Tooth sensitivity is common during whitening treatment. Almost all sensitivity experienced during whitening is transient and fades after the whitening treatment is discontinued (Li and Greenwall 2013). Because sensitivity is the most common side effect experienced during whitening, this chapter will look at the etiology of sensitivity, which patients are at risk for experiencing sensitivity, and prevention and reduction strategies.
There is a difference between the severity of the sensitivity experienced during home whitening and that experienced during power whitening. The intensity of the sensitivity experienced during power whitening can be more severe.
HISTORY OF PREEXISTING SENSITIVITY
If a patient has preexisting sensitivity, will he or she be more likely to experience sensitivity during whitening? It is thought that this may be the case and that it is essential to question the patient to obtain an accurate dental history. The patient should be asked about his or her experience with sensitivity to heat, cold, and sweet things; pain on biting; and pain with cold sensations (see Table 20.1 and 20.2 for the tooth sensitivity algorithm). Each sensitive stimulus will determine whether the pain is from gingival recession or a more severe cause such as acute pulpitis. Sensitivity to cold and pain on biting together can mean the presence of a crack in the tooth, and this should be attended to before any further whitening treatment is undertaken. This is because whitening gels go straight into a crack in a tooth (Kwon et al. 2012) and could make the tooth more sensitive. Use of a desensitizing toothpaste for 2 weeks before the whitening treatment has been shown to be effective in reducing the incidence and severity of pain during whitening.
Another treatment possibility is using a desensitizing toothpaste or a proprietary desensitizing material as a treatment for 1 hour in the tray each evening or placing the desensitizing gel in the tray overnight. This will make the teeth less sensitive, and the patient can then proceed with the normal whitening treatment (see Figure 20.4).
SENSITIVITY ELIMINATION OR REDUCTION
Sensitivity is a common side effect when whitening teeth (Haywood 1999). About 67% of patients may experience some type of sensitivity at some stage during whitening (Haywood et al. 1994, Nathanson 1997). Different levels of sensitivity may be experienced (Thitinanthapan et al. 1999, Albers 2000). Normally patients do not experience any sensitivity for the first three or four nights. It is not known what determines whether or not a patient will experience sensitivity. In a study conducted at the University of North Carolina School of Dentistry, Leonard and coworkers (1997) found that of those patients who changed the solution more than once per night, 55% had sensitivity. This factor was found to be significant (P < .02). Two thirds of the patients who demonstrated tooth characteristics such as gingival recession, defective restorations, and enamel-cementum abrasion reported sensitivity, but when these characteristics were statistically evaluated, they were not found to be statistically significant risk factors. No statistical relationship existed between age, sex, allergy, whitening solution used, tooth characteristics, or dental arch lightened and the development of side effects. (For relevant factors see Table 20.2.)
ORIGIN OF SENSITIVITY
The yellow color of dentin contributes to the overall color of the tooth. Dentin consists of millions of round tubules (see Figure 20.1). Movement of fluid in the dentinal tubules is detected by the pain fibers. The movement is triggered by temperature changes, differences in osmotic pressure among different oral solutions, and tactile pressure acting on the exposed dentin surface (Bartlett and Ide 1999). The sensitivity of dentin occurs when the dentinal tubules are open and exposed to the oral cavity. The presence of open tubules has been related to increased activation of the pain fibers within the pulp by cold stimuli when applied to tooth surfaces (Bartlett and Ide 1999). These factors may suggest why patients experience sensitivity during tooth whitening treatment. Treatment is aimed at blocking the tubules (see Figure 20.1).
From Greenwall L, Jameson C. Success strategies for the aesthetic dental practice, Quintessence: London, 2012, with permission.
• Inherent patient sensitivity
• Frequency of application (e.g., application twice a day can cause teeth to become sensitive)
• Concentration of the material
• History of sensitivity (assess at consultation)
• Hot or cold sensitivity?
• Pain on biting?
• Pain with sweet items?
TOOTH SENSITIVITY DURING WHITENING
It is common for patients to experience sensitivity during both home and power whitening. There are multiple simple and complex causes of tooth sensitivity experienced during whitening (see Table 20.3). For home whitening treatments, it is extremely important to establish a management strategy that includes a self-management home desensitizing regimen so that the patient can continue the whitening treatment (see Table 20.4). There are multiple treatment options, which are listed in Table 20.5. It is advisable to give the patient an alternative when administering home desensitizing treatments. The patient should brush with a desensitizing toothpaste during the time of whitening. It has also been shown that brushing with a desensitizing toothpaste for 2 weeks before whitening can help eliminate or reduce the sensitivity experienced during whitening. Then the patient is given instructions on how to use the proprietary soothing gels. Figure 20.10 shows a tray that has been set up for explaining the methods of soothing during whitening and the vast array of products available for this purpose.
• Addition of Carbopol and other thickening agents.
• Age of the patient (patients younger than age 40 experience more side effects)
• Anhydrous-based whitening products
• Chemical byproducts of carbamide peroxide
• Chemical interaction of the tray
• Concentration of whitening solution
• Dissolving media
• Exposure time
• Flavors added to the whitening solution
• Frequency of application
• Inherent patient sensitivity
• Medical status of the patient
• pH of the whitening solution
• Sex of the patient (women appear to experience more side effects than men)
• Tray material used
• Tray rigidity
Data from Leonard (1998) and Knight et al. (1997).
Stage 1 Prevention
Stage 2 Treatment
Stage 3 Avoidance: helping patients self-manage
• Cover deep cervical lesions with glass ionomer pretreatment (Class V restorations)
• Apply material into the tray
• Neutral sodium fluoride gel
• 5% potassium nitrate
• Amorphous calcium phosphate (ACP), MI Paste, MI Paste Plus
• Proprietary desensitizing materials and soothers
• Use new materials that incorporate soothers
• Brush with desensitizing toothpaste or ACP
• Apply soothers directly onto the teeth
• ACP varnish
• Immediate dentin sealing agent (e.g., HurriSeal)
• Dentin bonding agent
• Modify whitening technique
• Ensure all excess is removed
• Use lower concentration
• Reduce treatment times
• Apply every second or third night
• Trim back tray
• Interrupt treatment
• Stop treatment
METHODS FOR TREATING SENSITIVITY (SEE TABLE 20.5)
There are two methods to consider for the treatment of sensitivity during whitening treatment: the passive method and the active method.
• Altering the whitening time.
• Changing the frequency.
• Reducing concentration to find a comfortable solution for the patient.
• Allowing the patient to skip a night of whitening.
• Using less whitening gel in the tray.
• Trimming back the whitening tray so that it does not impinge on the gingival margins.
• In the active method, desensitizing materials are applied either directly onto the teeth or inside the whitening tray.
• Products used are fluoride or potassium nitrate applied in the tray as a pretreatment, at the onset of symptoms, or after a course of treatment.
• The use of fluoride and potassium nitrate to treat whitening sensitivity has been clinically researched and seems to work well (Haywood 1999).
Fluoride as a desensitizing material
Fluoride reduces sensitivity by blocking the tubules. This restricts the ingress of fluids according to the hydrodynamic theory of pain (Bartlett and Ide 1999). A neutral fluoride has been recommended for treatment use, such as PreviDent 5000 Plus (Colgate Oral Pharmaceuticals).