Get a normal cleaning .. it will become white . They Will charge u 800 - 1500

These can be simple stains which will go away with scaling or they can be fluorosis which can also be treated.

it may be due to fluorosis sir or it may be due to simple plaque deposits in the teeth. first go and check a dentist he will examine first do a professional cleaning if its due plaque deposit it will vanish off if its due to flourosis means we need some specialised treatment like veneering and all . no need to worry. thank you

These are stains on teeth, and can be managed by scaling and polishing procedure. Of course clinical checkup would exactly diagnose the issue. Also, It seems your teeth are little mal aligned, means not in proper arch. Because of this one can not do proper brushing. This is a common problem. Everyone has to get teeth cleaned once in a year or so to maintain oral hygiene.