Persistent dental problems in childhood are linked to a higher risk of atherosclerosis later in life. Children with many cavities and inflamed gums are more likely to end up with heart disease. School dental care may therefore be a previously overlooked place to identify signs of disease risk long before illness appears.
As a child, Maja was frequently called in for school dental check-ups. At each visit, new cavities appeared, her gums were sore and the dentist sent another note home. The teeth were drilled and filled, and everyday life went on.
Years later, she is lying in a hospital bed with electrodes on her chest while a cardiologist talks about blood clots and calcified coronary arteries. This course of events may seem like a bolt from the blue, but in a new registry study, researchers from the University of Copenhagen and University College London followed hundreds of thousands of Danes with childhoods like hers. They found that such children are more likely than others to develop atherosclerosis as adults.
The study’s lead author is Nikoline Nygaard, a postdoctoral researcher at the Department of Odontology at the University of Copenhagen with a background in public health science.
“What we see is a pattern in which children with persistent dental problems are more likely to develop cardiovascular disease as adults,” says Nikoline Nygaard.
“Part of the explanation may be pure biology and inflammation. Nevertheless, it may reflect how difficult it can be to maintain good health in general if you struggle to take care of your teeth when you are young. The mouth is, so to speak, a gateway to the rest of the body’s health – and sometimes one of the first places where problems appear.”
Children’s dental records reveal risks later in life
As Nikoline Nygaard explains, the study grew out of a sense that two worlds do not communicate enough with each other. From studies of adults, dentists and doctors already knew that poor dental health – for example, severe gum inflammation known as periodontitis – not only leads to tooth loss but is also often associated with type 2 diabetes, cardiovascular disease and other conditions.
Researchers had found oral bacteria in atherosclerotic plaque in the arteries of people who had died of cardiac arrest, and treatment of periodontitis had improved the blood sugar regulation of people with type 2 diabetes, even though their diabetes medication remained unchanged.
Yet an important piece of the puzzle was missing. Virtually nothing was known about how this connection might manifest itself earlier in life. Children rarely develop periodontitis, but they do experience other oral diseases in the form of far more cavities and a milder type of gum inflammation known as gingivitis.
The question, therefore, is whether these early problems in the mouth may in fact be early signs of cardiovascular disease that only becomes apparent many years later.
During her PhD studies at dental school, Nikoline Nygaard realised that Denmark offers something quite unusual for investigating exactly this question. First, it has a municipal school dental care programme that systematically records children’s dental health year after year. Second, Denmark has national patient registries that follow the same individuals into adulthood with records of diagnoses, hospitalisations and treatments.
Together, these data create a rare opportunity to examine whether dental health in childhood is linked to heart disease that only emerges many years later.
“It struck me how much information we actually have about children’s teeth – and how little we have used it to understand disease later in life,” says Nikoline Nygaard.
Dental records reveal long-term patterns in childhood health
This led to the project: to investigate whether the patterns seen in school dental records are also reflected in the heart diseases for which people are treated in the hospital system many years later.
To do so, Nikoline Nygaard and colleagues selected 568,778 Danes with repeated records from municipal dental services and linked their dental data to the national patient registries.
For each child, the researchers assembled the many dental check-ups into an overall picture of dental health throughout childhood, including information on the number of cavities and the prevalence of gingivitis. On this basis, they divided the participants into groups ranging from few problems to more pronounced ones.
The researchers then followed the children through their school years and observed whether their dental problems remained limited, stayed high most of the time or increased over time during the transition from baby teeth to permanent teeth.
A large part of the work involved reconciling old handwritten records with newer digital systems across age groups and municipalities so that the many dental check-ups could be assembled into a coherent sequence from childhood to adulthood.
When childhood oral disease predicts heart disease
When the researchers compared the dental records with the participants’ medical histories in adulthood, the figures showed that people who had more pronounced problems with cavities and gingivitis as children were more likely to develop atherosclerosis later in life.
