Sensitive Teeth: Why Cold Water Hurts and What Fixes It
A sharp jolt from cold water, ice cream or even cold air is one of the most common dental complaints. The sensation is distinctive, and the causes are a short, manageable list.
What is happening
A tooth has three layers. Enamel on the outside, hard and without nerves. Dentine beneath it, softer and riddled with microscopic tubules running inward. The pulp in the centre, containing the nerve and blood supply.
Those dentine tubules are filled with fluid. When dentine is exposed, temperature change, sweetness, acidity or touch causes that fluid to move, which stimulates the nerve. That is the sharp, brief, shooting pain.
The sensation is characteristic: short and sharp, triggered by a stimulus, and stopping quickly once it is removed.
Why dentine becomes exposed
Gum recession. The root surface has no enamel, so it is immediately sensitive once exposed. Causes include aggressive brushing with a hard brush, gum disease, ageing, grinding, and sometimes orthodontic movement.
Enamel erosion from acid. Dietary sources include citrus, vinegar, wine, carbonated drinks including sugar-free ones, and fruit juices. Medical sources include acid reflux, particularly at night, and repeated vomiting, which produces a distinctive pattern of erosion on the inner surfaces of the upper front teeth.
Abrasion at the neck of the tooth, a notch from years of hard horizontal scrubbing.
Grinding and clenching, which flexes the tooth and wears the biting surface.
After dental treatment. Sensitivity following a filling, a scale or whitening is common and usually settles over days to a few weeks.
Whitening products, which commonly cause temporary sensitivity.
A cracked tooth, which feels different and is covered below.
Decay, which eventually reaches dentine.
Telling it apart from something worse
This distinction matters, because it determines whether you need a desensitising toothpaste or a root canal.
Dentine sensitivity: sharp, brief, stops as soon as the stimulus goes, no spontaneous pain, no night pain.
Irreversible pulpitis: pain lingers for seconds to minutes after the stimulus, may come on spontaneously, often worse with heat, can wake you at night, and may be hard to localise to a specific tooth. This needs prompt dental treatment, usually root canal.
Cracked tooth syndrome: pain specifically on releasing a bite rather than on biting down, often on one tooth, sometimes with sensitivity to cold. Notoriously difficult to pin down and often diagnosed late. If you have a tooth that hurts when you let go after chewing, say exactly that to your dentist.
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Dental abscess: constant throbbing pain, swelling, tenderness to touch, sometimes fever and a bad taste. Facial swelling with dental pain needs same-day care, because infection can spread.
What to do
Switch to a desensitising toothpaste. The two main mechanisms are potassium nitrate, which calms the nerve, and stannous fluoride or arginine-based formulas, which plug the tubules. Use it twice daily and give it at least two to four weeks.
A technique worth knowing: rub a small amount directly onto the sensitive area with a fingertip and leave it on, especially at night, rather than only brushing with it.
Fix the brushing. Soft bristles, 45 degrees to the gum line, gentle pressure, small movements. If you hear scrubbing, you are pressing too hard. Electric brushes with pressure sensors help people who cannot moderate force.
Spit, do not rinse. Leaving fluoride in contact with the teeth matters more here than anywhere.
Manage acid.
- Do not brush for 30 to 60 minutes after anything acidic, because enamel is temporarily softened and brushing then removes it
- Rinse with water, or water with a little bicarbonate, immediately after acidic food or drink
- Use a straw for acidic drinks
- Keep acidic drinks to mealtimes rather than sipping through the day
- Treat reflux properly if present, including raising the head of the bed
- Finish a meal with something neutral such as cheese or milk
Address grinding. A night guard protects teeth from further wear. Treating the stress and sleep factors behind it helps more.
Avoid whitening products while sensitivity is active.
What a dentist can add
- Fluoride varnish applied in the surgery, which is considerably stronger than toothpaste
- Desensitising agents and sealants painted onto exposed root surfaces
- Bonded restorations to cover a worn notch at the neck of the tooth
- Gum grafting for significant recession
- A night guard made to fit
- Root canal treatment where the pulp is irreversibly inflamed, which resolves the pain
When to see a dentist rather than wait
- Sensitivity lasting more than a few weeks despite desensitising toothpaste
- Pain lingering after the stimulus is removed
- Spontaneous pain, or pain at night
- Pain on releasing a bite
- Swelling of the gum or face
- A visible hole, dark spot or chipped tooth
- Sensitivity in one tooth only, which is more likely to be a specific problem than general dentine exposure
What does not help
- Scrubbing harder, which worsens both recession and abrasion
- Hard-bristled brushes
- Abrasive charcoal and “whitening” pastes, several of which have high abrasivity and no fluoride, and which can accelerate the exact problem they are sold to fix
- Avoiding brushing the sensitive area, which allows plaque to accumulate and makes it worse
- Repeated courses of antibiotics for dental pain, which do not treat the cause and are only appropriate for spreading infection
The short version
Brief sharp pain that stops with the stimulus is exposed dentine, and usually responds to a desensitising toothpaste rubbed on at night, a soft brush at the gum line, and keeping acid away from teeth. Pain that lingers, wakes you, or appears when you release a bite is a different problem and needs a dentist rather than another tube of toothpaste.