We didn't do it, and my 12 year old dd has never had a cavity. However, we are not a cavity prone family. My hubby has never had a cavity and I've only had one. I don't know if this is a hereditary issue, but it kind of looks like it is in our case. I'm so glad we didn't spend our money on this - we got the hard sell too, and I felt bad at the time for turning it down.