When teeth are vital and do not offer the chance to bleach them from inside
the chamber, it is always possible to whiten them from the outside.
The substances used (peroxides) filter through the enamel: as a matter of
facts they run along some subtle interstice between enamel crystals made up by a
proteic matrix. Through this canal, the substances reach the dentin where, by
releasing oxygen they enact their bleachng action.
Practically, the most used method is the domiciliary one in which a kit is
given the patient, containing a sort of dental mask that is to hold the gel,
plus the tubes of the substance itself.
As an alternative, appointments can be done at the dentists', with or without
the use of UV rays to activate the substance.
At this point it's worth recalling that these procedures have the only aim of
accelerating the reaction but are not decisive.
Obviously, the substance is not "intelligent" and releases its action on the
proteic matrix of the enamel as well: the result is a partial denaturation of
this with a rise of the tooth temperature sensitivity and, according to certain
studies, also to caries permeability.
For this very reason it should be better to do the whitening process under
the supervision of a professional. The dentist choses the most balanced product,
surveys the patient's sensitivity, eventually proposing desensitizing
treatments, and decides the duration of the treatment.
The duration of the treatment and of the domiciliar protocol are extremely
variable and cannot be indicated in a definitive way.