Women infected with bacteria known to cause periodontal disease more likely to have more severe oral bone loss

A study conducted in a large sample of postmenopausal women by University at Buffalo epidemiologists has provided new information on the prevalence of certain gum-disease-causing oral bacteria in this population and the association of the bacteria with oral bone loss.

Results showed that women infected with four bacteria known to cause periodontal disease were more likely to have more severe oral bone loss than those without these oral pathogens.

Two widely recognized periodontal pathogens, called P. gingivalis and T. forsythensis, were found to infect 15.1 percent and 37.9 percent of the women, respectively. Two additional oral bacteria suspected to be pathogenic, P. intermedia and C. rectus, were found in 43.4 percent and 17.4 percent of women.

"This is one of the first studies in community-dwelling postmenopausal women that assessed bacteria presence and associated it with oral bone loss, while controlling for other factors, such as age, smoking status and income," said Jean Wactawski-Wende, Ph.D., associate professor of social and preventive medicine, UB School of Public Health and Health Professions, and senior author on the study

Results appear in the June 2007 issue of the Journal of Periodontology.

The study involved 1,256 postmenopausal women who were part of a larger population-based investigation of risk factors for osteoporosis and oral bone loss in postmenopausal women, which is an offshoot of the observational portion of the national Women's Health Initiative (WHI).

Participants in this study completed questionnaires, had physical measurements taken, had bone-density testing and an oral health examination. The oral health examination had several components, including microbiological sampling of subgingival plaque and oral X-rays.

Investigators used a measure called alveolar crestal height to determine the amount of oral bone loss. Alveolar bone surrounds the teeth and holds them in place in the upper and lower jaw. The lower the crest, or top of the bone, the more bone has been lost. Loss of alveolar crest bone eventually can lead to tooth loss.

The association between bacterial infection and oral bone loss turned out to be strongest in overweight women, compared to normal weight or obese women.

"We expected to see an increased risk for oral bone loss with increasing body mass index (BMI, a factor representing the relationship of weight to height)," commented Renee Brennan, Ph.D., research assistant professor of social and preventive medicine and first author on the study.

"However, the greatest risk was seen in overweight women. This was supported by a three-fold increase in these women. Other factors that we could not assess may be at play in the obese women. We need to explore further the impact of weight and BMI on the associations of oral bacteria and oral bone loss."

Blood levels of inflammation markers, which would provide a clear picture of overall risk weren't available at the time, but the researchers now are planning to investigate this association.

In addition to substantiating the relationship between certain known and suspected oral pathogens and oral bone loss, results confirmed that the three control bacteria included in the study, which have not been associated with periodontal disease, also were not associated with oral bone loss.

On the contrary, the two control bacteria -- S. sanguis and Capnocytophaga sp. -- were associated with healthier oral bone.

Brennan said the findings will help develop a more complete understanding of the mechanisms involved in periodontal disease.