Sensitivity: 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 and most widely accepted theory of how it arises.

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 dentin become exposed, most commonly caused by gingival recession or enamel wear.1
  • 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.1
  • Such movement can trigger nerves in the pulp, which may induce a short, sharp pain.1
  • Dentin Exposure

    Causes of exposed dentin

    How Dentin Tubules Become Exposed

    Dentin tubules become exposed by gingival recession, due to:1-3

    • Periodontal diseases
    • An over-vigorous brushing technique

    Read more about periodontal diseases

    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
    • Attrition (loss of tooth structure due to tooth-on-tooth contact) – contributing factors bruxism
    • Abfraction (physical wear) - contributing factors include tensile or sheer stress in the cemento-enamel region

    Read more about enamel wear


  • 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

    hot drink

    1. Thermal stimuli

    Cold, hot

    Toothbrush with paste

    2. Tactile stimuli

    Tooth brushing

    Sweet foods

    3. Osmotic stimuli

    Sour foods and drinks

  • Nerve Stimulation

    Tooth cross section

    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

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Impact on Patient Quality of Life

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