Tooth Sensitivity
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A short, sharp twinge when something cold, hot or sweet reaches the tooth — and then it settles. That is the pattern most people mean by sensitive teeth, and it usually has a mechanical explanation rather than a mysterious one.
The hard outer enamel of a tooth has no nerves in it. The layer underneath, dentine, does — it is threaded with microscopic tubules running toward the nerve. While enamel and gum cover that layer, nothing much reaches it. When something exposes it, temperature and sweetness start getting through, and the tooth reports it as a quick jolt.
So sensitivity is usually a sign that dentine has become exposed somewhere. That can be gradual and harmless, or it can point at something that needs attention. The distinction matters, and it is the reason the pattern of the pain is worth paying attention to.
What Commonly Causes It
Several things expose dentine, and more than one is often involved at once.
Gum recession
When gums draw back, they uncover root surface, which is not protected by enamel at all and is far more reactive than the crown of the tooth.
Enamel wear from acid
Frequent fizzy drinks, citrus, sports drinks and fruit juice soften enamel over time. Reflux can do the same from the inside.
Brushing too hard, or with a hard brush
This wears a notch where the tooth meets the gum and can push the gum back at the same time.
Grinding or clenching
Flattening and cracking the biting surfaces gradually thins the enamel that covers the dentine.
Decay, or a filling that is failing
Both open a route to the inner tooth.
A cracked tooth
Typically sharp on biting and releasing, rather than on temperature alone.
Recent dental work
Sensitivity for a short period after a filling, a clean or whitening is common and usually settles on its own.
When Sensitivity Is Worth Checking
Ordinary sensitivity is brief. It arrives with the trigger and leaves with it. The features below suggest something other than exposed dentine, and are worth an appointment rather than another tube of toothpaste.
The pain lingers well after the cold or hot thing has gone.
It starts on its own, with no trigger at all.
It wakes you, or is worse lying down at night.
It is one specific tooth rather than a general area.
There is swelling, a bad taste, or the gum near the tooth is tender.
It has appeared suddenly and severely rather than creeping in.
It is not improving after two to three weeks of desensitising toothpaste.
How a Dentist Works Out the Cause
Most of the answer comes from the history — which triggers set it off, how long it lasts, whether it is one tooth or several, and what has changed recently. That usually narrows it considerably before anything is examined.
An examination then looks for the mechanism: recession and exposed root surface, wear notches at the gum line, flattened or cracked biting surfaces, decay, and the margins of existing fillings. Controlled cold testing can identify which tooth is responsible when it is not obvious, and X-rays show decay between teeth and the state of the nerve where that is in question.
Common Treatment Approaches
Treatment follows the cause, which is why identifying it first matters. Approaches commonly used in dentistry include:
Desensitising toothpaste
, used consistently over several weeks rather than occasionally. It works gradually.
Fluoride application
at the practice to harden and protect exposed surfaces.
Sealing or bonding
exposed dentine and worn notches where the exposure is localised.
Treating decay or replacing a failing filling
where that is the route in. See general dentistry.
Addressing grinding
, which may include a protective appliance worn at night.
Gum treatment
where recession and gum disease are driving it. See gum disease treatment.
Root canal treatment
, only where the nerve itself is irreversibly inflamed — which the lingering, spontaneous pain described above may indicate.
Reducing the Risk
Use a soft brush and let the bristles do the work rather than pressing.
Wait about an hour after anything acidic before brushing — enamel is temporarily softened, and brushing straight away removes more of it.
Keep acidic drinks to mealtimes instead of sipping them through the day. How often acid reaches the teeth matters more than how much.
Clean between the teeth daily, which protects the gums that cover the roots.
Mention grinding if you know you do it, or if you wake with a tight jaw.
Keep regular check-ups, so recession, wear and early decay are caught while they are still small.
Tooth Sensitivity Questions, Answered
Related Treatments and Conditions
Cleaning & Gum Care
Scaling and gum treatment, where recession is behind the sensitivity.
Check-ups & Fillings
Examination, X-rays and fillings where decay is the cause.
Tooth Decay & Cavities
How decay develops, and why it is often silent until it is not.
This page is general information, not a diagnosis. What is causing your symptoms can only be established by examining you. If something in your mouth has changed, please arrange an appointment rather than self-treating.
Written by Dental Leaf Clinical Team. Last updated 2026-08-18.
Something Set Your Teeth on Edge?
Bring it in and we will find out which of the causes above is behind it. If the pain is lingering, spontaneous or keeping you awake, call rather than booking online.
