If you are avoiding certain types of food because your teeth are sensitive to cold or hot. It could be that you have abraded enamel. Enamel is the protective layer of the tooth covering a honeycomb mesh of dentin. Dentin is made out of microscopic tubules that are connected to the inner core of the tooth, the pulp. The nerve of the tooth is in the pulp.
The other signs of teeth erosion are yellowish appearance of the teeth as the enamel thins, a sandblasted, dull look on the surface of the teeth, transparency on the biting edge and small dents on the tooth surface.

Use of the hard or medium tooth brush causes enamel abrasion especially around the gum line and therefore teeth sensitivity. The brushing technique of circular and gum line brushing is more important and effective than using a hard bristle tooth brush. The hard bristles abrade away the gum. Make sure you always use a soft tooth brush.

One of the other more common causes of teeth sensitivity is the toothpaste. Tartar control formula tooth pastes cause sensitivity. The cause is the anti calculus component of the tartar control tooth paste. Tetrasodium and/or Tetrapotasium Pyrophospahate are the chemical names of these tartar control components. Pyrophosphates alone are not responsible for hypersensitivity. In order to mask the strong bitter taste of pyrophosphates the concentration of flavoring agents, known to cause sensitivity are increased. Also increased concentration of detergents is needed to make Pyrophosphates soluble in the dentifrice. These changes are the causative factors in hypersensitivity reactions. Stopping the use of the toothpaste stops the hypersensitivity.

The other cause of teeth sensitivity is the use of acidic food. Soft drinks like Pepsi and Coke even in the diet variety are very acidic, as is iced tea. This acidity eats away the teeth, abrades the enamel and causes teeth sensitivity. Sports drinks like Gatorade are even more acidic than orange juice. The acidity softens the teeth and brushing afterwards removes the protective layer of the tooth making it more temperature sensitive. If you have sensitive teeth you want to avoid soft drinks or sport drinks as they contribute to your sensitivity. Regular water is the best drink to quench the thirst.

If you have sensitive teeth make sure you are using soft tooth brush. Stop using tartar control formula toothpaste and see if your sensitivity goes away. Evaluate your diet and see if acidic food or drinks are part of your diet and eliminate those.

Dentists can seal the sensitive teeth with the use of fluoride varnishes. Sometimes a sensitive area on the tooth needs to be sealed with a bonded seal material to physically prevent the sensitizing irritants from contacting the tooth. Sometimes as a complement to this treatment a dentist might give you a tube of prescription fluoride tooth paste to use. Fluoride seals the enamel and prevents sensitivity,