Those Wechat business are selling fakes to fool people. It takes only three seconds to whiten teeth, which is deceptive. You know, rich people use cold light to whiten or bleach their teeth, and normal teeth are not as white as advertised. That white often has side effects. I want to whiten my teeth. Rinse your mouth after meals every day and brush your teeth for at least three minutes in the morning and evening. I always brush my teeth for five minutes. Even if I use an electric toothbrush now, I'd better wash my teeth once every six months to prevent calculus and periodontal disease. However, I must go to a regular big hospital to have my teeth cleaned. Small workshops are risky because blood can spread many diseases. If you add WeChat, don't be fooled. At best, it will reveal personal privacy. Advertisers often call or send messages to you. The network is virtual. If you have health problems, you should choose a regular medical institution. Good luck!