Receding gums / exposed roots.
Persons that have parts of the root exposed due to receding gums should not start tooth bleaching before treating this condition.
The bleaching agent will most likely cause sensitivity problems in the area of the exposed root of the tooth that is not protected by enamel.
Besides that, the whitening procedure will have different whitening effect on exposed tooth roots from the rest of the tooth,
because roots do not have an enamel layer like the crown area.
Tooth decay.
Cavities have to be treated before starting any whitening procedure.
Otherwise the bleaching agent can penetrate through the decayed enamel into the inner tooth layers (dentine) causing severe tooth sensitivity.
Fillings, crowns and other restorations.
Tooth-colored fillings and resin composite materials used in dental restorations (crowns, veneers, bonding, bridges) or false teeth do not whiten.
All bleaching agents used to whiten teeth will only work on natural tooth structure.
Therefore, bleaching of teeth that contain restorations will result in uneven whitening,
making the teeth without restorations appear lighter than those with restorations.
In these cases, dental bonding could be a more suitable alternative method than tooth bleaching.
• All dental work would need to be replaced to match the newly whitened teeth.
Darkly stained teeth.
Teeth with dark stains caused by tetracycline, fluorosis or trauma will not whiten by chemical bleaching.
Generally, gray-colored teeth do not respond well to bleaching and other cosmetic procedures have to be used (veneers, bonding, or crowns).
A similar problem may occur in case of very translucent teeth.
Allergies.
People who are allergic to peroxide should not use teeth bleaching products,
because the bleaching agent used in these products contains peroxide (either hydrogen peroxide or carbamide peroxide).
Age under 16.
Tooth whitening is not recommended in children under the age of 16, because the teeth and especially the pulp area are still developing.
The whitening process has an increased risk of irritating the pulp and causing tooth sensitivity.
Pregnancy.
Tooth whitening is also not recommended in pregnant or breast-feeding women.
There is not enough research about product safety in pregnant women.
For this reason, although there are no known specific side effects, manufacturers recommend not to bleach while pregnant
or nursing as a precautionary measure.
In all of these conditions, the results of tooth bleaching may prove to be undesirable,
less than expected or even to worsen the patient’s aesthetic appearance.
You should always visit your dentist for a complete dental examination before using any over the counter tooth whitening product.
The dentist will check for any existing conditions and advise you whether or not your teeth are suitable for tooth bleaching.
It is also very important to follow the instructions on the product label very carefully.
Overuse of the product is not healthy for your mouth and under use can result in very little effect.
