Dental hypersensitivity is a major problem. The pain and discomfort from this problem negatively affect the patient's ability to practice oral hygiene. As a result, plaque builds up and the teeth and periodontal apparatus become damaged.1
The following article reviews some of the common treatments for dental hypersensitivity (DHS) and gives a straightforward approach to treating DHS. It reviews some of the proposed theories for how DHS is caused and several treatments currently available on the market. It also reviews key issues to cover with a patient when DHS is found and treatment is started.
Proposed Mechanisms Resulting in Dental Hypersensitivity
There are currently 3 proposed mechanisms resulting in dental sensitivity.2 Under the first mechanism, nerve endings (nociceptors) located throughout the dentin are stimulated, resulting in sensitivity. Under the second mechanism, odontoblasts that are either chemically and or electrically related to nerves become stimulated, thus generating sensitivity. The third and most widely accepted mechanism is referred to as the hydrodynamic mechanism. Under this proposed mechanism, when stimulus is applied to dentin, it produces a displacement of the contents of dentinal tubules. This displacement then excites mechanosensitive nerve endings near the pulpal end of the tubules. Under this mechanism theory, the fluid within dentinal tubules obeys the laws of fluid movement, ie, stimuli cause movement of the fluid in the dentinal tubules that in turn causes stimulation of intradental nerves and a perception of pain. It is important to understand the mechanism of hypersensitivity to properly treat one's patients.
Multifactorial Causes for Dental Hypersensitivity
Before dentists decide to treat patients with DHS, they must first explain very carefully that DHS rarely is caused by just one thing. It is important for patients to understand that most DHS conditions have a multifactorial etiology.3 A clear understanding of this will help patients understand that DHS may not have a quick fix. In many cases, DHS requires several small treatment steps to resolve. One of the most important factors is diet. Giving patients a clear understanding of how diet affects DHS and how changing it can improve DHS is very important. Microscopic studies have shown that when dentine is exposed for 5 minutes to fluids like red and white wine, citrus fruit juices, apple juice and yogurt, they remove the smear layer and open up dentinal tubules.4 The loss of the smear layer is known to enhance dental hypersensitivity.5 One good tip is to tell patients not to brush right after ingesting acidic food or drink. A small sip of water after ingesting acidic food or drink will go a long way in helping DHS. Another important factor is brushing. Show your patients how to brush properly and recommend they change their toothbrush every 3 months, as that also will go a long way in reducing DHS.6
Effects of Dentin Exposure
Once dentin is exposed, it increases the likelihood of DHS. Dentin exposure is caused by recession or enamel loss. If the DHS is caused by recession alone, it is best treated by a connective tissue graft provided that the recession falls into a Miller's Class I or II lesion.7 A Miller Class I lesion has recession above the mucogingival junction (MJC), with no bone loss. A Miller Class II lesion also has no bone loss, but the recession is beyond the MJC. If a dentist is presented with either of these types of recession, along with DHS, the condition can predictably be treated by a connective tissue graft. By contrast, it is difficult to explain to a patient when one of these types of lesions is treated by a restoration that may then become an untreatable endodontic lesion that leads to extraction of the tooth.
Miller Class III or IV lesions both involve bone loss along with recession. In those instances, a connective tissue graft may be needed to gain attached tissue. However, attempting to treat recession and DHS simultaneously is likely to be ineffective due to the bone loss. As a result, the dentist must look at alternate ways to treat the DHS.
Over-the-Counter Treatment Options
Unless there is an obvious etiology requiring immediate treatment, it may be preferable to have the patient try an over-the-counter (OTC) product for 2 to 4 weeks to treat the DHS. Specialized toothpaste or mouthrinses are a couple of good OTC options. However, it is important to understand how these products work because a patient will often ask the dentist to explain how these alleviate DHS. Toothpaste or mouthrinse that contains strontium salts and fluorides claim to treat DHS by occluding dentinal tubules. There are even some OTC toothpastes that contain formaldehyde, which supposedly destroys vital elements within the tubules. Currently, most desensitizing toothpastes contain a potassium salt; such as potassium nitrate, potassium chloride, or potassium citrate. Toothpastes that contain these substances are thought to treat DHS by diffusing along dentinal tubules and decreasing the excitability of intradental nerves by altering their membrane potential. One important concept that a dentist must understand is that these toothpaste or mouthrinse additives must be able to perform in such a manner that they overcome hydrostatic pressure. When an additive is moving within the tubules, hydrostatic pressure is preventing more additive from entering the tubules.8 This may be one reason that additive-enriched toothpastes or mouthrinses have limitations in treating DHS. Notwithstanding, some patients may experience DHS relief from using such OTC products, if only because of the "Hawthorne effect" and their psychological belief that the products should work.
A 2-week follow-up visit is recommended after a patient has tried an OTC product to treat DHS. If the patient experiences improvement in DHS, continued use of the OTC product is recommended, along with a subsequent 4-week follow-up visit to assess whether the patient has experienced any additional benefit from continued use of the OTC product.
