Why do I experience tooth sensitivity or pain when drinking hot or cold water?

Have you ever felt a sharp pain when you’re eating food? Pain is commonly associated with dental decay that has reached deeper structures of your teeth, but not all pain is due to dental decay! Due to the vast network of neurons near your teeth, you may feel pain even from the tiniest stimulus!

Pain due to dental decay is acute, meaning it only occurs when there is a stimulus [i.e., when you eat hot/cold food]. The pain should subside after the stimulus is gone [i.e., you finish eating the ice cream]. Meanwhile, pain due to decay is chronic, which is the complete opposite. The pain you feel is semi-dull. You can feel it all day long.

If our teeth structure is intact, why do we still experience dental sensitivity?

The answer lies in the natural morphology of your tooth itself. Our teeth are not completely solid, it has 3 different layers:

why do I have sensitive teeth

When there is a hot stimulus, the fluid inside the dentine layer will expand.  When there is a cold stimulus, the same fluid will contract. Since the neuronal bodies lie immediately below the the dentinal layer, the expansion and contraction of fluid would stimulate these neurons. Stimulus is then sent to the brain, causing us to feel the sharp pain!