Sometimes when dental trauma or decay involves a tooth's nerve (dental pulp), a root canal treatment (endodontics) can not be avoided to save the tooth. Often the necrotic pulp causes the tooth discoloured, which will not change back after root canal treatment.
There are a few options, such as internal bleaching, porcelain veneers and crowns, to whiten endodontically discoloured teeth. Internal bleaching is the most conservative option which doesn't involve removing any tooth structure.
This procedure involves placement of bleaching agent (mixture of sodium perborate and peroxide) into the empty pulpal chamber. It is also a very safe procedure. Internal bleaching is more conservative compared with crowns, but sometimes crowns are required not only to improve colour, but also to strengthen the root canal treated tooth.