All I can say is this - last year I had a fucking terrible tooth ache. Absolutely horrendous pain. Only thing that helped was a high fluoride paste application. Now it's fine and I never lost the tooth. But normally I use a small amount of paste and only brush for a minute. The brushing is the part that ruins your enamel. Best to just let the fluoride sit in your mouth for a couple of minutes then rinse extremely thoroughly so you never swallow any.