I was given a 1.1% gel of sodium flouride gel made by Sypress. It is supposed to stay on for 1 to 2 minutes max, then spit it out but don't rinse. I have not had any problems with this but I'm only just finishing the first week of treatment. I have not heard about the Oral B foam, which woulds excellent. But this particular gel with the shorter time period has worked well for me.
David R.