I was told I would need to use my flouride trays for 10 minutes a day (before bed recommended). Almost every day for a year I used them. The occasional time I did not use them, I brushed my teeth with the gel before going to bed (it was quicker). My teeth are in great shape and I lost only 1/3 of my saliva. I bet it's even less now. The oral surgeon who made the recommendation recently told me that 3 times a week was fine for the trays. He said they really are not sure how often they should be used, and I would do no harm by using them more. He tells people every night and hopes for three. Now I use them 3 times and generally brush with flouride on the other nights. I'm guessing if my mouth was dryer or my teeth in worse shape, his recommendation might have been different.