How many times you need to do cold light teeth whitening depends on the cause of the staining of the patient’s teeth. If the patient’s teeth are only discolored due to exogenous staining such as smoking or drinking tea, it usually takes maybe 1-2 times to achieve a very good bleaching effect. Whereas, patients whose teeth are endogenously discolored due to tetracycline or patients whose teeth are endogenously discolored due to pulp necrosis will need to do maybe 3, 4, or even more bleaching sessions. Therefore, the final choice of how many times to do is made after the doctor’s diagnosis and examination. After the treatment of cold light whitener in order to achieve better results, first of all, patients should perform basic oral hygiene maintenance, brush for 3-5 minutes each time, rinse through professional mouthwash, and then review regularly in order to achieve better results. Also be sure to pay attention to rinse and brush your teeth as much as possible after eating foods that are easily colored in order to achieve better results and avoid relapse.