Which material is used for internal (non-vital) bleaching using the walking bleach technique?

Correct answer: A. Sodium perborate

• A. Correct. Sodium perborate, mixed with water or hydrogen peroxide and sealed into the pulp chamber, is the classic walking bleach agent for a discoloured endodontically treated tooth.
• B. Incorrect. Calcium hydroxide is an intracanal medicament and pulp capping material.
• C. Incorrect. Glass ionomer is a restorative and luting material; it is used here only for the protective cervical barrier placed before bleaching.
• D. Incorrect. Sodium fluoride is a remineralising agent, not a bleaching agent.