Tooth bleaching as a non-invasive cosmetic technology has been gradually accepted by people. Hydrogen peroxide and carbamide peroxide are the two most widely used bleaching agents in clinical practice, and their bleaching mechanism is realized by the redox effect of HP, which is a lively oxidizing agent that decomposes during the redox reaction, releasing new ecological oxygen and forming superoxide HO2ˉ, which can freely penetrate the enamel and dentin and combine with the chromophore in the dentin tubules to decompose it into small molecules. CP decomposes in aqueous solution to form HP and urea. 10% of CP contains about 3.5% of HP, therefore, the bleaching mechanism of CP is similar to that of HP. However, CP has better stability than HP, and the urea in its decomposition product can raise the pH value in the oral cavity, thus it has anti-caries effect. We mainly carry out two kinds of whitening techniques: 1. In-office bleaching is carried out by professional dentists, and a gel containing 30%-35% high concentration of HP is used as bleaching agent. In order to accelerate the bleaching process and enhance the effect, the treatment is often supplemented with various means, including heating and warming, light or laser, etc. 2.Nighttime braces bleaching technology: using gel containing 10% CP as bleaching agent, the physician first makes individual trays for the patient, and the patient goes home and wears the trays containing the solution for treatment as prescribed by the doctor.