I never found that the over the counter products worked. My husband also tried the crest strips and they didn't work on him. I had my dentist make custom trays and I slept with the trays--your teeth get very sensitive, but it goes away when you stop bleaching and the nice thing aout having the trays is that you can do touchups whenever they start getting stained again (you just buy the bleach), which they will from coffee, tea, certain types of foods, etc. I touch them up a few times a year and am very happy and get lots of compliments on my teeth, which seems sort of stupid, but people seem to need to comment on them.