Dentinal hypersensitivity

Eliminate guesswork in cases that often frustrate clinicians

By Anne Nugent Guignon, RDH, MPH

a professional responsibility to help them. Treating patients effectively comes from combining compassion with a solid understanding of the etiology and the professional treatment options.

While sensitivity can be an isolated single episode, many people have lived with tooth discomfort for years, so what may seem trivial is really a quality of life issue.2,3 Undiagnosed or untreated, patients become resigned to sitting through another uncomfortable "cleaning," avoiding a delicious frozen dessert, using a straw for every drink, or trying not to take a breath in near-zero weather.

Decades ago, there were few treatment options and a much more limited understanding of why people experienced this kind of sensitivity. Patients were often treated like hypochondriacs. Blaming patients for overzealous brushing and then handing them a tube of over-the-counter toothpaste for sensitive teeth is a quick, easy solution at our end. But that approach rarely provides long-lasting relief and does nothing to uncover how and why a patient developed dentinal hypersensitivity.

Numerous research studies have provided sound information on factors that contribute to sensitivity, and the role of diet and lifestyle is better understood.2,4 A plethora of products now exists that successfully treat this common malady. Today, it is quite possible to treat patients with hypersensitivity. A thorough understanding of all factors that underlie this condition results in successful identification, treatment, and long-term management of this painful condition.⁵ The best result is a happy, comfortable patient.

Recognizing a patient at risk

While it is critical to rule out other conditions such as a cracked tooth, caries, pulpal pathology, or occlusal trauma, dentinal hypersensitivity is most likely the source of discomfort. Depending on the study, the prevalence of dentinal hypersensitivity in the general population can be as high as 57%.¹ The prevalence in periodontal patients is even higher, ranging from 60% to 98%.⁴ The numbers don’t lie. A huge proportion of patients could benefit from effective treatment, but it is critical to understand the factors that elevate the risk for dentinal hypersensitivity.

Two conditions must exist for dentinal hypersensitivity to occur. There must be exposed dentin, and the dentinal tubules must be open. Open tubules allow the nerve at the other end to respond to an annoying stimulus such as cold water, an air blast, or the touch of a metal instrument. At times, it may be quite difficult to see exposed dentin, so patient symptoms should not be ignored. Not all exposed dentin is sensitive. Tubules can be microscopically blocked. According to Absi, sensitive patients have eight times more open dentinal tubules that are twice the mean diameter than those who do not report sensitivity.⁶ Exposed dentin is at particular risk for demineralization. Dentin surfaces are vulnerable to any acid source that has a pH of 6 or below.⁷

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More articles

• Dentin hypersensitivity
• Dental Hygiene Therapies: Hidden hypersensitivity

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Numerous studies have identified that certain demographic groups are more at risk. Conditions that cause gingival recession increase the risk for dentin exposure and resulting sensitivity.2-4 More people than ever are keeping their teeth for a lifetime and have exposed dentin, increasing the risk for sensitivity. Females report sensitivity more often than males, and those with sensitive teeth tend to fall between the ages of 20 to 40.^1,4 Research has shown that people with natural red hair can carry a gene that alters the response to anesthesia,8 requiring higher doses to achieve comfort. Observant clinicians often notice redheaded patients, or those with fair, freckled complexions experience more dentinal hypersensitivity. Excessive tooth bleaching can also lead to sensitivity. Premolars are the most commonly affected teeth and buccal surfaces are at greatern risk(38%).⁴

Role of acids and dry mouth

A history of regurgitation is an intrinsic risk factor. Conditions such as GERD, pregnancy, medication side effects, gastritis, alcohol abuse, and chemotherapy can lead to stomach acid coming into contact with the teeth involuntarily. Eating disorders involving purging also subject tooth surfaces to acid.9,10 In addition, there are many dangerous, anecdotal recommendations on the Internet such as drinking apple cider vinegar or warm lemon water prior to meals to aid digestion or enhance weight loss, claims that are unsubstantiated by the scientific community.

