I have been performing teeth whitening since 1989. In general it is very safe. The key to safety with teeth whitening, as well as getting the best results is to vista with your cosmetic dentist.Everyone gets different results from teeth whitening. You need a good exam first to see what problems are you trying to correct. Also- some people can get amazing "TV-results" type whitening, where they get very white. But not everyone can get that. You need to have clear expectations about how white it will get.In addition, there are different types of whitening. After performing teeth whitening for over twenty years, the key is to match the type of whitening (for example, home trays, Zoom in office or Deep Bleaching) to you. With every style you as the patient have a role in complying to get good results. There is part that the cosmetic dentist has to plan right and do right for you, but there is part that only you have to do. A great cosmetic dentistry office can help you sort out these issues and help you find the fastest, safest, most personalized way to get your teeth the whitest. Best wishes for success!