Hello there... The blackish discoloration can be due to many reasons like underlying tooth infection, stains etc ... All u can do is visit a nearby dentist and get it diagnosed properly so that it can be treated In a systematic way.
Take care ..!!
Hello, Outer or ‘extrinsic’ discoloration of tooth simply stains on the visible outer surface. The actual underlying color of the tooth is unaffected.
• Coffee; especially black coffee. Coffee stains more than tea does.
• Tea; again, especially when black.
• Red wine.
• Dark cola drinks and some fruit juices (cranberry and grape for example).
• Certain foods such as curries and dark berries.
• Smoking (and chewing) tobacco.
• Chlorhexidine mouthwash; a common example of what stains teeth, but one that you may not be aware of!
• Poor oral hygiene can result in green or black staining.
• Iron supplements and some medications.
Consult a nearest dentist to get it washed or for bleaching.