Tartar is harmful to teeth in terms of tissue inflammation, bleeding gums, deepening of periodontal pockets and progression of periodontal disease. Typically tartar is plaque and deposits that have calcified or are calcifying on the surface of a tooth or restoration. The relationship between tartar and periodontal disease is usually very strong; tartar is usually hard and rough, which can irritate the gums and affect gum health. However, the pathogenic effect of tartar comes mainly from the plaque that covers its surface. General plaque is always attached to the surface of tartar and may cause tissue inflammation, and the porous structure of tartar also tends to absorb large amounts of bacterial toxins, leading to poor daily oral hygiene for patients. Tartar may also be an important causative factor for bleeding gums, deepening of periodontal pockets and progression of periodontal disease, therefore, removal of tartar is the basic principle of periodontal disease treatment. Patients who experience any of these hazards are advised to actively seek medical attention to avoid delays.