There are two main ways for patients with yellow teeth to get whiter teeth: first, go to the hospital for ultrasonic scaling and tooth polishing; second, go to the hospital for cold light whitening. Ultrasonic scaling and tooth polishing is suitable for teeth yellowing due to exogenous staining, such as smoking and drinking tea, coffee people will have yellow-brown pigmentation on the tooth surface, so that the teeth become yellow-brown and look unattractive, then you need to go to the hospital to do ultrasonic scaling, which is usually called scaling, the use of ultrasonic scaling machine high-frequency oscillation and water spray rinse to make the pigmentation of the tooth surface from the tooth surface, to restore the original face of the teeth. The ultrasonic scaler’s high-frequency oscillation and water mist rinse will make the pigment on the teeth come out of the surface and restore the original face of the teeth, thus achieving a rapid whitening effect. Cold light whitening technology is mainly applied to the yellowing of teeth caused by endogenous tooth coloring, mostly seen in patients who are born with yellow teeth or tetracycline teeth or fluorosis teeth. The whitening agent can be introduced into the teeth under the light source of cold light to neutralize the pigment inside the teeth and achieve the rapid whitening effect.