Dentin hypersensitivity is a common dental condition characterized by sharp, short pain in response to various stimuli. This discomfort often arises when teeth encounter cold or hot temperatures, sweet or acidic foods, or even light touch. This sensitivity is a discomfort, not necessarily a sign of tooth decay or infection, unless diagnosed otherwise. This article explains how this dental sensitivity occurs and how it can be managed.
The Mechanism Behind Sensitive Teeth
The structure of a tooth involves several layers, each playing a role in its function and sensation. The outermost layer of the tooth crown is enamel, the hardest substance in the human body, providing protection. Beneath the enamel lies dentin, a porous layer that also forms the bulk of the tooth root, normally covered by cementum. Dentin contains millions of microscopic channels called dentinal tubules, which extend from the outer surface inward towards the pulp.
The pulp is the innermost part of the tooth, housing nerves, blood vessels, and connective tissue. These dentinal tubules contain fluid and connect the exposed outer surface of the dentin directly to the nerves within the pulp. The widely accepted “hydrodynamic theory” explains that when external stimuli, such as cold air or sugary drinks, cause fluid movement within these dentinal tubules, it stimulates the nerve endings in the pulp, leading to the characteristic sharp, temporary pain. This fluid movement can be caused by thermal, mechanical, osmotic, or chemical changes.
Dentin hypersensitivity occurs when the protective layers of enamel or cementum wear away, exposing the underlying dentin and its tubules to the oral environment. This exposure can result from various factors, including gum recession, aggressive toothbrushing, tooth grinding, or enamel erosion due to acidic foods.
Principles of Nerve Desensitization
Managing dentin hypersensitivity primarily involves two general approaches to reduce painful sensations. One method focuses on physically blocking the microscopic channels in the dentin, known as tubule occlusion. By sealing these pathways, external stimuli are prevented from reaching the sensitive nerve endings within the tooth pulp.
The other primary approach involves interfering with the ability of the nerves in the tooth pulp to transmit pain signals, often referred to as nerve deactivation or modulation. Certain agents can reduce the excitability of these nerves, making them less responsive to stimuli that would trigger pain. Instead of blocking the tubules, this method directly calms nerve activity, diminishing discomfort even if fluid movement still occurs.
Common Desensitization Treatments
Many treatment options for dentin hypersensitivity are available, ranging from at-home products to professional dental procedures, each employing either tubule occlusion or nerve modulation. At-home treatments often serve as a first line of defense due to their accessibility and non-invasive nature.
Desensitizing toothpastes are widely used and commonly contain ingredients like potassium nitrate, which works by depolarizing nerve fibers to reduce their excitability and prevent pain signal transmission. Other toothpastes may include strontium chloride or stannous fluoride, which help occlude dentinal tubules by forming precipitates or solid deposits on the dentin surface and within the tubules.
Beyond specialized toothpastes, adopting proper oral hygiene practices is important for managing sensitivity. Using a soft-bristled toothbrush and gentle brushing techniques helps prevent further wear of enamel and cementum, which could expose more dentin. Limiting consumption of acidic foods and beverages also protects tooth enamel from erosion, preserving the tooth’s natural protective layers.
When at-home methods are insufficient, professional dental treatments offer more targeted and immediate relief. Fluoride varnishes are applied in-office to strengthen enamel and block dentinal tubules by forming calcium fluoride precipitates and fluorapatite. Dental bonding agents or resins can be applied to cover exposed dentin, creating a physical barrier that seals the tubules and reduces fluid movement. Laser therapy can also be employed to treat sensitivity by sealing dentinal tubules through a thermal effect, or by directly influencing nerve responses. For severe cases of gum recession that expose significant root surfaces, a surgical gum graft may be recommended. This procedure involves transplanting a small piece of gum tissue to cover the exposed root, effectively shielding the dentin. In instances of severe, persistent pain unresponsive to other treatments, root canal therapy, which involves removing the affected nerve, can be a last resort to eliminate sensitivity.