There are several methods to whiten teeth: first, cold light whitening, cold light whitening is mainly for endogenous staining of teeth resulting in yellow and black teeth, such as tetracycline teeth, fluorosis and dead pulp teeth. The technology is to introduce the whitening agent into the dentin under a certain cold light source to neutralize the pigment in the dentin, so as to achieve the whitening effect; second, scaling and surface polishing, the treatment is mainly for exogenous staining of teeth, such as people who have the habit of smoking and drinking strong tea, the black and brown pigment and tartar are deposited on the teeth, scaling and surface polishing can completely remove the pigment and tartar, so as to achieve Third, the production of porcelain veneers or all-porcelain crowns, mainly for teeth with bad color, but also accompanied by abnormal tooth morphology, through the doctor for dental preparation, the production of models, to the processing plant processing out of porcelain veneers or all-porcelain crowns, and then the clinician will veneers and crowns pasted to the teeth, so as to improve the color and shape of the effect.