Hello sir!
Teeth stains or discoloration are the surface stains due to actual changes in your tooth material. It can be extrinsic or intrinsic.
Extrinsic stains are the stains on the surface of the tooth. It can be due to more consumption of coffee, tea, tobacco, etc. It responds well to regular cleaning and brushing.
Intrinsic stains are the stains below the surface of the tooth. It can be due to excessive fluoride, tetracycline. These may require bleaching using professional and at home chemical teeth whitening procedures. For permanent solutions you can go for esthetic correction- veneers.
The cause of your stains should be ruled out first and fluoride being the cause should be confirmed.
Next Steps
Kindly visit the dentist.