Tooth Sensitivity

What Is Tooth Sensitivity?

Beneath the hard enamel that covers every tooth lies a softer layer called dentine. This layer contains thousands of microscopic tubules — tiny channels that run from the outer surface of the dentine directly to the nerve (pulp) at the centre of the tooth. When enamel is intact, these tubules are sealed and protected. When the enamel thins, wears away, or when gum recession exposes the root surface, the dentine tubules become open to the oral environment.

Temperature changes, acidic foods, sweet substances, and even cold air can cause the fluid within these tubules to shift. This fluid movement stimulates the nerve endings inside the tooth, producing the characteristic short, sharp pain associated with tooth sensitivity to hot and cold. The sensation typically fades within seconds once the trigger is removed.

It is important to distinguish sensitive teeth pain from a general toothache. Sensitivity produces a quick, momentary response to a specific stimulus. A toothache, by contrast, tends to be more persistent, may throb or ache for extended periods, and often indicates a deeper issue such as infection, significant decay, or pulp inflammation. Both warrant professional assessment, but the underlying causes and treatment approaches differ considerably.

Common Causes of Tooth Sensitivity

Dentine sensitivity develops when the protective barriers of the tooth are compromised. Understanding the underlying cause is essential because effective treatment targets the specific reason for the exposure rather than simply masking symptoms.

• Enamel erosion — acidic foods and drinks, gastric reflux, and aggressive brushing gradually dissolve or wear away the enamel surface, reducing the protective barrier over the dentine and exposing the microscopic tubules beneath
• Gum recession — when gum tissue pulls back from the tooth, the root surface becomes exposed; unlike the crown of the tooth, the root has no enamel covering, leaving the dentine directly open to external stimuli
• Tooth decay — cavities break through the enamel and create pathways for bacteria and temperature changes to reach the sensitive inner layers of the tooth
• Cracked or worn teeth — fractures, chips, and general wear from grinding or clenching can expose the dentine layer, particularly on the biting surfaces and along the gumline
• Teeth grinding (bruxism) — the excessive forces generated by grinding and clenching accelerate enamel wear, flatten biting surfaces, and create microfractures that allow sensitivity to develop
• Recent dental treatments — some dental procedures can cause temporary sensitivity that typically resolves within a few days to weeks as the tooth settles
• Excessive or incorrect brushing — brushing too hard or using a hard-bristled toothbrush wears away enamel and damages gum tissue, contributing to both enamel loss and recession

Symptoms of Tooth Sensitivity

The symptoms of sensitive teeth are distinctive and typically easy to recognise. The key characteristic is a brief, sharp pain that occurs in direct response to a specific trigger and fades quickly once the stimulus is removed.

• Sharp pain when drinking cold liquids — cold water, iced drinks, and cold beverages are among the most common triggers, producing an immediate, sharp response in affected teeth
• Discomfort with hot food and drinks — hot tea, coffee, soup, and heated foods can trigger a similar brief pain; sensitivity to heat may sometimes indicate more advanced dentine exposure
• Pain when eating sweet or acidic foods — sugary foods, citrus fruits, vinegar-based dressings, and fizzy drinks can provoke a sharp, momentary reaction
• Discomfort when brushing — the bristles of a toothbrush contacting exposed dentine or root surfaces can cause a brief, uncomfortable sensation during daily cleaning
• Sensitivity to cold air — breathing in cold air through the mouth, particularly during winter, can trigger sharp pain in teeth with exposed dentine
• Pain when biting — sensitivity when biting or chewing may indicate a crack or fracture in the tooth rather than simple dentine sensitivity, and warrants professional assessment

Why Teeth Become Sensitive to Hot and Cold

The mechanism behind tooth sensitivity to hot and cold centres on the hydrodynamic theory of dentine sensitivity. The dentine layer contains approximately 45,000 tubules per square millimetre, each filled with fluid and connected to the nerve at the centre of the tooth.

When a cold stimulus reaches exposed dentine, the fluid within these tubules contracts and moves away from the nerve. When a hot stimulus is applied, the fluid expands and moves toward the nerve. Both movements activate mechanoreceptors — specialised nerve endings that detect pressure changes — triggering the sharp, brief pain characteristic of dentine sensitivity.

