Dear Doctor,

I never drink coffee and didn't smoke but my teeth naturally got black stain. I go to dentist almost every 6 months to wash my mouth and try different dentist but the black stain will come back again around in 3 months time. All doctor also do not know why how come I got black stain. Some say it is cause by my saliva.

May I know do you have long term solution for this?

Thanks.