Gingivitis is an inflammatory reaction of the tissues surrounding the teeth, clinically manifested as gingivitis or periodontitis. Symptoms include bleeding while eating or brushing teeth. Periodontitis needs to be treated early and can be managed by dental cleaning to remove local irritative factors. Dental calculus is divided into supragingival calculus and subgingival calculus. Supragingival calculus can be removed by dental cleaning, while subgingival calculus requires subgingival scaling. Early treatment of periodontitis can preserve the teeth; if not treated promptly, periodontitis may further lead to the resorption of the alveolar bone, requiring tooth extraction in severe cases.