Harris Interactive has conducted a survey in the year 2010 for new Orajel® advanced tooth desensitizer. According to this survey 46% of adult Americans have been affected by tooth sensitivity in the last five years. Out of this half the population did not take any remedial actions for their sensitive tooth whereas many were dissatisfied with their treatment options. As per this survey tooth sensitivity has changed the lives of 55% of affected people whereas 41% changed their way of eating and drinking to avoid pain due to sensitivity.

This survey also has found that the reasons for tooth sensitivity are as follows:

• Bruxism/ teeth clenching or grinding – 21%
• Receding gums – 21%
• Cracked or chipped teeth – 18%

In the US 45 million people are affected by hypersensitivity and 10 million have chronic sensitive teeth.

Tooth sensitivity is tooth discomfort or pain in one or more teeth that is triggered by eating hot, cold, sweet or sour foods and drinks, or even by breathing cold air. The pain can be sudden, sharp and the pain can travel into the nerve endings of your teeth. Touching one tooth with another tooth or tongue might also cause tooth sensitivity.

Two types of tooth sensitivity occur – Dentinal and Pulpal.

• Dentinal sensitivity - The crowns of healthy teeth are protected by a layer of enamel and this is the hardest substance in the human body. Similarly root of the tooth under the gum line is protected by a layer known as cementum. Between the enamel and the cementum lies dentin that is relatively soft as compared to enamel or cementum.

  Dentine is the main, calcareous part of a tooth and this is beneath the enamel and surrounds the pulp chamber and root canals. If the dentine is exposed it will result in a sharp, shooting pain from the teeth, whenever you eat hot or cold food and drinks. The dentin contains microscopic tubules and once the enamel layer which is the protective covering of the tooth is removed these tubules allow heat/ cold and acidic/ sticky foods that stimulates the nerves and cells inside the tooth. This is more predominant while eating cold items such as ice cream. This pain could be a constant nagging pain at times.

• Pulpal sensitivity – occurs due to the reaction of the tooth's pulp. Pulpal sensitivity affects only a single tooth.

Your tooth becomes sensitive when the dentin which is the underlying layer of your tooth is exposed. The uncovered roots without hard enamel contain thousands of tiny tubules that lead to the tooth's nerve center – the pulp. These dentinal tubules allow the hot, sweet or cold food items to reach the nerve in your tooth thereby causing pain and sensitivity. In addition, it is possible that your tooth has micro cracks that are invisible to the naked eye and this can also cause sensitivity.

The following factors are responsible for the development of tooth sensitivity are:

• Acidic foods – consumption of acidic foods – citrus fruits, tomatoes, pickles, tea – regularly causes erosion of tooth enamel.
• Brushing hard – or brushing with a hard-bristled toothbrush will result in the tooth wear thereby exposing the soft dentin. This can also result in pulling out of gum tissue from the teeth thereby causing gums recession.
• Bruxism or Teeth Grinding - wears down the tooth enamel thereby exposing the soft dentin.
• Cracked teeth – bacteria from plaque will fill the broken or chipped/ cracked teeth and enter the pulp causing Inflammation.
• Gingivitis or Gum Disease – Inflamed gum tissue results in the loss of supporting ligaments thereby exposing the root surface and the tooth nerve and this will cause tooth sensitivity.
• Gum Recession – due to periodontal disease exposes the root surface.
• Plaque – on the surfaces of the root might cause sensitivity.
• Poor Oral Hygiene – allow tartar build up at the gum line causing the tooth to become sensitive.
• Tooth whitening products or toothpaste with baking soda and peroxide - will make your teeth highly sensitive.
• Recent dental procedures - like teeth cleaning, crown placement, root planing and restoration of tooth might increase sensitivity; these are temporary in nature and will vanish after 4 to 6 weeks.
• Untreated Cavities

Your tooth might become sensitive after a deep filling and this may take number of weeks to disappear. If the filling is too high that puts more pressure on the tooth the height might have to be reduced.

If the sensitivity does not reduce for a long time the tooth might require a root canal treatment.

The sensitivity of your dentine will cause acute pain and you will feel uncomfortable; however, if you get the problem diagnosed and treated it is possible to eliminate this problem. In order to accomplish this, it is essential for you to change your eating as well as oral health habits so as to prevent exposure of dentine again.

Before treating for sensitivity it is necessary for your dentist to identify the reasons for your tooth sensitivity. The pain could have been caused by dentine sensitivity, tooth decay, replacement requirement for existing filling or crack in the tooth. If the diagnosis shows dentine sensitivity, the dentist might recommend use of brushes suitable for sensitive teeth, sensitive toothpastes and mouth rinses. Application of a small amount of toothpaste on the affected area at frequent intervals throughout the day is also advised by certain dentists to overcome this problem. This paste forms a protective layer over the affected area of the teeth. The fluoride in the toothpaste not only reduces the sensitivity but also prevents tooth decay or caries.

If the sensitivity is due to tooth decay the dentist might go for root canal treatment. On the other hand, if it is due to a crack in your tooth he might give you a crown to hold the tooth together. If over-brushing has caused recession in your gums because of which your tooth has become sensitive your dentist will educate you on the correct technique of brushing; you may also benefit by using electric brush.

For severe sensitivity of your tooth, the dentist might treat you with adhesives, resins or varnishes to seal the area exposed.