My first experience with dental research was a chewing gum study conducted in the mid-1970s at the University of Minnesota. My job was to collect the data. If I remember correctly, I didn't mind chewing gum before that time, but after a summer devoted to measuring plaque levels before and after chewing gum — and plaque pH levels — gum seemed to lose its appeal.
The study subjects were dental students, paid to chew gum instead of brushing and flossing. They all rotated through three different test groups: 1) a sugar-free gum from Scandinavia called Bit, 2) a sugar gum, and 3) another sugar-free gum.
Something unexpected happened during that study. The dental students liked the Bit gum better than the other two gums tested and kept coming back for more, even though they were each given the exact number of pieces needed for each phase of the study. It turned out that they were sharing the gum with family and friends ... or maybe even selling it. By the end of the study, all of the participants wanted to buy stock in the company because the Bit gum was softer and more flavorful than the other gums.
Thoughts of my long-forgotten experiences with chewing gum research surfaced recently as I read an article on the use of licorice-flavored chlorhexidine chewing gum for nursing-home residents. They found that chewing either chlorhexidine plus xylitol gum or plain xylitol gum for 15 minutes after breakfast and dinner significantly reduced plaque and gingivitis levels.
Compared to a control group that didn't chew any gum, the gum-chewers reported improved taste and chewing as well. Those in the control groups reported that their oral hygiene received more attention from the nursing home staff during the study. Despite more attention, plaque and gingivitis levels remained the same for the control group. This confirms other reports that oral hygiene provided by nursing home care-givers is not adequate. We need hygienists in nursing homes every day to establish and maintain good oral health. Until hygienists are part of every nursing home and until chlorhexidine chewing gum is available in this country, nursing home residents might benefit from chewing xylitol gum after meals.
Remembering the problems associated with my own experience, I found the obstacles they encountered as interesting as the study outcomes. When planning the study, the organizers realized that they couldn't have all three test groups at each nursing home because residents might share gum and feel sorry for those in the control group who were not getting any gum and give them some of theirs! To avoid these potential problems, subjects at each of the in 21 nursing homes in England participating in the study were assigned to a single treatment group.
Some of the study participants liked chewing the gum and didn't want to give it back after 15 minutes, and some wanted to chew it more often that just after breakfast and dinner. This created problems for the care-givers assigned to collect the gum after chewing and to make sure it was properly disposed of.
As you would expect with this elderly population (63 years to 99 years in age), some people didn't complete the 12-month study. A few died, some were hospitalized, and others moved back home with family. What I found surprising, however, was that five of the nursing homes withdrew from the study. The staff at three of the homes complained that it was too much work to hand out the gum and collect the chewed pieces after 15 minutes. One of the homes went out of business and closed. The fifth home hired a new manager who refused to let the dental research team have access to the residents.
Back to chewing gum. Research already has confirmed that chewing xylitol gum reduces the incidence of caries in children, up to 75 percent in some studies. It works first by stimulating saliva and, secondly, by depriving the Streptococcus mutans bacteria of a fermentable carbohydrate source, thereby preventing plaque pH from dropping below 5.7. These findings also are seen with xylitol candy, not just chewing gum. Both stimulate saliva flow, so it isn't the chewing after all.
Research has shown that mothers who chew xylitol gum do not transmit Streptococcus mutans to their children. In another study, the caries-reduction benefits of chewing xylitol gum lasted several years after stopping the gum-chewing and, surprisingly, the benefits extended to teeth that erupted after the gum-chewing trial period. In the xylitol candy study, interruption due to summer school breaks did not reduce the caries preventive effects of xylitol. Perhaps the benefits of xylitol go beyond salivary stimulation to beneficial changes in the bacterial flora.
Besides xylitol chewing gums, you may have seen some of the new, potentially therapeutic gums containing baking soda, coenzyme Q-10, aloe vera, calcium, and vitamins. Some claim to remove stains, remineralize enamel, or clean between the teeth. More research is needed before we can draw any conclusions about the newest claims for chewing gums.
Now for some chewing gum trivia
More than 1,000 varieties of chewing gum are manufactured and sold in the United States, and American kids spend half a billion dollars on bubble gum every year! The chewing gum market is estimated to be $5 billion. According to Dr. Imfeld of Switzerland, 560,000 tons of chewing gum, or 374 billion pieces, lead to 187 hours of gum-chewing each year. The most popular flavors today are cinnamon, spearmint, and peppermint.
The first chewing gums were actually chunks of tree resin. In Central America, the Mayan Indians chewed chicle, the sap of the sapodilla tree. American Indians chewed sap from spruce trees.
The first chewing gum patent was issued in 1869 to a dentist. Black Jack was one of the first flavored gums, using licorice flavor. It was introduced in 1871, and discontinued in the 1970s. Are any of you old enough to remember Black Jack?
Dr. Beeman sold bottles of pepsin compound to relieve indigestion. His secretary suggested adding the pepsin to chewing gum, which he did. The wrapper had a picture of a pig on it with this slogan: "with pepsin, you can eat like a pig." Sales increased when the pig on the wrapper was replaced with Dr. Beeman's bearded face!
In the 1800s, "nice" girls didn't chew gum. Jonathan P. Primley made the first fruit-flavored gum and called it "Kis-Me." If a girl asked for a piece of "Kis-Me" gum, a fellow could always claim she really said, "Kiss me." The chewing gum's slogan, "Far Better Than a Kiss," encouraged chewers to try both and see for themselves!
In the 1890s, William Wrigley began making flat sticks with flavor. Wrigley's Spearmint and Juicy Fruit still are among today's most popular chewing gums.
During the Prohibition era in the 1920s and early 1930s, speakeasies gave out Clove chewing gum to freshen the breath of people drinking the illegal liquor.
The Frank H. Fleer Company sold candy-coated Chiclets by the ounce and is credited with inventing bubble gum in 1906. Unfortunately, Blibber-Blubber gum was so sticky, it was never marketed. In 1928, an accountant at the same company devised a successful formula. They made it pink because that was the only color they happened to have right then. The color just stuck (forgive the pun). Dentyne was the first "dental gum" on the market.
Do any of you remember Amurol sugar-free gums and candies? In 1948, an Illinois dentist founded the Amurol Company, making ammoniated toothpaste and tooth powder. The "Amurol" name was derived from product ingredients: ammonia (AM) and urea (UR) and taken orally (OL). He soon developed sugar-free chewing gum with ammonia to counteract acid in the mouth. In 1958, Amurol Products became part of the Wrigley Company, and continued to produce sugar-free products. Sugar-free bubble gum, called Blammo, was introduced in the late 1960s. Since the mid-1980s, the company discontinued the sugar-free products and, instead, pursued the lucrative novelty gum market, making dozens of sugar-sweetened gums.
To avoid the mess associated with chewing gum disposal, Singapore instituted a $1,000 fine for chewing gum in public.
Despite the encouraging research findings with zylitol chewing gums and candies, very few choices are available in that category — and most of them must be purchased at health-food stores.
To change this situation, we must share the research findings with friends, family, patients, and clients. Finally, we also must encourage chewing-gum companies to provide customers with more choices.
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 www.perioreports.com. She can be reached by phone at (800) 374-4290 and by e-mail at [email protected]