The nerves in the pulp of the teeth make them sensitive to cold when the roots of the teeth are exposed to gum problems. The dentinal tubules are the pathways that are filled with a fluid, which moves when cold air or liquid comes in contact with exposed tubules. This movement triggers painful sensation in the nerves.
Furthermore, small cracks develop when your teeth expand and contract on exposure to hot and cold temperature. These cracks develop a new additional path to the nerves, which in turn, develops teeth sensitivity to cold. The factors that are responsible for this problem are mentioned further with their treatment options.
A common condition that leads to a tooth sensitive to cold and sweet is deep tooth decay. Tooth decay or dental caries first begins in the enamel of the tooth, from where it proceeds to the second layer, i.e the dentin. Dentin is the semi-porous structure present in the tooth and when caries reaches the dentin, it leads to exposure of the dentinal tubules.
This is what makes the tooth sensitive to cold. More often than not, this will not be sensed as proper and full-blown pain related to a decayed tooth, but instead will be felt as a mild and dull pain, mostly associated only with consumption of cold food or water.
If the tooth decay is in this stage, then you should ideally contact your dentist immediately and he will evaluate your condition and plan the treatment accordingly. Usually, tooth filling should be the treatment for such a condition.
You may land up with this problem due to receding gums. The usual gum line is at the point where the enamel ends and cementum begins, i.e., at the point where the white crown ends and the yellow root begins. Due to habits like tobacco chewing and vigorous brushing, the gum line may recede and this could lead to exposure of the root surface of the tooth.
The root surface of the tooth is sensitive in nature and this may be why, you could suffer from this condition. The treatment of this problem entails a surgery wherein, a gingival graft is placed over the exposed region, so that the root is not exposed in the oral cavity anymore.
Some other dental conditions can lead to cold sensitivity in teeth. A person may have sensitive teeth after the procedure of filling. This happens when a tooth has deep caries, and the dentist, to avoid something as invasive as root canal, fills the cavity with silver amalgam, while applying a base of calcium lining to encourage closure of exposed dentin.
So initially, there may still be sensitivity in the tooth after this treatment, till the dentin bridge forms. You may feel tooth sensitivity to cold after filling, but no treatment is needed. However, if a person has throbbing pain after the filling, it means that the caries have reached the pulp and now there is no other way but to perform a root canal.
At times, a tooth that has a dental crown may also be sensitive to cold. This would signify that either the root canal done by the dentist was not proper, due to which the sensitivity points towards pain or it may mean that the cap is ill-fitting and impinging on the gingival border, leading to a receding gum line and root sensitivity.
Either way, the person will need to get an x-ray done, so as to evaluate the cause, and then decide whether there is a need for second root canal or the dental cap needs to be resized or refitted.
If you have a tooth sensitive to hot and cold temperature, then there are high chances that the caries have reached the pulp of the tooth, in which case, you will have to go in for a root canal treatment.
So, if you experience any kind of tooth problem, then it is best to visit the dentist immediately, so as to avoid root canal treatment or worse, tooth extraction. After all, one should never take one's dental health for granted!