Intrinsic discolouration of teeth which have not originated from developmental defects of the enamel and dentin:

Intrinsic discolorations such as those occurring with amelogenesis imperfecta or dentinogenesis Imperfecta are impossible to eliminate because they originate from developmental defects of the enamel and dentin. Hematological disorders such as erythroblastosis fetalis, thalassemia, and sickle cell anemia might also be caused due to intrinsic discoloration.