Enamel thinning is one of the primary reasons this process begins. As the enamel layer becomes thinner through erosion, abrasion, or natural wear, the insulating barrier between the external environment and the dentine diminishes. Eventually, temperature changes pass through more readily, and the fluid movement within the tubules becomes significant enough to activate the nerve response.

The same process occurs when gum recession exposes the root surface. The root is covered by a thin layer of cementum rather than enamel, and this cementum can wear away quickly, leaving the root dentine directly exposed to the oral environment. Exposed tooth root surfaces are particularly responsive to temperature changes, making gum recession one of the most common contributors to sensitivity.

Tooth Sensitivity Triggers

Knowing what triggers your sensitivity helps you manage daily discomfort while you seek professional assessment. Common triggers fall into several categories, and most patients find that one or two specific stimuli provoke the strongest response.

• Cold drinks and ice — cold water, iced beverages, and ice cream are the most frequently reported triggers; the rapid temperature drop creates immediate fluid movement in exposed tubules
• Hot beverages and food — hot tea, coffee, soup, and freshly cooked foods stimulate the nerve through fluid expansion within the dentine
• Sweet foods — sugar creates osmotic pressure changes at the dentine surface, drawing fluid out of the tubules and activating the nerve response
• Acidic foods and drinks — citrus fruits, tomatoes, vinegar, and carbonated drinks not only trigger sensitivity but can also contribute to further enamel erosion with repeated exposure
• Brushing with excessive pressure — pressing too firmly during brushing stimulates exposed dentine directly and, over time, worsens enamel wear and gum recession
• Biting and chewing — sensitive teeth when biting may indicate a crack or fracture rather than typical dentine sensitivity; consistent pain on biting warrants professional evaluation

Diagnosis and Assessment

Identifying the cause of tooth sensitivity requires a thorough clinical assessment. A dental examination enables your dental team to determine whether the sensitivity stems from enamel erosion, gum recession, decay, a crack, or another underlying factor.

• Clinical examination — your dental team inspects each tooth surface, checking for visible signs of enamel wear, erosion patterns, exposed dentine, and surface cracks
• Gum assessment — checking for gum recession, measuring the depth of gum pockets, and identifying areas where root surfaces may be exposed
• Identifying enamel wear — examining for signs of erosion, abrasion, or attrition that may be thinning the enamel and reducing its protective function
• Stimulus testing — applying cold air or cold water to specific teeth helps locate the exact source of sensitivity and assess its severity
• Checking for decay or cracks — ruling out cavities, fractures, and failing restorations that may be causing symptoms similar to dentine sensitivity
• Medical and dietary history — discussing your diet, oral hygiene habits, brushing technique, and any medical conditions that may contribute to enamel erosion or dry mouth

Tooth Sensitivity Treatment Options

Effective tooth sensitivity treatment targets the underlying cause rather than simply masking symptoms. Your dental team will recommend an approach based on the specific reason for your dentine exposure, the severity of your symptoms, and any contributing factors identified during assessment. A range of options is available through general dentistry services to help stop tooth sensitivity and provide lasting sensitive teeth relief.

Fluoride Treatment for Sensitive Teeth

Professional fluoride treatments are one of the most effective first-line approaches for managing dentine sensitivity. Concentrated fluoride varnish applied directly to the affected teeth strengthens the remaining enamel by promoting remineralisation — the natural process by which minerals are deposited back into weakened enamel.

Fluoride also helps occlude (block) the open dentine tubules, reducing fluid movement and dampening the nerve response to temperature changes. Regular professional fluoride application, combined with daily use of fluoride toothpaste, builds cumulative protection over time. This approach is non-invasive, painless, and suitable for patients with mild to moderate sensitivity across multiple teeth.

Desensitising Agents and Bonding

For localised areas of exposed dentine, your dental team can apply professional desensitising agents that seal the open tubules. These agents create a barrier on the dentine surface, preventing fluid movement and reducing the nerve response to external stimuli.

In cases where the dentine exposure is more pronounced, a thin layer of bonding resin can be applied to the sensitive area. This provides a durable physical barrier that protects the tubules for an extended period. The procedure is quick, non-invasive, and can be completed during a routine appointment.

