Bismuth oxide is often used in dental materials to make them more opaque to x-rays than the surrounding tooth structure. In particular, bismuth oxide has been used in Mineral trioxide aggregate (MTA) from 10 to 20% by weight with tricalcium silicate powder. MTA is used for dental treatments such as: Apicoectomy, Apexification, Pulp capping, Pulpotomies, Pulp regeneration, Internal Repair of Iatrogenic Perforations, Repair of Resorption Perforations, root canal sealing and obturation. MTA sets into a hard filling material when mixed with water. Some resin-based materials also include MTA with bismuth oxide. Problems have arisen with bismuth oxide because it is not inert. That is, it slows the setting of MTA, and over time can discolor [6] by exposure to light or reaction with other materials that may have been used in the tooth treatment, such as chlorhexidine or sodium hypochlorite