Dentine hypersensitivity: two different mechanisms, two categories of product

Dentine hypersensitivity is the complaint reported most often after caries, and the one on which over-the-counter products promise most with the vaguest explanation.

The accepted mechanism is hydrodynamic. Exposed dentine exposes the dentinal tubules, microscopic fluid-filled channels communicating with the pulp.

A thermal or osmotic stimulus moves that fluid, and the movement activates the nerve endings at the pulpal end. The pain arises not at the surface but from that displacement.

Two entirely different strategies follow, and it is the distinction that allows a choice to be made rather than a trial at random.

The first occludes the tubules, reducing fluid movement. It includes strontium salts, arginine with calcium carbonate, calcium sodium phosphosilicates, and high-concentration fluorides.

The effect is mechanical and relatively quick, but liable to removal: abrasion from brushing and dietary acids reopen the tubules, which is why use must continue.

The second acts on nerve transmission rather than on the fluid. Potassium nitrate deposits potassium ions around the nerve ending, reducing its capacity to generate the signal.

This second mechanism needs time. A patient trying a potassium toothpaste for three days and concluding it does not work has simply stopped before it acted: several weeks of continuous use are required.

Communicating this is what changes the outcome, because early abandonment is the main reason for perceived failure.

Professional products applied in the surgery act by occlusion, using varnishes, adhesive resins or phosphosilicate preparations, and offer faster relief that combines with home maintenance.

What precedes all of this, however, is the search for the cause, because sensitivity is a symptom. Recession from brushing, acid erosion, cervical abrasion, bruxism, ongoing whitening, or a caries lesion nobody looked for.

Treating the symptom without correcting the cause gives relief that lasts as long as the patient uses the product, and the problem returns as soon as they stop.

In summary: the pain comes from fluid movement in the tubules, occlusion acts quickly but must be maintained, potassium takes weeks and must be explained to prevent abandonment, and the cause must be sought first because a symptom alone always returns.