Childhood Oral Infections Linked to Adult Atherosclerosis in Prospective Study

Though causality is not proven by these data, the lead author believes infection-related inflammation and bacteria play a role

New data from a long-term cohort study suggest a connection between childhood oral infections and subclinical carotid atherosclerosis later in life. The findings lend further credence to the notion that inflammation can play a role in the genesis of cardiovascular disease, according to a study author.

Prior work has established that “oral infections and atherosclerosis develop hand in hand,” lead author Pirkko Pussinen, PhD (University of Helsinki, Finland), told TCTMD. “Where there are infections, for example, there is also low-grade inflammation in the system, and atherosclerosis also develops this low-grade inflammation. They are working in the same direction.”

While the analysis cannot confirm the relationship between oral infections and atherosclerosis is causal, she said, there are several mechanisms by which the former might make someone more susceptible to the latter. “For example, if you have an oral infection, there is a spread of bacteria in the circulation directly through the bleeding gums and also through saliva,” Pussinen explained. “When you swallow saliva—1.5 liters every day—the bacteria gets in the system and they might modulate the gut microbiota, and that's one of the proposed mechanisms behind that association.”

For the study, published online last week in JAMA Network Open, Pussinen and colleagues looked at data from 755 individuals enrolled in the Cardiovascular Risk in Young Finns Study in the 1980s. Participants underwent oral examinations initially at age 6, 9, or 12 years and then received clinical cardiovascular follow-up in 2001 or 2007 when they were anywhere from 27 to 39 years old. Overall, only 4.5% of children showed no signs of oral infections—defined as bleeding on probing, periodontal probing pocket depth, caries, and dental fillings—while 34.1% had all four signs.

The number of oral infections a participant had was linked with their overall cardiovascular risk in adulthood. Additionally, the presence of periodontal disease (P = 0.01), caries (P =0.008), or both (P = 0.004) were associated with increased carotid intima-media thickness (IMT) in adulthood. In fact, any sign of oral infection in childhood was associated with a heightened risk of increased IMT (RR 1.87; 95% CI 1.25-2.79) and all four signs present were associated with an almost doubled risk (RR 1.95; 95% CI 1.28-3.00).

The findings were even more pronounced in boys, whose risk of increased IMT in adulthood was linked with periodontal disease (RR 1.69; 95% CI 1.21-2.36), caries (RR 1.46; 95% CI 1.04-2.05), and all four signs of oral infections (RR 2.25; 95% CI 1.30-3.89).

Several Explanations

In an accompanying editorial, Anwar Merchant, DMD, ScD (University of South Carolina, Columbia), and Salim Virani, MD, PhD (Michael E. DeBakey Veterans Affairs Medical Center, Houston, TX), write that there are three possible explanations for the study findings. For one, individuals who have poor oral health as children likely also have poor oral health as adults, and previous research conducted in adults has established a link between poor oral health and atherosclerosis. Next, they continue, poor oral health may not have a causal effect; instead, the link could stem from shared risk factors for poor cardiovascular and oral health, including smoking, poor diet, physical inactivity, or unknown genetic factors. A third explanation would be selection bias, a possibility that the editorialists dismiss as unlikely.

“Even if the question of causality remains unanswered, with issues pertaining to the performance of a conventional randomized clinical trial in this context, the article by Pussinen et al underscores the idea that the distinction between oral health and systemic health is blurred and somewhat artificial,” the editorialists conclude. “Cardiovascular disease and periodontal disease share common risk factors, and controlling those risk factors could result in better overall health.” Better communication between primary care physicians and dentists would ultimately reduce the risk of both diseases, they note.

Pussinen agreed. “At least in Finland, the medical doctors and the dentists study together for 2 years and then they are separated. . . . After that they never hear from each other—like the mouth is separate from the rest of the body,” she said. “That doesn't make any sense. It should be looked after from both sides, dental and medical.”