The most difficult part is setting the tooth correctly, but it stayed all day for me, no problem.  I wish they would make the liquid solution resealable. We get powder capsules for multiple applications, and after one use I had some of the solution left over. It ended up turning over and melting the plastic case where it spilled.  The teeth can't be beat though. They are very realistic looking; they look great in pictures and on tv (I was on G4 with these in HD).