My friend, now that science is so developed, tooth washing is not the best whitening method. If money is not a problem, you can do cold light tooth whitening at a price ranging from 6- 1200. This is not effective. My friend's mother is really good, not as white as it was washed, and it may be unsafe ... Now all major plastic surgery hospitals in Shenyang have cold light tooth whitening technology (such as Xinglin Plastic Surgery Hospital) and so on, but which one do you choose?