Dr. Pramod Narsinghani

For people with no dental problems, the teeth seem to be white pearls which add beauty to a person’s smile and face. However, there is more to it. The tooth does have layers which can make it sensitive and even painful. Those who have sensitivity when sipping cold water or eating sweets know how bad the experience can be. To understand how the sensitivity sets in a tooth, it is first important to understand the structure of the tooth.

There are 3 layers to the tooth from outside inwards – the outer white layer of enamel, a second sensitive layer of dentin, and the innermost one called the pulp. The enamel is devoid of any sensation and provides a protective covering for the tooth. It is the second hardest material in the body. The next inner layer, known as dentin, is made of fine tubules, which is responsible for sensation. The third innermost layer known as the pulp contains the blood and nerve supply essential for the tooth.

The tooth also has a crown and a root portion. The crown portion is what is visible in the mouth. The root portion is what is hidden in the jaw bone, provides an anchor, and is covered by the gums. The structure of the root is very similar to the crown, except that the first layer of enamel is replaced by a much softer material known as the cementum. As the gums recede, which often happens with age, the cementum is exposed to the oral environment, which then wears off much faster, and then sensitivity sets in.

How does sensitivity sets in?
The oral cavity is a very active environment with food particles, saliva, and millions of microorganisms. In this moist environment, food is degraded and acids are produced. These acids act on the enamel and there is a constant loss of enamel. The enamel does not have any sensation, and other than cosmetic concerns, enamel loss is asymptomatic. However, once the enamel layer is completely lost, and the dentin is exposed to the oral environment, the acids that are produced penetrate the fine tubules which cause sensitivity. Due to old age, when the gums recede, the cementum is exposed, and the rate at which cementum is lost is much rapid than that of enamel. Therefore, the dentin on the root surface produces sensitivity much faster than the crown surface.

To summarize, let us take a look at some of the most common causes of sensitivity:

• Tooth decay, often worsened by soft, sticky foods which produce acids more than grains and vegetables
• Use of hard brush which can lead to enamel wear-off
• Improper dental fillings, allowing seepage of the acid into the dentin
• Age, leading to gum recession

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