Why Do Teeth Become Sensitive? Causes of Cold and Hot Sensitivity
A tooth that throbs with a cold drink may point to causes ranging from enamel wear to gum recession. How sensitivity works and which findings are urgent.
How Does Tooth Sensitivity Arise?
The short, sharp sensation felt with a cold drink, a sweet food or while breathing cold air is described as tooth sensitivity. It passes quickly once the stimulus is removed, which distinguishes it from pain that persists or starts spontaneously.
The mechanism behind sensitivity
The enamel covering the outer surface of the tooth protects the dentine beneath it. Dentine contains microscopic channels (dentinal tubules) that extend towards the tooth nerve. If enamel thins or the root surface becomes exposed, these channels open to the outside environment. Stimuli such as temperature change and sweetness cause movement of the fluid within the tubules, and this movement creates a brief signal at the nerve ending. This is the reason for the sharpness that is felt.
Factors that cause enamel wear
- Acidic foods and drinks: Frequent consumption of citrus, fizzy drinks and vinegar-containing foods can dissolve the enamel surface over time.
- Aggressive brushing: Hard-bristled brushes and horizontal brushing with pressure can create wear at the enamel and gum margin.
- Clenching and grinding: Wear on the chewing surfaces and notching at the neck of the tooth may relate to this habit.
- Reflux and frequent vomiting: Enamel loss can accelerate where stomach acid reaches the mouth.
Gum recession and the exposed root surface
The root surface is not covered by enamel; it is covered by a thinner tissue called cementum and is more susceptible to external factors. When the gum recedes, this area becomes exposed and sensitivity becomes pronounced. The cause of recession may be gum disease, but it may equally be an incorrect brushing technique.
Temporary sensitivity after procedures
Sensitivity lasting a few days may occur after scaling, fillings or whitening. This is part of the ordinary tissue response to the procedure and usually subsides on its own. If it increases progressively, it should be assessed.
Measures that can be taken at home
Switching to a soft-bristled brush, using a gentle circular technique, rinsing with water and waiting a while rather than brushing immediately after acidic food, and using desensitising toothpastes regularly may help. These measures relieve the symptom but do not eliminate the cause if decay, a fracture or gum disease lies underneath.
What is not simple sensitivity?
Pain that lasts minutes after the stimulus is removed, starts spontaneously, increases at night or is difficult to control with painkillers may indicate a different condition. If swelling of the gum, pain on biting or a change in tooth colour accompanies it, a dentist should be consulted without delay.
This article is for general information purposes and does not replace a clinical examination. The cause of sensitivity and the appropriate approach can only be determined after clinical and, where required, radiological evaluation.
Frequently Asked Questions
What does sensitivity that starts suddenly indicate?
Sensitivity appearing abruptly in a tooth that has been trouble-free for years may point to a different cause from gradually developing dentine exposure. New decay, leakage at the margin of a filling, a crack in the tooth, or a recent restoration left high in the bite come to mind. Sudden sensitivity concentrated in one particular tooth is assessed differently from generalised sensitivity and requires examination.
Why does sweetness cause sensitivity?
The concentration gradient created by a sweet stimulus moves the fluid within exposed dentinal tubules, and this movement is perceived as pain. The mechanism is the same as for cold sensitivity. Sensitivity that develops only to sweet things and lingers, however, suggests that decay may have reached the dentine; this distinction is made by examination and, where needed, a radiograph.
Which foods increase sensitivity?
Acidic foods and drinks temporarily soften the enamel surface and cause erosion over time: lemon and citrus, vinegar, fizzy drinks, energy drinks and some fruit juices are the main ones. Consuming them frequently carries more risk than consuming a large amount at once. Brushing immediately afterwards increases loss of substance from the softened surface.
Is a filling needed for sensitivity?
Not every case of sensitivity requires a filling. Where the cause is an exposed root surface, correcting the brushing technique and using desensitising products are considered first. Where there is marked loss of substance, a notch or decay at the neck of the tooth, a covering restoration comes into question. Which is appropriate is determined at examination according to the extent of the loss and the severity of the complaint.