Researchers find association between oral bacteria and esophageal cancer

University of Louisville School of Dentistry researchers have found a bacterial species responsible for gum disease, Porphyromonas gingivalis, is present in 61 percent of patients with esophageal squamous cell carcinoma (ESCC). The findings, published recently in Infectious Agents and Cancer, only detected P. gingivalisin 12 percent of tissues adjacent to the cancerous cells, while this organism was undetected in normal esophageal tissue. 

"These findings provide the first direct evidence that P. gingivalis infection could be a novel risk factor for ESCC, and may also serve as a prognostic biomarker for this type of cancer," said Huizhi Wang, M.D., Ph.D., assistant professor of oral immunology and infectious diseases at the UofL School of Dentistry. "These data, if confirmed, indicate that eradication of a common oral pathogen may contribute to a reduction in the significant number of people suffering with ESCC." 

The esophagus, a muscular tube critical to the movement of food from the mouth to the stomach, is lined with two main kinds of cells, thus there are two main types of esophageal cancer: adenocarcinoma and squamous cell carcinoma. The latter is more common in developing countries. 

In collaboration with the College of Clinical Medicine of Henan University of Science and Technology in Luoyang, China, Wang and his UofL colleagues Richard J. Lamont, Ph.D., Jan Potempa, Ph.D., D.Sc., and David A. Scott, Ph.D., tested tissue samples from 100 patients with ESCC and 30 normal controls. 

The research team measured the expression of lysine-gingipain, an enzyme unique to P. gingivalis, as well as the presence of the bacterial cell DNA within the esophageal tissues. Both the bacteria-distinguishing enzyme and its DNA were significantly higher in the cancerous tissue of ESCC patients than in surrounding tissue or normal control sites. The researchers also found the presence of P. gingivalis correlated with other factors, including cancer cell differentiation, metastasis and overall survival rate. 

According to Wang, there are two likely explanations: either ESCC cells are a preferred niche for P. gingivalis to thrive or the infection of P. gingivalis facilitates the development of esophageal cancer. 

If the former is true, Wang says simple antibiotics may prove useful or researchers can develop other therapeutic approaches for esophageal cancer utilizing genetic technology to target the P. gingivalis and ultimately destroy the cancer cells. 

"Should P. gingivalis prove to cause ESCC, the implications are enormous," Wang said. "It would suggest that improving oral hygiene may reduce ESCC risk; screening for P. gingivalis in dental plaque may identify susceptible subjects; and using antibiotics or other anti-bacterial strategies may prevent ESCC progression."

According to the Centers for Disease Control, about 15,000 people in the United States are diagnosed with esophageal cancer each year. As with most cancers, there are a number of risk factors including chemical exposure, diet, heredity and age. It is somewhat difficult to diagnosis this cancer early, and it is characterized by rapid progression and high mortality.

Periodontitis linked to a higher mortality rate in patients with kidney disease

New findings from the University of Birmingham show that patients with chronic kidney disease patients and periodontitis (severe gum disease) have a higher mortality rate than those with chronic kidney disease alone.

The research, published in the Journal of Clinical Periodontology, adds to the growing evidence for poor oral health being associated with other chronic diseases.

Data from 13,734 participants in the US-based Third National Health and Nutrition Examination Survey (NHANES III) were analysed to show that individuals with both periodontitis and chronic kidney disease had an all-cause mortality rate of 41% at 10 years, compared to 32% for those with chronic kidney disease alone.

To put this into context, the increase in 10 year mortality associated with diabetes in patients with chronic kidney disease, independent of periodontitis, is from 32% in non-diabetics to 43% in diabetics.

Periodontitis is a chronic non-communicable disease, and in its most severe form is the sixth most prevalent human disease, affecting 11.2% of the world's population.

Chronic non-communicable diseases, such as kidney disease, are increasingly prevalent, partly as a result of an aging population and an increase in sedentary lifestyles and refined diets. Their impact upon the global disease burden and healthcare economy is significant, and evidence suggests that 92% of older adults have at least one chronic disease.

Professor Iain Chapple, from the University of Birmingham, explained, "It's important to note that oral health isn't just about teeth. The mouth is the doorway to the body, rather than a separate organ, and is the access point for bacteria to enter the bloodstream via the gums. A lot of people with gum disease aren't aware of it, perhaps they just have blood in their spit after brushing teeth, but this unchecked damage to gums then becomes a high risk area for the rest of the body."

Mr Praveen Sharma, a co-author of the study, added, "We are just beginning to scratch the surface of the interplay between gum disease and other chronic diseases; whether that be kidney disease, diabetes or cardiovascular disease. Knowing the heightened risk that gum disease presents to patients who already have another chronic disease tells us that oral health has a significant role to play in improving patient outcomes."

