The fluoride that tends to stain some people's teeth is Stannous Fluoride (usually about 0.4%).

The fluoride that does not seem to stain the teeth is Sodium Fluoride (usually about 1.1%).

I was switched early on due to a severe staining problems. I was also told the Sodium Fluoride is as effective overall, because we apply it so frequently.

The brand of Sodium Fluoride I use is call Neutra Maxx 5000 GEL, but there are a lots of brands that should be equivalent.

I get mine for $12 per a 4.3oz squeeze bottle at the Cancer Center's Prosthodontist office. Also my regular dentist has told me he can get it for me.

I have been using my trays for two years with no cavities - 10min, no food or drink for 1hr, usually at night (but not always).