There is a constant war going on between us and the bacteria that live in and on our body. If our defenses have the upper hand we don't get sick; when the germs overwhelm our defenses we get sick. Most medical and dental treatments for these infections are designed to improve our defenses or kill enough of the germs to give our immune system the advantage.

The gum pocket is an interesting place. Bacteria that live there generally are not actually inside our body. They are on the tooth and the inside surface of the gum pocket. That's why drugs from the blood stream are ineffective. Until recently, the all treatments involved mechanically removing the germs from the pocket.

 Bacteria are microscopically tiny. Using fine dental instrument to remove them is a laborious and difficult task. The instruments are too big. Smaller instruments would break because of the force necessary to remove the tartar in which the bacteria are embedded. The bacteria are capable of rapid multiplication. Missing one tooth brushing and flossing session in 24 hours is enough to start the formation of tartar

The gum pocket can be deep and difficult to reach because of the shape or alignment of the teeth. Pockets that are 0-3 mm are relatively easy to clean and most dentists have good results. These pockets are healthy. When gum disease deepens these pockets it becomes progressively more difficult to clean them. Pockets 4-6 mm deep can be cleaned by some, not all skilled operators most of the time. Pockets 7 mm or deeper can not be fully cleaned. Experiments that let skilled operators spend up to 55 minutes per tooth cleaning showed tartar on over 50 percent of root surfaces. Even when a surgical approach was used to expose the roots for easier cleaning, 1/3 of the roots were left with residual tartar. It is fortunate that complete remove is not necessary. If it were, gum disease would be impossible to treat.

Professional cleanings remove most of the bacteria the average patient can't reach. Because the bacteria constantly multiply (and we get new ones daily from the environment) professional cleanings need to be repeated whenever the number of bacteria gets too high.