When a tooth is knocked the nerves and blood vessels that enter the tip of its root can be damaged. When this happens the tooth can die. This means that the nerve inside your tooth no longer works and the the blood vessels leak blood inside your tooth. This is why the tooth changes colour.

The first thing to do is to get a dentist to check the tooth and to make sure that the root is not fractured ( an X-ray is required for this). Provided the root is ok a root filling is carried out to remove the dead nerve etc. This sounds painful but remember your nerve is dead so it is relatively easy to make sure the treatment is pain free. Once this is completed the internal part of the tooth can be bleached to lighten your tooth back to its normal colour.

The cost for this treatment varies depending on how dark your tooth is but a fee of £300 to £500 would be reasonable.

Regards,