Stone also known as dental calculus, it is by the food residues, necrosis shedding of oral epithelial cells and saliva in the minerals calcium after attached to the tooth surface and form. Calculus at the surface of teeth and neck, above the gingival margin on the calculus, the margin for the following sub gingival calculus. Sub gingival calculus on a yellow or white, because smoking can also become dark. Calculus easily deposited in the salivary duct openings relative tooth surface. Following the Shemian front teeth and the cheek teeth on the surface. Calculus can be deposited on the loss of functional chewing surface of teeth, such as the wrong habit of chewing teeth and the unilateral non-functional teeth surface of the teeth. The real teeth stone formation mechanism is not clear. However, it is formed by the saliva composition, dietary habits and oral hygiene habits and other factors. Calculus is a plaque at the best location, its easy absorption calculus of bacteria or toxins. These bacteria and toxins and stimulate the local calculus, the gingival tissue inflammation. Sub gingival calculus in the form of periodontal pocket, as calculus and fixtures to stimulate the toxin, so that periodontal pocket wall in ulcers, and difficult healing epithelial wall, causing bleeding gums and periodontal infection increase. So calculus is periodontal inflammation in the development of important factors.