Dentin hypersensitivity is a condition that affects a wide spectrum of patients. The statistics below demonstrate the pervasiveness of this common condition. Varying data exist regarding the worldwide occurrence of dentin hypersensitivity. Clinical findings demonstrate, however, that approximately 1 in 5 people in the United States suffer from the condition.² Although sensitivity affects people of all ages, those between the ages of 25 and 50 are more commonly affected,³ and the condition is slightly more prevalent in women.⁴ In the United States, periodontal patients experience sensitivity at very high rates,⁵ and patients undergoing professional tooth whitening also are especially prone to tooth sensitivity. In fact, 55% to 75% of patients suffer from whitening-related sensitivity.⁶

Clearly, dentin hypersensitivity is more prevalent than dental professionals may realize. Data show that 42% of patients do not report consulting their dentist about their condition, and only 27% of those suffering report using a desensitizing dentifrice to help manage the condition.⁷ Instead, many patients modify everyday behaviors to avoid sensitivity, and may not even be aware they are doing so. For example, some patients avoid hot or cold foods or beverages. Others may avoid brushing sensitive areas, placing them at risk for plaque buildup, calculus formation, and even gingivitis.

DIAGNOSING DENTIN HYPERSENSITIVITY

Making the proper diagnosis is the first step in assisting your patients suffering from dentin hypersensitivity. Identifying patients who are sufferers can be achieved through close examination of existing conditions and by careful analysis of patient behaviors.

In addition to periodontal patients and those undergoing professional tooth-whitening procedures, other groups at risk for dentin hypersensitivity include those who exhibit gingival recession due to aggressive oral hygiene habits, consumers of high-acid food and drink, patients with parafunctional habits, and patients suffering from xerostomia.

In addition to paying special attention to these circumstances, a comprehensive and thorough examination is necessary to diagnose dentin hypersensitivity. Care must be taken to exclude other conditions such as  dental caries, pulpitis, cracked tooth syndrome, marginal leakage, fractured restoration, and restoration polymerization shrinkage.

In a typical workday, the retail pharmacist may field several questions about oral care and oral discomfort. Patients may complain about one or more teeth that are intermittently painful. The pain is invariably triggered by actions such as drinking a hot or cold beverage, eating a sweet or sour food, or dental manipulations such as touching the tooth or directing an air blast on it.

The patient may have concern that the tooth requires a filling or that it may need to be extracted. However, the problem, known as dentinal hypersensitivity, may be a relatively simple one to treat.

The crown is the section of tooth normally exposed to the interior of the mouth; the section below the gingival line, buried in alveolar bone, is the root. The crown is covered with enamel, the hardest substance in the human body. Enamel is 96% to 97% inorganic. The root is covered with a softer substance known as cementum. Cementum resembles bone in that it is composed of 45% to 50% organic material. Beneath the enamel and cementum is a material known as dentin, which encloses the tooth’s sensory mechanisms, such as the dental pulp or nerve root. Dentin is 70% inorganic material, 18% organic material, and 12% water. Dentin is riddled with thousands of small channels known as dentinal tubules. Dentinal tubules contain odontoblastic processes (portions of the dentin-producing cells, also known as Tomes’ fibers), tissue fluids that bathe the processes and fill the tubules, and minerals.

Prevalence

A significant portion of the aged population is edentulous (lacking natural teeth). Prior to the advent of fluoridated water, it was expected that people would begin a pernicious process of tooth loss as they reached the age of 30. This loss usually accelerated during the patient’s thirties and forties until a full set of dentures was required to masticate food. Widescale fluoridation, which was first introduced in the baby boomer generation, dramatically reduced the incidence of edentulousness; thus people have kept their natural teeth for longer periods than before. However, cumulative damage from years of exposure to mechanical and environ- mental insults increases the incidence of problems peculiar to aged teeth. Recent reports place the prevalence of dentinal sensitivity at 40% to 45%, a figure that is certain to rise as the average age of the population increases.

Why should certain teeth in certain people become hypersensitive? This question was elegantly answered by a set of facts and suppositions that collectively became known as “the hydrodynamic theory.” While this theory is not yet regarded by all as completely factual, it explains most of the available clinical observations and anatomical realities.

