Oral Bacteria Linked to Stroke Risk

Researchers at the National Cerebral and Cardiovascular Center in Osaka, Japan, have discovered a potential link between oral health and the risk of stroke. According to their data, 26% of their patients who had experienced intracerebral hemorrhage had cnm-positive Streptococcus mutans in their saliva. Meanwhile, only 6% of patients who suffered from other types of stroke tested positive for the bacterium.

Also, MRIs revealed significantly higher numbers of cerebral microbleeds in subjects with cnm-positive S. mutans than in those without the bacterium. Cerebral microbleeds are small brain hemorrhages that may cause dementia and often underlie intracerebral hemorrhages. The researchers believe S. mutans may bind to blood vessels weakened by age and high blood pressure, causing arterial ruptures in the brain and leading to small or large hemorrhages.

“This study shows that oral health is important for brain health. People need to take care of their teeth because it is good for their brain and their heart as well as their teeth,” said Robert P. Friedland, MD, co-author of the study and the Mason C. and Mary D. Rudd endowed chair and professor of neurology at the University of Louisville School of Medicine.

“The study and related work in our labs have shown that oral bacterial are involved in several kinds of stroke, including brain hemorrhages and strokes that lead to dementia,” Friedland said. He also noted that the cnm-negative strain of S. mutans causes tooth decay and is found in approximately 10% of the population. Currently, he is researching how oral bacteria may influence other diseases affecting the brain.

“We are investigating the role of oral and gut bacteria in the initiation of pathology in the neurodegenerative disorders Alzheimer’s and Parkinson’s with collaborators in the United Kingdom and Japan,” he said.

The study, “Intracerebral Hemorrhage and Deep Microbleeds Associated with cnm-positive Streptococcus Mutans; a Hospital Cohort Study,” was published by Scientific Reports.

- See more at: http://www.dentistrytoday.com/news/industrynews/item/749-oral-bacteria-linked-to-stroke-risk#sthash.EjE28gZ1.dpuf

-DentistryToday

Shark Genes Offer Clues to Tooth Regeneration

Sharks are infamous for their ability to regrow teeth throughout their lifetime, while human beings only get a couple of sets. Researchers at the University of Sheffield in the United Kingdom, though, have identified the genes that give sharks their regenerative capacity, with an eye on someday giving people the same ability.

“We know that sharks are fearsome predators, and one of the main reasons they are so successful at hunting prey is because of their rows of backward-pointing, razor-sharp teeth that regenerate rapidly throughout their lifetime and so are replaced before decay,” said Dr. Gareth Fraser of the University of Sheffield.

The researchers have identified how a special set of epithelial cells, known as dental lamina, forms in sharks. These cells are responsible for lifelong tooth development and regeneration in sharks, conserved throughout 450 million years of evolution. Human beings have these cells too, but they only form baby and adult teeth before they are lost.

“The Jaws films taught us that it’s not always safe to go into the water, but this study shows that perhaps we need to in order to develop therapies that might help humans with tooth loss,” said Fraser.

By analyzing the teeth of catshark embryos, the researchers characterized the expression of genes during stages of early shark tooth formation. They found that these genes participate in the initial emergence of the teeth and are redeployed for further tooth regeneration.

At the beginning of the sharks’ evolutionary history, the researchers said, their teeth most likely were continuously regenerated and used a core set of genes from members of key developmental signaling pathways that were instrumental in evolving to redeploying the genes to replace teeth when needed.

Shark dentition is formed and patterned via these highly conserved signals, which are used by all toothed vertebrates, the researchers said. Slight genetic alterations, they added, could be the difference between the limited replacement supply of teeth that mammals have and the unlimited dentition that sharks have.

The study, “An Ancient Dental Gene Set Governs Development and Continuous Regeneration of Teeth in Sharks,” was published by Science Direct. It was supported by the Natural Environment Research Council and the Leverhulme Trust.

- See more at: http://www.dentistrytoday.com/news/industrynews/item/744-shark-genes-offer-clues-to-tooth-regeneration?highlight=WyJzaGFyayIsInJlZ2VuZXJhdGlvbiJd#sthash.qExoksZ1.dpuf

-DentistryToday

Tooth Decay May Prohibit Growth in Children

Tooth decay may be even worse than originally thought.

A new study suggests that tooth decay may push back growth in children. The study appeared in the online version of Pediatrics journal and was conducted at University College London and King Fahad Armed Forces Hospital in Saudi Arabia.

