You take a sip of cold water and there's a quick, sharp pain in one — or several — of your teeth. It passes in a second or two. You forget about it. Then it happens again the next day, and the day after that. Sound familiar?
Tooth sensitivity to cold is one of the most common complaints we hear. It's also one of the most misunderstood — because the same symptom can be caused by half a dozen different things, and the treatment depends entirely on which one.
What's Actually Happening Inside the Tooth
Beneath the hard enamel layer is dentine — a softer tissue that contains thousands of microscopic tubules running from the outer surface of the tooth down to the nerve. When enamel is intact, these tubules are sealed off. When it's not — because of erosion, a crack, or gum recession — cold temperatures or sweet/acidic stimuli cause fluid movement inside the tubules. That movement triggers the nerve. You feel it as a short, sharp pain.
This is called dentinal hypersensitivity, and it affects somewhere between 10 and 30 percent of adults. It's very common, and it's very treatable.
Common Causes — and What's Different About Each One
Enamel erosion. The outer layer of enamel wears away from acid exposure — citrus, carbonated drinks, vinegar-based foods — or from acid reflux. Once enamel is gone, it doesn't grow back. You can stop further erosion, but you can't reverse what's already happened without restoration.
Gum recession. When gum tissue pulls back, it exposes the tooth root, which has no enamel covering it — just cementum, which is more porous and sensitive. Gum recession is often caused by aggressive brushing, gum disease, or simply genetics. The exposed root is a common source of cold sensitivity in adults over 30.
Cracked tooth. A crack doesn't always show up on an X-ray. But it can cause sharp, localised pain — especially on biting or with temperature. If your sensitivity is in one specific tooth and gets worse when you bite down, a crack is worth investigating.
Tooth decay. A cavity that's reached the dentine layer will cause cold sensitivity. It's usually accompanied by visible darkening of the tooth or a rough texture you can feel with your tongue. If left untreated, decay reaches the pulp and turns into a root canal situation.
Recent dental work. Sensitivity after a filling or crown is normal and usually settles within a few weeks. If it's been more than 6 to 8 weeks and it's getting worse rather than better, let your dentist know.
Teeth whitening. Professional whitening temporarily increases sensitivity in most patients for 24 to 72 hours after treatment. This is predictable and passes on its own.
Sensitivity Toothpaste — Does It Work?
Yes, to a point. Desensitising toothpastes contain either potassium nitrate (which calms the nerve) or stannous fluoride or arginine compounds (which physically block the dentinal tubules). Used consistently twice a day, they reduce sensitivity for most people within 2 to 4 weeks.
But they manage the symptom — they don't fix the underlying cause. If you're brushing twice daily with Sensodyne and you still wince every time you drink something cold, the toothpaste is masking a problem that needs to be properly assessed.
When to Actually See a Dentist
If the sensitivity has been going on for more than a few weeks, or it's getting worse, or it's in one specific tooth — go. You want to rule out a cavity, crack, or receding gum before those things become significantly more expensive to fix.
If the pain lingers for more than 30 seconds after the cold stimulus is gone, that's a different signal. Prolonged pain often means the nerve is inflamed — which can indicate the early stages of pulpitis. That's a step before needing a root canal, and catching it early matters.
For most people, sensitivity that's been around for a while turns out to be enamel erosion or gum recession. Both are manageable — often with tooth-coloured composite bonding, a desensitising varnish applied in the clinic, or fluoride treatment. If it's a cavity, a filling sorted early is a 30-minute appointment. Ignored, it becomes a root canal.
Our restorative team assesses exactly this kind of presentation. You can find out more about what's involved on our restorative dentistry page, or book a check-up and we'll find out what's causing it.
Pain with every cold drink? Book a check-up today →