer of liquid from the gel into the sugar in what is called an osmotic effect. The latter is a move to balance out the water content of the tubules with the sugars which are in saliva. So exposed tubules can cause painful stimulation due to cold air or liquids, sugar in food and to brushing.

There are a number of methods of treating this situation. Several sensitivity tooth pastes are available. They work by helping to close the tubules, thus preventing the afore mentioned stimuli. A number of years ago I attended a lecture where the speaker suggested using a bonding agent which is part of white filling materials. It is a liquid which is painted on the sensitive areas. The liquid bonding agent is what is called hydrophilic, that is it is attracted to liquid, which is the gel in the tubules. This can be sensitive at first, as the bonding agent evaporates cooling the surface; but, when the material evaporates it leaves behind a polymer plastic material which closes the openings of the tubules. In effect it is like thousands of small plugs. This prevents the gel from coming in contact with the outside environment. This protection may wear off in time but it has been shown to be very effective. And it can be renewed with no harm. I also recommend that the patients acquire a desensitizing tooth paste. I suggest they place small amounts with a finger, on sensitive areas as this will supplement what we have applies.

Dr Michael Pilon

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