The research team wanted to explore the relationship between oral health and growth after previous studies failed to show definitive evidence one way or the other. In this study, the researchers looked at the dental decay and the correlation between height and weight in Saudi Arabian children ages 6 through 8.

The oral health of the children was graded on the DMFT scale, which is a scale that determines the seriousness of decayed, missing and filled teeth.

The research team later analyzed the statistics and concluded that there was, in fact, a relationship between low height/weight and a greater number of cavities. Children with severe decay had a higher chance of being underweight and shorter when compared to their peers.

Even when some secondary factors, like demographics and social values, were factored in, the correlation between decay and stunted growth still existed. Based on this study, it’s fair to say there is an inverse relationship between growth and tooth decay in children. More research is necessary to confirm this study’s findings.

-DentistryToday

Red Wine Not Shown to Prevent Cavities

Have you seen news stories declaring the cavity fighting powers of red wine? Think it seems too good to be true? 

You’re right to be skeptical. Despite recent stories, it turns out that drinking red wine hasn’t been shown to be good for your teeth. The stories were based on a study in the Journal of Agricultural and Food Chemistry which found that red wine with or without alcohol had no effect on the growth of S. mutans, the bacteria that causes cavities. What the researchers actually reported was that red wine and dealcoholized red wine were effective in limiting growth of F. nucleatum and S. oralis—two bacteria that are closely associated with gum disease. 

So, does this mean red wine may be good for gum health? Maybe. If you hold it in your mouth for two minutes every seven hours for seven days like the researchers did. For now, the ADA recommends you stick to brushing for two minutes twice a day and flossing daily for good dental health.

-MouthHealthy

Beyond tooth decay: why good dental hygiene is important

In this spotlight feature, to coincide with National Dental Hygiene Month, we peer beneath the plaque to investigate what other - perhaps unexpected - health conditions are affected by poor dental health.

Alzheimer's disease
In 2010, researchers from New York University (NYU) concluded that there is a link between gum inflammation and Alzheimer's disease, after reviewing 20 years of data on the association.

However, the number of participants in the NYU study was fairly small. The researchers analyzed data from 152 subjects enrolled in the Glostrop Aging Study - a study looking at psychological, medical and oral health in Danish men and women. The study spanned a 20-year period and ended in 1984, when the subjects were all over the age of 70.

Comparing cognitive function at ages 50 and 70, the NYU team found that gum disease at the age of 70 was strongly associated with low scores for cognitive function.

Study participants were nine times more likely to have a score in the lower range of the cognitive test - the "digit symbol test" (DST) - if they had inflammation of the gums.

Although this study took into account potentially confounding factors like obesity, cigarette smoking and tooth loss unrelated to gum inflammation, there was still a strong association between low DST score and gum inflammation.

In 2013, UK-based researchers from the University of Central Lancashire (UCLan) built on the findings of this study, by comparing brain samples from 10 living patients with Alzheimer's with 10 brain samples from people who did not have the disease.

Analysis showed that a bacterium - Porphyromonas gingivalis - was present in the Alzheimer's brain samples but not in the samples from the brains of people who did not have Alzheimer's. What was interesting was that P. gingivalis is usually associated with chronic gum disease.

The team followed up this research in 2014 with a new mouse study, the results of which were published in the Journal of Alzheimer's Disease. Medical News Today spoke to co-author Dr. Sim K. Singhrao regarding the findings.

Dr. Singhrao says that there is sufficient scientific evidence to show that two of the three gum disease-causing bacteria are capable of motion (or "motile") and have been consistently found in brain tissue.

"These motile bacteria can leave the mouth and enter the brain via two main routes," he explains. "They can use their movement capability to directly enter the brain. One of the paths taken is to crawl up the nerves that connect the brain and the roots of teeth. The other path is indirect entry into the brain via the blood circulation system."

In a patient who has bleeding gums, says Dr. Singharo, the gum disease-causing bacteria will enter the blood stream every time they clean their mouth and even when they eat food.

He continues:

"P. gingivalis is particularly interesting as it has found ways to hitch a lift from red blood cells when in the blood stream and instead of getting 'off the red blood cell bus' in the spleen, they choose to get off in the brain at an area where there are no immune checkpoints. From there, they spread to the brain at their will. In addition, in older individuals, the blood vessels tend to enlarge and become leaky."

"The published work confirmed P. gingivalis placed in the mouths of mice finds its way to the brain once gum disease becomes established first," Dr. Singhrao concludes. "Furthermore, our hypothesis is strengthened by the recent results demonstrating that the chemicals released by the brain's immune system in response to P. gingivalis reaching the brain 'inadvertently' damage functional neurons in the area of the brain related to memory."