Following this paper, the team are now investigating the link between gum and kidney disease further, to identify if the association is causal, and if so, whether treating gum disease and maintaining oral health can improve the overall health of patients with kidney disease.

Professor Chapple said, "It may be that the diagnosis of gum disease can provide an opportunity early detection of other problems, whereby dental professionals could adopt a targeted, risk-based approach to screening for other chronic diseases."

Chewing sugar free gum after eating or drinking helps prevent tooth decay

The NHS could save £8.2 million a year on dental treatments -- the equivalent to 364,000 dental check-ups -- if all 12-year-olds across the UK chewed sugar free gum after eating or drinking, thanks to the role it plays in helping to prevent tooth decay.

So says a study involving researchers from Plymouth University Peninsula Schools of Medicine and Dentistry published in the British Dental Journal.

Tooth decay is preventable but treating it is an increasing burden on the NHS and family finances. The latest Government figures show that young people in the UK experience unacceptably high levels of tooth decay and that it can have a real impact on their self-esteem as well as their health, with 35 per cent of 12 year olds reporting being embarrassed to smile or laugh due to the condition of their teeth.

New health economic research published in the British Dental Journal demonstrates that the NHS could save up to £2.8m on dental treatments per year if all 12-year-olds across the UK were to chew one additional piece of sugar free gum per day. This cost saving raises to a potential £3.3m if two pieces of sugar free gum were to be chewed per day by all 12-year-olds and to £8.2m for three pieces. This research is the first of its kind in the UK and was conducted by York Health Economics Consortium and Peninsula Dental School, University of Plymouth with support from The Wrigley Company Ltd.

Sugar free gum could be an easy and effective addition to families' oral health routines. The British Dental Health Foundation recommends that, while brushing for two minutes, twice a day is still the best way to keep teeth clean and healthy, for children over the age of seven, chewing sugar-free gum during the day can be extremely effective in breaking down lingering food, neutralising harmful plaque acids and reducing the risk of decay.

Chewing sugar free gum after eating and drinking increases the production of saliva, which helps to wash away food particles and neutralise harmful plaque acids which, over time, can weaken teeth and lead to tooth decay. It also promotes the remineralisation of tooth enamel. The important role of sugar-free gum in oral care is widely recognised and accepted by experts, dental associations and regulatory authorities around the world. The European Commission (EC) has approved five oral health claims for sugar-free chewing gum, one of the few food categories to gain such recognition. The oral care benefits of chewing sugar-free gum are also recognised by the World Dental Federation (FDI), and endorsed by the British Dental Health Foundation.

Professor Liz Kay of Plymouth University Peninsula Schools of Medicine and Dentistry, and co-author of the study says: "The findings of this study are hugely exciting as they reveal a new and easy way of helping people improve their oral health. Crucially, whilst these figures are significant, they refer only to cost reductions for treating 12-year-olds in the UK; if this model was to be applied to the whole population then there is a real potential to create substantial NHS savings. Clinical evidence has already proved that sugar free gum can help prevent caries and now we can also see a clear financial advantage."

Dr Mike Dodds, Lead Oral Health Scientist at Wrigley comments: "This study demonstrates the role that sugar free gum can play in preventing dental decay. Wrigley is committed to supporting people across the UK to improve their oral health through the simple step of chewing sugar free gum after eating and drinking, especially while they're on the go.
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The cost of dental disease in the UK

Each week, more than 1 million patients in the UK use NHS dental services -- many of them seeking treatment for dental disease, the consequences of which costs the NHS a huge £3.4bn a year. A 2013 study showed that 34% of 12-year-olds surveyed in the UK had obvious decay in their permanent teeth, while other studies have demonstrated that poor oral health as a child or adolescent can lead to poor oral health as an adult, creating a potentially vast NHS cost throughout the patient's lifetime, through the replacement of fillings and the implantation of crowns, bridges and prosthetics. A recent survey of hygienists and dentists found that they are most anxious about the state of their paediatric patients' oral health, with hygienists noting that teens were the second group of concern, making these age groups key targets for interventions.

In the UK, official oral care guidance has rarely explicitly mentioned sugar free gum. However the evidence described above suggests that the potential benefits of including sugar free gum in preventative oral health advice should be considered. With the NHS facing a huge funding gap, new solutions -- such as sugar free chewing gum -- need to be considered to help tackle the totally preventable problem of tooth decay.

Oral bacteria linked to risk of stroke

In a study of patients entering the hospital for acute stroke, researchers have increased their understanding of an association between certain types of stroke and the presence of the oral bacteria (cnm-positive Streptococcus mutans). Robert P. Friedland, M.D., the Mason C. and Mary D. Rudd Endowed Chair and Professor in Neurology at the University of Louisville School of Medicine, was a co-author of the study, published online this month in Scientific Reports, a journal of the Nature Publishing Group.

