The appearance of dental calculus, mainly is the human saliva contains minerals, and acidic secretions in the mouth to produce a reaction, human physiological needs determine the human must secrete a lot of saliva every day, due to saliva secretion, the minerals in the saliva has with the oral acidic liquid long-term continuous reaction conditions, the result of this long-term reaction, the production of acidic compounds, become dental “stone “These reactive substances are easily attached to the back of the teeth, or the gums and teeth bonding and other brushes. Calculus is mostly deposited in the neck of the teeth, if not removed, long-term stimulation of the gum tissue, will cause edema, congestion, gum edge erosion of the gum tissue, and the gums are prone to bleeding and a series of symptoms of gingivitis. Some people wake up early in the morning with a mouth full of blood, 99% of which is caused by dental calculus. If it continues to develop, it can cause periodontal tissues to overflow with pus, bad breath, destruction and resorption of alveolar bone and even loosening of teeth, especially in children, who, if they do not pay attention to prevent the formation of tartar, will easily become a member of the periodontal disease patients in adulthood. Therefore, the presence of dental calculus is harmful.