Sensitive Teeth: Why It Happens and How to Actually Fix It

Tooth sensitivity is a symptom rather than a disease. It is your tooth signalling that its protective layers have been breached somewhere, so the nerve inside is responding to things it normally would not feel. A sensitive toothpaste can quieten that signal, but it does nothing about the cause. The useful question is not which toothpaste to buy, but why the teeth have become sensitive.

What is happening inside the tooth

A tooth has three layers. Enamel on the outside is hard and has no nerve supply. Beneath it is dentine, a softer layer threaded with microscopic tubules that lead inward. At the centre is the pulp, where the nerve sits. While enamel and healthy gum cover the dentine, those tubules are sealed. When enamel thins, or the gum recedes to expose the root (which has no enamel at all), the tubules open. Cold, heat, sweetness and even cold air can then travel down them and stimulate the nerve.

Every effective treatment works in one of two ways: blocking the open tubules, or calming the nerve's response. Lasting relief also means stopping whatever is exposing the dentine.

Typical signs

• A sharp, short twinge from cold drinks, ice cream or cold air that fades once the trigger has gone
• Discomfort with sweet or acidic foods
• Sensitivity when brushing, especially near the gum line
• Sensitivity at the neck of one or two teeth where the gum has receded
• Sensitivity for a few days after a filling, a clean or whitening

Signs that suggest something more

Pain that lingers for many seconds after the trigger, sensitivity to heat in particular, throbbing, pain that wakes you, or sensitivity that is focused on one tooth and getting worse are different patterns. These can point to a crack, decay or an inflamed nerve, and they need an examination rather than another tube of toothpaste.

Sensitivity has several possible causes, and the right fix differs for each. Most patients have one main cause and a contributing one.

• Gum recession. When the gum pulls back, the root surface is exposed. This is why sensitivity often sits at the gum line of one or two teeth while the rest of the mouth feels fine. See gum recession.
• Acid erosion. Frequent acidic food and drink, such as citrus, fizzy drinks, fruit teas and wine, softens and dissolves enamel over time. How often you have them matters more than how much. Acid reflux, including the quieter kind that reaches the mouth at night without obvious heartburn, can do the same; if you often clear your throat, wake with a sour taste or notice hoarseness, it is worth discussing with your GP. Dry mouth from mouth breathing reduces the saliva that would otherwise neutralise acid.
• Heavy brushing. A firm brush, strong pressure and a scrubbing action wear enamel at the gum line and encourage recession. People with the most sensitivity are often the most diligent brushers. Brushing straight after acidic food or drink adds to the wear, because enamel is briefly softened.
• A cracked tooth, decay or a failing filling. These allow cold and sweetness to reach the dentine through a gap. They are the causes that must not be missed, because early repair is far simpler than treatment once the nerve is affected.
• After dental treatment. Sensitivity after a filling, a clean or whitening is common and usually settles within days to a couple of weeks. Whitening briefly opens the tubules, which is one reason it should be supervised and correctly dosed. See sensitive teeth and whitening.
• Grinding and clenching. Night-time grinding wears and flexes the teeth, creating notches at the gum line. Jaw tightness, morning headaches and flattened teeth are clues. See teeth grinding and bruxism.
• Early gum disease. Inflamed gums can be tender to temperature, and early recession exposes root surfaces. Sensitivity together with bleeding on brushing points this way. See gum disease and bleeding gums.

Pregnancy can contribute through hormonal gum changes and, where there is sickness, acid exposure. Gentle, regular hygiene support during pregnancy helps.