One year out from treatment, no tooth problems yet. I have noticed yellowing of the teeth a little, but nothing too bad. I use my trays when I go to bed, don't take them out until I wake-up for water. I asked my dentist if there was a limit to how long they were safe to wear, and he said no problem. They seem to help me with dry mouth when I sleep. I keep my mouth closed more and there is probably a slight hydration benefit. Normally I wake every two hours with a dry mouth, this way I can get 3-5 hours. I don't remember the brand but it has never burned. I do over-flow the trays and then spit out the excess right before I get into bed. Last dentist visit they said I had the cleanest teeth of the day!