Yellow teeth are caused by endogenous or exogenous staining, and can only be effectively whitened by dental bleaching or ultrasonic cleaning.
1. Endogenous staining of teeth (such as fluorosis or tetracycline) is caused by external influences during the development of teeth, resulting in staining of hard tissues inside the teeth and yellow or brown color; the doctor must use professional bleaching agents such as urea peroxide to bleach the teeth internally, in order to effectively remove pigmentation inside the teeth, to achieve whitening results.
2. Exogenous staining of teeth mainly refers to the tartar or calculus on the surface of teeth, which can also cause yellowing of teeth; must seek medical treatment for periodontal scaling, such as ultrasonic scaling, to remove the tartar or calculus on the surface of the teeth and other attachments to the teeth can be quickly whitened.