Treating Gum Recession

When gum recession is the primary cause of sensitivity, addressing the underlying gum health is essential. Receding gums expose the root surface, which lacks the protective enamel covering that shields the crown of the tooth. The exposed root dentine is particularly responsive to temperature, touch, and chemical stimuli.

Managing gum recession involves identifying and addressing the cause — whether aggressive brushing, gum disease, or bite-related factors — and implementing measures to protect the exposed root surfaces. Professional desensitising treatments, fluoride application, and bonding agents can all help reduce sensitivity from recession. In more advanced cases, gum grafting procedures may be considered to cover the exposed root.

Restorative Treatment for Damaged Teeth

When tooth sensitivity results from significant enamel loss, cracks, fractures, or large areas of wear, restorative treatment may be needed to rebuild the protective surface and eliminate the source of discomfort. Dental crowns provide full-coverage protection for teeth that have lost substantial structure, encasing the entire visible portion of the tooth and sealing all exposed dentine.

For less extensive damage, dental fillings or composite bonding may be sufficient to cover the exposed area and restore the tooth's protective barrier. The choice of restoration depends on the location and extent of the damage, the tooth involved, and the forces it needs to withstand during normal function.

Sensitive Teeth After Whitening

Temporary sensitivity after teeth whitening is a well-recognised and common experience. The whitening agents (hydrogen peroxide or carbamide peroxide) temporarily increase the permeability of the enamel, allowing the bleaching gel to penetrate the tooth surface and reach the dentine. This temporary change in permeability mildly irritates the nerve, producing short-lived sensitivity.

Enamel dehydration also plays a role. During the whitening process, the tooth loses some moisture content, which increases its sensitivity to temperature. As the enamel rehydrates over the following days, the sensitivity typically diminishes and resolves completely.

Most patients find that whitening-related sensitivity settles within a few days to two weeks after treatment. Your dental team may recommend using a desensitising gel before and after whitening sessions to minimise discomfort. Pre-existing sensitivity should be assessed and addressed before starting any whitening treatment to ensure a comfortable experience.

Preventing Tooth Sensitivity

While not all causes of sensitive teeth can be prevented, many of the most common contributing factors are within your control. Consistent daily habits and regular professional care help protect enamel, maintain gum health, and reduce the likelihood of developing sensitivity.

• Use a soft-bristled toothbrush — a soft brush cleans effectively without wearing away enamel or damaging gum tissue; replace your brush every three months or when bristles begin to splay
• Brush gently with proper technique — use small circular motions rather than aggressive back-and-forth scrubbing; let the bristles do the work without pressing hard against the teeth
• Use fluoride toothpaste — brushing twice daily with fluoride toothpaste (1350–1500 ppm) strengthens enamel and helps protect against sensitivity; desensitising toothpastes provide additional relief
• Limit acidic foods and drinks — reduce consumption of citrus fruits, fizzy drinks, wine, and vinegar-based foods; when consumed, rinse with water afterwards and wait 30–60 minutes before brushing
• Wear a night guard if you grind your teeth — a custom-fitted guard protects the enamel from the excessive forces of bruxism during sleep
• Attend regular dental hygiene appointments — professional cleaning by a dental hygienist removes plaque and tartar, maintains gum health, and provides personalised guidance on protecting your enamel
• Stay hydrated — adequate water intake supports saliva production, which helps neutralise acids and protect enamel throughout the day

When to See a Dentist About Sensitive Teeth

While occasional mild sensitivity is common, certain patterns warrant professional assessment to identify the cause and prevent further progression.

• Sensitivity that persists for more than two to three weeks without improvement
• Pain when biting or chewing, which may indicate a crack or deeper structural problem
• Sensitivity that worsens over time or spreads to additional teeth
• Visible signs of enamel wear, gum recession, or discolouration alongside sensitivity
• Prolonged or throbbing pain that lingers after the trigger is removed
• Sensitivity localised to a single tooth, which may suggest decay, a crack, or a failing restoration

At St Paul's Medical & Dental in the City of London, our experienced team provides thorough assessment of tooth sensitivity, identifies the underlying cause, and offers a full range of treatment options tailored to your individual needs. Book a consultation to discuss your symptoms and receive clear, personalised guidance on achieving lasting relief.

Frequently Asked Questions About Tooth Sensitivity