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Did you know that dentin hypersensitivity is among the most frequent complaint of patients? At the same time, dental practitioners least understand it as the little emphasis is given to this important yet common dental condition. This blog will provide a basic guideline that will help you better understand key concepts, etiology, and theories of dentin hypersensitivity.
The dentin hypersensitivity is associated with a short sharp pain that arises from the exposed dentin and occurs in response to various stimuli such as tactile, chemical, thermal, and osmotic stimuli. The terms‘ dentin sensitivity’ and ‘dentin hypersensitivity’ are used interchangeably in the literature, but dentin hypersensitivity is more accurate. Other terms that are less commonly used to describe the hypersensitive dentin in the literature are cervical hypersensitivity, root hypersensitivity, and cementum hypersensitivity.
The dentin hypersensitivity has a detrimental effect on the quality of life of an individual as it affects the physical and psychological well-being of the patient. The dentin hypersensitivity also affects the selection of diet and makes oral hygiene maintenance difficult.
The hypersensitive dentin is a commonly encountered and least understood dental complaint, and its incidence is reported between 10% to 15%. This problem mostly affects young adult females between 20-40 years of age. The tooth surfaces commonly associated with dentin hypersensitivity are the labial surfaces of canines and buccal surfaces of premolars, especially in the dentition with gingival recession.
In the hypersensitive dentin, the exposed dentinal tubules are patent. In some cases, where the exposed dentin is not hypersensitive, there is a more like a hood that the dentinal tubules are occluded with the deposition of sclerotic dentin.
Etiology of Dentin Hypersensitivity
It is important to understand that dentin hypersensitivity is not a disease but a symptom of one or a combination of the following underlying causes.
Gingival recession
There are numerous causes of gingival recession. One of the reasons for the gingival recession is the overzealous brushing of teeth. The gingival recession of this kind is typically present on the labial and buccal gingiva of the canines and premolars.
Attrition
It is a form of tooth tissue loss that involves the incisal and the occlusal surfaces of teeth. It is mostly seen in individuals with a history of night grinding of teeth (bruxism). These patients are likely to show the symptoms of dentin hypersensitivity.
Abrasion
An abrasion is a tooth surface loss that occurs because of tooth brushing with a hard toothbrush, improper tooth brushing technique, or using toothpaste or tooth cleaning powder with a higher abrasive. Abrasion of the enamel due to the over-enthusiastic brushing of teeth is one of the causes of hypersensitive dentin.
Erosion
Erosion is a form of tooth surface loss caused by the intrinsic acids (gastric acid due to gastroesophageal reflux disease) or extrinsic acids (overconsumption of citrus fruit juices and drinks) that may result in hypersensitive dentin.
After dental treatment
After dental procedures such as periodontal surgery, tooth whitening, scaling, and polishing, there is dentin hypersensitivity in some patients.
Internal or external resorptions
Normally the dentine is resorbed during the exfoliation of deciduous teeth. Dentine in permanent teeth is normally stable throughout life. The pathological dentin resorption may be initiated from two surfaces: from the dental pulpal surface, known as internal dentin resorption, or from the surface of the root, known as external dentin resorption. Mostly the causes of this internal and external resorption are unknown, but tooth hypersensitivity may be the earliest symptom.
Theories of Dentin Sensitivity
The following three theories have been proposed to explain the dentin sensitivity.
Direct Innervation theory
This theory of dentin sensitivity suggests that “Dentinal tubules contain nerve endings that respond to the external stimulus.”
Several arguments are against direct innervation theory. The specialized histological sections of dentin also confirm that the nerves within the dentinal tubules appear absent in the dentin’s outer part near the dentin enamel junction (DEJ). While in the inner part of the dentin that is towards the dental pulp, very few tubules have nerve endings. Besides, the application of local anesthesia on the exposed dentin does not eliminate the dentin hypersensitivity.
Transduction theory
The transduction theory of dentin sensitivity is also known as odontoblast receptor theory. According to this theory of dentin sensitivity “Odontoblasts serve as a receptor and are connected to the nerve endings that are present in the dental pulp”.
The transduction theory is also not widely recognized because there is no physiological evidence that shows that the odontoblast process is similar to nerve fiber and can conduct the impulses towards the dental pulp. In addition to that, odontoblast processes in most of the tubules are not extended to the dentin- enamel junction (DEJ) and in the majority of the dentinal tubules and the odontoblasts are not connected synaptically with the nerve fibers.
Hydrodynamic theory
The hydrodynamic or the fluid movement theory states that” when a stimulus is applied to the dentin it causes fluid movement through the dentinal tubules. This movement of fluid causes depolarization of the nerve endings that are present in the inner part of dentinal tubules and the cell-free zone of dental pulp just below the odontoblastic zone”.
The fluid movement theory is the most widely accepted theory that explains dentin hypersensitivity. Several findings support the hydrodynamic theory for example when the cavity is prepared small drops of fluid can be seen on the floor of the cavity. The hydrodynamic theory also explains why the application of local anesthesia at the site of exposed dentin fails to block the dentin hypersensitivity.
Treatment of Hypersensitive Dentin
The correct patient history and intraoral examination are important for the diagnosis of any disease or condition and the same is true for dentin hypersensitivity. As dentin hypersensitivity present similar to several conditions such as dental caries, cracked teeth, and irreversible pulpitis. Therefore, the detailed patient history, nature of pain, factors that increase or reduce the pain are important with the intraoral examination to confirm the diagnosis.
Treatment of dentin hypersensitivity is a complex process and involves several steps such as behavioral modifications, patent education, removing the causative or etiological factors that are associated with hypersensitive dentin, home, and dental office treatments.
Exposed dentin treatment aims to reduce or eliminate the sensitivity of the exposed dentin. The dental products that are commonly suggested occlude the open dentinal tubules that are desensitizing toothpaste, mouthwashes, and topical agents. These products usually contain calcium phosphate and fluoride ions, silver diamine fluoride (SDF), or a mixture of arginine, calcium carbonate, and fluoride. Recently the use of bioactive glass in the toothpaste has been suggested for hypersensitive dentin treatment as it occludes the open dentin tubules.