Hi, Sometimes plaque deposits, tobacco, excessive coffee intake, pan or gutka, excessive iron in saliva due to high intake of beetal leaf, etc., are various causes of blackening of teeth in general. Sometimes just one teeth alone gets blackened due to trauma or impact long time ago. So discussing your history with doctor is crucial to get rid of the problem permanently. Regards

Cleaning is advised once a year for each and every individual according to oral health recommendation.manual cleaning doesn't clean that effectively even if you do it thrice a day and in regular circular manner.that is part of maintaining your oral health.so get cleaning done every year regularly  and maintain it .Black staining might be a result of various habits.so you have to bring a change in your lifestyle

It again  need professional cleaning after that u have to maintain  it. Avoid smoking, tobacco and do proper brushing.