The black stains on your teeth are caused by pigments from the pan masala adhering to plaque and tartar. Standard or medicated toothpastes alone cannot completely remove these deep stains. I highly recommend visiting a dentist for a professional cleaning called scaling and polishing, which safely removes the buildup. For daily maintenance, you can use a toothpaste containing mild abrasives like hydrated silica or whitening agents like carbamide peroxide. Most importantly, quitting pan masala is the best way to prevent the stains from returning and to protect your oral health. Please don't worry, as these stains are highly treatable with professional care.