The prognosis of bleaching of a discoloured tooth is good in all the given conditions except:
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.
Discolouration due to products of pulp decomposition.
Discolouration due to food debris.
Discolouration due to metallic salts.
Discolouration due to chromogenic bacteria.