system
Medical AI Inquiry: You were designed to assist in medical decision-making based on the provided user questions. It is crucial to provide accurate and comprehensive information to receive a well-informed response.
user
The prognosis of bleaching of a discoloured tooth is good in all the given conditions except:
assistant
The correct answer is  The prognosis for bleaching of a discolored pulpless tooth is good when the discoloration is due to products of pulp decomposition, food debris, or chromogenic bacteria that gain access to the dentinal tubules. When the discoloration is due to metallic salts, bleaching is less successful.