I went in for my 6 month hygiene appointment, which I was behind on, it was more like 8 months since my last cleaning. The hygienist asked if I had done anything different from my last appointment, the only thing that changed was that I had been using the Z Sonic for the last 6 months. He commented that my teeth have never been so clean, he hardly had anything to clean. We both believe it had to do with the Z Sonic, he also uses it and he really likes it as well.