The link between 3rd molars and periodontal disease

Adult African Americans, Hispanics, and those with socioeconomic disadvantages are more likely to have retained their wisdom teeth, making them more at risk for periodontal disease, according to a study published online on September 14 in Public Health.

However, those who still had their third molars did not have elevated serum C-reactive protein (CRP) levels, which is an indicator of systemic inflammation associated with periodontal disease and a possible modifiable risk factor of cardiovascular disease.

"Although we did not observe an association between M3 [third molar] presence and elevated serum CRP, our analysis supports that M3 presence is a risk factor for periodontal disease, independent of a number of known risk factors for the condition," wrote the authors, led by Yuqing Zhang, a doctoral candidate at the College of Nursing and Health Sciences at the University of Massachusetts Boston.

The oral-systemic link

Evidence has shown that asymptomatic third molars can contribute to gum disease. Periodontal disease affects approximately 47% of the population and about 70% of those 65 and older in the U.S. Gum disease has come into greater focus since it has been linked to systemic disease, including heart disease, diabetes, obesity, and stroke. Though it is unclear whether gum disease plays a causal role in these conditions, scientists presume that repeated, lasting oral infections induce proinflammatory cytokine secretions, which result in increased inflammation throughout the body.

Data from the 2009-2010 National Health and Nutrition Examination Survey (NHANES) were analyzed for the current study. NHANES included 3,752 people 30 years or older who participated in periodontal exams. Zhang and colleagues aimed to determine the associations among the presence of wisdom teeth, gum disease, and CRP levels to generate population-based evidence to inform heart disease prevention and dental care.

Gum disease and wisdom teeth

Of the individuals analyzed, 39% retained at least one of their third molars, and 41% had periodontal disease. Having at least one third molar was independently associated with a 61% greater likelihood of having periodontal disease, the researchers found.

The presence of wisdom teeth was highest among men, younger adults, African Americans, Hispanics, those who did not go to college, and participants with low incomes. When third molar presence was adjusted for sociodemographic and health characteristics, it was independently associated with periodontal disease at an odds ratio of 1.61 (95% confidence interval [CI], 1.31-1.97). Though 19% had elevated serum CRP levels, having wisdom teeth was not associated with elevated serum CRP (odds ratio, 1.02; 95% CI, 0.79-1.31), they wrote.

A start

The analysis had some limitations, including a cross-sectional design. Therefore, a causal relationship between periodontal disease and elevated serum CRP or between third molar presence and subsequent periodontal disease could not be claimed, the authors noted. Despite this, it is plausible that retaining wisdom teeth precedes the development of gum disease, they wrote.

Though the researchers found expected associations between wisdom teeth presence and periodontal disease, they believe more research is needed, especially regarding how the retention of third molars may be related to cardiovascular health hazards.

"Longitudinal studies are needed to determine whether retention of third molars contributes to periodontal disease and other possible health consequences, and further, to examine whether these relationships are mitigated by health behaviors and other factors," they wrote.