by Dawn Kasper, RDH
Have you ever experienced one of those lightbulb moments, when a thought suddenly occurs to you and you wonder why you didn't realize it sooner? I had one of those moments yesterday while seeing my last patient of the day, Cindy. Cindy had been experiencing sensitivity, mostly to cold, occurring only sporadically, and at times set off by chewing or warmth. Of course, as dental hygienists, we conduct a thorough questioning of the patient, trying to determine the cause or causes of their sensitivity. I reviewed Cindy's medical history, asked the appropriate questions, took necessary X–rays, did a complete oral examination, and ruled out other possible conditions. The end result was a diagnosis of dentinal hypersensitivity. That's when the lightbulb moment occurred to me. After 28 years of practicing dental hygiene, I have come to realize that the majority of our patients experience some sensitivity at one time or another. Just what is dentinal hypersensitivity, and why is it so prevalent today?
Dentinal hypersensitivity is defined as a sharp, sudden, painful reaction when the teeth are exposed to hot, cold, chemical, mechanical, touch, or osmotic (sweet or salt) stimuli, and cannot be attributed to any other form of dental pathology or defect. In its simplest form, it can be described as a short, sharp pain from exposed dentin in response to stimuli. In order to exhibit a response to the stimuli, the tubules would have to be open at the dentin surface as well as the pulpal surface of the tooth.
Here are some facts about dentinal hypersensitivity:
- It affects more than 40 million people in the United States annually.
- It impacts one in five adults.
- It is most common between the ages of 30 and 40.
- It is experienced by women at a younger age than men.
- It shows patients with periodontal diseases are particularly high risk — between 72% and 98%.
- “Hyper” sensitivity means painful response to stimuli not normally associated with pain.
- Response to stimuli varies from person to person due to differences in pain tolerance, environmental factors, and emotional state.
Most frequently observed on the premolars, dentinal hypersensitivity occurs when tubules at the exposed dentin surface lead to sharp pain when exposed to a stimulus or trigger. Common triggers include hot or cold air and acidic, sweet, or sugary foods or beverages.
The dentinal tubule is the portal through which stimuli gain access to the pulp. The odontoblasts and associated nerve fibers are able to detect dentinal fluid movement. Very little appears to be required to disturb and move odontoblasts and their associated pulpal nerve fiber endings into the proximal ends of the dentinal tubules.
Several theories have been cited throughout the years to explain the mechanism involved in dentinal hypersensitivity, including the transducer theory, modulation theory, “gate” control and vibration theory, and hydrodynamic theory.
The latter, hydrodynamic theory, developed in the 1950s and based on two decades of research, is the most widely accepted explanation of the cause of tooth sensitivity. It concludes that when the fluids within the dentinal tubules are subjected to temperature changes or physical osmotic changes, the movement stimulates a nerve receptor sensitive to pressure, which leads to the transmission of pain. The most important variable affecting the fluid flow in dentin is the radius of the tubules. If the radius is reduced by one–half, the fluid flow within the tubules falls to one–sixteenth of its original rate. Consequently, the creation of a layer or obliteration of the tubule can greatly increase the effectiveness of the treatment of this malady.
Discovering the reason for tubules to be exposed or open should be assessed, and a comprehensive examination will ultimately rule out other underlying conditions for which sensitivity is a symptom, such as a cracked tooth, fractured restoration, chipped teeth, dental caries, gingival inflammation, postrestorative sensitivity, marginal leakage, and pulpitis. It is important to allow the patient to assist in diagnosis by identifying the pain–inciting stimuli as well as describing the type of pain and location involved.
The most commonly cited reason for exposed dentinal tubules is gingival recession — reduction of the height of the marginal gingiva to a location apical to the CEJ (predisposing factor). Recessed areas may become sensitive due to the loss of cementum or enamel, ultimately exposing dentin, which is then prone to abrasion, erosion, and hypersensitivity from exposure of open tubules to the oral environment. Chronic exposure to bacterial plaque, toothbrush abrasion, and gingival laceration from oral habits such as toothpick use, excessive flossing, crown preparation, inadequate attached gingiva, gingival loss secondary to disease or surgery, normal aging, abnormal tooth position in the dental arch, and periodontal surgery are some but not all causes of gingival recession. It is very important to record probing depths, recession measurements, and sensitivity reported by the patient in order to monitor the patient's disease activity over time.
Treatment is challenging for both the patient and health–care provider, because it is difficult to measure or compare various patients' pain and difficult for patients to change the habits that initially caused the problem. Hypersensitivity can resolve without treatment or may require several weeks of desensitizing agents before improvement is seen. There are two principal treatment options:
- Plug the dentinal tubules preventing fluid flow.
- Desensitize the nerve, making it less responsive to stimulation.
