Hello & welcome,
Eating the pan parag for so long period of 5 yrs, makes the teeth to stain which are very hard to remove with the tooth brush only.
This is because, with time & with continued use of Pan Parag these stains extend to enamel or the crosses the outer layer of the teeth & thereby is very difficult to clean with tooth brush only because brushes are meant for surface cleaning & not to deal with such stains.
Visit your dentist
& get your teeth cleaned with ultra sonic scaler to remove such stains. You may require to undergo scaling in two or three sittings if dentist thinks single sitting scaling won't suffice.
Remember, you have to stop the habit after scaling because scaling makes the teeth surface a little rough thereby attracting more stains on the surface if the habit continues.
Most important is eating Pan Parag for prolonged period may cause cancer which is of more concern than staining.
Take care to maintain your oral hygiene
after scaling by proper use of brush & even mouth wash for short period as staining may lead to accumulation of plaque
& thereby causing gingival & periodontal diseases.