Pancreatic cancer
A research team from Harvard School of Public Health in Boston, MA, were the first to report strong evidence on a link between gum disease and pancreatic cancer, back in 2007.

The type of gum inflammation associated with pancreatic cancer in the study was periodontitis, which affects the tissue that support the teeth and can cause loss of bone around the base of the teeth.

The other main kind of gum disease - gingivitis; where the tissue around the teeth becomes inflamed - was not linked to increased cancer risk. However, gingivitis can lead to periodontitis if persistent. Gingivitis happens when bacteria in the plaque around the base of the teeth build up due to bad dental hygiene.

Examining data on gum disease from the Health Professionals Follow-Up Study, which involved a cohort of more than 51,000 men and began collecting data in 1986, the Harvard researchers found that men with a history of gum disease had a 64% increased risk of pancreatic cancer compared with men who had never had gum disease.

The greatest risk for pancreatic cancer among this group was in men with recent tooth loss. However, the study was unable to find links between other types of oral health problems - such as tooth decay - and pancreatic cancer.

The researchers suggest that there may be a link between high levels of carcinogenic compounds found in the mouths of people with gum disease and pancreatic cancer risk. They argue that these compounds - called nitrosamines - may react to the digestive chemicals in the gut in a way that creates an environment favorable to the development of pancreatic cancer.

However, a follow-up study from the team in 2012 was unable to prove whether the periodontitis bacteria are a cause or result of pancreatic cancer - the study could only prove that the two were linked.

"This is not an established risk factor," admitted author Dominique Michaud. "But I feel more confident that something is going on. It's something we need to understand better."

Heart disease
Perhaps more well established is the association between dental hygiene and heart disease.

In 2008, MNT reported on research from joint teams at the University of Bristol in the UK and the Royal College of Surgeons in Dublin, Ireland, who found that people with bleeding gums from poor dental hygiene could be increasing their risk of heart disease.

The researchers found that heart disease risk increased because - in people who have bleeding gums - bacteria from the mouth is able to enter the bloodstream and stick to platelets, which can then form blood clots, interrupting the flow of blood to the heart and triggering a heart attack.

"The mouth is probably the dirtiest place in the human body," said Dr. Steve Kerrigan from the Royal College of Surgeons, explaining that there are up to 700 different types of bacteria co-existing in our mouths.

Prof. Howard Jenkinson, from the University of Bristol, added:

"Cardiovascular disease is currently the biggest killer in the western world. Oral bacteria such as Streptococcus gordonii and Streptococcus sanguinis are common infecting agents, and we now recognise that bacterial infections are an independent risk factor for heart diseases."

The Bristol University researchers investigated how the bacteria interact with platelets by mimicking the pressure inside the blood vessels and the heart. Prof. Jenkinson's team found that the bacteria use the platelets as a defense mechanism.

By clumping the platelets together, the bacteria are able to completely surround themselves. This platelet armor shields the bacteria from attack by immune cells and makes them less detectable to antibiotics.

Although some of the associations we have looked at in this spotlight feature are still under investigation, good dental hygiene remains important for lowering risk of a variety of conditions.

The American Dental Hygienists' Association (ADHA) recommend that we should brush for 2 minutes, twice daily. The ADHA guidelines also stress the importance of flossing daily and rinsing with mouthwash. You can read the full recommendations on the ADHA website.

Written by David McNamee

ADA Recommends Earlier Fluoride Distribution for Children

It may be beneficial for children to be given fluoride even earlier than they receive it now, according to the American Dental Association.

Previous information suggested children receive fluoride by the time they were 6. This new information, however, suggests that children be administered fluoride even earlier. The new ADA recommendation states that children should be given fluoride as soon as their first teeth develop.

When children use fluoride toothpaste at an early age, it can lower the rate of decay. Research suggests that around one quarter of children develop a cavity before reaching kindergarten but more children using fluoride at an earlier age can lower that number.

The change in position on when a child should start using fluoride comes after a study from the Journal of the American Dental Association.

The study also indicated that pea-sized quantities of toothpaste can lead to a higher risk of fluorosis when toothpaste is ingested. Children younger than 3 should use smaller amounts of toothpaste. The ADA recommends parents watch their children clean their teeth to make certain the children spit out the toothpaste as opposed to swallowing it.

More studies on fluoride will be conducted to determine when is the exact time children should initially use it. There are many different opinions regarding how people feel about fluoride and this information won’t change those beliefs.

-DentistryToday

We drink milk because it is good for us, but we rarely stop to think "Why?"