In-Office Topical Application Options
If the patient does not experience marked improvement in DHS from the use of OTC agents, a topical application product is a suggested next step. In order to assess which topical application is appropriate for any given patient, the dentist must first determine whether the patient is missing any dentin. If dentin is missing, then topical applications containing dentin adhesive products such as varnish or bonding agents can be used. These types of applications can often produce immediate results; however, a potential downside is that they can be easily removed, thereby undermining their effectiveness.9 Moreover, such applications have limited effectiveness when no dentin is missing, as they do not easily adhere to enamel. Often, such topical agents are incorrectly prescribed or misused because the practitioner has no understanding of their limitations.
There are other topical products that can be applied to an exposed root to treat DHS. These products range from resins to glass ionomer cements. Resins seal exposed dentinal tubules and provide an immediate blockage of pain-producing stimuli to pulpal nerves.10 Glass-ionomer cements11 are hydrophilic and can also block pain-producing stimuli. One downside of this category of products, however, is that they may require at least some preparation of the tooth.
An Extended Contact Varnish Versus Conventional Fluoride Varnishes
An example of another professionally applied topical product that can provide some versatility in treating DHS is the light-cured extended contact varnish designed for site-specific application. One such product, Vanish XT (3M ESPE), is composed of resin-modified ionomer material that releases fluoride, calcium, and phosphate. According to the manufacturer, the product acts by filling dentin tubules, thereby blocking DHS pain and, once it is applied, it releases more fluoride than conventional fluoride varnish; doing so every time the patient brushes.
The following 2 case examples will demonstrate the appropriate use of a light-cured extended contact varnish as a method for treating DHS.
CLINICAL CASE PRESENTATIONS
This case of DHS was diagnosed after full-mouth periodontal surgery was done on a patient (Figure 1). At about 4 weeks postoperatively, the patient complained of constant pain. The patient was asked to try an OTC fluoride mouth rinse and was given a prescription for fluoride toothpaste. Neither option yielded any relief. The patient was then told about Vanish XT, which is available for the clinician in a simple-to-use package (Figure 2). To dispense the product, the cap is first removed and the lever is pressed until there is an ample amount of the product to cover the affected surface (Figure 3). Because the patient was highly sensitive, local anesthetic was administered before applying the extended contact varnish (Figure 4). Also before application, the periodontal pockets were checked to make sure the patient did not have a gingival abscess or any residual subgingival calculus (Figure 5). The product was then applied with a plastic instrument and smoothed out to give it an aesthetically pleasing and functional appearance. The patient experienced about an 80% reduction in DHS, possibly due to the fluoride release that may have accompanied the initial application of extended contact varnish.
Upon inspection of the root subgingivally, a small amount of exposed dentin was identified. Upon subgingival probing of the exposed dentin, the patient acknowledged pain in that area. A surgical flap was reflected and additional extended contact varnish was placed subgingivally.
After 4 weeks of healing, the patient communicated that her DHS was completely gone and that the product was unnoticeable (Figure 6). The patient's testimonial about the product may be due to the fact that it has excellent translucent properties and can be applied in sufficiently thin layers that most patients do not even know it is there. It matches roots and enamel well enough in color that there is little to no identifiable difference in coloration pre- and postoperatively. Even though the manufacturer states that the product will slowly be removed by brushing and oral habits, this patient has experienced relief from DHS more than a year after the initial application of the Vanish XT extended contact varnish.
This case of DHS is one that dentists see frequently (Figure 7). These types of lesions are often the result of excessive/aggressive tooth brushing, or some other destructive oral habit. The patient was advised to change his toothbrush every 3 months and to use a medium-texture brush. Unfortunately, instructions were not followed and a severe case of DHS resulted. The patient was then advised to use OTC fluoride mouthrinse and a prescription for a 5,000 ppm fluoride toothpaste. After 4 weeks of use, the patient had no relief. Vanish XT was then applied as directed and the patient experienced immediate relief (Figures 8 and 9). The relief was so significant and welcomed that he asked for the material to be applied in other areas of recession, even though he had no current symptoms of DHS in those areas.
As the above case presentations reflect, DHS is a persistent dental problem with a variety of causes and treatments. Extended contact varnish, such as Vanish XT, is one of several clinical treatment options available for the patient suffering with DHS. This treatment is indicated for exposed root surfaces, newly erupted teeth, around orthodontic brackets, and in locations where patients have acid erosion. The above empirical results demonstrate the product's effectiveness in treating patients with DHS resulting from exposed dentin. The author has also found that because light-cured extended contact varnish can be applied to the tooth like a traditional restoration, this material forms a physical barrier between the affected area and the surrounding environment, which may also help in reducing DHS.
In order to determine what product and method(s) of treatment are appropriate for treating a patient's DHS, the practitioner must invest the necessary time in evaluating the factors that may be contributing to the patient's condition. The clinician must also have a thorough understanding of how different treatment options operate in relieving DHS.
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Disclosure: Dr. Stadeker reports no disclosures.