Dentine Hypersensitivity
On this page
Direct answer
Brännström's hydrodynamic theory explains the whole condition: exposed dentine with open tubules lets thermal, evaporative, tactile or osmotic stimuli move tubular fluid, and that mechanical drag on A-delta nerve fibres at the pulpal end produces the sharp, short, non-spontaneous pain that disappears with the stimulus. Diagnosis is exclusory — caries, cracked tooth, pulpitis, restorative microleakage and post-operative sensitivity must each be ruled out before the label sticks — and management follows the mechanism: occlude the tubules (arginine-calcium carbonate, stannous fluoride, oxalates, 22,600 ppm fluoride varnish, Gluma) or calm the nerve (potassium nitrate 5 per cent at home), while correcting the cause — brushing technique, erosive diet, recession — so treatment is not spent re-exposing tubules.
What you must remember
- Definition worth reciting: sharp, short pain from exposed dentine to thermal, evaporative, osmotic or tactile stimuli, that cannot be ascribed to any other defect or pathology — the textbook phrasing examiners expect.
- Hydrodynamic mechanism: fluid movement within patent tubules mechanically stimulates pulpal A-delta fibres; sensitive dentine shows markedly more open tubules than insensitive exposed dentine — the classic scanning electron microscopy finding.
- Tubule-occluding agents: arginine 8 per cent with calcium carbonate (forming arginine-calcium carbonate plugs), stannous fluoride, potassium oxalate, 5 per cent sodium fluoride varnish (22,600 ppm), and casein phosphopeptide pastes.
- Nerve-calming agents: potassium nitrate 5 per cent in toothpastes, which raises extracellular potassium and inactivates nerve fibre excitability over weeks of use.
- In-surgery armamentarium: fluoride varnish, Gluma (glutaraldehyde coagulating tubular proteins plus HEMA), resin bonding, glass ionomer for restorable defects, and laser therapy (diode, Nd:YAG, CO2) with supportive evidence for tubule-sealing fusion effects.
- Cause correction: overzealous or horizontal brushing, erosive dietary acids (citrus, cola) and gastric reflux, periodontal disease and therapy, and whitening gels — each re-opens tubules that treatment just closed.
- Differential discipline: a cracked tooth gives release-of-bite pain, pulpitis lingers, caries is visible — hypersensitivity never lingers and never wakes the patient.
Building a ladder for chronic post-periodontal sensitivity
A 55-year-old returns six weeks after periodontal surgery with cold-sensitive, hypersensitive root surfaces on multiple recession-exposed teeth. First, exclude mimics: bitewings and probing for caries, transillumination for cracks, pulp tests showing brief normal responses — this is hypersensitivity, not pulpitis. Then treat in the ordered ladder the exam wants. Home phase: desensitising toothpaste with 5 per cent potassium nitrate, used twice daily with a soft brush and a modified Stillman technique, plus dietary review removing the twice-daily lime soda whose citric acid both etched tubules open and dissolved any plugs they formed. Review at four weeks; the subset of teeth still symptomatic receives in-surgery care — polish, isolate, apply 22,600 ppm fluoride varnish, and for the worst canine apply Gluma, whose glutaraldehyde coagulates tubule proteins in situ. Persistent single teeth earn bonded resin sealing or glass ionomer over the exposed surface, and any tooth still recalcitrant gets laser therapy or a retreat of the diagnosis: a tooth that fails every rung of the ladder is re-tested for a crack or pulpal problem, because management-resistant "sensitivity" is usually a misdiagnosis.
Where students slip
The mechanism MCQ is stolen by one word: hydrodynamic, credited to Brännström, with tubular fluid movement and A-delta fibre stimulation as the required elaboration. The classification slip is remembering which agents work by which route — potassium nitrate acts on the nerve (potassium ions), nearly everything else occludes tubules; stems deliberately scramble them. The Gluma composition (glutaraldehyde plus HEMA) is a named-answer item in Indian papers, as is the varnish concentration of 22,600 ppm fluoride. The behavioural marks go to brushing timing after acid exposure: waiting thirty to sixty minutes before brushing, because immediate brushing of acid-softened dentine abrades tubules open — a detail that separates prepared candidates from generic ones.
Frequently asked questions
What is the currently accepted mechanism of dentine hypersensitivity?
Brännström's hydrodynamic theory — stimuli move fluid within open dentinal tubules, mechanically stimulating A-delta nerve fibres at the pulpal end.
How does potassium nitrate desensitise?
Raised extracellular potassium depolarises and inactivates the nerve fibres, reducing excitability over two to four weeks of twice-daily use.
What is in Gluma and how does it work?
Glutaraldehyde coagulates tubular proteins and plugs the tubules while HEMA improves penetration — an in-surgery desensitiser with rapid effect.
Which home and office agents occlude dentinal tubules?
Arginine 8 per cent with calcium carbonate, stannous fluoride, oxalates, 5 per cent sodium fluoride varnish and casein phosphopeptide pastes occlude; lasers seal by fusion effects.
When should "hypersensitivity" prompt a search for another diagnosis?
When pain lingers after the stimulus, is spontaneous or nocturnal, localises to release-of-bite pressure, or resists the full treatment ladder — pointers to pulpitis, a crack or caries.