Dentin Hypersensitivity

What is Dentin?

Dentin is one of the major components of the teeth. Tooth is composed of an outer layer called enamel, inner layer called dentin, dental pulp encased within dentin and cementum at the base of the tooth that holds the tooth in the jaw. Dentin is a calcified tissue of the body, covered by enamel on the upper part of the teeth called crown and cementum on the base of the teeth. Dentin is composed of mineral hydroxylapatite, collagen, and water and is yellow in appearance. Enamel is translucent; therefore when enamel is eroded, dentin gets exposed which gives a yellowish tinge to the teeth. Enamel protects the teeth from extreme stimuli and abrasions.

Dentin is attached to the pulp through microscopic channels called dentinal tubules. These tubules are lined by dentin producing cells called odontoblasts. Sensitivity to pain, pressure, temperature and abrasions are transferred from dentin to the nerve in the pulp through these tubules. Tooth is innervated by myelinated A fibers and unmyelinated C fibers which are responsible for the sensitivity of dentin.

What are the Causes of Dentin Hypersensitivity?

Dentin hypersensitivity progresses in phases, initially starting as a local lesion with erosion of enamel, and then further progressing to exposure of dentin tubules. Major factors leading to this are:

Gingival recession: Gingival recession is the exposure of dentin in the roots of the teeth resulting from loss of gum tissue over the root of the teeth. It is a periodontal disease also called as receding gums. It usually occurs in people with poor level of oral hygiene and happens owing to improper tooth brushing or excessive brushing. Lack of tooth brushing leads to accumulation of dental plaque deposition at the root of the teeth resulting in receding of gum tissue called gingival, thereby exposing the root of the teeth called cementum. This further leads to demineralization of the tooth structures.

Tooth wear and tear:

• Tooth abrasion – Tooth loses its enamel if exposed to vigorous brushing, or consumption of hard fibrous diets or low pH oral fluids that cause dissolution of mineral content of the enamel.
• Tooth attrition – Tooth to tooth contact during excessive teeth grinding or jaw clenching also results in damage to the tooth enamel. Such activities are called para-functional habits, termed as bruxism.
• Tooth erosion – Repeated exposure of teeth to anaerobicchemical processes or acids whether by consumption of acidic foods or by regurgitation of intrinsic acids leads to damage of the tooth.

Age: With increasing age, primary dentin starts wearing off but secondary dentin is deposited and restored throughout life.

What are the Risk Factors of Dentin Hypersensitivity?

• People who have very heavy acidic diets or drinks or have frequent munching habits are at high risk.
• Having large amounts of beverages in the form of carbonated drinks, canned juices, beer, flavored waters, machine prepared tea or coffee, energy drinks, sour candies and foods are at high risk.
• People with a history of GERD (gastro-esophageal reflux), gastritis, pregnant women,  and people on chemotherapy are at high risk.
• Dry mouth disorder, i.e. people with inadequate saliva formation are at high risk as it allows acidogenic micro organisms to thrive in the mouth.

What is the Diagnosis of Dentin Hypersensitivity?

Diagnosis depends on a thorough clinical examination. The dentist will take a detailed medical and dental history of the patient and also will ask questions about the eating habits and oral hygiene practices that the patient follows. Apart from this, the dentist may use some techniques to differentiate dentin hypersensitivity from other localized tooth problems.

• Response to pain on tapping the teeth to rule out inflammation of dental pulp tissue (pulpitis)
• Response to pain biting a hard surface, like a wooden stick to rule out fracture
• Dental X ray to diagnose fractures
• Affected area is exposed to a jet of air to examine the response to pain

What is the Treatment for Dentin Hypersensitivity?

If dentin hypersensitivity is in the initial stages, the doctor would recommend some self care measures:

• Over-the-counter toothpastes available in the market are the most cost-effective way of dealing with dentin hypersensitivity.

• Brushing is an important part of oral hygiene; therefore, great attention needs to be given to the correct way of brushing the teeth.
• Teeth need to be brushed twice a day with a soft-bristled brush.
• The size and the shape of the brush are very important as it should fit in the mouth properly and should reach every corner of the mouth.
• Tooth brush needs to be changed every three or four months. If the bristles of the tooth brush are frayed, it needs to be changed immediately.
• Only American Dental Association accepted fluoride toothpaste should be used.
• Toothbrush should be placed at an angle of 45-degree to the gums and brushing needs to be done back and forth in short strokes.
• Entire mouth needs to be brushed, the outer, inner and chewing surfaces of the teeth.
• Do not put excessive pressure on the mouth during brushing.
• Do not excessively scrub the cervical part of the tooth.
• Do not use excessive amounts of dentifrice during brushing.
• Use desensitizing dentifrices with potassium salts as it helps in reducing tooth sensitivity.
• Use toothpastes containing sodium fluoride and calcium phosphates. The most recommended ones are the toothpastes with potassium nitrate.
• Use mouth wash containing potassium or sodium salts.
• Reduce the quantity of acidic food intake.
• Avoid brushing teeth immediately after taking acidic food or drinks.
• Keep a gap between food intake, and after every meal rinse your mouth with water.

The dentist might recommend the application of desensitizing agents or nerve desensitization therapies to reduce the pain.

Occlusive therapy: If the dentin tubules get exposed, they are plugged and dentin is covered with a protective layer of desensitizing agents to reduce its permeability and sensitivity. Various agents used are varnish, calcium compounds, fluoride compounds, oxalates, strontium chloride, formaldehyde, glutaraldehyde, anti-inflammatory agents such as corticosteroids, adhesive resin materials and bioactive glass.

Laser therapy: Use of Erbium YAG laser or Er: YAG laser application to recrystalize dentin, thereby resulting in nonporous surface that obliterates dentin tubules, helps reduce permeability and sensitivity of dentinal tubules. Laser also affects the neural transmission thereby stimulating the coagulation of proteins in the dentin fluid.

Ozone therapy: Ozone is made to penetrate the exposed tubules, thus eliminating bacteria and allowing mineralization.

Application of resin-based materials: Sodium fluoride varnish, or an aqueous solution of glutaraldehyde and hydroxyethylmethacrylate is painted over the exposed dentin to reduce the hypersensitiveness of the tooth.

Use of oxalates: Precipitation of oxalate particles over the exposed dentin surface reduces the perception of pain in response to stimuli.

Iontophoresis: This is a technique of occlusion of exposed dentinal tubules by using a low galvanic current to allow the precipitation of insoluble calcium with fluoride gels. These precipated particles get deposited on open dentinal tubules.

Gingival grafts: This is used to treat gingival recession which stands to be one of the major causes of dentin hypersensitivity. This is done by the placement of adhesive composite resin on the receded area or by glass ionomer restoration.