The first component of the theory is the observation that dentin is normally covered by cementum or enamel. When this covering is in place, the teeth are not hypersensitive. However, when cementum or enamel are absent due to erosion, abrasion, dental manipulation or a tooth defect, dentin is exposed.

The second part of the theory focuses on the dentinal tubules, which are open at the surface of the dentin, allowing a direct channel to the nerve pulp. Supposedly, any of the abrasive or erosive forces that expose dentin also open these tubules to the oral interior. When any trigger is present, the tissue fluids inside the tubules move slightly inward or outward. Cold causes the tissue fluid volume to shrink slightly, and heat causes it to expand. Strongly osmotic sugar or sour solutions cause fluid to be drawn out of the tubules. An air blast on the tooth (by a dental instrument) dries a tiny portion of fluid at the distal end of the tubule, causing a significant outer flow of fluid in the tubule. Touching the tooth with a dental instrument or periodontal cleansing aid forces a small amount of fluid into the tubule. Intratubular fluid shifts are interpreted as pain by the Tomes’ fibers and/or central nerve root of the tooth.

The hydrodynamic theory also explains many of the epidemiological observations on the causes of dentinal hypersensitivity.

Brushing Habits

Sustained and overzealous brushing (especially with harder-bristled brushes) is known to thin enamel and cause gingiva to recede, exposing the softer subgingival cementum, which is also damaged by brushing. Right-handed people tend to brush their left teeth more zealously and vice versa, which results in hypersensitivity in those teeth. Also, since people tend to brush the front teeth and outer tooth surfaces more zealously, those areas are more likely to be sensitive than back teeth and inner surfaces, mirroring the incomplete brushing habits of most people.

Tooth Grinding

Patients who grind their teeth experience a higher incidence of dentinal hypersensitivity. This action wears down the enamel on teeth, exposing the dentin.

Gender

Women are more prone to dentinal hypersensitivity. This is because women of any age, generally speaking, are more attentive to basic hygiene than an age-matched group of males. Since this includes dental care, female teeth are more likely to have exposed dentinal tubules as a result.

Age

There is also an age link to dentinal hypersensitivity. The problem does not occur in most people until they reach their late twenties, thirties or forties because overzealous brushing and other factors begin to take their toll at this time.

Diet

Habitual ingestion of acidic substances causes erosion of enamel and dentin, subsequently opening dentinal tubules. The citric acid in citrus fruits (e.g., lemons) dissolves enamel. Similarly, ingestion of other acidic foods and beverages (e.g., ginger ale, which has the lowest pH of any drink commonly available) discussed in this month’s patient information should be avoided whenever possible, since they effectively strip away the tooth’s protective smear layer (a layer of dead organic material that occludes the dentinal tubules, preventing the outward flow of tubular solution). Further, brushing directly after ingestion of these substances causes direct damage to enamel and must be avoided.

Smokeless Tobacco

Users of smokeless tobacco more frequently experience dentinal hypersensitivity. The “quid” of smokeless tobacco placed between the gum and cheek is a well-known cause of gingival recession. As the gingiva recede in response to this noxious chemical, softer subgingival cementum is exposed. Continual brushing erodes the cementum, opening the dentinal tubules.

Disease

There is an increased risk of dentinal hypersensitivity in bulimics and those afflicted with gastroesophageal reflux disease. Both conditions increase intraoral acidity, subsequently causing the type of enamel erosion that leads to dentinal hypersensitivity.

Periodontal disease and gum disease may also result in dentinal sensitivity. With these conditions, the tooth’s root surface is exposed through recession of the gums or loss of supporting ligaments.

Several approaches have been investigated for treating dentinal hypersensitivity. One option is simply to occlude the dentinal tubules through the use of a particulate toothpaste ingredient, such as abrasive silica. Hypothetically, even partial tubule occlusion could be of great benefit, since Poiseuille’s law holds that reducing the tubule radius by 50% reduces the flow through the tubule to 6.25% of its original value. However, the use of toothpastes containing silica particles is widespread, and does not appear to have substantially affected the prevalence of dentinal hypersensitivity. Therefore, any special toothpaste ingredient must demonstrate the ability to desensitize teeth to a statistically greater extent than the toothpaste alone. To date, only potassium nitrate has met this requirement. It is thought to act directly on the pulpal sensory nerves. After an initial depolarization of sensory nerve fiber membranes, excess potassium halts repolarization. Thus, the ability of potassium nitrate to quell dentinal hypersensitivity may be due to an irreversible depolarization.

