Advise deep cleaning, polishing, whitening (bleaching) procedures, artificial enamel filling or capping. Advance procedures can be done with laser. Use Snowdent tooth paste for whitening until then. Apply SNOWDENT paste on the teeth. Wait for 10 to 15 min. Then brush your teeth with the same paste. Applying it overnight for better results. Cause of discoloration ? Smoking, coffee, tea, drugs, aging, staining food (wine, blueberry, etc) genetics.