Eat Your Way to Better Dental Health

When people eat food or sip a drink containing commonly used preservatives, they may be unconsciously improving their oral health in a way they didn’t expect.

That’s the news from researchers at the University of Rochester, New York, Medical Center who presented their findings at the April 8-9 annual meeting of the International Association of Dental Research. Their studies, performed at of one of the world’s leading programs in dental research, showed that common food preservatives such as benzoates and sorbates enhance the caries-protective action of fluoride.

One of the researchers, microbiologist Robert Marquis, PhD, performed laboratory studies that showed many food preservatives seem to mimic fluoride’s anticaries effects.

"We found that food preservatives inhibit bacteria in much the same way that fluoride does in bacteria like Streptococcus mutans," he says. "It puts protons, basically weak acid, into its cells. The bacteria try to move the acid out of their cells because their enzymes are not acid-tolerant."

Marquis says the preservatives and fluoride work to push bacteria to exhaustion, using molecular action to continually lower the pH within bacteria, while the bacteria constantly pumps it back out. Losing energy, the bacteria’s cells stop producing the caries-causing acid.

"Fluoride and preservatives prevent the bacteria from acidifying the plaque and causing caries," Marquis says. "The bacteria are still there, but they’re not causing damage."

Fellow Rochester researcher William H. Bowen, BDS, PhD, took Marquis’ research a step further, conducting studies to investigate the effects of food preservatives and fluoride on caries in rats.

"They’re an excellent model because they get decay just like humans do," says Bowen, a Welcher Professor of Dentistry and a member of the National Institute of Medicine. "And the same substances that prevent caries in rats stop them in people."

In one study, Bowen’s team measured the number of cavities in rats from several groups: some received fluoride, some received benzoates, some received neither, and some both. All the rats that received fluoride in their diets had far fewer cavities than those that didn’t. But fluoride’s effect was stronger in animals that also received benzoates or sorbates.

Benzoates are used in a wide range of foods to help keep the food supply safe from bacteria and other toxins. Benzoates also come from natural sources, including cranberries, prunes, and cinnamon. Sorbates, the other preservative used in the study, are used in many common items such as lunchmeats, mayonnaise, dried fruits, and candy bars. They may one day be used in oral care products such as toothpaste to increase fluoride’s effectiveness, according to the researchers.

"We would like to test preservatives initially in rats and then on humans to see if the studies work out as we anticipate," Bowen says. "We certainly think there’s every prospect of ending up with commercial products."

Marquis says that an eventual goal of the research is to develop the optimal weak acid as an anti-caries agent.

"That’s desirable, because many people feel they’re getting too much fluoride," Marquis says. "Our view is that if we can reduce the amount of fluoride in toothpaste by incorporating weak acids into it, we may reduce the incidence of fluorosis."

Bowen says that he and Marquis are not questioning the effect and safety of fluoride; they’re looking for methods to enhance its effectiveness.

"When something like fluoride works, people get excited and sometimes don’t look beyond the obvious," he says. "There are a lot of things going on in our food supply that provide oral health benefits that haven’t occurred to people."

Dennis Mangan, PhD, chief, infectious diseases and immunity branch of the National Institute of Dental and Craniofacial Research, was involved with the grant that supported the work. He also says that there are many factors influencing what’s happening in the oral cavity.

"We know fluoride has certain effects, but don’t completely understand the other influences food or other things have," he says. "This is an example of research that shows us how intricate or complex the oral cavity is. It’s not a static environment where only one factor like fluoride affects it. When we ingest anything there are multiple influences."

Noted fluoride research expert Gary Whitford, PhD, DMD, Regents’ Professor at the Medical College of Georgia, wasn’t surprised by the research results.

"If any agent were capable of inhibiting bacterial acid production, it would be expected that the effect would be additive to fluoride’s. That doesn’t surprise me."

Whitford says that caries is a multifactorial disease that we don’t yet fully understand.

"There are a number of things we still don’t understand about its cause and factors that influence its development," he says. "There are a variety of things in the diet that could add to the effects of fluoride, and in future years as they are identified they could improve the situation."

Marquis and Bowen have published their work in abstract in the Journal of Dental Research and are writing a paper that they expect to have published later this year.

Bowen says that preservatives are a serendipitous oral health benefit of our diet today.

