Quick answer: Tooth sensitivity happens when dentine, the layer beneath enamel, becomes exposed and the tiny tubules within it transmit stimuli to the nerve. Common causes are gum recession, enamel wear from grinding or acid, cracked teeth, decay and recent dental treatment. The right treatment depends entirely on the cause.
Why teeth become sensitive
Enamel has no nerves. Dentine, the layer underneath it, is riddled with microscopic tubules that run towards the pulp. When dentine is exposed — because enamel has worn away or the gum has receded off the root — cold, heat, sweetness and touch reach those tubules and register as a sharp, brief jolt.
The usual causes
Gum recession
Roots are not covered by enamel, so when the gum recedes the exposed root is immediately sensitive. Recession comes from gum disease, from brushing too hard, or simply from age.
Enamel wear
Grinding and clenching wear the biting surfaces. Acid — from fizzy drinks, citrus, wine, or reflux — dissolves enamel more broadly. Brushing immediately after anything acidic accelerates the loss, because the softened enamel is scrubbed away.
A cracked tooth
Sensitivity to cold combined with a sharp pain when you release biting pressure is a classic pattern for a cracked tooth, and it needs examining rather than managing with toothpaste.
Decay or a failing restoration
New decay, or an old filling whose margin has started leaking, both produce sensitivity that gets worse over time rather than better.
Recent treatment
Mild sensitivity after a deep filling, a cleaning that removed heavy tartar, or whitening is common and usually temporary.
What helps
- Desensitising toothpaste, used consistently over several weeks rather than occasionally. It works gradually.
- A soft brush and lighter pressure. Hard brushing causes recession and abrasion rather than cleaner teeth.
- Wait before brushing after anything acidic. Rinse with water and give it time.
- Treat grinding. A night guard protects what enamel remains.
- Fluoride applications at the practice to strengthen exposed surfaces.
- Restoring the exposed area with bonding where recession has created a notch.
When sensitivity is telling you something more
See a dentist rather than reaching for another toothpaste if: the pain lingers for more than 30 seconds after the stimulus, it is concentrated on one tooth, it wakes you at night, it hurts to bite, or the gum near it is swollen. Those patterns point to the pulp or to a crack, and they need diagnosis. A root canal may be involved.
Get it looked at
Sensitivity is a symptom, not a diagnosis. A comprehensive exam establishes which of the above is actually causing it. Call (860) 756-5423.
Frequently asked questions
Why are my teeth suddenly sensitive to cold?
Sudden sensitivity usually means dentine has become exposed, through gum recession, enamel wear, a crack, new decay or a failing filling. Recent dental treatment or whitening can also cause temporary sensitivity.
Does desensitising toothpaste work?
It does, but gradually. It needs to be used consistently over several weeks rather than occasionally, and it does not address an underlying problem such as decay, a crack or a leaking filling.
Can brushing too hard cause sensitivity?
Yes. Hard brushing, especially with a firm brush, contributes to gum recession and wears the tooth surface near the gum line, both of which expose dentine. A soft brush used with light pressure cleans just as effectively.
When is sensitivity a sign of something serious?
If pain lingers more than about 30 seconds after cold, is focused on one tooth, wakes you at night, hurts when biting, or comes with gum swelling, it points to pulp involvement or a crack and needs examining rather than managing at home.
Should I stop whitening if my teeth become sensitive?
Sensitivity during whitening is common and usually temporary. It can often be managed by shortening wear time or spacing sessions further apart. Tell the practice rather than pushing through it.
Book with Connecticut Family Dental Group
Connecticut Family Dental Group is at 88 New Britain Avenue, Rocky Hill, CT 06067. Call (860) 756-5423 or request an appointment. The practice is open Monday through Thursday.
This article is general information for patients and is not a substitute for an examination or individual clinical advice. If something in your mouth is painful, swollen or changing, call the practice.