The next generation of plaque control?

Feb. 1, 2002

Professional removal of supragingival plaque biofilm can change the subgingival periodontal ecosystem.

In the 1970s, there was talk of the dental hygiene profession being eliminated — not by changes in the law or by giving our duties to dental assistants, but rather through extinction. Back then, researchers, using advanced microscopy and culturing techniques, were close to identifying the one bacteria they thought was responsible for periodontal disease. With that discovery, there certainly would be a vaccine to eliminate all signs of periodontal disease, and therefore also eliminate the need for dental hygienists. Some were quite excited at the mere thought of dental hygienists becoming extinct! On the other hand, hygienists were only amused by the idea.

Researchers concentrated on the "specific plaque hypothesis," looking for the one bad bacteria. Each month, the researchers identified another bug, giving rise to what was called the "bug of the month club!" As you all know, periodontal disease is not caused by a single bacteria, but by the body's immune response to a shift in balance of the normal bacterial flora of the mouth. Rather than just one, researchers found over 450 bacterial species in the mouth.

Have you ever wondered how we get bacteria in our mouths? We all start our lives as germ-free newborns. In nature, we see that animals often lick their infants. Humans do something similar. We spit on our babies. Haven't you ever used saliva to wipe food or dirt off a child's face or mouth? Moms instinctively lick their fingers or a tissue to clean smudges off kids' faces. I don't even have children of my own, and I've found myself spitting on kids in the family! I see kids in the grocery store who could use a little spit wash. The family dog even takes a turn licking the kids. Before putting a spoon of warm food in a baby's mouth, we put it in our mouth to test it. I've even seen moms pick up a pacifier that's landed on the floor, and, before giving it to the baby, it first goes into mom's mouth to be cleaned. Gross, sure, but it happens!

Scientists in England suggested we should avoid this transfer of bacteria and therefore never kiss babies! That's taking science too far, don't you think? We need bacteria in our mouths to start the digestive process, and the way we get those bacteria now is perfectly fine. Of course, we want to be sure parents have healthy mouths so the babies receive only a minimum amount of bacteria. The germ-free mouth at birth soon harbors millions of bacteria.

The key to oral health is an optimum balance of these bacteria, the right mix, to insure proper digestion and avoid disease. In adults, changes in this balance lead to periodontal disease.

Have you ever wondered where bacterial plaque comes from after the teeth have been cleaned? Since we can't completely sterilize the mouth or subgingival areas, there always will be some microscopic bacteria remaining. These bacteria are the source of new bacterial colonies. Supragingival plaque will influence subgingival plaque. As supragingival plaque forms, it moves subgingivally. Gingivitis leads to tissue-swelling, making previously supragingival plaque now subgingival plaque. Gingival inflammation encourages subgingival plaque formation. The increased gingival crevicular-fluid flow associated with inflammation provides added nutrition for subgingival bacteria.

Studies involving school children show that professional supragingival plaque control every two weeks will eliminate gingivitis and nearly eliminate caries. In adults, tissue health is maintained with two-week dental hygiene visits for the first six months after surgery, followed by three-month maintenance visits.

One-week dental hygiene visits were recently tested on perio maintenance patients with remaining pockets and bleeding. After quadrant scaling and root-planing using local anesthesia, they began weekly visits for supragingival plaque removal. During these visits, the hygienist applied disclosing solution, removed supragingival deposits with hand instruments if necessary, polished with toothpaste, and finished with thorough flossing.

The researchers expected to see changes in plaque amounts and composition during the three months of weekly visits. What they didn't expect was prolonged good results. The clinical indices measured at three months remained the same for one year. Perhaps the extended results are due to changes in motivation and daily plaque removal by the patients. It also may be that professional removal of supragingival plaque biofilm can change the subgingival periodontal ecosystem.

When plaque samples from these patients and periodontally healthy patients were compared, average bacterial counts were actually lower in the test patients compared to the periodontally-healthy patients!

Without a vaccine to eliminate periodontal disease, mechanical plaque removal will continue to be an essential part of disease control and prevention. Until we have full-mouth, custom brushing and oral-irrigation systems for effectively daily plaque removal, we should consider weekly or biweekly dental hygiene visits. Professional plaque removal will control active periodontal disease. I'm sure you can think of at least one of your patients who would benefit from this approach.

Sometimes, we just need to try a new approach. Rather than on their way to becoming extinct, dental hygienists are needed now more than ever!

Trisha E. O'Hehir, RDH, BS, is a senior consulting editor of RDH. She also is editor of Perio Reports, a newsletter for dental professionals that addresses periodontics. The Web site for Perio Reports is She can be reached by phone at (800) 374-4290 and by e-mail at [email protected].