Cell Damage Caused By Brushing May Help Keep Gums Healthy

Bristles wielded with even gentle force tear holes in the epithelial cells that line the gums and tongue, causing a momentary rupture. Tearing enables calcium, abundant in saliva, to move into the cells, triggering internal membranes to move up and patch the hole. But in the seconds that repair takes, growth factors that promote growth of collagen, new cells and blood vessels leak out of injured cells.
Cell injury also turns on expression of the c-fos gene, an early-response gene often activated under stress that may be the first step in a response such as cell division or growth.

"It's very clear that brushing your teeth is a healthy thing to do; no one questions that brushing removes bacteria and that's probably its main function," Dr. McNeil says. "But we are thinking that there might be another positive aspect of brushing. Many tissues in our bodies respond to mechanical stress by adapting and getting stronger, like muscles. We think the gums may adapt to this mechanical stress by getting thicker and healthier. It's the no pain, no gain theory the same as exercising."

"… (W)e suggest that, in addition to its well-know ability to remove bacteria and their harmful products from teeth, brushing may, by causing plasma membrane disruptions, lead to local cell-adaptive responses ultimately of benefit to gingival health," the researchers write.