In the single hospital study, researchers at the National Cerebral and Cardiovascular Center in Osaka, Japan, observed stroke patients to gain a better understanding of the relationship between hemorrhagic stroke and oral bacteria. Among the patients who experienced intracerebral hemorrhage (ICH), 26 percent were found to have a specific bacterium in their saliva, cnm-positive S. mutans. Among patients with other types of stroke, only 6 percent tested positive for the bacterium.

Strokes are characterized as either ischemic strokes, which involve a blockage of one or more blood vessels supplying the brain, or hemorrhagic strokes, in which blood vessels in the brain rupture, causing bleeding.

The researchers also evaluated MRIs of study subjects for the presence of cerebral microbleeds (CMB), small brain hemorrhages which may cause dementia and also often underlie ICH. They found that the number of CMBs was significantly higher in subjects with cnm-positive S. mutans than in those without.

The authors hypothesize that the S. mutans bacteria may bind to blood vessels weakened by age and high blood pressure, causing arterial ruptures in the brain, 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," Friedland said. "The study and related work in our labs have shown that oral bacteria are involved in several kinds of stroke, including brain hemorrhages and strokes that lead to dementia."

Multiple research studies have shown a close association between the presence of gum disease and heart disease, and a 2013 publication by Jan Potempa, Ph.D., D.Sc., of the UofL School of Dentistry, revealed how the bacterium responsible for gum disease worsens rheumatoid arthritis.

The cnm-negative S. mutans bacteria is found in approximately 10 percent of the general population, Friedland says, and is known to cause dental cavities (tooth decay). Friedland also is researching the role of oral bacteria in 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."

There are always bacteria lurking in dental equipment, suggests research

Bacteria lurking in the water lines at the dentist's office are tougher than we thought, according to a new paper published in Water Research. The study reveals that the disinfectants recommended by companies that manufacture the water lines don't actually shift all the bacteria in the lines, which means they're never completely clean.

Dental equipment is particularly prone to contamination with bacteria, yeasts and other microbes because it comes into contact with people's mouths. Dentists use dental unit water lines to keep their electrical equipment cool. 

In the new study, researchers from Université de Poitiers in France analyzed three disinfectants used by some European dentists to control biofilms in dental water lines: Calbenium®, Oxygenal 6® and Sterispray®. The team tested how well the disinfectants removed biofilms from dental water lines and found that none of them were completely effective on a polymicrobial biofilm.

"During dental procedures, patients and dentists can be exposed to microorganisms present in the water circulating inside dental units," said Dr. Damien Costa, lead author of the study from Université de Poitiers. "Infections may occur if this potentially microbiologically contaminated water is inhaled or splashed. We wanted to determine the best way to keep dental lines clean and avoid infection." 

There has long been concern about how clean dental lines are, and there have been some - albeit rare - documented cases of them causing infections in people. In 2011, an 82-year-old woman was admitted to hospital with trouble breathing and was diagnosed with Legionnaire's disease, which she had contracted via a contaminated dental water line. She died two days later.

One challenge associated with keeping dental water lines clean is that bacteria can grow in communities with protective layers over themselves, called biofilms. Biofilms can be particularly difficult to prevent and remove even using disinfectants.

Dr. Costa and his colleagues grew biofilms in the laboratory in conditions similar to dental water lines. The biofilms contained several different microbes, to mimic the complex biofilms that form in real lines: the bacterium Pseudomonas aeruginosa, which can cause pneumonia and septic shock, the fungus Candida albicans, which can also cause superficial and severe infections, and free living amoebae Vermamoeba vermiformis. These amoebae can be dangerous - they're known as "Trojan horses" because they carry some bacteria that can infect humans, like Legionella pneumophila, which causes Legionnaire's disease.

All three disinfectants were especially active against the fungus, but none of them were completely effective at clearing the entire biofilm. Calbenium® was most effective at clearing biofilms and stopping new ones from forming, even at concentrations below what the manufacturers recommend. However, it did not kill the free living amoebae.

"Unfortunately, our results showed that none of the three disinfectants commonly used are completely effective," said Dr. Costa. "What is most worrying is that none of the disinfectants could kill the amoebae, which means they are still dangerous to patients and dentists even after water lines have been sterilized."

The researchers say preventing the formation of biofilms as long as possible is key to keeping the lines clean, as once they have formed, they can't be killed using disinfectant. It's difficult to stop biofilms from forming, since microbes naturally cling on to surfaces. However, the research highlighted three approaches to prevention: use good quality water that isn't contaminated with microbes, use a disinfectant for prevention, rather than to remove biofilms that have already formed, and avoid letting water stagnate.