Sensitive teeth: causes and fixes

Reviewed by Dr. Samar Fadavi, DDS

Short answer: Sensitive teeth usually happen when the inner layer of the tooth, called dentin, is exposed by worn enamel or receding gums. Cold, sweet or acidic foods then reach the nerve. A toothpaste for sensitive teeth, a soft brush, less acid and fluoride treatments help most people. Sensitivity in one tooth can also signal a cavity or crack, so have it checked.

What tooth sensitivity feels like

Tooth sensitivity is a short, sharp pain when a tooth meets cold air, ice cream, a hot drink, something sweet or something sour. It usually fades within seconds once the trigger is gone. It can affect one tooth or many, and it often comes and goes over months.

Sensitivity is very common in adults. The good news is that most causes can be managed with simple changes at home and treatments at the dental office. This guide explains why teeth become sensitive, how to tell harmless sensitivity from a problem that needs treatment, what helps at home and what the dentist can do. It is general information for patients in Scarborough, the Danforth and East Toronto, not a diagnosis.

Why teeth become sensitive

A tooth has a hard outer shell of enamel on the crown and a thin layer of cementum on the root. Under both is dentin, which is full of microscopic tubes that lead to the nerve in the centre of the tooth. When the enamel or cementum wears away, or the gum pulls back to expose the root, those tubes open. Cold, heat, sugar or acid can then move the fluid inside the tubes, and the nerve reacts with a quick, sharp pain.

Common causes

Gum recession

When gums pull back, the root surface is exposed. Roots have no enamel, so they are much more sensitive. Recession can come from gum disease, brushing too hard, grinding, crooked teeth or simply age. Our guide on gum recession explains causes and care.

Brushing too hard

A hard-bristled brush and a heavy scrubbing motion can wear enamel and push gums back, especially near the gum line of the canines and premolars.

Acid erosion

Frequent sips of pop, sports drinks, citrus juice, wine, kombucha or vinegar-based foods soften enamel. Acid reflux and frequent vomiting also bring stomach acid into the mouth. Over time, softened enamel wears away. Our guide on coffee and your teeth covers another common drink.

Grinding and clenching

Night-time grinding wears down the chewing surfaces and can cause tiny cracks and notches near the gum line.

Cavities and leaking fillings

Decay or a worn filling edge can let cold and sweet things reach the dentin. Sensitivity to sweets in one spot is a classic sign of a cavity.

A cracked tooth

A crack can cause sharp pain with cold and when biting. Our guide on cracked tooth symptoms explains how to recognize it.

Whitening

Whitening gels can cause short-term sensitivity that usually settles within a few days after treatment ends. Our guide on tooth whitening explains how to whiten with less sensitivity.

Recent dental work

Teeth can be sensitive for a few days to a few weeks after a cleaning, a new filling or a crown. This usually fades on its own.

Sensitivity that is normal and sensitivity that is not

Short, sharp pain that fades within seconds and affects several teeth is usually from exposed dentin. Book a check-up to confirm the cause, but it is not urgent.

See the dentist sooner if:

• One tooth is sensitive and the pain is getting worse.
• Pain lingers for more than 30 seconds after the trigger is gone.
• The tooth hurts when you bite or let go.
• Pain throbs or wakes you at night.
• There is swelling, a bad taste or a bump on the gum.

Lingering pain can mean the nerve is inflamed, which may need a root canal. Our guide on different types of tooth pain explains what each kind of pain can mean.

What helps at home

1. Use a toothpaste for sensitive teeth. These toothpastes contain ingredients such as potassium nitrate, stannous fluoride or arginine that calm the nerve or block the open tubes. Use it twice a day for at least two to four weeks. Results build over time.
2. Smear a little on the sensitive spot at night. After brushing, dab a small amount on the sensitive area and do not rinse.
3. Switch to a soft brush. Use gentle circles at the gum line instead of hard back-and-forth scrubbing. An electric brush with a pressure sensor can help heavy brushers.
4. Use fluoride. Fluoride strengthens enamel and helps block exposed dentin. Our guide on fluoride in toothpaste explains how it works.
5. Cut down on acidic drinks. Drink them with meals rather than sipping all day, use a straw, and rinse with water afterwards.
6. Wait before brushing after acid. After an acidic drink or reflux, wait about 30 to 60 minutes before brushing so softened enamel can harden again.
7. Wear a night guard if you grind your teeth.
8. Treat reflux. If you have heartburn or reflux, talk to your doctor; managing it protects your teeth too.

What to avoid

• Avoid hard-bristled brushes and whitening toothpastes with strong abrasives if your teeth are sensitive.
• Avoid brushing right after acidic foods, drinks or vomiting.
• Avoid sipping pop, juice or sports drinks throughout the day.
• Avoid switching toothpastes every few days. Sensitivity toothpaste needs consistent use to work.
• Avoid ignoring sensitivity in one tooth that keeps getting worse.

What the dentist can do

At the visit, the dentist will ask when the sensitivity happens, look for worn enamel, recession, cavities, cracks and leaking fillings, and test the teeth with air and cold. X-rays help rule out decay and infection. Treatment then depends on the cause:

Fluoride varnish or desensitizing agents

A fluoride varnish or a desensitizing liquid painted on the exposed areas can reduce sensitivity quickly. It may be repeated at check-ups.

Bonding or sealing exposed roots

Tooth-coloured bonding material can cover exposed roots or notches at the gum line, protecting the dentin.

