General whitening rarely fixes a single dark tooth, because the cause is usually inside the tooth rather than on it. That distinction changes the treatment entirely.
If the nerve is dead, external whitening will not lighten it meaningfully; internal whitening after root canal treatment, or a restoration such as a veneer or crown, are the usual routes. If a restoration is the cause, replacing it may be enough.
The first step is a test and an X-ray, because the answer depends entirely on which of these applies.
A page can inform you. It cannot examine you.
A vitality test and X-ray answer this quickly. Do not spend months on whitening strips first.
General information reviewed by Mankirat Gill, DDS · August 2026. Not a substitute for an in-person examination.