Bleaching (also called whitening) is the only purely cosmetic procedure in dentistry. In other words, there is no functional component to bleaching. Lighter or whiter teeth are not any healthier than dark teeth, nor do they allow more effective chewing or more distinctive speech. Nevertheless, it is the rare individual who does not desire whiter teeth.
There are essentially two main types of bleach: power and home. A third type, assisted, has been used as a booster for home bleach. However, since several home bleaches are virtually the same concentration as those targeted for assisted procedures, the line between these subcategories is fuzzy at best.
Evaluating the Whitening Effect
With virtually all the manufacturers of bleaching materials and equipment claiming double digit shade changes, you may wonder the following questions:
1. How are shade changes calculated?
Most manufacturers and researchers use a Vita shade guide that has been rearranged from lightest to darkest. It seems the consensus of this rearrangement is:
Therefore, if a patient can be lightened from A3 to B1, that would count as 8 or 9 shades changes (depending on how you do the math). However, it is debatable whether this method of bleaching effectiveness is really valid. Therefore, we have discontinued using this scale and prefer to use a qualitative measurement comparing a bleached arch to an unbleached control. In this system, we can determine whether the bleached arch has lightened significantly, somewhat, or not at all. See #3 below.
2. When are the shade changes determined?
This is the biggie! If a manufacturer wants to tout the success of its bleach, it will take the "after" shade immediately at the conclusion of the procedure. However, this period is the most unreliable time to take the "after" shade. Typically, the teeth are dehydrated to some extent and this effect can distort the bleaching results. We believe the best way to evaluate the effectiveness of the bleaching procedure is to check for any color change after one week, then one month and three months later.
3. How do you determine the success of the procedure?
Most manufacturers want you to bleach the maxillary and mandibular teeth together, a protocol certainly also supported by patients. This means that you will need to use the aforementioned shade guide held up beside some of the anterior teeth and decide which comes closest. This is a notoriously difficult procedure and prone to error.
The far better way and much more reliable is to bleach only one arch initially, using the untreated arch as the control. In this scenario, the maxillary arch is usually the target of the initial bleaching, while the mandibular teeth wait their turn. If the bleaching process was successful for the maxillary teeth, then the mandibular can be whitened at a subsequent appointment or with home bleach and trays. But if the maxillary teeth were not whitened, comparing them edge-to-edge with the mandibular teeth will demonstrate another approach to whitening should be contemplated.
These products contain various concentrations of carbamide peroxide or hydrogen peroxide. While most versions keep the concentration at 22% carbamide or lower, home bleaches with strengths as high as 35% carbamide peroxide are now being sold, signifying the trend is to use stronger bleaches for shorter periods of time. Even Crest Whitestrips, which Proctor & Gamble has chosen not to submit for evaluation, has a "supreme" version that contains 14% hydrogen peroxide (equal to about 42% carbamide), although the marketing adds "some people may experience sensitivity"!
Other differences between the products are based on viscosity, flavor, packaging, and marketing. And all of them have the potential to cause gingival inflammation and/or tooth sensitivity if not used properly.
Since consumers can choose to have their hair color changed in a salon or with a self-applied product purchased in a supermarket or discount store, it should not come as a surprise that a self-administered and directed home bleaching protocol can also be obtained over-the-counter. The aforementioned Whitestrips seem to be the most popular of these products, but there are many others from which consumers can choose. While we rarely test OTC products, we have completed a preliminary evaluation of a product called WhiteLight.
The system consists of flexible maxillary and mandibular stock plastic trays that extend posteriorly to the second premolars, a dual-barrel syringe of peroxide bleach (specific composition and strength not disclosed by the manufacturer), and a small LED light that partially fits between the trays and the lips. The LED light, which is about the size of a small garage door opener, emits a blue light that can only be described as very weak. It is difficult to even imagine that anyone would believe this light can catalyze bleach, but with a convincing infomercial and strong Web presence, there is no doubt many WhiteLight kits have been sold.
Our evaluation, which involved masking the right half of the maxillary tray with black electrical tape and not using the mandibular tray at all, was only performed on three patients. But the outcomes were virtually pre-ordained: there was absolutely no whitening after 30 minutes, which was triple the recommended bleaching time, regardless of whether the bleach was "activated" by the light or not.
While your warning patients about getting ripped off by these shameless hucksters may be viewed as just sour grapes, we continue to feel that it is your responsibility to expose these worthless systems for what they are. The really sad fact is that a number of these systems, including WhiteLight, are being promoted by members of the dental profession.
Even Dr. Oz on TV, who is a physician (according to his bio, he is vice chair of surgery and professor of cardiac surgery at Columbia University), not a dentist, has investigated OTC bleaching kits and has given his exalted blessing to three of them. The obvious question is what is a cardiac surgeon doing evaluating bleaching kits? Has he run out of things to do in his own specialty?
Carbamide peroxide is the main ingredient for most home bleaches, but hydrogen peroxide is thought to be more active. While we have indicated which form of peroxide each product contains, most of the independent research plus our evaluator ratings have failed to find any significant differences between them.
For carbamide peroxide products, the range is from 10% to 35%. It would seem the higher the percentage, the more effective the material. However, there are other factors such as the viscosity, which seem to be just as important as concentration. For hydrogen peroxide products, 3% to 14% is the range.
Has been implicated in causing sensitivity. It follows, therefore, that a more neutral pH bleach would be less likely to cause sensitivity.
Thicker and stickier is usually better. The more adherent the bleach is to teeth, the more effective it probably is and the easier it is to keep it off the soft tissue and from flowing down the throat. On the other hand, those extra sticky bleaches are sometimes difficult to remove, especially from embrasures.
Convenience is a major item in this category, since patients will only use the bleach if it is easy and not a hassle. All of our CHOICES are offered in individual syringes, which can be given to patients a few at a time. This effectively forces patients to return to the office on a regular basis (as often as you feel necessary) to have their teeth and tissues checked. Several of the manufacturers also include their toothpastes and mouthrinses in these kits. One evaluator felt toothpaste and mouthrinse do not belong in this type of kit while other evaluators reported that patients appreciated these extra components.
Bleaching Tray Material
Most of the bleaches come with material for bleaching trays. All of these tray materials are very flexible and comfortable. We tested each tray material for ease of fabrication and thickness. There are also different names given for bleaching trays, ranging from nightguards, mouthguards, whitening trays, application trays, and mouth splints. The only one from that group that really describes its purpose is whitening tray. We continue to favor bleaching tray.
These are applied to the facial surfaces of teeth on the model prior to making the tray. It provides a narrow space (about 1.0mm) between the teeth and the bleaching tray. This space presumably allows more bleaching gel to stay in contact with the teeth.
NOTE: Our own clinical study showed there were no differences in bleaching, regardless of whether a reservoir was used or not. Therefore, we do not recommend reservoirs in bleaching trays.
We have left this information in each commentary, just in case you choose to continue using reservoirs. Some of these products also have other uses. Please see BLOCK-OUT RESINS - REPAIRS AND RESERVOIRS for more information.
Most manufacturers of peroxide products, regardless of whether they are destined for office or home use, recommend refrigeration until they are dispensed. This means you should tell your patients to keep their bleach in the refrigerator when they are home and not to leave the bleach or their bleaching tray in their car when the weather is warm or hot. They should be active for one year if refrigerated.