Examples of when a tray-based tooth whitening system can be expected to be effective.
Using teeth whitening treatments to minimize the color discrepancy between dental crowns and neighboring teeth.
As a general rule, teeth whitening treatments cannot be expected to have a lighten effect on existing dental work (there are, however, some exceptions). In most instances this fact becomes an obstacle for those seeking a whitening solution. The dental patient is faced with a dilemma where after the whitening treatments have been completed their existing dental work will have to be replaced because it no longer matches the new color of their teeth.
This same rule can, in some situations, be exploited so it becomes an asset as opposed to a detriment. Many people have porcelain dental crowns on front teeth that, at the time of their placement, matched the color of their neighboring teeth precisely. However now, some years later, they no longer appear cosmetically pleasing.
In most cases the phenomenon that has taken place is one where, either due to the normal aging process and/or exposure to chromogenic agents such as coffee or tobacco products, the person's natural teeth have stained over the years while their porcelain crowns have remained stable in color. An obvious solution is to use teeth whitening products to re-lighten the natural teeth back to their original shade of white, the one that matches the color of their porcelain crowns.
At-home tray-based teeth whitening can possibly lighten teeth that have porcelain veneers.
One exception to the rule that existing dental work will not lighten when teeth whitening treatments are performed involves teeth that have porcelain veneers on them. Porcelain veneers are translucent shells of porcelain that have been bonded onto the front side of a person's teeth.
When a tray-based whitening system is used, the whitener will penetrate into the tooth not from the front side through the porcelain veneer but instead through the back side of the tooth. Since the tooth does get a dosing of the whitener there is potential that it will lighten. Since veneers are translucent, if the tooth becomes lighter the net effect can be that the tooth, from the front side, appears whiter.
Whitening individually darkened teeth.
While it is possible that a tray-based teeth whitening system will produce a satisfactory result for cases involving an individually darkened tooth, it might not be the most appropriate method to choose. The awkwardness associated with using a tray-based whitening system in this type of situation is that instead of trying to lighten all of a person's teeth uniformly, the goal is to lighten a single tooth a great deal and others comparatively less so.
Your dentist will probably have other whitening recommendations for this type of situation. Either one where the offending tooth is treated individually in their office or else a situation where an at-home product, one capable of being applied to a single tooth at a time, is used such as a paint-on teeth whitener.
Masking white-spot lesions with whitening treatments.
If patients who wear braces don't clean their teeth effectively, white-spot lesions can form on the tooth enamel that surrounds their orthodontic brackets. (These lesions are the earliest visible sign of cavity formation.)
If this occurs, once the brackets have been removed the affected teeth will appear as if they have "bull's-eyes" on them.
In some situations, it may be possible to use whitening treatments to mask this damage.
The treatments are used to lighten the color of the tooth's undamaged enamel. As this effect takes place, the color discrepancy between it and the white discolorations becomes less apparent.
It's important to understand that this approach should never be attempted without the supervision of a dentist. Before this technique can be initiated, the dentist must first determine that the lesions are benign and inactive. Only a dentist has the knowledge and expertise to be able to make this determination.