This is a process where the bleaching product is placed within the tooth.
This is only done on teeth which have been root treated, where the blood vessels and nerves have been replaced.
The treatment involves drilling a hole into each tooth, putting the product in, and then sealing it. The procedure should be pain free due to the lack of nerves within the teeth.
Generally a week later the filling and bleach are removed then the teeth are filled with colored filling. This technique may be combined with others to give the required shade.