Many products are available to treat dentinal hypersensitivity. Potassium nitrate-containing toothpastes include Aqua-fresh Sensitive, Colgate Sensitive, Crest Sensitivity Protection, Dental Care Sensitive Formula, Sensodyne Extra Whitening, and Sensodyne Fresh Mint. One toothpaste, Sensodyne Tartar Control Plus Whitening, also contains tartar control and whitening ingredients. Other products for sensitive teeth are Protect Sensitive Teeth Gel Toothpaste, Rembrandt Whitening Toothpaste for Sensitive Teeth, and Orajel Sensitive Pain Relieving Toothpaste for Adults. All of these toothpastes contain fluoride to strengthen dental enamel and protect against cavity formation.

A dentist can relieve dentinal hypersensitivity by applying fluoride paste, bonding agents or dentin sealer to the exposed root surface.

DO

Brush twice daily, with a soft-bristled toothbrush
Use a toothpaste containing fluoride
Brush inner, outer and chewing surfaces with a back-and-forth motion
Hold brush at 45° angle to the gums to clean gumline
With the ‘toe’ of the toothbrush, clean the inner surface of the front teeth using an up-and-down stroke
Brush the tongue gently
Replace toothbrush every three months

DON’T:

Brush too vigorously
Brush too frequently
Use a toothbrush too large to easily clean all surfaces.

Patient Information

Help For Hypersensitive Teeth

Many people notice a painful sensation when they consume a food or beverage that is hot, cold, sweet or sour, or when brushing their teeth, or when a dentist cleans or dries the tooth with an air blast. The teeth may not hurt at any other time. This condition is dentinal hypersensitivity.

Treatment

If you already have dentinal hypersensitivity, you may find relief in any of several brands of toothpastes for sensitive teeth. They contain potassium nitrate plus a fluoride. Potassium nitrate is the only ingredient presently proven to be effective for the problem. To use the toothpaste, you should choose the softest bristle brush you can find (this is also the best advice for patients without dentinal hypersensitivity, unless advised otherwise by a dentist). Place a one-inch strip of toothpaste on the brush and brush for at least one minute twice daily, morning and evening. Make sure that you allow the toothpaste to come into all areas where you noted dental pain. Brush no more than twice daily. Avoid excessive force when brushing.

Do not use these toothpastes for more than four weeks without a diagnosis of dentinal hypersensitivity from a dentist. The reason is that your tooth pain may be due to a much more serious problem, such as a chipped tooth, a cracked filling, erosion underneath a dental filling, bruxism (i.e., tooth grinding), or damage from malocclusion (i.e., an uneven bite). Once a dentist has ruled out these serious problems, you may continue to use the toothpastes for as long as hypersensitivity is present.

Prevention

It is best to avoid causes of dentinal hypersensitivity. Acidic food and drinks can damage tooth enamel. From most acidic to least, some of the foods and drinks to use cautiously include ginger ale, limes/lemons and their juices, wine, cranberry sauce, coffee, vinegar, pickles, cola and citrus-based drinks, apples, rhubarb, raspberries, root beer, relish, strawberries, fruit jams/jellies, peaches, sauerkraut, blueberries, pineapples/pineapple juice, cherries and grapes. It is especially important not to brush right after ingesting these foods, because they strip away the tooth’s protective layer, and you will be brushing naked enamel, which is more prone to damage. Never suck directly on limes/lemons or allow these to be placed into a baby bottle given at night. This permits them to be in prolonged contact with the teeth, causing “nursing bottle mouth” (i.e., there are severe cavities in the section of the mouth bathed by the milk).

Avoid buying small packets of sour, acidic powders or candies coated in them. Their acidity is too high for tooth health.

Do not use smokeless tobacco. Constantly exposing the gums to this toxic substance causes them to recede, exposing the softer tooth sections below the gumline. They are then more prone to damage during brushing.

Follow proper oral hygiene and see your dentist regularly for evaluation and professional care.

Does one advise brushing with it or mere application and brushing with a regular paste?

However there are a few brands that can be used to brush like a regular paste