“White teeth” is the basic standard of modern health and beauty, and the new international standard is to show 8 perfect teeth when smiling. However, due to the water quality and other reasons, some people’s teeth are getting more and more yellow, and it is very embarrassing to smile, which greatly reduces the perfect image in other people’s eyes. A mouthful of “yellow teeth” can only make people smile without showing their teeth or no longer smile, and even affect the mental health of serious cases. Clinically, tooth coloring is mainly exogenous coloring and endogenous coloring. Exogenous staining refers to foreign pigmentation on the surface of the tooth crown, such as tea, coffee, smoking, soy sauce, betel nut, intraoral bacterial staining. Endogenous staining refers to tooth color changes caused by internal or systemic factors, which are formed during tooth development, such as tetracycline, dental fluorosis, ageing dentin staining, hereditary yellow teeth, and dead pulp teeth. For these different types of tooth coloring, you can choose different “medical whitening” methods. There are essentially only two methods of teeth whitening, one is chemical bleaching and the other is masking. The preparation for medical whitening is the restoration of the original color of the teeth through scaling, cleaning and sandblasting. At-home tray whitening involves making a mold of your teeth very simply based on the shape of your teeth. The whitening agent is placed in the mold every night, and the mold is worn for 30 minutes before being removed, and used continuously for about 3 weeks. The whitening effect lasts for about 1 year. Advantages: Can be done at home, have some teeth whitening effect. Disadvantages: for tetracycline and fluoride teeth and other endogenous staining of the teeth is little effect, because the teeth are black or yellow, even if the bleaching at the time, a few months later often return to the original color; for sensitive teeth are prone to cause discomfort; maintenance time is not long. Applicable people: for exogenous mildly pigmented teeth. Cold light, dazzling light, nano blue light whitening, etc., all refer to the use of “whitening drugs + blue light irradiation” way of whitening, more than 30% of the whitening effect of home braces, the operation process takes only 30 minutes, whitening effect can be maintained for more than 2 years. Advantages: short clinical operation time, whitening effect is better. Disadvantages: for heavy pigmented teeth, especially medium and heavy dental fluorosis, tetracycline teeth effect is general, for sensitive teeth is easy to cause discomfort, sometimes before and after the treatment need to take oral painkillers; maintenance time is general. Applicable people: suitable for mild to moderate pigmentation Laser whitening, is currently the most safe, effective and fast teeth whitening method, refers to the use of “whitening drugs + near infrared laser irradiation” way to achieve deep whitening. The laser can selectively act on the pigment particles deposited on the teeth, and the wavelength of the near infrared can penetrate the enamel and reach the dentin layer, which can whiten more than 50% of the heavily pigmented teeth than the cold light, and the operation process only takes 30 minutes, and the whitening effect can be maintained for more than 5 years. At the same time, the appropriate dose of laser irradiation can close the dentin tubules, reduce the permeability of dentin, reduce dentin sensitivity symptoms occurring in the process of teeth bleaching, and can be used for the treatment of dentin allergy, so as to achieve safe and long-lasting whitening effect. Advantages: short clinical operation time, deep whitening, without any side effects, without harming the dental tissues, without harming the dental nerve, long maintenance time, wide range of indications. Disadvantages: For severe dental fluorosis, tetracycline teeth, etc. need more than 2 times of treatment. Applicable people: suitable for light to medium and heavy pigmented teeth; especially medium and heavy fluorosis, tetracycline teeth, with mild enamel underdevelopment of the preferred whitening method without damage to the teeth. This kind of enamel underdevelopment, can be in the whitening treatment with penetrating resin repair defective enamel, the effect will be better. However, the patient herself feels that this is already very good, and she feels that she can finally laugh happily without having to smile without showing her teeth. Laser whitening contraindications 1, dead pulp teeth bleaching treatment fades quickly, not suitable for laser light whitening; dead pulp teeth suitable for “intracrown bleaching + full crown (porcelain or all-ceramic crown) repair”; 2, whitening agent on the filling body and porcelain crowns do not have any effect, so such patients do not belong to the laser whitening indications of the population; but the tooth color is not satisfied with its own strong demand for whitening However, patients who are not satisfied with the color of their teeth and strongly request whitening can have their teeth restored according to the color of their teeth after laser whitening treatment. 3.Pregnant women are not suitable for laser whitening due to nervousness during the treatment and can wait for the whitening treatment to be done after delivery. After laser whitening (normal pulp teeth whitening effect is the best) Precautions before and after laser whitening 1, 1 week before the treatment needs to be scaling, sandblasting and polishing, in order to clean the surface of the teeth, so as not to affect the efficacy of laser whitening; 2, after the treatment of the teeth need to be coated with a protective agent, avoiding excessively cold or too hot food for 24 hours; 3, within 2 weeks to avoid eating food and drinks with color, try to consume white and colorless food, avoiding Use colored strips of toothpaste and colored mouthwash, avoid smoking; 3, 2 weeks after the follow-up appointment on time. Veneer whitening is to stick a layer of veneer on the surface of the teeth, which plays a role in hiding the discolored teeth. Nowadays, the popular veneers can be categorized into resin veneers and porcelain veneers. Resin veneers, which are applied to the surface of the teeth after some of the teeth have been worn away, can keep the shape of the teeth the same as the original. Porcelain veneers, on the other hand, bring together the advantages of porcelain and resin veneers, both beautiful and realistic, which is by the latest computerized ultra-precision sculpture cutting equipment and technology, and tooth enamel similar to the “whitening veneers” cut into a completely close to the teeth of the shape of the veneer with a special active interface material will be closely inlaid in the teeth, and thus the price of more expensive! Porcelain veneers are more expensive because they last longer than resin veneers, theoretically up to ten years. Advantages: Compared with resin veneers, porcelain veneers have good color and shape, almost indistinguishable from real teeth, and its production process is very delicate, which is the main method of treating dental defects and missing teeth. Disadvantages: damage to the teeth, can not bite hard objects, easy to fall off, easy to discolor, easy to cause swelling of the gums, bleeding and inflammation and other sequelae; resin veneers have a certain thickness, which will make the mouth and lips slightly convex, the appearance of the aesthetics of a certain impact, and the price is not expensive. Applicable people: dental defects of fluorosis, tetracycline, drug discoloration and hereditary yellow teeth.