Archaeologists and geneticists have been puzzling this question since it was revealed that the mutations which enable adults to drink milk are under the strongest selection of any in the human genome.

These mutations cause the intestinal enzyme lactase -- which digests lactose milk sugar during infancy -- to continue to be produced long after weaning. This lactase persistence is prevalent only in some populations around the world such as in Northern Europe. In most other people of the world, the lactose cannot be properly digested and can cause diarrhea, or other symptoms of lactose intolerance resulting from the gases produced by fermentation by the gut bacteria.

Some dairy products such as yoghurt and cheese have had their lactose content reduced or removed through processing. In the case of cheese, the lactose ends up in the whey, where it is often fed to pigs and other animals. If it is so easy to remove milk sugars, and the mutation is only required for drinking raw milk or whey -- why is it under such strong selection?

An international team of researchers involving the Universities of York, Oklahoma and Copenhagen, and University College London (UCL) has shed new light on this puzzling question through an unusual source -- investigations of calcified dental plaque on ancient human teeth.

To understand how, where and when humans consumed milk products, it is necessary to link evidence of consumption directly to individuals and their livestock. Previous research by archaeologists has used indirect lines of evidence, such a high frequency of adult females in animal herds or milk lipids present on pots, to identify evidence of dairying.

Now a breakthrough by the international team, reported in the journalScientific Reports, provides the first direct evidence of milk drinking from an increasingly important archaeological reservoir -- human dental calculus, a mineralized form of dental plaque. Using the latest mass spectrometry-based techniques for ancient protein sequencing, the team detected a milk protein, beta-lactoglobulin (which they had previously reported from a modern dental plaque sample) in ancient remains.

Lead author Jessica Hendy, from the University of York's BioArCh research facility, said: "It seemed too good to be true; beta-lactoglobulin is the dominant whey protein -- the one used by bodybuilders to build muscle mass -- and therefore the ideal marker for milk consumption. We kept finding sequences of beta-lactoglobulin and at first we thought it could be modern contamination. But we repeated the analysis several times, at three different laboratories in three different countries, each time finding the same results."

Lead author Dr Christina Warinner, from the Department of Anthropology, University of Oklahoma, said: "The study has far-reaching implications for understanding the relationship between human diet and evolution. Dairy products are a very recent, post-Neolithic dietary innovation, and most of the world's population is unable to digest lactose, often developing the symptoms of lactose intolerance."

Professor Dallas Swallow, from the Research Department of Genetics, Evolution and Environment at UCL, added: "It is only within the last several thousand years that genetic mutations arose in Europe, East Africa, and the Arabian Peninsula that allowed lactase to persist into adulthood, a genetic trait that enables lifelong milk consumption."

The new research provides direct protein evidence that cattle, sheep, and goat whey has been consumed by human populations for at least 5,000 years. This corroborates previous isotopic evidence for milk fats identified on pottery and cooking utensils in early farming communities. Until now it has been difficult to investigate both human genetic milk adaptations and direct evidence of milk consumption at the same time, in part because milk preserves so poorly in the archaeological record.

"The discovery of milk proteins in human dental calculus will allow scientists to unite these lines of evidence and compare the genetic traits and cultural behaviors of specific individuals who lived thousands of years ago," says Dr Warinner.The team found direct evidence of milk consumption preserved in human dental plaque from the Bronze Age to the present day.

Professor Matthew Collins, of BioArCh in York's Department of Archaeology, said: "Some of the findings were as we expected. For example, we did not find any evidence of milk protein in 19th century West African individuals from regions where dairying was uncommon. But we found widespread evidence for milk consumption at European sites spanning a period of 5,000 years."

Dr Camilla Speller, from York's BioArCh research facility, said: "Most of the molecular evidence for milk consumption has previously come from residues on ceramics. While pot residues can tell you that people are using dairy products, it can't tell you which individuals in the group are actually consuming the milk. This study is very exciting, because for the first time, we can link milk consumption to specific skeletons, and figure out who has access to this important nutritional resource."

Dr Enrico Cappellini, from the Centre for GeoGenetics, Natural History Museum of Denmark, University of Copenhagen, says the milk protein beta-lactoglobulin is also an important find because it contains sequence variants that allow different milk-producing livestock to be distinguished.

"We found widespread evidence of cows' and sheep milk consumption as early as the Bronze Age, whereas evidence for goat milk consumption was limited to Bronze Age northern Italy," he said.

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Story Source:

The above post is reprinted from materials provided by University of York.Note: Materials may be edited for content and length.

-ScienceDaily