Researchers find association between gum disease and ischemic stroke risk

Adults with gum, or periodontal, disease may be at greater ischemic stroke risk, according to research presented at the American Stroke Association's International Stroke Conference 2017.

Researchers assessed 6,711 adults, who had not had a stroke, for periodontal disease and categorized the adults according to whether they had mild, moderate or severe periodontal disease. They followed patients for 15 years for the incidence of stroke, also documenting the stroke subtype based on cause.

A total of 299 ischemic strokes occurred during the 15 years, including 47 percent that were thrombotic stroke, from a clot within the brain's blood vessels; 26 percent that were cardioembolic, when a blood clot forms in the heart; and 20 percent that were lacunar strokes, which occurs when there is a blockage of small arteries that supply blood to the brain.

They found:

Participants with mild periodontal disease were 1.9 times more likely to have an ischemic stroke than those without periodontal disease. Those with moderate periodontal disease had 2.1 times higher ischemic stroke risk and adults with severe gum disease were 2.2 times more likely to suffer an ischemic stroke than those who had no periodontal disease.

The association between increasing levels of periodontal disease and stroke risk was most pronounced in the cardioembolic and thrombotic stroke subtypes.

The graded association between the level of gum disease and incident ischemic stroke, supports a possible causal association between gum disease and ischemic stroke, researchers said.

Estrogen therapy shown effective in reducing tooth and gum diseases in postmenopausal women

Estrogen therapy has already been credited with helping women manage an array of menopause-related issues, including reducing hot flashes, improving heart health and bone density, and maintaining levels of sexual satisfaction. Now a new study suggests that the same estrogen therapy used to treat osteoporosis can actually lead to healthier teeth and gums. The study outcomes are being published online today in Menopause, the journal of The North American Menopause Society (NAMS).

As estrogen levels fall during menopause, women become more vulnerable to numerous health issues, including loss of bone mineral density which can lead to osteoporosis. Around the same time, changes in oral health also are common as teeth and gums become more susceptible to disease, which can lead to inflammation, pain, bleeding, and eventually loose or missing teeth.

In the Menopause article "Association between osteoporosis treatment and severe periodontitis in postmenopausal women," 492 postmenopausal Brazilian women aged 50 to 87 years, 113 in osteoporosis treatment and 379 not treated, were evaluated to determine whether osteoporosis treatment could help increase the bone mineral density in their jaws and, subsequently, improve overall oral health.

The study found that the rate of occurrence of severe periodontitis was 44% lower in the postmenopausal osteoporosis-treatment group than in the untreated group. Treatment consisted of systemic estrogen alone or estrogen plus progestin, as well as calcium and vitamin D supplements, for a minimum of six months.

"Osteoporosis can occur throughout the body, including the jaw, and lead to an increased risk of periodontal disease," says Dr. JoAnn Pinkerton, NAMS executive director. "This study demonstrates that estrogen therapy, which has proven to be effective in preventing bone loss, may also prevent the worsening of tooth and gum disease. All women, but especially those with low estrogen or on bisphosphonate treatment for osteoporosis, should make good dental care a part of their healthy lifestyles."

Mapping a path to better oral health

Dentists aren't the only people who influence how we take care of our teeth; our friends and family play a big role, too. That is the conclusion of Brenda Heaton, an assistant professor of health policy and health services research at Boston University's Henry M. Goldman School of Dental Medicine, who is presenting her research on February 19, 2017, at the American Association for the Advancement of Science (AAAS) conference in Boston.

Heaton specializes in social epidemiology with a focus on oral health. In 2008, she, along with other members of BU's Center for Research to Evaluate & Eliminate Dental Disparities, began a new line of research, focused on understanding oral health and disease among residents in Boston public housing. The majority of the work to date has focused on whether or not "motivational interviewing" can influence how women care for their children's diet and oral health--specifically, the impact on kids with dental caries (also known as tooth decay). There is mounting evidence that one-on-one behavioral interventions, like motivational interviewing, may change short-term behavior, but the effects don't last long. "We started to get a sense that there may be more influences that we need to acknowledge beyond just the individual," says Heaton. She found that social networks--not Facebook and Twitter, but networks of friends, family, and acquaintances--may play an overlooked role in oral health care.

