Dental calculus can be harmful to periodontal tissues, causing alveolar bone resorption, gum inflammation, oral odor and pigmentation affecting aesthetics. 1. Alveolar bone resorption: calculus itself as a mechanical stimulus, long-term retention is prone to cause progressive resorption and destruction of the alveolar bone, resulting in an increase in the gap between the teeth, the roots of the teeth are exposed, appearing black triangle. 2. Inflammation of gums: Bacteria or toxins attached to the surface of dental calculus can cause inflammation of the soft tissue of the gums, swelling and bleeding. 3. Oral odor: the microporous structure on the surface of dental calculus can easily adsorb food debris and soft tartar, and under the action of bacteria, it will emit a rotten and necrotic odor, and mix with the oozing of blood, resulting in oral odor. 4. Pigmentation: the rough surface of dental calculus will adsorb exogenous pigment, so that the color becomes yellowish brown or dark black, affecting aesthetics. Usually should pay attention to oral hygiene, morning and evening brushing, regular oral examination; when found in the mouth with calculus formation should be timely to the regular hospital for cleaning to avoid the development of the disease.