Dental Desensitizing Agent/ Obtundents

Chemical substances that are used to diminished or desensitize dentinal sensitivity due to exposure of dentinal tubules are called Dental Desensitizing Agent or Obtundents.

Tooth Sensitivity/ Dentine Sensitivity

A sharp pain produced in response to mild stimuli that usually disappear with the removal of the stimulus is called dental sensitivity.

Causes of tooth sensitivity

1.) Loss of enamel that occurs due to attrition, abrasion, erosion, and bruxism.

2.) Dental caries

3.) Fracture of the tooth

4.) Cracked tooth syndrome

5.) Dental trauma

6.) Periodontal diseases

7.) Gingival recession

8.) Fracture of restoration

9.) Unlined deep metallic filling

Classification of Dental Desensitizing Agent /obtundents

1.) Essential oil (e.g. clove oil, eugenol)

2.) Agents occluding dentinal tubules (e.g. potassium nitrate, potassium oxalate, calcium hydroxide, fluoride)

3.) Formaldehyde

4.) Metallic compounds (e.g. silver nitrate, zinc chloride, strontium fluoride)

5.) Tannic acid

6.) Physical method such as GIC and composite

Mechanism of action of obtundants

1.) Act by penetrating the dentinal tubules. Therefore paralysis of the peripheral nerve fibers and blocks the nerve impulse thus desensitize the exposed dentine. E.g. clove oil and eugenol

2.) Act by precipitating the protein of the protoplasmic nerve fibers and resulting into blocking of the nerve fibers—E.g. Zinc Flouride, silver nitrate, stannous fluoride, paraformaldehyde.

3.) By permanently destroying peripheral nerves. E.g 100% alcohol

4.) Secondary dentine or calcific barrier formation.

Uses of obtundents

  • Relieve pain during cavity formation.
  • Desensitize the exposed dentine due to abrasion, erosion, bruxism, attrition.
  • Achieve bacteriocidal or bacteriostatic effects, obtundents may be used as an antiseptic in RCT.

Ideal properties of Dental Desensitizing Agent / obtundants

  • Non-irritant to the pulp.
  • Relatively painless on application.
  • It can be quickly applied.
  • Rapid onset of action.
  • Effective permanently.
  • Should not stain the teeth.
  • Consistently effective.

Management of sensitivity of tooth

At first, taking a proper history from patient & identifying the precise cause & immediate management according to the reason.

  • Use of obtundents such as clove oil and eugenol.
  • In generalized hypersensitivity, we can use desensitizing toothpaste.
  • If loss of enamel is more then use restorative material.
  • If the effect is in dentine or close to the pulp, RCT will be the best option.

Dental Pain Theory

A) Neural Theory

Pulpal tissue contains several polypeptides that can act as a regulator of neural transmissions, which may alter the permeability of the odontoblast cell membrane. Such hyperpolarization could make the pulp more sensitive to various external stimuli.

B) Receptor theory

Odontobalst has a sensory function, i.e., serving as a transducer between external stimuli and nearby pulpal nerve plexus. When there is a disruption of odontoblast, the dentin becomes very sensitive.

C) Hydrodynamic theory

Dental tubules contain fluid. A blast of air or hot and cold stimuli will cause a rapid movement of fluid within the tubules. This movement will cause the deformation of both the odontoblast process and adjacent nerve fibers. This nerve deformation causes pain.

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