Stern warnings have been issued regarding "home remedy" teeth whitening treatments, by Dr. Hans Malmstrom, a dental expert from University of Rochester. The use of baking soda and lemon juice may damage the teeth, as lemon is highly acidic and will erode tooth enamel. Also, he warns agains using hydrogen peroxide as a tooth whitener since it may damage the teeth if used in high concentrations.

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http://www.universityherald.com/articles/33986/20160711/teeth-whitening-at-home-the-dangers-of-teeth-whitening-kits-as-told-by-dental-experts.htm