To date, no single agent or form of treatment has been found to be effective for all patients. There are, however, solutions that have been tried with varying degrees of success. Professional interventions range from applying fluoride varnish to promoting remineralization to more aggressive, low–level laser treatments that occlude or fuse the tubules (the goal). Home–care recommendations include professionally endorsed desensitizing toothpaste with active agents:
- Potassium salts (nitrate, chloride, and citrate) interfere with transmission of stimuli by depolarizing the nerve surrounding the odontoblasts.
- Strontium salts (chloride or acetate) penetrate and occlude the tubules, thereby stopping flow of fluid.
- Sodium citrate and various fluoride compounds act as barriers to dentinal tubules, preventing fluid movement and thereby reducing sensitivity.
Other recommendations proven to be effective in the management of dentin hypersensitivity are prescribed depending on the severity of the condition:
- Calcium compounds like casein phosphopeptide–amorphous calcium phosphate (CPP–ACP) occlude dentinal tubules and can be administered at home via custom tray, toothbrush or finger application.
- Use of a custom tray filled with dentifrice containing potassium nitrate increases medicament–tooth contact time, thus increasing effectiveness.
- Iontophoresis delivers a low voltage charge of sodium fluoride into the dentin.
- Methacrylic polymers, which are applied as a base or composite restoration.
- Sodium fluoride varnishes that are painted on the tooth surface and set in presence of moisture.
Other suggestions include modifications of home care including toothbrushing to control plaque buildup and reduce toothbrush abrasion, caries–control measures with fluoride rinses, diet counseling, and proper brushing and flossing. The recommendation of an electric or battery–operated toothbrush to reduce abrasion, plaque accumulation, and massage the gingival tissues would be an excellent addition to a home–care routine.
More recently, dentifrices have been introduced containing combinations of desensitizing agents, fluorides, anticalculus, and/or whitening ingredients to provide multiple therapeutic and cosmetic benefits. In making treatment recommendations, it is important to have an understanding of the clinical data that support the product's efficacy and safety.
Dentinal hypersensitivity is a chronic problem that plagues many patients and is consistently underdiagnosed. A comprehensive assessment is essential, as is appropriate treatment to decrease the dentinal flow and relieve discomfort. The majority of cases begin with gingival recession. Once the tubules are exposed, the patient will experience pain. The initial treatment choice is to cover up the tubules to desensitize the nerves or interfere with the transmission of the pain signal at the synapse. Professional as well as over–the–counter treatment options to eliminate the sensitivity should be presented to the patient with the product of choice based on the scientific evidence supporting each active ingredient and the patient's preference for products that will fit most easily into his or her oral hygiene regimen. Including patients in the decision–making process is essential, since some of their daily habits may be contributing factors to the problem.
As in the case with my patient Cindy, forming an alliance to create an individualized approach to treating dentinal hypersensitivity will increase patient compliance during treatment, resulting in enhanced outcomes without patient discomfort.
- Jacobsen PL, Gretchen B. Clinical dentin hypersensitivity: understanding the causes and prescribing a treatment. The Journal of Contemporary Dental Practice 2.1 Winter Issue 2001; 1–8.
- Barrow SL. Dentin hypersensitivity — an overview. The Journal of Professional Excellence, Dimensions of Dental Hygiene, June 2006; 4(6):28, 30. http:www.dimensionsofdentalhygiene.com/print.asp?id=852.
- Walters P. Dentinal hypersensitivity: a review. The Journal of Contemporary Dental Practice 6.2 Spring Issue, May 15, 2005; 110–112,115.
- Stefanou LB. Brighter, whiter, ouch: treating whitening induced dentin hypersensitivity. The Journal of Professional Excellence, Dimensions of Dental Hygiene, June 2007; 5(6):24, 26. http://www.dimensionsofdentalhygiene.com/ddhright.aspx?id=1156.
Useful Diagnostic Tools
- Air/water syringe
- Dental explorer (touch)
- Percussion testing
- Bite stress tests
- Thermal tests (ice)
- Assessment of occlusion
Potential Risk Factors
- Excessive dietary acids
- Citrus juices
- Citrus fruits
- Carbonated drinks
- Energy drinks
- Toothbrush abrasion
- Chemical erosion
- Thin enamel
- Gingival recession
- Exposed dentin
- Eating disorders
About the Author
Dawn Kasper, RDH, has been a practicing dental hygienist since 1981. She is the president of Trusted Success, a dental practice–management company, and speaks on numerous topics, specializing in pain management, dentinal hypersensitivity, and new dental products. Dawn has authored several published articles and is a product evaluator for Dental Products Shopper. She has been an active member of the American Dental Hygienists' Association, the American Dental Education Association, and other professional associations. She can be contacted at [email protected].