1, the mechanism of dental bleaching The main ingredient of the drug used in dental bleaching is hydrogen peroxide or peroxide, which decomposes in the presence of metal, light and heat to produce OH or HOO, which contain asymmetric electrons and are very unstable and easily combined with other atoms to form molecules. They cut off the unsaturated divalent bonds (coloring molecule lock) in the organic ingredients within the colored teeth and combine with them, and after oxidation and decomposition, form low molecular colorless substances, and further reaction can form carbon dioxide and water. 2, the bleaching efficacy of the factors affecting the final bleaching effect of the main ingredients is unstable free radicals, which directly affects the number of bleaching efficacy. It has many influencing factors, summarized in the following aspects: first, the pH of the tooth surface or even in the mouth, second, the role of light, and third, the free radicals can reach the location of the colored material is also very necessary. 3, whether bleaching agent is harmful to human body Research results found that: bleaching agent will not cause decalcification of teeth, nor will it cause damage to dental pulp, on the contrary, because some peroxide such as hydrogen peroxide can kill some bacteria, long time use of bleaching agent can reduce lactic acid bacteria and streptococcus deformans in saliva, which can prevent the occurrence of caries, and make periodontal pockets shallow, and improve oral hygiene.