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Home Study Course

Dentinal Sensitivity:
Cause and Treatment by Noel Kelsch, RDH

Defined: Dentinal hypersensitivity refers to a sharp, sudden pain when teeth are exposed to a stimulus.' Stimulus can be tactile sensations (such as those that occur during brushing or flossing or when an explorer is rubbed over the root dentine) or changes in temperatures (such as cold food or even air). No vital tooth is immune to this condition.^

Introduction
Dentinal hypersensitivity is one of the most common dental complaints in dentistry and yet even its name is misunderstood, often leading to misdiagnosis and insufficient treatment. The prevalence of hypersensitivity in the general population is as high as fifty-seven percent of the adult population and, in periodontal patients, is reported as high as sixty to ninetyeight percent.' Oral pain can be a complex set of circumstances caused by a combination of factors that lead to pain. Health care professionals must learn to use differential diagnosis to treat the causes, not just the symptoms of hypersensitivity. Ruling out more serious conditions and treating underlying causes can make a difference in the longevity of tooth structure and the quality of life for the patient. Definitive diagnosis can lead the dental professional to provide better counseling and treatment.

enamel it was not sensitive to the patient but as soon as they invaded the area of dentine it became very sensitive for the patient. While they assumed the dentine had nerves that extended to the enamel, anatomists discovered there were no nerves in the tubules.

There has been much controversy about the function and anatomy of dentine until the early 196O's. Martin Brannstrom observed that patients were sensitive to air blasts, drilling, scratching with an explorer, heat and cold and especially osmotic stimuli. Brannstrom used freshly extracted human teeth and removed the end of the root and sealed a glass capillary tube to the pulp chamber. The tube and root were filled with water. When stimuli was applied, such as ice, to the exposed dentine in extracted

Etiology and History
The issue of dentinal hypersensitivity has been a concern in dentistry since its inception as a science. In 1884 Calvo wrote "There is a great need of a medicament, which while lessening the sensitivity of dentine, will not impair the vitality of the pulp."^ When dentists first started drilling into teeth they seldom used anesthesia.
They discovered that when they worked on the
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defttin cause fluid movement in tubule

Brannstrom's theory (Proctor and Gamble)

CDHA Journal

Vol. 22, No. 3

teeth, the fluid in the capillary moved toward the crown. Some stimuli caused inward movement and some outward. Brannstrom showed the direction of the fluid movement did not matter, but rather it was the quickness of the movement that caused the pain.

Hydrodynamics
Assumptions of the hydrodynamic theory conclude that when the fluids within the dentinal tubules are subjected to temperature changes or physical osmotic changes, the movement stimulates a nerve receptor sensitive to pressure, which leads to the transmission of the stimuli and, subsequently, to pain.
The hydrodynamic theory, still used today, has shown that any shift in fluid can lead to pain and stopping the change in fluid movement can halt pain".

Why Some and Not Others
Dentine is composed of a mineralized connective tissvie containing hydroxyapatite and an organic matrix of collagenous proteins. Individual teeth have different configurations and diameters. One square millimeter of dentine can contain up to thirty thousand tubules. For a patient to develop dentinal hypersensitivity two processes have to be in place: 1) the dentine lias to be exposed (lesion localization), and 2) the dentinal tubule system has to be opened and be patent to the pulp (lesion initiation).
Confusion as to why root surfaces are sensitive and others not led to a study by Absi, who reported that