Why are my teeth sensitive? Causes, toothpastes and warning signs

Your teeth are sensitive because something has opened a path from the outside of the tooth to the nerve inside it. In most adults that path is exposed dentine, the layer under the enamel, and dentists call the problem dentine hypersensitivity. It causes a short, sharp pain with cold, hot, sweet or sour food, or with cold air, that stops as soon as the trigger is gone. It is common, it is usually manageable at home, and it is rarely dangerous. The exception is sensitivity that behaves differently, which we cover further down.

What is going on inside the tooth

A tooth has three layers. The hard enamel on the outside has no feeling. Under it is dentine, which is full of microscopic tubes running inwards to the pulp, where the nerve and blood supply sit. Below the gum line, the root has no enamel at all, only a thin coating that wears away easily.

When dentine is exposed, the ends of those tubes are open. A cold drink or a sugary sweet makes the fluid inside the tubes move, and the nerve reads that movement as pain. This is the explanation most researchers accept, and a 2020 evidence overview in BMC Oral Health describes it as the basis for most treatments: either block the tubes or calm the nerve.

The usual causes

Dentine becomes exposed in a few main ways. Many people have more than one.

• Receding gums. When the gum pulls back, the root is uncovered. This is the most common cause in people over 50. Our guide to receding gums covers why it happens.
• Acid erosion. Fizzy drinks, fruit juice, wine, citrus fruit, sipping vinegar-based drinks and acid reflux all soften enamel. The Oral Health Foundation's erosion page explains how frequent acid exposure thins enamel over time.
• Brushing too hard. A hard brush and a sawing action wear notches in the root at the gum line, especially straight after acidic food.
• Grinding and clenching. Grinding wears the biting surfaces flat and can expose dentine on the tips of the teeth.
• Whitening. Bleaching gels often cause sensitivity during treatment and for a few days after.
• Recent dental work. A new filling, a scale and polish or gum treatment can leave teeth sensitive for a short while.

Why it often gets worse after 50

Many people find their teeth become more sensitive in their fifties and sixties, even if they never had trouble before. There are a few reasons for this, and none of them means you have done anything wrong.

Gums tend to recede gradually with age and after years of brushing, so more root surface is on show. Enamel thins with decades of chewing and acid, especially on the biting edges and at the necks of the teeth. Old fillings shrink slightly or develop small gaps at their edges. Many common medicines, including some for blood pressure, depression and allergies, reduce saliva, and saliva is what normally helps to repair and protect the tooth surface.

On the other hand, the nerve inside a tooth also shrinks with age and lays down extra dentine, which can make older teeth less reactive. So two people of the same age can have very different experiences. If your sensitivity is new, has spread quickly or is getting worse month by month, mention it at your next check-up rather than putting it down to age.

Sensitive toothpastes: what the evidence says

A toothpaste for sensitive teeth is the first thing to try, and for many people it is all they need. They work in one of two ways.

The evidence is real but modest. A Cochrane review of potassium toothpastes found a benefit for some measures of sensitivity, though the studies were small and varied. In practice, it is worth trying one product for a month before deciding it does not work, and then trying a different ingredient.

To get the most out of any of them:

1. Use it twice a day, every day. Missing days lets the effect fade.
2. Spit, do not rinse. Leave the paste on the teeth after brushing.
3. Dab some on. Rub a small amount onto the sensitive area with a clean finger at bedtime and leave it.
4. Keep going. Sensitivity usually returns if you stop.

Other things that help at home

• Switch to a soft brush and gentle circles, or an electric brush with a pressure light
• Keep acidic drinks to mealtimes, use a straw for fizzy drinks, and have water or milk afterwards
• Wait about an hour after acidic food or drink before brushing, as softened enamel wears more easily
• Chew sugar-free gum after meals to boost saliva, which helps repair enamel
• Talk to your GP about reflux if you often have heartburn or a sour taste
• Ask about a night guard if you wake with a sore jaw or worn teeth

When sensitivity means something else

Exposed dentine produces a short, sharp pain that stops within seconds of the trigger going. Pain with a different pattern can come from a problem that needs treatment, and a toothpaste will only hide it. See a dentist if you notice:

• Pain that lingers for more than a few seconds after a cold or hot drink
• Throbbing or aching that starts on its own or keeps you awake
• One tooth only, especially if it has a large filling or a crown
• Pain on biting, particularly a sharp pain as you let go, which can mean a cracked tooth
• Sensitivity to heat that is relieved by cold water, which can point to an inflamed nerve
• Swelling, a bad taste or a gum boil, which can mean an abscess

Decay, a leaking filling, a cracked tooth and gum disease can all start as "just sensitivity". A sore upper back tooth during a cold can also come from the sinuses. The NHS toothache page sets out when to see a dentist and when to call 111.

What a dentist can offer

If home care has not been enough, a dentist will first check the cause: looking at the gum line, testing teeth with a puff of air, checking fillings and taking X-rays where needed. Treatment then depends on what they find.

• Varnishes and sealants. Fluoride varnish or a desensitising liquid painted onto the exposed areas, sometimes repeated.
• Prescription toothpaste. High-fluoride toothpaste for people with a lot of exposed root or a high risk of decay.
• Bonding. A thin layer of tooth-coloured composite over notches or exposed roots.
• Gum treatment. Treating gum disease, and in some cases a gum graft to cover an exposed root.
• Fixing the underlying problem. Replacing a failed filling, treating decay, or root canal treatment if the nerve is damaged.

Crowns and veneers are not a treatment for ordinary sensitivity. Preparing a tooth for a crown removes enamel and can itself make a tooth sensitive for a time.

How we handle sensitivity at Precious Dental

Patients often mention sensitive teeth when they ask us about crowns or veneers, and sometimes assume that covering the teeth is the fix. Our dentists look at why the teeth are sensitive before suggesting anything. Where gums have receded or there is gum disease, the gums come first, and you can read about that on our gum treatment page. Where a few notches at the gum line are the cause, bonding may be enough. We prefer to keep healthy teeth rather than crown them, and your written plan will explain the reason for each item. You can meet the people who make those decisions on our dentists page.

Sources

1. Oral Health Foundation: Sensitive teeth
2. Liu XX et al. Pathogenesis, diagnosis and management of dentin hypersensitivity: an evidence-based overview for dental practitioners. BMC Oral Health 2020
3. Poulsen S et al. Potassium containing toothpastes for dentine hypersensitivity. Cochrane Database Syst Rev 2006
4. Oral Health Foundation: Dental erosion
5. NHS: Toothache

Checked October 2026. Where we give our own view as a clinic, we say so.