> Bleaching means whitening the teeth with special oxidizing agents such as hydrogen peroxide. Oxidizing agents such as tooth enamel penetrate the crystalline structure of the rod and oxidize the pigments deposited between the enamel pyramids. Over time, the oxidizing agents penetrate into the dentin and become the color of the dentin, which is placed on the lower part of the tooth, which also becomes lighter. In recent years, many whitening products in the pharmacy and supermarkets... they are thick, less than ten percent, and due to the lack of supervision by dentists, their use is not recommended.. **types of bleaching** 1- One of the bleaching methods is home bleaching... the dentist prepares a special mold for the patient and delivers it to the patient along with a special bleaching gel with a very low concentration for use at home... 3- But the most reliable and effective bleaching method is bleaching in the office (office bleaching) using a special bleaching device with a dental care device with a special dental care device... office ** First, the dentist covers all the gums around the front teeth to protect them with a special gum protection gel... the patient's lip is also pushed aside and completely protected by a special mouth opener... then a special bleaching gel, which is a 37% hydrogen peroxide gel, is carefully placed on the outer surfaces of the front teeth, and then a special gel device with high bleaching properties is placed on the teeth... it produces radiation and a blue color... and this operation is done several times carefully It needs to be repeated.... This radiation causes the bleaching gel to be strongly activated and its effect is fast, so that the bleaching treatment is successfully completed in one session of about one hour.... **Bleaching effect rate** Bleaching makes teeth between 2-3-4 degrees whiter and brighter... Of course, the amount of teeth bleaching varies depending on the type of teeth and the type of tooth discoloration in different people, and it has a great effect on some color changes.. You should not think that once you whiten your teeth, you will no longer need to whiten them... Teeth whitening does not have permanent effects, but teeth usually stay white for several years... less...