by Sheri B. Doniger, DDS
A review of the at-home whitening systems available enables practitioners to guide patients to appropriate care.
With the overabundance of media attention to the "whitest, brightest smile," patients continually ask for methods to alter the shade of their teeth. Some practices, though, do not offer the immediacy of the in-office bleaching techniques. Some patients are not concerned with the fast results and would prefer to gradually lighten their teeth. Whitening modalities are available for satisfying these esthetically concerned patients.
Custom formed-tray bleaching has been available for more than 10 years. Initially, both glyoxide and proxigel were used when orthodontists found whitening of the teeth a side effect of their treatments for gingival irritation due to the orthodontic appliances. The proxigel contained 10 percent carbamide peroxide and was viscous enough to stay in the custom-fitted mouthguards.
The technique has evolved to a custom tray made of a plastic material, usually between 0.015 and 0.040 inches thick. This plastic tray is adapted over the teeth to just the gingival level. The patients utilize various concentrations of hydrogen peroxide or carbamide peroxide in prescribed quantities for periods of two to six weeks. The carbamide peroxide breaks down to 3 percent hydrogen peroxide and 7 percent urea. The hydrogen peroxide will oxidize the stains from within the enamel matrix.
Ninety percent of patients will achieve at least two shades of whitening in the six-week period of use. This whitening usually lasts one to three years. The patient selected must be highly motivated, and patient compliance for success needs to be relatively high.
The products available on the market today all contain either hydrogen peroxide (4.5 to 7.5 percent) or carbamide peroxide (10, 15, 16, or 22 percent), depending on the manufacturer. The concentration differences in carbamide peroxide afford the choices of speed of whitening. The 15, 16, and 22 percent carbamide peroxide may lighten the teeth at a faster rate, but, after the six-week period, the level of lightening will be equal with the 10 percent material.
The at-home whitening procedure is relatively simple. It is imperative that a thorough health history and oral examination is made. A diagnosis must be made about the type of stain present. Stains due to aging (usually yellow) and light brown stains are the most receptive to treatment, demonstrating the most predictable results.
After a thorough diagnosis, the patient is informed about his or her treatment regimen. Patient compliance, as stated previously, is of the utmost importance in the success of the home whitening procedure. Some offices use in-office "power" bleaching as a start and will have patients' follow-up with the trays at home as well. When using the at-home products on their own, patients need to follow the instructions set forth by the office. Since the appliance must be worn a minimum of two hours a day, the patient needs to be highly motivated for success. Some practices recommend "refreshing" the solution every two hours, if the matrix is to be worn for a longer period of time.
A timeline for the at-home procedure supervised by the dental office might include:
- Medical history
- Complete oral examination and evaluation
- Informed consent
- Fee discussion
- Financial arrangements
- Study models
- Tray fabrication
- Instructions to patient (written and oral)
- Office should call patient after the first day, the third day, and the seventh day to assess progress and any indications of sensitivity
- Final assessment and photographs after one to two shade difference (usually six weeks)
- Re-evaluation and assessment at subsequent preventive recare visit
Patients' perceptions and expectations should be addressed at length during the diagnosis appointment. "Chicklet" white is not an esthetically desired result. Patients should be advised that over-bleaching (application of the product beyond the effective two shade desired end) might result in loss of tooth structure. Over-saturation will cause the tooth to appear bluish due to loss of pigment. Again, patient compliance is the key. In this case, too much of a good thing is really too much.
Contraindications to treatment need to be presented at the diagnostic visit. Some patients will insist on "this white stuff they see on TV." As practitioners, we need to advise and counsel on both the positive and negative aspects of whitening. Some patients should not undergo the procedure. This is what separates the professionally dispensed material from the over-the-counter or "infomercial" product.
Possible contraindications to treatment include:
- Noncompliant patient
- Many mismatched dental restorations (unless patient is willing to restore)
- History of dentinal sensitivity
- Stain present that would be better treated with other modalities (microabrasion, restorative)
- Vast areas of dentinal abrasion
Currently, in addition to "infomercials," magazine advertisements, houseware shows, "flea markets," etc., sell carbamide peroxide in 10 to 15 percent packaging. The same dispensing syringes found in dental offices for much less money are being sold by non-professionals.
