IT is quite common for dental practitioners to hear persons describe dental pain as an “edging” or “shocking” when they eat or drink anything sweet or sour, or when the food is hot or cold, or even with simply brushing. If you experience this, then you are among the approximately 70,000 Guyanese adults who suffer from dentine hypersensitivity.

Dentine is mineralised tissue transected from the pulp chamber (at the centre of the tooth) to enamel or cementum by minute tubules. Within the tubules are protoplasmic projections (“tentacles” of cells) with the cell body itself being located in the pulp chamber. Stimulating these cells emits only one sensation, pain.
There are currently four hypotheses of pain transmission through dentine, of which the hydrodynamic theory is the most widely accepted. According to this theory, the movement of fluids within the dentine and pulp stimulates the nerves causing pain. All external stimuli translate into hydrodynamic changes that alter the pulp equilibrium and elicit pain. So even contact with air can result in pain.

Pain can be caused by mechanical, chemical, thermal (temperature) or bacterial, stimuli. Stimulation sources may include: toothbrushing, digital (finger) probing; desiccation (a blast of air); acids sweet, sour hot and cold products: and acid products from plaque bacteria.

There are varied predisposing factors to dentinal hypersensitivity but to no single cause. The tooth becomes sensitive after enamel loss or root surface exposure. Enamel loss follows mechanical wear (biting surface wear), neck abrasion or possibly tooth flexure after grinding, which fractures enamel rods chemical erosion (acid foods or stomach regurgitation), gingival recession (retracting gums) and subsequent tooth root exposure allow more rapid and extensive exposure of dentinal tubules because the cementum layer overlying the root surface is thin and easily removed.

The many causes of gingival retraction include normal ageing, chronic periodontal disease, abnormal tooth position in the dental arch, periodontal surgery, incorrect tooth brushing habits and root preparation for crowns. All of the precipitating factors allow the exposure of dental tubules, which create the condition for dentine hypersensitivity.

Treatment modalities fall into two main categories: chemical and physical. All available treatments work to differing degrees depending on the treatment and severity of the patient’s hypersensitivity. Pain is extremely subjective so that effective treatment often depends on the individual’s pain threshold. Some desensitising agents can be used at home; others require a visit to the dentist.

Chemical desensitising agents can be sub-classified by their action: anti-inflammatory, protein precipitating and tubule blocking.
Corticosteroids, one of the many groups of chemical agents, have been used typically for their anti-inflammatory effects, but are not particularly effective.
The second group of chemical agents, the protein precipitants, includes silver nitrate and zinc chloride. Silver nitrate was widely used in the past. Unfortunately, both substances cause teeth to stain permanently and are harmful to gums and pulp. Strontium chloride and formaldehyde (in Sensodyne toothpaste) belong to the group of agents that precipitate proteins within the tubule. Other drugs used to treat the condition include calcium hydroxide, fluoride, and sodium citrate. Patients may also be treated with composites (fillings), resins varnishes, sealants, soft tissue grafts, glass ionomer cements and laser sealing of the tubules.