Some women Heaton interviewed "had been born and raised in the unit that they were living in, and were now raising their own child in that unit," she says, "so we had grandmother, mother, and child in one unit." Those close connections influenced how people behaved, and to make significant progress against diseases like tooth decay, Heaton had to tap into those networks herself.

That is not easy, but it is important, says Thomas Valente, a professor of preventive medicine at the University of Southern California and an expert in social networks in health care. People believe information more when it comes from someone they know or respect, and evidence suggests that people are more willing to trust people who are like them. All too often, says Valente, who was not involved in this study, health information is handed to a community by people on the outside, and it is less impactful. "It's like West Side Story," says Valente. "It's like being a Shark and having a Jet come up to you and tell you to do something. It is just not going to happen."

Heaton wants to spread resources about good oral health, not only to combat tooth decay but also because oral health is intertwined with other health concerns. "Sugar-sweetened beverage [consumption is] something that we are very interested in, not only because it is a huge risk factor for oral health outcomes, but it is also a huge risk factor for obesity and other obesity-related health conditions," she says.

To understand the connections that already existed within the community, Heaton needed to draw a social map. Since 2008, her team has interviewed close to 200 women living in Boston public housing and identified nearly 1,000 individuals who were influential. Heaton is using those network maps to find similarities about how information flows through these communities.

The ultimate goal, she says, is to use the map to introduce health information and resources into a community in ways that change long-term behaviors.

"You can't design those interventions until you actually have a really strong grasp of the network structure," says Heaton. For instance, if you want to make an impact, should you look for community members with the most personal connections or for people with large influence but fewer personal ties? Should you take advantage of existing connections or seed new ones?

The power of this approach is that it focuses on prevention rather than cures, says Heaton. It might take a village, but tooth decay "is an entirely preventable health outcome."

Genetic defects in tooth enamel conducive to development of caries

Why do some people develop caries even though they always brush their teeth carefully while others are less stringent regarding dental hygiene yet do not have any holes? Ultimately, both have bacteria on the surface of their teeth which can attack the enamel. Enamel forms via the mineralization of specific enamel proteins. If the outer layer of the teeth is defective, tooth decay can strike.

Researchers from the University of Zurich have now pinpointed a gene complex for the first time that is responsible for the formation of tooth enamel. Two teams from the Centre of Dental Medicine and the Institute of Molecular Life Sciences used mice with varying mutations of the enamel proteins involved in the so-called Wnt signaling pathway. Thanks to this transmission route, human and animal cells respond to external signals and specifically activate selected genes in the cell nucleus. The signaling pathway is essential for embryonal development and also plays a pivotal role in the development of cancer or physical malformations.

Mutations in proteins trigger defective tooth enamel

"All mice with mutations in these proteins exhibit teeth with enamel defects," explains Pierfrancesco Pagella, one of the study's two first authors. "Therefore, we demonstrated that there is a direct link between mutations in the genetic blueprints for these proteins and the development of tooth enamel defects." This genetic discovery goes a long way towards improving our understanding of the production of tooth enamel.

The team of researchers was the first in the world to use modern genetic, molecular and biochemical methods to study tooth enamel defects in detail. "We discovered that three particular proteins involved in the Wnt signaling pathway aren't just involved in the development of severe illnesses, but also in the qualitative refinement of highly developed tissue," says co-first author Claudio Cantù from the molecular biologist research group lead by Prof. Konrad Basler. "If the signal transmission isn't working properly, the structure of the tooth enamel can change."

Increased risk of caries with defective tooth enamel

The hardness and composition of the tooth enamel can affect the progression of caries. "We revealed that tooth decay isn't just linked to bacteria, but also the tooth's resistance," says Thimios Mitsiadis, Professor of Oral Biology at the Center of Dental Medicine. Bacteria and their toxic products can easily penetrate enamel with a less stable structure, which leads to carious lesions, even if oral hygiene is maintained.

Understanding the molecular-biological connections of tooth enamel development and the impact of mutations that lead to enamel defects opens up new possibilities for the prevention of caries. "New products that hinder the progress of tooth caries in the event of defective tooth enamel will enable us to improve the dental health of patients considerably," adds Mitsiadis.