Root canal treatment involves removing the dead tissue in a tooth, cleaning and irrigating the inside of the tooth before filling up the canal of the tooth.

Sometimes teeth requiring root canal may be discolored. Most often appearing "greyish" which is caused by blood, dead tissue being trapped within the tooth. The natural color of the tooth could be restored by bleaching the tooth from the inside after root canal.

After a root canal is done, the tooth will not automatically darken. The darkening is usually caused by blood inside of the crown that broke down and discolored. (sort of like a bruise) The tooth can sometimes be bleached lighter or it can have a porcelain crown placed over it. The darkness you might be seeing at the gum line of a crown could be metal that is sometimes used under the porcelain. Go for an all porcelain crown if you can.