No one has really talked about how often to use the trays.

My dentist (oncology patient specialist) has advised they need to be used twice per day. This is consistent with other information I have found on the internet that suggests that the flouride is more effective if used twice per day.

Anyway, that nothwithstanding, I usually just leave mine in for 1/2 hour, although I was advised I only need to keep them in for 5 minutes then leave the flouride alone (no water) for the next 25 minutes.

Best wishes,

Chris