Down in the Mouth
words by merry sue baum / photograph by pete byron
ou’ve probably seen the ads for toothpaste that is “effective in helping to prevent and reduce tooth decay, gingivitis, plaque above the gum line and bad breath.” And there’s the mouthwash that “kills germs that cause bad breath and gingivitis.”
Before a company can make such claims, it has to do its homework. That means getting highly skilled researchers to use scientifically sound, clinical research methods to test their products. For Johnson & Johnson and Colgate-Palmolive Company, those researchers are members of the Oral Biology Department at UMDNJ-New Jersey Dental School.
Daniel Fine, DMD, says he and his colleagues have been evaluating the effects of oral antimicrobial agents on bacteria in the mouth for more than 20 years. Most recently, they tested toothpaste that contains one percent zinc. “We look at the effects of these agents on microorganisms that cause periodontal disease, bad breath and cavities,” he says. “We use a unique design known as a crossover study.” He explains that while everyone’s mouth contains similar bacteria, the exact combination is unique in each individual. To reduce variability in the testing, everyone in the trial uses the product as well as a control. Therefore, when participants “cross over” to the second product, they are, in fact, their own controls.
The tests are conducted like this. The 20 to 40 healthy participants have baseline oral examinations and plaque samples taken before they begin using the test product (mouthwash or toothpaste). They use the product for two weeks and at the end of that time have another oral exam and plaque sample taken. For the following two weeks, known as the washout period, the participants use their own products. They then switch to a control for two weeks, which is a second product that does not contain the active ingredient found in the first. Those in the trial don’t know the order in which they receive the test product and control, making it a double blind study.
At the end of the trial, the researchers evaluate reduction in plaque formation and gingival inflammation using clinical indices, which is the classic method. They also analyze the plaque samples to determine the total number of culturable bacteria and the reduction in the number of bacteria specifically responsible for periodontal disease and cavities. A 20 percent reduction is considered statistically significant.
“We do the math and give the company a final report,” says Fine. “We can tell them if the product is effective, how effective it is on specific bacteria that cause cavities and periodontal disease, and whether we saw a reduction in inflammation. In the past, we’ve also tested mouthwashes — including Listerine — to determine how long, if at all, they control bad breath.”
The results of the tests go beyond helping the average consumer make a choice in the oral hygiene aisle at the drug store, however. Dentists and their patients benefit as well. Fine says high-speed drills that spray water, like ultrasonic scalers, produce a “back spray” of bacteria-filled water that spatters the dentist’s face. The oral biologists have demonstrated through testing that the bacteria in the back spray are significantly reduced if a patient rinses with an antimicrobial mouthwash before the procedure. The scientists also demonstrated that pre-procedural rinsing and irrigation below the gums with an antimicrobial mouthwash reduce bacteremia events by about 90 percent. These events usually occur when a dental patient is having an invasive procedure that allows bacteria to get into the bloodstream.
“It is extremely interesting and rewarding to do this work,” Fine says. “I know when people use an oral health product that we’ve tested, it will live up to the claims being made about it. And that’s good to know.”
Newark-based Study Benefits Teens
Fine and his colleagues are conducting clinical research that directly benefits participants now, as well as in the future. The professor has received a $3.4 million grant from the NIH’s National Institutes of Dental and Craniofacial Research to study Localized Aggressive Periodontitis or LAP, an oral infection that affects some 70,000 children in underserved areas. LAP occurs 15 to 20 times more frequently in African-American children and 10 times more frequently in Hispanic children than it does in Caucasians. LAP leads to premature loss of front teeth and molars, affecting a child’s appearance, self-esteem and nutrition. Scientists have long believed the onset of the disease can be predicted by a microorganism known as Aggregatibacter actinomycetemcomitans (Aa), however, a longitudinal study was lacking. Fine and his colleagues decided to change that.
Using a specially equipped dental van donated by Colgate-Palmolive Company, the research team has been visiting schools throughout Newark, where they have screened more than 1,000 students for caries and the presence of Aa. Each of the 11- to 16-year-olds also gives a saliva and plaque sample. Those children who have caries or LAP receive free treatment, and all of the participants receive free cleanings, toothbrushes, toothpaste and instructions on proper oral hygiene.
Two groups of children form the basis of the study: one with Aa and a second without. Only 15 percent of the subjects had Aa. Students with Aa and an equal number without are asked to return for oral exams and to give samples every six months for at least two years. The samples from those who develop the disease are being compared to those who do not, and will be analyzed prior to sighting the disease and at the time of diagnosis. In addition, the saliva will be used to determine host susceptibility factors in those who develop the
“Our findings indicate that all the subjects who developed the disease had Aa but many with Aa remained healthy,” says Fine. “However, we found a salivary marker known as MIP-1 alpha. That’s a very important discovery, because MIP-1 alpha has been shown to be a marker that pre-dates X-ray evidence of bone loss by six to nine months in multiple myeloma, an aggressive form of bone cancer. We’ve begun to design strategies for early detection of LAP so cost-effective methods of prevention can be developed. This study is unique in that while we’re moving closer to stemming a devastating oral disease in underserved children across the country, we’re also helping them right now.”