What’s real and what’s not? Myths about sensitivity in professional tooth whitening abound. Here are the myths and the facts to consider:

Myth: “Zero-Sensitivity.”
Fact: The label, “zero-sensitivity,” is a misnomer. Double-blind clinical studies of nightguard bleaching products that claim zero-sensitivity have shown that sensitivity occurs in 55% to 75% of treatment groups. The placebo groups also experienced between a 20% and 30% rate of sensitivity.1 Sensitivity is a reality of tooth whitening that has no silver bullet. Managing it starts with knowledge of how to best utilize carbamide peroxide treatments.

Myth: Lower Concentration = Less Sensitivity.
Fact: Lower concentrations take longer to work and, therefore, require longer wear time. Longer wear time means the teeth are subjected to the dehydrating effects of the gel for longer periods. The short modality of high concentration offers lower sensitivity. With treatments of only 20-30 minutes, At-Home 30% maximizes rapid whitening due to the high oxidative concentration. Re-hydration can occur before the hydrostatic imbalance (the pulpal mechanism that elicits pulpal sensitivity) reaches the threshold that creates pain for the patient. Furthermore, Dr. Drosman’s 1,400 patient study using At-Home 30% showed an amazingly low pulpal sensitivity rate of less than 5%. Dr. Michael Miller of Reality supports the high-concentration approach, “I believe higher concentrations are going to be the major trend in home bleaching . . . Sensitivity is a non-issue if you follow the manufacturer’s directions.”2

Myth: Overnight Bleaching.
Fact: Overnight bleaching can lead to increased sensitivity due to dehydration. The longer the teeth are exposed to the gel and sealed away from saliva, the more a patient will experience dehydration. Dehydration can only be resolved once the trays are removed and the teeth are given time to rehydrate. Consider the recent study of overnight bleaching using Colgate’s Platinum. Over 50% of the patients tested experienced sensitivity.3 Then consider the CRA study that showed that the majority of active ingredient is spent in the first hour.4 Why continue dehydrating the teeth when most of the whitening is over?

Myth: Potassium nitrate belongs in whitening gel.
Fact: Potassium nitrate has been a successful and safe desensitizing agent in toothpaste. However, desentitizing toothpaste is used over weeks and is given time to be absorbed into the dentinal tubials. It is unclear potassium nitrate works in bleaching gel. Plus, in toothpaste, it is used on the teeth and then expect- orated, not swallowed. Patients are prone to swallowing whitening gel. It doesn’t make sense to medicate ALL patients when most won’t have sensitivity, and those who do will find better relief by using the toothpaste 2 weeks in advance of whitening treatments.

Myth: The use of Reservoirs on whitening trays.
Fact: On the surface, reservoirs seemed to make sense. Reservoirs were built into trays to increase active ingredient available for bleaching. A 1997 Haywood article states, “There is no indication that the presence or absence of a reservoir-type spacer or similar foam insert has any effect on bleaching time.”5 This year Reality Publishing stated, “Our own clinical study showed there were no differences in bleaching, regardless of whether a reservoir was used or not. Therefore, we no longer recommend reservoirs in bleaching trays.”6 At the same time, reservoirs are predisposed to gel leakage and swallowing and as a result can encourage gingival irritation. Reservoirs defeat van der Waal’s Force, the principal that creates a seal between the tray and the teeth; it holds the stent in place and helps resist saliva penetration and gel leakage. Additionally, some patients have a tendency to suck on the trays - reservoirs only provide more material to be swallowed.

Myth: Lasers, curing lights, plasma arc lights, or heat instruments significantly enhance tooth whitening.
Fact: Light/heat tools are precarious with limited benefit. As CRA points out, “The degree of in-office tooth whitening depends on active ingre- dient concentration, and contact time and not application of heat and/or light. Addition of light or heat provides positive psychological stimulus for patients and added ‘flair’ to the procedure, but CRA data do NOT show increased liberation of active ingredient or lightening due to these stimuli.”7 CRA went on to point out that most laser bleaching owners studied used their system in conjunction with at-home bleaching anyway and disliked the amount of time and hands-on effort that was required.

Dr. Michael Miller of Reality stated, “Our studies, both vitro and in vivo, as well as independent studies conducted elsewhere show that there is no advantage to using any of these curing-type lights for bleaching. Heat is applied for such a short period of time, as opposed to the earlier-generation lamps that were used, that you don’t catalyze the bleach very much.” Miller also stated, “We’ve done tests in which we used light on one side of the mouth and no light on the other half and we found virtually no difference.”8 Furthermore, multiple studies warn us that the use of 35% H2O2 and heat can result in pulpal damage.9 As Dr. William Strupp explains, “Studies warn against this potentially damaging combination. I see no reason to put a patient into that kind of situation.”10

1. Haywood, Van B., et al., “Tray delivery of potassium nitrate-fluoride to reduce bleaching sensitivity,” Quintessence International, Feb. 2001: 105-109.
   
2. “A conversation with Dr. Michael Miller Part 2.” Dental Practice Report. July/August 2001: 40–44.
   
3. Haywood, Van B., “Extended bleaching of tetracycline-stained teeth,” Cont. Esth. & Rest. Practice, Sept. 1997: 14:21.
   
4. Clinical Research Associates, “Tooth Bleaching, State-Of-Art.” CRA Newsletter, April 1997, Vol.21: 4, p. 2.
   
5. Haywood, Van B. Extended Bleaching.
   
6. Miller Michael, et al., Reality 2001, Houston: Reality Publishing Co., 2001, p.1-45.
   
7. Clinical Research Associates, “Tooth Bleaching, State-Of-Art.” CRA Newsletter, April 1997, Vol.21:4, p. 2.
   
8. Miller, A conversation 40-44.
   
9. Bowles WH, Thompson LR, Vital bleaching: the effect of heat and hydrogen peroxide on pulpal enzymes. J Endodon 1986;12:108-12.
   
10. Whitener, Strupp Uses only 30%, Q3 2000 issue, pp 3-6.

In support of the disaster relief rescue workers and victims of the Washington DC, New York, and Pennsylvania terrorist attacks, Life-Like Cosmetic Solutions will be continuing the Life-Like Community Service Program.