Are at-home teeth whitening systems effective? Dr. John Joseph: I think they do work. The brands like the Procter and Gamble, the Crest white strip probably work really good. Most of them are pretty good. Do whitening systems harm my teeth in any way? Dr. John Joseph: The problem is that you just can’t overdo it. Some of the things we have in office we cannot control. Unfortunately, some people who do it at home they will of a little bit do it blend just going to overdo it and that creates some problems.