1, external bleaching method: such as the drug whitening of teeth Suitable for the crowd: suitable for a wide range of people, exogenous staining, namely smoking, age yellow teeth, drinking coffee, colored drinks, etc. caused by the yellowing of teeth. Pain index: almost no pain, slight soreness of teeth during individual medication. Advantages: simple, easy to operate, no damage to the teeth. Disadvantages: more or less rebound, tetracycline teeth, fluorosis, etc. with other treatments, the effect varies from person to person. 2, internal bleaching method: suitable for people: pulp nerve necrosis of the teeth, especially for single teeth. Pain index: painless. Advantages: no damage to the teeth. Disadvantages: The effect is general, and this method was mostly used in the past. 3. Resin veneers: suitable for the crowd: most of the teeth yellow, do not want to wear teeth, do not accept porcelain teeth, hope to see the same day to solve the problem, aesthetic effect requirements of high patients. Pain index: most almost painless. Advantages: quick results, no damage to the teeth, repeatable, good results, easy to accept the price. Disadvantages: avoid biting hard objects with the edges of veneers. 4. Porcelain teeth: Suitable for the crowd: multiple or individual teeth black and yellow, the financial ability allows, aesthetic effect requires high patients. Pain index: the overall grinding of the teeth will be small, to be local anesthesia of the teeth. Advantages: good results, stable nature, more durable. Disadvantages: grinding the teeth as a whole a little more.