Current status and recommendations for dentist-prescribed, at-home tooth whitening.
Since its introduction in 1989, night guard vital bleaching (often called dentist-prescribed, at-home whitening using a10% carbamide peroxide in a custom-fitted tray has made a significant impact on the practice of esthetic and restorative dentistry. Over time, a significant amount of laboratory and clinical research, as well as numerous case reports have supported the technique. The American Dental Association (ADA) established its guidelines for safety and efficacy in 1994. Many of the more recent articles provided a better understanding of the whitening process and its applications. A1999 ADA statement included the following. The preponderance of scientific evidence currently available in the literature supports the safety of the home -use and dentist- prescribed tooth- bleaching products when properly applied and monitored.
The material used: 10% carbamide peroxide. Almost all the major research in the world has been conducted on 10% carbamide peroxide, and only 10% of carbamide products (3% hydrogen peroxide) currently have approval for at-home use. Recently, the Food and Drug Administration (FDA) approved the use of 3% hydrogen peroxide in toothpaste for the life of the patient as safe, which adds confidence to using the dentist-prescribed, at-home whitening technique. At this time, there is no significant research to support the at-home use of concentrations of carbamide peroxide higher than 10%, or hydrogen peroxide higher than 3%. This does not mean that other products are not safe, but it does mean that it is not known what degree of safety and efficacy exists.
Duration and Extent of Treatment: Most products available promise quick and easy results in 14 days or less. This may be true for some patients, but success depends more on the patient than the product. The original night vital bleaching article recommended 2 to 6 weeks of treatment with10% carbamide peroxide. It is important for the dentist to prepare the patient for treatment that will last longer than a few days, in case the patient's teeth are not as responsive as anticipated, then the patient will be more likely to comply with home treatment until the best color change is achieved rather than become discouraged. If the color change occurs in a few days, the patient is even happier.
Application: Nightly treatment is the most effective use of material per application, and patients in extended treatment comply better with nightwear. Clinical studies have shown the 10%peroxide material to still be active in the tray at 4 hours and even after 10 hours of application. Daywear can achieve the same results but may take longer or use more material. It has been shown in the laboratory that higher concentrations of the material may result in faster lightening. However, clinically, the higher concentrations invite more sensitivity, which has been cited as the only real detriment to compliance by the patient.
The most effective whitening recommendation is the use of 10% carbamide peroxide applied nightly until the teeth either reach the desired shade or cease to change shades over a week’s treatment. For tetracycline-stained teeth, the patient should be willing to commit to at least 2 months of treatment, continuing up to 12 months if needed.
Short–Term Treatment: Treatment time can be very short for some patients, but the dentist cannot predict either the length of treatment or the final shade outcome. Sometimes it has been observed that the teeth whiten in as little as 3 nights. The dentist can help patients choose a method that best fits their lifestyle, goals for treatment(including time and cost), parafunctional habits (bruxism and gagging), etc.
Long-Term treatment: In some cases, whitening can be a long-term treatment. Extended treatment times of 2 to 6 months or longer have been reported. These extended treatment times can be necessary for stubborn stains, such as nicotine or tetracycline. Discoloration in the gingival third of the tooth is less responsive to whitening, especially in the case of grey tetracycline staining, in these situations, patients must be prepared to view treatment as a longer-term commitment, much like a weight-loss or exercise program.
Fees: The national average fee for one-arch / dual arch whitening depends on geographic location, office overhead, range and length of treatment, and type of whitening material used. The fees for extended treatment can be based on the amount of material used per month (which depends on the arch size, the tray design, and the patient's application technique) and the number of months treated. The patient can be seen monthly to evaluate progress, with a fee for each monthly recall to include the amount of material necessary for another month of treatment. In this manner, the patient pays for the treatment as it progresses, without the dentist having to change either an unreasonably high or low fee at the outset of treatment.
Sensitivity: Probably the only major detriment to whitening is the occasional occurrence of sensitivity during treatment. Examining all the available data from double-blinded clinical trials indicates that in the treatment groups, about 55%to 75% of the patients experience sensitivity. This sensitivity may be a result of the easy passage of the hydrogen peroxide and urea through the enamel to the dentin, which can occur in a matter of minutes. This easy passage also explains why we are able to change the internal color of the tooth, and possibly how sensitivity is related to the pulpal response to peroxide. The issue of sensitivity is one of the many reasons why patients should be under professional supervision.
Many advertisements claim superiority in sensitivity reduction with a particular whitening product, but to date, there are no published scientific studies supporting these claims. In fact, if one evaluated the best evidence-based studies on whitening, all studies report sensitivity as a side effect. This sensitivity does not necessarily interrupt the treatment and may last only 1 day.
Also, most studies indicate that in the placebo group (those not exposed to the carbamide peroxide ), generally 30% to 35% experience sensitivity, perhaps as a result of tray rigidity, or the flavor, base vehicle, or other ingredients in the placebo.
Even more significant is that one study reported that wearing the tray alone (with no treatment or placebo product applied) resulted in 15% to 20% of the patients developing sensitivity. The forces of the tray, the forces of occlusion, the insertion path of the tray, and pressure from saliva can elicit a sensitivity response.
Data from these studies seem to indicate that sensitivity is a multi-factorial event related to both the patient’s host response as well as the material, the tray, the arch anatomy, and treatment time. No one product has demonstrated superiority in sensitivity reduction of any significance. In fact, it may be an advantage to the practice to have more than one product available. The two products could be the same concentration of carbamide peroxide, but be very different in base composition, vehicle, flavoring, etc. If a patient has problems with a particular material, the other material could be substituted.
One retrospective study indicated that the only predictors for sensitivity were either the application of the product more than once per day, or a history of or examination revealing sensitive teeth. The age or sex of the patient, the presence of cracks, exposed dentin, caries, pulp size, etc. does not help the dentist predict who will have sensitivity. The best option is to inform patients that they have a good chance of experiencing sensitivity and that it is usually mild, short-lived, and ceases on termination of the treatment.
Passive and Active Treatment for sensitivity: There are two methods to consider for the treatment of sensitivity related to whitening: Passive and active. The passive method consists of altering the treatment time, frequency, or duration to find a comfortable solution for the patient.
The active method employs either the use of fluoride or potassium nitrate applied in the tray as a pre-treatment or at the onset of sensitivity. It is important to distinguish between the action of these two materials.
Flouride: Fluoride is basically tubular. It occludes the dentinal tubules, restricting the ingress of fluid flow as described in the hydrodynamic theory of pain. A neutral fluoride has been the recommended treatment either applied in the whitening tray, in the office, or through brushing with a prescription fluoride toothpaste.
Potassium Nitrate: Potassium nitrate acts on the tooth in a different manner to reduce sensitivity. It passes freely through the tooth to the pulp and either prevent the repolarization of the nerve after firing or aids in the release of nitric oxide. Either way, the effect is directly on the nerve, resulting in a calming effect on the tooth. This effect has been long known and most desensitizing toothpaste contains potassium nitrate. Generally, brushing with a potassium nitrate-containing toothpaste takes about 2 weeks to reduce sensitivity. Five percent potassium nitrate is the maximum concentration approved by the FDA. In patients experiencing sensitivity during whitening, potassium nitrate can be applied in a tray for 10 to 30 minutes before or after whitening, or when the sensitivity occurs.
Other Treatment Options: The only side effect so far associated with using desensitizing toothpaste in a tray is tissue burn in some patients. Another option available to the dentist is to supply a fluoride gel manufactured specifically for tray application. These materials can be applied as needed, or alternated with the whitening treatment.
