The process of cleaning the most severe dental calculus consists of steps such as preoperative preparation, scaling, examination and polishing. 1. Pre-operative preparation: For severe intraoral calculus, it is recommended to rinse the mouth with a low concentration of hydrogen peroxide or chlorhexidine solution to reduce aerosol contamination, etc. before the procedure. 2. Cleaning: In a certain order, the ultrasonic equipment is used to shake down the large pieces of adherent calculus on the surface of each tooth at a time, and then clean the small, tightly bonded tartar. 3. Examination: The patient is allowed to rinse his/her mouth and is examined to prevent any omissions. 4. Polishing: The surface of the teeth will be polished by special polishing paste, and for some patients with high pigmentation, sandblasting can be exceptionally performed. There may be sensitivity symptoms in the short term after cleaning, which can be relieved within 2 weeks in general. It is recommended to clean teeth regularly every 6~12 months. If there is any discomfort, timely consultation is recommended.