The association was evident in several serious outcomes, including heart attacks, strokes and bleeding in the brain as well as narrowing of the coronary arteries. What stood out most was not individual years with dental problems, but rather cases in which the records showed persistent disease in teeth and gums year after year.
The pattern over time pointed in the same direction. Children who moved from relatively few problems to more cavities and greater inflammation appeared more frequently in the statistics on cardiovascular disease as adults than children whose dental problems decreased or remained limited.
“This tells us that children’s different dental health trajectories are associated with differences in the occurrence of heart disease at the population level,” says Nikoline Nygaard.
How bacteria and inflammation link the mouth and the heart
According to Nikoline Nygaard, the statistical association between childhood dental health and heart disease in adulthood fits into a broader biological picture that researchers have already begun to outline in studies of adults. She points out that the oral cavity is densely supplied with blood vessels and that the gums bleed easily when they are inflamed.
When the gums bleed, small openings into the circulatory system can form. From there, bacteria can spread throughout the body, and the distance to both the heart and the brain is short.
“Inflamed gums bleed easily, giving bacteria easier access to the rest of the body,” says Nikoline Nygaard. “When you look for them, you find bacteria that we normally associate with the oral cavity both around the heart and in abscesses in the brain.”
She also points out that the relationship works in the other direction. People with diabetes are more likely to have oral problems, partly because dry mouth and changes in the sugar content of saliva affect both the mucous membranes and tooth enamel. In this way, the oral cavity becomes both a place where other diseases can take hold and a place where new disease processes may begin.
Nevertheless, she emphasises that dental records do not only reflect biology. Children with persistent dental problems are more likely to grow up in families in which finances, time and energy are stretched. In such circumstances, sweet drinks, irregular meals and chaotic daily routines are more common. Brushing teeth can more easily slip out of the routine.
“School dental care is a place where we can spot health inequalities many years before the first blood tests and blood pressure measurements begin to show them,” says Nikoline Nygaard.
This means that school dental services may also be one of the earliest places in the healthcare system where an increased risk of disease becomes visible – long before illness is detected elsewhere in the body.
What happens between childhood and the development of illness?
The registry study is good at showing the big picture in the population but less suited to telling us everything that happens between the dentist’s chair and the hospital. The national registries contain no information about sugar intake, smoking, jogging or evenings spent on the sofa. Nor do they capture who has managed to replace unhealthy habits with healthier ones.
Nikoline Nygaard and colleagues have adjusted for educational level and type 2 diabetes as broad markers of living conditions and health, yet some of the differences may ultimately reflect social conditions and lifestyles that were never recorded in any registry.
Dental health in adulthood is also only partly captured in the analyses at this stage. The study describes what the participants’ teeth looked like as children and what diseases they later developed but not how their dental health evolved in the years in between.
To get closer to this missing part of the story, the research group is now working with medical records from private dental care, where the dental health of around 1 million Danes as adults is registered. Some of these individuals can be linked to the childhood cohort, enabling the analysis to be repeated in a large subgroup in which both childhood and adult dental data are available.
“It may turn out that heart disease particularly affects those who have had many dental problems both as children and later in life,” says Nikoline Nygaard. “It may also be that early exposure in itself leaves a mark, even if the teeth later look fine. Both scenarios will tell us something important about when in life we can best intervene.”
In addition, she is planning studies of other diseases with a strong inflammatory component, including rheumatoid arthritis and inflammatory bowel disease, to determine whether the same pattern appears there.
“When we can follow people from their milk teeth into adulthood and at the same time examine several different diseases, we have a better chance of understanding what the oral cavity can reveal about the health of the rest of the body,” says Nikoline Nygaard. “And regardless of the precise mechanism, the results already suggest that much can be gained by taking children’s teeth and gums seriously while there is still time to change course – long before disease manifests elsewhere in the body.”