"But you can’t rely only on serendipity to protect your teeth."

Large Study Supports Smoking and Cleft Palate Link

Women who smoke during pregnancy are more likely to have a baby with cleft lip or palate than are nonsmoking women, according to a large study involving information from the U.S. Natality database.

The Natality database from 1996 and a case-control study design were used to investigate the association between maternal smoking during pregnancy and having a child with cleft lip or palate.

The records of 3.8 million live births from the database were extracted to obtain cleft lip and palate cases and random controls.

"In about 4 million births in the U.S. in 1996, 13 percent of mothers reported to have smoked during pregnancy," said Dr. Kevin Chung, lead author of the study. "This translates to a huge public health issue."

More than 2,200 cases of cleft lip or palate were recorded in babies born to the women who smoked.

Women who smoked were up to 70 percent more likely to have a baby with cleft lip or palate. Even after the data was adjusted for other factors prevalent in smoking women -- such as hypertension and lower education -- women who smoked 1 to 10 cigarettes per day were 30 percent more likely to have children with cleft lip or palate.

Antimicrobials Found in Chewing Sticks

For thousands of years, much of the developing world has been preventing cavities and gum decay by using chewing sticks from the root, stem, or twig of local trees and shrubs.

Researchers have now isolated the antimicrobial agents in some of these chewing sticks that they believe act to kill bacteria in the mouth and surrounding the teeth. Their findings were published in the March 20, 2000, issue of the Journal of Agricultural and Food Chemistry.

Researchers at the University of Stellenbosch in Tygerberg, South Africa, specifically looked at the properties of one particular chewing stick in Namibia commonly referred to as "muthala." An earlier oral health survey of more than 2,000 Namibians had indicated that the 20 percent of the population that use muthala had lower cavity rates than those who did not use any dental hygiene method.

The sticks are prepared by cleaning the wood, removing the bark, and cutting and bundling them into usable sizes that are sold in local markets. Over time, the sticks become frayed by chewing, which serves to clean teeth not only by passively releasing such compounds but also by active repeated mechanical use in brush-like fashion.

In the current investigation, the researchers were able to isolate four compounds found in the pencil-sized chewing sticks that demonstrated an ability to inhibit oral bacteria.

Sleep Apnea Associated With Hypertension

An association has been found between sleep-disordered breathing and hypertension in a large multicenter study, according to an article in the April 12, 2000, issue of the Journal of the American Medical Association.

F. Javier Nieto, MD, PhD, from Johns Hopkins School of Hygiene and Public Health in Baltimore and colleagues reported on the association between hypertension and sleep-disordered breathing, which includes sleep apnea (a complete or almost complete cessation of airflow during sleep often characterized by snoring). The researchers reported on data from 6,132 participants 40 years old and older who participated in the Sleep Heart Health Study, a multicenter study that recruited patients with sleep apnea from other studies in order to examine the associations between sleep apnea and cardiovascular conditions.

The researchers found that the prevalence of hypertension (defined as resting blood pressure at least 140/90 or use of antihypertensive medication) increased as average sleep-disordered breathing episodes per hour increased. Participants in the category of highest frequency of breathing disorders (30 or more apnea-hypopnea index episodes per hour) had a higher risk (adjusted odds ratio of 1.37) of experiencing hypertension than those in the lowest category (less than one and a half apnea-hypopnea index episodes per hour). The crude rates of hypertension ranged from 43 percent for those in the lowest apnea-hypopnea index category (less than 1.5 per hour) to 67 percent for those in the highest apnea-hypopnea index category (30 or more per hour).

"After controlling for the main potential cofounders (age, sex, BMI [body mass index] and other measures of adiposity [fat just beneath the skin]) as well as for other potentially relevant variables (alcohol intake, smoking), high levels of [apnea-hypopnea index ] or sleep time below 90 percent oxygen saturation were associated with greater odds of hypertension in a dose-response fashion [the higher the levels of (apnea-hypopnea index ) or sleep time below 90 percent oxygen saturation the higher the blood pressure levels]."

The researchers used the apnea-hypopnea index to assess sleep-disordered breathing. The apnea-hypopnea index included the average number of apnea episodes plus the average number of hypopnea episodes per hour of sleep. Hypopnea was defined as a 30 percent or greater decrease in airflow or a 30 percent or greater decrease in chest and abdomen movement accompanied by a 4 percent or greater decrease in oxygen saturation in the blood.

