People ask me all the time (I know, I sound like George Foreman), "When can I eat after my cleaning?" The answer is: "Whenever you want!"
We tend to make the assumption that the bacteria that form what is called plaque and tartar and cause periodontal disease live on our diet. But they do not. The bacteria that are the cause of tooth decay are different from the bacteria that cause periodontal disease. The bacteria that are responsible for periodontal disease and bone loss around our teeth are not interested in our dietary choices. In contrast, the bacteria that cause tooth decay definitely do depend on our diet.
The bacteria that cause tooth decay dine on and ferment the sticky carbohydrates that get stuck on and in between our teeth. As they ferment the sugars in these foods, the acids produced dissolve away the hard enamel that covers our teeth. This is called tooth decay.
Decay is even more of a problem for people who have recession of the gum. Recession exposes the roots of the teeth, which do not have the hard enamel covering, so they are even more susceptible to decay. Treating decay in the roots is problematic for a number of reasons, access being one of them.
The bacteria that cause tooth decay are different from the bacteria that cause inflamed, bleeding gums, and ultimately bone loss around the teeth. These periodontal pathogens do not live on our food. Their source of nutrients is found in the saliva that bathes our teeth. So even if you fast, the saliva is always present, and thus these bacteria are always well-nourished.
That is one reason why routine dental maintenance is so essential. They keep these bacteria from causing periodontal problems and eventually tooth loss.