How often should adults come for their dental cleanings?

Adults should come for their cleanings at least three times a year. With adults, we are concerned about controlling gum disease. The bacteria that we associate with destructive gum disease re-forms about three months after a cleaning. The cleaning disrupts bacterial colonies, allowing us to control gum disease. I did not say cure. Gum disease is similar to diabetes in that it is controllable but not curable. We can decrease the number of the bacteria, the amount of bleeding, and the loss of bone, but the mouth will always contain bacteria and hence the chance for gum disease to flare up.