Tooth sensitivity can be caused by a variety of factors, and it is a common dental problem experienced by many people. Here are some possible reasons why your teeth may be sensitive:

1. Tooth decay: Tooth decay, or cavities, can cause tooth sensitivity when the decay has reached the inner layers of the tooth where the nerves are located.

2. Gum recession: Gum recession occurs when the gums pull away from the tooth, exposing the sensitive roots. This can be caused by brushing too hard, periodontal disease, or aging.

3. Tooth grinding: Grinding or clenching your teeth can wear down the protective enamel layer, exposing the sensitive dentine layer underneath.

4. Acidic foods and drinks: Consuming foods and drinks that are high in acid, such as citrus fruits and soda, can wear down the enamel layer of your teeth, making them more sensitive.

5. Teeth whitening: Some teeth whitening products can cause tooth sensitivity, especially if used incorrectly or for too long.

6. Cracked or chipped teeth: A crack or chip in a tooth can expose the sensitive inner layers, causing discomfort.

7. Dental procedures: Teeth may be sensitive for a short time after certain dental procedures, such as fillings or crown placements.

If you are experiencing tooth sensitivity, it is important to visit your dentist to determine the underlying cause and receive appropriate treatment. Your dentist may recommend desensitising toothpaste, fluoride treatments, or other interventions to alleviate your symptoms.