I tried the sensodyne iso-active foaming gel. I can honestly say that I tried to use it a few times before I couldn't do it anymore. I really had a hard time to get the gel to come out the first time I used it. But once you get it started its no problem after that.  It does foam up as you are using it. It seems to fill your mouth up. I really had a hard time getting past the taste. I just did not like the flavor or the after taste that lingered.