Tooth Sensitivity: What It Is and Why It Happens

You bite into ice cream — and a sharp pain shoots through your tooth. This is tooth sensitivity, or hyperesthesia. Let's look at what happens and why it occurs.

What tooth sensitivity (hyperesthesia) is

Hyperesthesia is increased sensitivity of the hard tissues of the tooth. It manifests as brief, sharp pain in response to stimuli: thermal, chemical, or tactile. The pain usually lasts about 10–30 seconds. Its intensity varies — from mild discomfort to severe pain that makes eating and brushing difficult. Sensitivity can be limited, when one or several teeth react, or generalized, when most or all teeth become sensitive. By course, three degrees are distinguished: the first — a reaction to heat and cold; the second — also to sweet, sour, and salty; the third — to all stimuli, including touch. Prevalence is high: over the past twenty years the rate has risen by 35–42% and covers 57% to 68% of the adult population. Hyperesthesia occurs significantly more often in women than in men.

Why teeth hurt from cold and hot

Dentin — the yellow layer beneath the enamel — is penetrated by microscopic openings that lead to the pulp and nerves. Normally these tubules are covered by enamel. If the enamel wears away, stimuli more easily affect the tooth's nerve bundle. Hence the reaction to cold, heat, sour and sweet foods, and even to ordinary toothbrushing. In the cervical region the enamel is thinnest, and in a healthy state the gum covers the neck of the tooth. This area becomes sensitive when gum disease leads to exposure of the necks and roots. The mechanism of pain is not fully understood; the hydrodynamic theory is the most widely accepted — pain arises from changes in the circulation of dentinal fluid in the tubules under the influence of external factors.

Causes of increased sensitivity of enamel and dentin

There are several causes: the consequences of caries, increased tooth wear, enamel chips, and non-carious processes — wedge-shaped defect, hypoplasia, erosion, necrosis. Most often hyperesthesia accompanies non-carious lesions and is a direct reaction to their destructive impact. There is sensitivity associated with loss of hard tissues (preparation, caries) and sensitivity not associated with it — in intact teeth in general diseases of the body, neuropsychiatric and endocrine disorders, and periodontal diseases. The appearance of sensitivity on apparently healthy areas is an early sign of non-carious lesions. In women with such lesions, reduced levels of ionized calcium and magnesium in the blood and decreased bone mineral density have been identified, so they are considered at risk for osteoporosis.

Why sensitivity may appear suddenly

Sensitivity may be associated with loss of hard tooth tissues as a result of preparation, caries, and other causes. A sharp reaction is also possible against the background of an exacerbation of a non-carious process: during the exacerbation phase hyperesthesia intensifies, during remission it decreases. If teeth react to cold and hot without an obvious cause, this is a reason to see a doctor — sensitivity may be an initial signal of a problem.

How a dentist determines the cause

The doctor asks about symptoms, examines the teeth, and probes them with instruments. In some cases an X-ray is needed. They assess which stimuli cause pain, whether individual teeth or most teeth react, whether there is exposure of the necks, wear, or enamel defects. By the presence or absence of hyperesthesia in the area of non-carious lesions, the doctor judges the stage of the process — exacerbation or remission.

When to see a dentist

• The pain lasts longer than 2 days or does not go away after a painkiller.
• There is fever, pain when biting down, red gums, or an unpleasant taste in the mouth.
• The cheek or jaw is swollen.

Tooth sensitivity by itself is not a reason to call an ambulance. Call 103 or 112 if, along with toothache, there is swelling around the eye or on the neck, and also if swelling in the mouth or on the neck makes it difficult to breathe, swallow, or speak.

This material is for reference: it helps to understand what is happening but does not replace a doctor's consultation — the exact cause will be determined by a dentist at an appointment.

This content is for reference and does not replace a doctor's consultation. Medical disclaimer