Salt brushing can only play the role of rubbing agent, can partially remove the soft scale and pigment on the tooth surface, only the effect of cleaning and can not make the teeth white, and it is not recommended to brush teeth with salt for a long time, because excessive salt intake will have adverse health effects, such as high salt triggers high blood pressure. There are two main reasons for the dark yellow teeth: first, the exogenous staining of the tooth surface, and second, the endogenous coloring of the teeth, long-term smoking, tea, coffee, and unclean brushing people will have tartar and pigmentation on the tooth surface, causing exogenous coloring, you need to go to the hospital for ultrasonic cleaning, sandblasting and polishing, to remove the tartar and pigmentation, restore the original face of the teeth, to achieve the effect of whitening teeth; teeth Endogenous coloring is mainly ageing yellowing, tetracycline and dead pulp teeth, etc. To make these teeth white, you need to go to the hospital for cold light whitening.