Treating cavities and replacing worn fillings

If decay or a leaking filling is the cause, a new filling seals the tooth.

Crowns for cracked or heavily worn teeth

A crown can protect a cracked tooth or one with severe wear. Our crowns and bridges page explains this treatment.

Gum treatment

Treating gum disease helps stop further recession. In some cases, gum surgery to cover exposed roots is discussed.

Night guard

For grinders, a custom night guard protects enamel and reduces wear. Our night guards and TMJ page explains how guards are made.

Root canal treatment

Rarely, when sensitivity is severe and nothing else helps, or the nerve is inflamed, root canal treatment removes the nerve and ends the pain in that tooth.

Sensitivity after whitening

Whitening gels open the tubes in the dentin for a short time. To reduce sensitivity, use a sensitivity toothpaste for two weeks before and during whitening, use lower-strength gels for shorter periods, take breaks between sessions and avoid very cold drinks for a day or two after each session. Professional whitening lets the dentist adjust the strength and protect the gums.

Sensitivity after a filling or crown

Some sensitivity for a few days or weeks after new work is normal. If it lasts longer, gets worse, or the tooth hurts when you bite, the bite may be slightly high or the nerve may be irritated. Call the clinic; a small bite adjustment often helps.

Sensitivity in children and teens

Children can have sensitivity from new adult teeth, cavities, grinding or acidic drinks. Sports drinks, juice and pop sipped through the day are common causes in teens. Talk to the dentist before using adult sensitivity toothpaste for young children. Our children’s dentistry page explains care for young patients.

Sensitivity in older adults

Gum recession and dry mouth from medicines make sensitivity more common with age. Exposed roots also decay more easily, so fluoride is especially important. Our seniors’ dental care page explains care for older patients.

A simple daily routine for sensitive teeth

• Morning: brush gently for two minutes with a soft brush and sensitivity toothpaste. Spit, do not rinse.
• During the day: drink water, keep acidic drinks to mealtimes and rinse with water after them.
• Evening: floss or use interdental brushes, then brush with sensitivity toothpaste. Dab a little extra on sensitive spots.
• Night: wear your night guard if you have one.

Common triggers and easy swaps

• Ice water and iced drinks: drink them cool rather than ice-cold, or sip through a straw placed toward the back of the mouth.
• Ice cream: eat it with a spoon rather than biting into it, and let it soften slightly.
• Citrus fruit and juice: enjoy them with a meal and follow with water or a piece of cheese, which helps neutralize acid.
• Pop and sports drinks: switch to water or plain milk most of the time, and keep acidic drinks to mealtimes.
• Hot coffee and tea: let them cool a little and avoid swishing them around the teeth.
• Sticky candy and sweets: these can trigger sensitivity and feed cavities; choose sugarless options and brush or rinse afterwards.
• Pickles and vinegar dressings: eat them as part of a meal instead of as snacks through the day.

Choosing a brush and toothpaste

Look for a toothbrush labelled soft or extra soft with a small head that reaches the back teeth. Replace it every three months or sooner if the bristles splay. If you use an electric brush, let the brush do the work and choose a model that warns you when you press too hard.

For toothpaste, choose one made for sensitive teeth and containing fluoride. Avoid toothpastes that promise strong whitening, which can be more abrasive. Use a pea-sized amount, spit after brushing and do not rinse with water, so the active ingredients stay on the teeth longer.

Myths about sensitive teeth

• “Sensitive teeth are just part of getting older.” Sensitivity is common with age, but it has causes that can usually be managed.
• “Brushing harder keeps sensitive teeth cleaner.” Hard brushing wears enamel and pushes gums back, which makes sensitivity worse.
• “If it only hurts for a second, it does not matter.” Brief sensitivity in one tooth can be the first sign of a cavity or crack, so it is worth a check.
• “Sensitivity toothpaste works on the first day.” It usually takes two weeks or more of steady use.

Questions to ask at your visit

• What is causing my sensitivity, and which teeth are affected?
• Do I have gum recession or worn enamel, and is it getting worse?
• Would fluoride varnish or bonding help these areas?
• Am I brushing too hard, and can you show me a gentler technique?
• Do I show signs of grinding?

When to see a dentist

Book a check-up if sensitivity lasts more than a couple of weeks despite sensitivity toothpaste, if one tooth is getting worse, or if you notice recession or worn spots near the gum line. Seek care sooner for pain that lingers, throbs, wakes you at night or comes with swelling. Our family dentistry page explains check-ups at our clinic, and our emergency dentist page explains same-day visits.

Questions about sensitive teeth

How long does sensitivity toothpaste take to work?

Many people notice a change within two weeks, with more benefit after four weeks of twice-daily use. Keep using it to maintain the effect.

Can sensitive teeth go away on their own?

Sometimes, for example after whitening or a new filling. Sensitivity from recession or erosion usually needs ongoing care to stay under control.

Is sensitivity a sign of a cavity?

It can be, especially if one tooth is sensitive to sweets. A check-up and x-rays can tell.

Why are my teeth more sensitive in winter?

Breathing cold air through the mouth can trigger exposed dentin. Breathing through the nose and using sensitivity toothpaste can help.

Can mouthwash help?

A fluoride mouthwash can help strengthen enamel. Avoid mouthwashes with strong alcohol or acidic ingredients if your teeth are sensitive.

Can I still whiten my teeth if they are sensitive?

Often yes, with adjustments. Talk to the dentist first so the cause of sensitivity is treated and the whitening plan is gentler.