Patients with acidic (low pH) diets, frequent snacking habits, or beverage intakes are also at risk. Dietary culprits include both sugared and artificially sweetened beverages. As companies create new forms of liquid refreshments, the list grows longer every day. Beverages such as carbonated soft drinks, juices, wine, beer, and other alcoholic products now compete with flavored waters, commercially prepared teas, energy drinks, sports drinks, and beverage-enhancing liquids and powders for a spot in our total liquid intake. Fruits (especially citrus), vinegars, sour acid candies and powders, and foods with added citric, malic, and ascorbic acid are also culprits. Don't forget the contributions of supplements and medications such as chewable vitamin C or aspirin, cough drops, and liquid medications that contain citric acid.9-10

Dry mouth increases risk

The incidence of xerostomia or dry mouth has increased dramatically through the years. An adequate flow of healthy saliva helps neutralize or buffer acids.11 Lack of saliva allows acidogenic and aciduric microorganisms to proliferate. Acidogenic microbes produce copious amounts of acid. Aciduric organisms are capable of surviving in a lower pH range. Within 30 minutes of a pH drop, aciduric microbes begin producing acid. Saliva that lacks buffering capacity also contributes to an overall reduction in the pH of the oral cavity.4,11,12

Decades ago, it was rare to encounter a patient with dry mouth, especially in younger patients. Now, dry mouth is an issue that plagues all age groups, from young children to seniors. Thousands of pharmaceuticals and over-the-counter medications list dry mouth as a side effect. People often take multiple medications, which compounds the problem.11

Medical conditions also play a role in inadequate salivary flow: radiation treatment, chronic renal failure, diabetes, autoimmune disorders, salivary gland pathology, sleep apnea, and menopausal hormonal imbalance. Lifestyle issues that contribute to salivary dysfunction include stress, dehydration, smoking, excessive alcohol or coffee intake, recreational drugs, and laxative or diuretic abuse.9-11

Getting the details

Since most patients are not looking for reasons to visit a dental practice, it is important to believe in their pain or discomfort. Today's patients have come to expect lightning-fast diagnostics and immediate, effective treatment. The most successful treatment outcomes include the patient in the process. Pain and discomfort are subjective, so patient responses only paint part of the picture.

At times, it can be difficult to see an area of exposed dentin, but a gentle stream of air, water from a syringe, or a light touch with a metal probe can initiate an episode of dentinal hypersensitivity. Positive responses to air and cold are also diagnostic markers for a cracked tooth. A history of occlusal trauma or biting discomfort in a specific area of the mouth increases the probability that a fracture is the primary issue, but both conditions can be present at the same time. Successful treatment of dentinal hypersensitivity will not relieve symptoms of cracked tooth syndrome. Surprisingly, patients who complain about the sound of an ultrasonic scaler can actually be suffering from dentinal hypersensitivity.

The following questions will elicit a bounty of useful information:

1. Is the pain sharp, dull, or achy
   
2. Does it last for more than a minute, or does it go away quickly
   
3. Is the discomfort triggered by hot or cold, touching a tooth surface, or chewing tough food
   
4. Does it happen out of the blue or during a particular time of day
   
5. Is the discomfort confined to one tooth, an area, or the whole mouth
   
6. Is it worse in the morning
   
7. Do certain foods create discomfort
   
8. Do you avoid certain foods or beverages
   
9. How long have you had this discomfort

Once the diagnosis of dentinal hypersensitivity is confirmed, most patients want immediate treatment. Today, there is a wide range of professionally applied products and treatments that are quick, easy to use, and provide varying levels of relief (see related article). In addition to treating the clinical symptoms, is important to have a discussion about why dentinal hypersensitivity developed, and what type of supportive activity, dietary modification, or products should be used to prevent further recurrences.

Given the wide array of options, why not make it a goal to effectively diagnose dentinal hypersensitivity, uncover contributing factors, and provide an effective therapeutic protocol that includes both in-office treatment and supportive home-care and lifestyle tactics?

