Tooth scaling, especially for periodontitis patients, is blood-foaming, and blood is a high-quality carrier of infectious diseases. So dental scaling for the disinfection of instruments is more demanding, non-disposable instruments must be sterilized by high temperature autoclaving, to ensure that one person a change. Or they are all disposable, but some things are too expensive or too brown. The current big hospitals in this regard is still more reassuring, because this aspect of the big hospitals do not calculate the cost, or this cost and the income of doctors and nurses are not linked, so you know. Some good clinics also do a good job, some better than hospitals, because there are fewer patients, these preparations are done more carefully. And there are really people who are constantly checking these aspects. But if you say the opposite example, there are, at present the most well-known is that the American dentist, at present found in his infected patients have dozens of people, hepatitis AIDS have. Of course, these unlucky patients may not have had their teeth cleaned at his place. As for the damage to the teeth, it's a philosophical question. Guns don't kill people, people kill people. Tools and techniques are innocent. So it is also still the same, scaling teeth to find a reliable place, some places in the country, such as the doctor's qualifications are still problematic. Is it necessary to clean the teeth, I do not want to talk about science, cliché. Let's talk about money, scaling is recognized in the dental industry does not earn money, the same time and physical strength to do something else than scaling more money, so the doctor suggests that you go to scaling is not to pit your money. In addition, the U.S. side of the insurance, no matter how bad, will be reimbursed twice a year cleaning, a treatment measure if the insurance company are highly recommended, that is to say that this really can bring health benefits.