I was on Rifampin for 18 months, and found twice daily, thorough use of my electric toothbrush with an extra soft head kept the discoloration away. I didn't realize it was making such a difference until we went on a two week trip and I just took a regular brush to save space - by the time we got home, I had staining and it took 2 weeks of 3x/day brushing to dislodge it. I use it on on gums and tongue as well as teeth. My dentist has some infectious disease training, and explained that in addition to the staining properties of Rifampin, one of my other meds was causing "stickier" than normal plaque, which made things worse. Perhaps this is the difference in whether patients see staining from Rifampin or they don't?
Sue