Tooth sensitivity: 7 common causes and how to treat it

What exactly is tooth sensitivity?

Tooth sensitivity (or dentin hypersensitivity) manifests as a brief, sharp pain in response to an external stimulus: cold, heat, sugar, acid, or even air passing over the tooth. It occurs when the dentin — the layer beneath the enamel — is exposed. Dentin contains thousands of tiny tubules that lead directly to the tooth's nerve. When these tubules are exposed, every stimulus reaches the nerve and causes that characteristic pain.

• Brief, sharp pain (not continuous like a deep cavity)
• Triggered by cold, heat, sugar or acid
• Affects about 1 in 3 Canadian adults
• Can affect a single tooth or multiple teeth

The 7 most common causes of tooth sensitivity

Identifying the cause is the first step to effectively treating sensitivity. Here are the 7 causes I encounter most frequently at the clinic.

• Worn enamel — Brushing too hard or using a hard-bristled toothbrush gradually wears down the protective enamel. This is the most common cause in motivated patients who brush too aggressively.
• Gum recession — When the gum recedes, it exposes the tooth root which is not protected by enamel. Causes: periodontitis, aggressive brushing, natural aging.
• Tooth decay — An untreated cavity breaks through the enamel and exposes the dentin. The sensitivity is then localized to a single tooth.
• Bruxism (teeth grinding) — Nighttime grinding wears down the enamel on chewing surfaces. Bruxism patients often have generalized sensitivity across multiple teeth.
• Recent teeth whitening — The peroxide used in whitening products can temporarily open the dentin tubules. This is normal and reversible within 24 to 72 hours.
• Recent filling or treatment — After a filling, root canal or crown, temporary sensitivity lasting 1 to 2 weeks is common.
• Crack or micro-fracture — An invisible crack in the enamel can let stimuli through. This diagnosis requires a thorough in-office examination.

When to see a dentist urgently

Tooth sensitivity is rarely an emergency, but certain signs should alert you and warrant a prompt appointment.

• Spontaneous pain that persists without a stimulus (possibly an infection)
• Swelling of the gum or cheek (sign of an abscess)
• Intense sensitivity on a single tooth that gets worse (advanced cavity or crack)
• Pain that wakes you at night (pulp inflammation)
• Sensitivity that appeared after an impact or trauma

Professional treatments available on the Plateau

Depending on the identified cause, several professional treatments are available at the clinic. During your consultation, we determine the exact source of your sensitivity and recommend the most appropriate treatment.

• High-concentration fluoride varnish — Applied directly to sensitive areas, it seals exposed dentin tubules. Relief in a single session.
• Dentin sealant — A protective resin that covers sensitive surfaces to block stimuli.
• Gum graft — In cases of severe recession, a gum tissue graft permanently covers the exposed root.
• Root canal — If the sensitivity is caused by irreversible pulp inflammation, root canal therapy permanently eliminates the pain.
• Bruxism nightguard — For patients who grind their teeth at night, a custom nightguard protects the enamel and reduces sensitivity.

What you can do at home

While waiting for your appointment or as a complement to professional treatment, these simple measures can significantly reduce daily sensitivity.

• Use a desensitizing toothpaste (Sensodyne, Colgate Sensitive Pro-Relief) — the active compounds (potassium nitrate, calcium phosphate) gradually block the tubules.
• Switch to a soft-bristled toothbrush — and brush with gentle, circular motions, never in a back-and-forth horizontal pattern.
• Avoid very acidic foods (citrus, vinegar, carbonated drinks) that erode enamel.
• Wait 30 minutes after an acidic meal before brushing — enamel temporarily softened by acid is more vulnerable to brushing.
• Rinse your mouth with water after consuming acidic or sugary foods.

Sensitivity after dental work: is it normal?

Yes, in most cases. After a filling, deep scaling, whitening, or crown placement, temporary sensitivity is normal and expected. It typically lasts from a few days to 2 weeks. If the sensitivity persists beyond 3 weeks or intensifies, contact your dentist — it may indicate an issue with the restoration fit or pulp inflammation that requires follow-up.

Frequently asked questions