Dentin Hypersensitivity: Causes and mechanisms

Scanning electron microscope image of exposed dentin tubules

What causes dentin hypersensitivity?

Dentin hypersensitivity is a common dental problem that can develop over time. Here we take a closer look at the aetiology of dentin hypersensitivity.

The hydrodynamic theory of dentin hypersensitivity

Brännström’s hydrodynamic theory is currently the most commonly accepted theory of how dentin hypersensitivity arises:^1,2

Dentin hypersensitivity arises when tubules found within dentine become exposed, most commonly caused by gingival recession or enamel wear
Once exposed, these tubules may come into contact with stimuli such as hot, cold and sweet foods and drinks, which can induce the movement of fluid within the tubules
Such movement can trigger nerves in the pulp, which may induce a short, sharp pain

Dentin exposure
How dentin tubules become exposed

Dentin tubules become exposed by gingival recession, due to:³

Periodontal diseases

An over-vigorous brushing technique

Tooth wear processes expose dentin tubules through one or more of the following:⁴

Erosion (chemical breakdown of enamel) – contributing factors include exogenous acids (dietary acids), endogenous acids (gastroesophogeal reflux)

Abrasion (mechanical wear) – contributing factors include incorrect toothbrushing i.e. brushing too hard and improper oral hygiene

Attrition (loss of tooth structure due to tooth-on-tooth contact) – contributing factors tooth clenching or grinding

Read more about enamel wear

Whitening treatments

Research indicates that 55-75% of patients experience sensitivity after professional whitening treatments.⁵ Certain at-home whitening methods can also trigger sensitivity.⁶ While sensitivity experienced due to whitening treatments differs from dentin hypersensitivity, clinical studies have shown that toothpastes containing potassium nitrate, like Sensodyne, can reduce the sensitivity caused by whitening procedures.⁵
Triggers

Dentin hypersensitivity triggers

Exposure of dentin tubules allows fluids within the tubules to move, which can be triggered by multiple types of stimuli.^1,2

Thermal stimuli

Cold (more likely), hot

Tactile stimuli

Tooth brushing

Osmotic stimuli

Sugary foods and drinks
Nerve stimulation

Nerve stimulation and pain

It is theorized that the rapid movement of fluid within dentin tubules triggered by external stimuli can stimulate the nerves within the dental pulp, causing pain.^1,2