While the idea of marketing a dental product out of the hands of the practitioner is not new, there are several flaws in the process. The hygienist will be asked, "Why can't I just use the stuff on TV instead of the same high priced white stuff you sell? Isn't it the same?" In theory, yes, but in practice, no. The product marketed to the general population lacks the appropriate diagnosis and treatment planning. The boil and bite trays are cumbersome, awkward, never properly fit and can cause undue occlusal stresses if worn together. The purchaser of the TV brand - even though "instructions" may be enclosed - cannot be fully apprised of the dynamics of the shade changes, the solutions to the sensitivity that may occur, or the careful case selection determined within a dental office. The bottom line is that, although written directions are present, the full understanding of these directions and lack of professional guidance are nonexistent. This may bring the patient back in the office very quickly!
Other modalities for home whitening procedures include toothpastes. These can either contain calcium peroxide or hydrogen peroxide. The effect may take up to three years to achieve whitening. The actions of these products take off the surface stains, but do not enter into the enamel. In addition, the abrasiveness of each product will vary. Some toothpaste also contains titanium dioxide, which is a white pigment. These products are marketed to the general population via television and print advertisements. Patient expectations are usually high, due to the low cost, but they need to be informed that the process takes time.
The most reliable form of at-home tooth whitening appears to be carbamide peroxide or hydrogen peroxide gels, dispensed by dental offices and which go from precise dosages into custom-formed matrix trays. The professional diagnosis, treatment planning, and follow-up care are paramount to the success of the procedure. Informing the patient of the potential sensitivity issues and shortcomings of the product fall into the realm of professional care. The hygienist plays an integral role in educating the patient in these aspects.
Patients, as always, are consumers and free to choose. It is our professional responsibility to direct the patient with as much technical and scientific information to allow for a treatment plan which best serves the patient's oral needs.
References available upon request.
Sheri B. Doniger, DDS, practices in Lincolnwood, Ill. She graduated from the University of Illinois College of Dentistry in 1983 and obtained her bachelor's degree in dental hygiene from Loyola University of Chicago in 1976. She can be reached at (847) 677-1101 or [email protected].
At-home product overview
Hydrogen peroxide (3 to 7.5 percent) and carbamide peroxide (10, 15, 16, and 22 percent)
Time needed to achieve shade change
Initial shade change: within two weeks. Final shade change: up to six weeks (depending on product and strength used)
Plastic strips impregnated with material; gel dispensed in syringe form
Sensitivity can increase with the use of higher concentrations of carbamide peroxide. Patients who have a history of dentinal sensitivity would be better off using a concentration of 10 percent for the bleaching procedure and an additional fluoride to be applied in the matrix during nonwhitening intervals.
Dentin consists of highly packed tubules, housing the distal extension of the odontoblasts. The cell bodies are in the pulp chamber. If one envisions a box of straws, the top of the box would be where the roots are exposed and open tubules go into pulp chamber, or the base of the straws. Carbamide peroxide causes the water that is normally in the tooth to be drawn out of open dentin tubules, causing the odontoblasts to react with the only sensation they can - pain. Hence, the sensitivity.
This sensitivity usually lasts up to four days. Patients are advised of the possibility of this sensitivity and are informed to shorten the process time or utilize a desensitizing agent, such as a potassium nitrate toothpaste or fluoride.
Proper diagnosis will alert patients to the higher potential for sensitivity. Patients prone to dentinal sensitivity and those with exposed root surfaces are at greater risk of experiencing procedural sensitivity. As previously stated, the patient may be advised to use a fluoride gel in the trays or a desensitizing toothpaste in addition to shortening the duration of time the tray is in the mouth.
Other causes of sensitivity have been cited as:
- Prolonged contact of the product onto the tooth or gingival tissues
- Irritation due to the misconstruction of the matrix
- Occlusal disturbances due to tray thickness
- The thickening agents present in the products.
These problems are simply addressed by giving further instruction to the patient or adjusting the margins of the plastic matrix tray.