I used about half of my box at the end of fall semester and then saved the rest to use later. My teeth were noticeably whiter and have stayed that white up until now when I have started using them again because I have a less hectic schedule. When ever I put them on I always end up having to wipe some of the gel off of my tongue since it tastes nasty. And as soon as I take them off I rinse my mouth out to get the leftover gel out. I definitely reccomend them, they made a big difference, and now I have really white teeth
