This information is provided so there is a reasonable perspective of the bleaching process and, hopefully, no unexpected and alarming surprises.

Bleaching of teeth is an elective procedure as it rarely adds to dental health.
Often promises are made which cannot be kept.

Tooth colour is individual and bleached teeth will still only be a lighter shade of their natural colour.

Teeth Whitening - Unbleached Filling
Filling hasn’t bleached with surrounding teeth

Sometimes/mostly lightening of teeth by bleaching can be straight-forward and people can quite quickly achieve a shade within the range they want.

But, sometimes the process can start well, then slow down.

And then, sometimes the process may not work for a while, perhaps even for a
fortnight, despite regular applications. This delay can then be followed by a rapid colour change although the rate of change may be inconsistent.

And, it is important to note, gum and neck of teeth sensitivity can be expected and is often experienced as discomfort.

Maintenance is necessary to retain the desired shade so consider bleaching to be an ongoing process. Remember, ongoing maintenance of a particular shade of lightness also brings ongoing costs particularly for a colour change using white light or laser, although home bleach kits are cheaper.

Mostly existing fillings in front teeth will need to be replaced, particularly if the
bleach/fill match is poor. Otherwise there will be a blotchy rather than a desirable effect. Replacement fillings are also an additional cost.

Bleaching is now a very acceptable cosmetic procedure and builds social confidence in many people. But as with all invasive work it does not always live up to expectations.