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At-Home Treatment of Dentinal Hypersensitivity
Over-the-counter desensitizing dentifrices, usually in the form of toothpastes, are a major category of dentifrice. In the United States, the change in demographics for people over age 50, the fastest-growing segment of our population, will lead to many more people needing and using desensitizing toothpastes.
Table 2
Table 2. At-Home Desensitizers—ppm Fluoride
What are desensitizing toothpastes, and do they work? Dentifrices claiming a desensitization effect come under scrutiny by the U.S. Food and Drug Administration. The claim must be substantiated by either clinical trials or the addition to the toothpaste of an ingredient recognized as being an effective, active agent for the treatment of the condition listed, at the FDA-accepted therapeutic concentration. Because the addition of fluorides to toothpastes has been shown to reduce caries, a claim can be made that the presence of different types of fluoride additives to toothpastes reduces caries.
Two potassium compounds, potassium chloride and potassium nitrate, have been added to toothpastes to reduce dentinal hypersensitivity. While both have been shown to reduce sensitivity, potassium nitrate is the more effective (and popular) of the two.47,48 According to the FDA monograph, for a toothpaste to be desensitizing it must contain 5 percent potassium nitrate as an active ingredient. Potassium nitrate’s mode of action has been described as a penetration of the potassium ions through the tubules to the A-fibers of the nerves of the pulp, where repolarization of these fibers is prevented after initial depolarization.49,50,51 The potassium levels act to block the potential for action generated in intradental nerves. If elevated levels of potassium nitrate are maintained, the depolarized state decreases the perception of pain. It can almost be described as a numbing effect on dentinal hypersensitivity.
A second type of desensitizing toothpaste that has been popular for the treatment of dentinal hypersensitivity is a gel that contains 0.4 percent stannous fluoride (Gel-Kam® gel) and acts by blocking the tubules. A third type is a dentifrice containing 0.4 percent stannous fluoride and 5 percent potassium nitrate for desensitization. This has been found in clinical studies to be an effective desensitizer.44 The currently available popular over-the-counter desensitizing dentifrices contain 1,000–1,100 ppm fluoride, which is the same level of fluoride contained in regular fluoride dentifrices and provides the same level of caries protection. Patients who experience dentinal hypersensitivity have varying degrees of risk for root caries due to their exposed root surfaces. While such patients can benefit from additional fluoride protection, it is unrealistic to expect that many patients will be compliant in the use of more than one dentifrice—one for hypersensitivity and another containing a high, prescription level of fluoride.
More recently, desensitizing dentifrices have become available with prescription-level 5,000 ppm neutral sodium fluoride and potassium nitrate, providing a high level of fluoride for additional caries protection for patients at risk for root caries. For these to be considered effective desensitizers by the FDA, they must contain the FDA-monographed level of five percent potassium nitrate. With a combined five percent potassium nitrate and 5,000 ppm prescription-level fluoride, such dentifrices provide a clinically appropriate desensitizing treatment and provide the best possible level of fluoride protection against root caries on exposed roots with at-home use. The 5,000 ppm fluoride dentifrice Colgate® Prevident® has been clinically proven to remineralize root caries by up to 57 percent over a six-month period.52
Clearly the least invasive treatment option the dental professional has available is the recommendation of a dentifrice product for home use, whether an over-the-counter or prescription dentifrice. Many desensitizing toothpastes contain fluoride for an anticaries effect and may contain antitartar, antigingivitis, and/or whitening ingredients. There is no doubt that toothpastes containing 5 percent potassium nitrate are effective in reducing hypersensitivity of the dentin and root. Many clinical trials have provided evidence of a reduction in tooth sensitivity with potassium nitrate.53,54,55,56,57,58 In most cases the dentifrice needs to be used for at least two weeks to see an effect, and continued use is required to avoid relapse.