Internal bleaching

Internal bleaching procedures are performed on devitalized teeth that have undergone endodontic therapy (a.k.a. "Root Canal") but are discolored due to internal staining of the tooth structure by blood and other fluids that leached in. Unlike external bleaching, which brightens teeth from the outside in, internal bleaching brightens teeth from the inside out. Bleaching the tooth internally involves drilling a hole to the pulp chamber, cleaning, sealing, and filling the root canal with a rubber-like substance, and placing a peroxide gel into the pulp chamber so the gel can work directly inside the tooth on the dentin layer.[citation needed] In this variation of whitening the peroxide is sealed within the tooth over a period of some days and replaced as needed, the so called "walking bleach" technique.