Yellow teeth not only affect a person’s outward appearance, but also affect the health of the organism. Yellow teeth are usually caused by diet, hygiene habits, medications and water quality, as well as ageing yellow teeth. 1, food: many cuisines can lead to yellowing of teeth when consumed for a long time. Foods that tend to cause yellowing of teeth are red wine, cola, tea, coffee, etc.. Because the pigment of these foods are easy to adhere to the surface of the teeth, so that the teeth gradually become yellow and black, if the pigment is not removed in a timely manner, long-term down substances will be from the surface of the teeth deep into the teeth and the formation of internal substances, it is difficult to remove. 2, drugs and water quality: If in the process of tooth development long-term use of tetracycline and other drugs, it is easy to lead to yellowing of teeth. Water quality will also affect the color of teeth, for example, some areas with high fluoride content in the water, too much drinking will lead to yellowing of teeth. 3, hygiene habits: If you do not pay attention to oral care in daily life, do not develop the habit of brushing your teeth in the morning and evening, rinse your mouth after meals, food residues, dirt is easy to accumulate on the surface of the teeth, long-term teeth will become yellow. 4, ageing yellow teeth: with the growth of the body, teeth will also be aging, the color will turn from bright white to dull yellow. Usually the yellowing of the body’s teeth is due to the above-mentioned reasons, it is recommended to choose according to their own needs.