In-office strategies: Fluoride, calcium/phosphate, and arginine bicarbonate/calcium carbonate

There is no one perfect way to treat dentinal hypersensitivity. While we may find a product that works well for most, it’s a really good idea to have several options available for situations that don’t respond to your primary technique. The most popular chairside desensitizing agents available in the United States involve occluding dentinal tubules or coating the sensitive area with a thin protective layer of material.1,4

The goal is to provide significant and immediate reduction in discomfort, supplemented with a plan focused on keeping the area comfortable between office visits. Desensitizing medicaments come in a variety of application platforms:1,4 topical creams, varnish, enhanced prophy pastes, air polishing powder, single-dose applicators, powder/liquid compounds, and modified resin surface protectants. Some clinicians use laser technology to desensitize teeth.13

Traditional fluoride varnish products are widely used to treat sensitivity. Varnish products are easy to work with and occlude dentinal tubules. Formulations and product enhancements vary per manufacturer. Fluoride varnish is typically applied at the end of the appointment. 14-16 There is also fluoride desensitizing compound housed in a handy, unit-dose swab.

Calcium-phosphate technology forms the basis for many popular in-office desensitizing products. Amorphous calcium phosphate (ACP) was developed in 1991. Calcium and phosphate ions are released in the presence of saliva to accelerate remineralization, but the molecule lacks stability. ACP can be found in prophy paste, fluoride varnish, and fluoride gels.17-18

CPP-ACP, also known as Recaldent, uses casein phosphopeptides (CPP) to stabilize the amorphous calcium phosphate molecule, which increases the concentration of calcium and phosphorus in the oral cavity. CPP-ACP pastes, formulated with or without fluoride, can be applied directly to the tooth surface as a desensitizing medicament.19 A single dose professionally applied during a dental hygiene appointment may need to be supplemented with additional applications at home to achieve complete relief from sensitivity.

NovaMin, a type of bioactive glass, is a calcium sodium phosphosilicate compound. When NovaMin comes in contact with moisture in the mouth, the calcium and phosphate ions form a layer on the tooth, which crystallizes to form hydroxyapatite, essentially blocking dentinal tubule orifices.17,19, 20 In the clinical setting, NovaMin chemistry has been added to a traditional stain-removing prophy paste and is the primary ingredient in a commercially available air polishing powder.21

Another desensitizer creates hydroxyapatite using a powder made from tetracalcium phosphate and dicalcium phosphate anhydride that is mixed with liquid. The slurry paste is rubbed onto the tooth surface using a micro-tipped applicator for a minimum of 30 seconds.22

Pro-Argin technology is an arginine bicarbonate calcium carbonate complex that plugs dentinal tubules, providing immediate relief from dentinal hypersensitivity. Both the arginine and bicarbonate help maintain a neutral pH, a factor that facilitates the deposition of calcium and phosphate molecules into the tubules.¹ A professional paste that contains Pro-Argin is applied with a slowly rotating polishing cup prior to scaling.23 Many clinicians reapply the Pro-Argin paste at the end of the appointment, and patients experience sustained relief long past the professional application.24-27

A thin layer of a light-cured glass ionomer can provide a durable, long-lasting way to protect sensitive surfaces that has an additional benefit. Glass ionomers (GI) can be placed in moist environments and have the unique ability to absorb fluoride from products such as toothpaste, resulting in a continuous release of fluoride over time. One GI varnish is enhanced with tricalcium phosphate, a formulation that releases fluoride, calcium, and phosphate simultaneously.16

ANNE NUGENT GUIGNON, RDH, MPH, provides popular programs, including topics on biofilms, power driven scaling, ergonomics, hypersensitivity, and remineralization. Recipient of the 2004 Mentor of the Year Award and the 2009 ADHA Irene Newman Award, Anne has practiced clinical dental hygiene in Houston since 1971.

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