The researchers measured apnea-hypopnea index using a polysomnography during a one night home visit to measure a number of factors including airflow and chest and abdominal movement. The participants also completed a self-administered questionnaire about sleep habits that included questions about awareness of a history of snoring, awareness of sleep apnea, awareness of treatment for sleep apnea and experience of sleepiness. The researchers also measured the number of arousals from sleep per hour and the percentage of sleep time where the oxygen saturation was below 90 percent.

Pickin’ and Grinning

Humans were using toothpicks up to 1.8 million years ago, according to research on a fossilized tooth done at the University of Arkansas.

Microscopic scratches were found on a tooth discovered by noted anthropologist Mary Leakey in the Olduvai Gorge. The strange grooves are consistent with toothpick use, according to Peter Ungar, an associate professor of anthropology at the school.

He and his colleagues suspect that the marks were left by pieces of bone or grit on a stick that was used for cleaning teeth. Ungar believes the practice became common about the time ancient humans started eating meat.

Honors

Eddie K. Hayashida, DDS, MBA; Susan A. Bittner, DDS; and Frank A. Brucia, DDS, have received the 2000 Medallion of Distinction Award from the University of the Pacific School of Dentistry. (photos of all)

Craig S. Yarborough, DDS, MBA, has been appointed associate dean for institutional advancement. (photo from Jan. Journal -- chair of Sessions council)

Robert L. Merin, DDS, MS, will be installed this month as president of the California Society of Periodontists. (photo)

Mahmoud Torabinejad, DMD, MSD, PhD, has been re-elected treasurer of the American Association of Endodontists.

Web Watch: Online Journals

Following is a partial list of dental journals that can be found online.

* Journal of Dental Research -- http://www.iadr.com/jdr/jdr.html

* British Dental Journal -- http://www.bdj.co.uk/

* Journal of the Canadian Dental Association -- http://www.cda-adc.ca/jcda

* Journal of Periodontology -- http://www.perio.org/journal/journal.html

* Journal of the American Dental Association -- http://www.ada.org/prof/pubs/jada/index.asp

and, of course,

* Journal of the California Dental Association -- http://www.cda.org/cda_member/pubs/journal/index.html

A listing here does not constitute endorsement by the California Dental Association. As is the case with all Web sites, content is subject to frequent change.

Upcoming Meetings

2000

June 12-13 "The Face of a Child" -- Surgeon General’s Conference on Children and Oral Health, Washington, D.C., (301) 588-6000, www.nidcr.nih.gov/sgr/children/children.htm

July 26-28 Pacific Northwest Dental Conference, Seattle, www.wsda.org

July 30-Aug. 2 Congress of the International Society for Lasers in Dentistry, Brussels, Belgium, +32 2 648 80 59.

Aug. 14-16 Association of Philippine Orthodontists National Congress, Manila, Philippines, (632) 890-2824

Aug. 30-Sept. 2 Surfaces in Biomaterials 2000, Scottsdale, Ariz., (612) 512-9103, http://www.surfaces.org/00pp.htm

Sept. 15-17 CDA Scientific Session, San Francisco, (916) 443-3382, Ext. 4470

Sept. 17-20 American Academy of Periodontology Annual Meeting, Honolulu, www.perio.org

Oct. 14-18 ADA Annual Session, Chicago, (312) 440-2500

Oct. 19-21 Academy of Surgical Research Annual Meeting (612) 545-1919, http://www.surgicalresearch.org/00sess.htm

Oct. 26-28 American Society for Dental Aesthetics, Millennium International Conference, San Francisco, (800) 454-2732, www.asdatoday.com

Nov. 29-Dec. 2 FDI World Dental Congress, Paris, http://www.fdi.org.uk/congress/index.htm 2001

April 19-22 CDA Scientific Session, Anaheim, (916) 443-3382, Ext. 4470

May 4-8 Australian Dental Congress, Brisbane, +61 (0) 7 3369 0477

Sept. 14-16 CDA Scientific Session, San Francisco, (916) 443-3382, Ext. 4470

To have a meeting included on this list, please send the information to Upcoming Meetings, CDA Journal, P.O. Box 13749, Sacramento, CA 95853 or fax the information to (916) 443-2943.