An inexpensive, cavity-fighting liquid called silver diamine fluoride (SDF) works as well as dental sealants to keep tooth decay at bay in a school cavity prevention and treatment programme, according to a new study by researchers at New York University (NYU) College of Dentistry.

The study, which followed more than 4,000 elementary school students for four years and is published in JAMA Pediatrics, shows that SDF is an effective alternative to sealants, and can increase access to dental care while reducing costs.

Dental caries (cavities) is the most prevalent chronic disease in children and can lead to pain, school absences, and lower academic performance. To prevent cavities, especially among children less likely to see a dentist, the Centers for Disease Control and Prevention (CDC) supports the use of school sealant programmes. In sealant programmes, dental professionals visit schools to apply a thin, protective coating to the surface of teeth that hardens and safeguards against decay.

Researchers at NYU College of Dentistry led CariedAway, the nation’s largest school-based cavity prevention study, to compare the use of SDF and traditional sealants. The study included approximately 4,100 children in New York City elementary schools.

At each school visit, either sealants or SDF were applied followed by fluoride varnish. The researchers reported last year in the journal JAMA Network Open that a single treatment of either SDF or a sealant prevented 80% of cavities and kept 50% of existing cavities from worsening two years later. The team continued their study for another two years, and in their study published in JAMA Pediatrics, found that SDF and sealants prevented roughly the same number of cavities after children were followed for a total of four years. Moreover, both sealants and SDF reduced the risk of decay at each follow-up visit.


Oral cancers and precancerous mouth lesions are considered especially difficult to diagnose early and accurately. But a team of researchers, led by a clinician scientist at the Case Western Reserve University (CWRU) School of Dental Medicine in Ohio in the United States, has discovered a non-invasive, low-cost test to detect oral cancer, monitor precancerous lesions and determine when a biopsy is warranted.

Their findings, published the journal Cell Reports Medicine, are based on a scoring system linked to the levels of two proteins in cells brushed from suspicious oral lesions of patients at dental clinics or the ear, nose and throat department at university hospitals (UH).

One of the proteins (hBD-3) is expressed at high levels in early-stage oral cancer, while the second (hBD-2) is low or unchanged. The ratio of hBD-3 to hBD-2 in the lesion site generates a score, called the beta defensin index (BDI). A score above a predetermined threshold implies cancer; anything below does not.

“When we first discovered hBD-3, we saw it acted as a ‘good guy’, involved in wound-healing and killing microbes,” said Aaron Weinberg, chair of the Department of Biological Sciences at the CWR School of Dental Medicine and the study’s lead researcher.

He explained that when they found hBD-3 was regulated the same way certain cells grow uncontrollably, they started studying it in the context of oral cancer: “We found it was not only promoting tumor growth but it was overexpressed in the early stages of the disease, while another member, hBD-2, wasn’t changing. This difference in levels of expression of the two proteins compared to the opposite side in the same patient led us to examine the BDI’s ability to distinguish cancer from benign lesions”.


Researchers at Trinity College Dublin have recovered remarkably preserved microbiomes from two teeth dating back 4,000 years. Genetic analyses of these microbiomes reveal major changes in the oral microenvironment from the Bronze Age to today.

The study, carried out in collaboration with archaeologists from the Atlantic Technological University and the University of Edinburgh, was published Molecular Biology and Evolution. The authors identified several bacteria linked to gum disease and provided the first high-quality ancient genome of Streptococcus mutans, the major culprit behind tooth decay.

While S. mutans is very common in modern mouths, it is exceptionally rare in the ancient genomic record.

The sampled teeth were part of a larger skeletal assemblage excavated from Killuragh Cave, Co. Limerick, by the late Peter Woodman of University College Cork. While other teeth in the cave showed advanced dental decay, no cavities were visible on the sampled teeth. However, one tooth produced an unprecedented amount of S. mutans DNA, a sign of an extreme imbalance in the oral microbial community.

“We were very surprised to see such a large abundance of S. mutans in this 4,000-year-old tooth,” said Dr Lara Cassidy, an assistant professor in Trinity’s School of Genetics and Microbiology, and senior author of the study, “It is a remarkably rare find and suggests this man was at a high risk of developing cavities right before his death”.

The team also found evidence to support the “disappearing microbiome” hypothesis, which proposes modern microbiomes are less diverse than those of our ancestors. This is cause for concern, as biodiversity loss can impact human health.

Very few full genomes from oral bacteria have been recovered prior to the Medieval era. By characterising prehistoric diversity, the authors were able to reveal dramatic changes in the oral microenvironment that have happened since.


Researchers from Japan report that a particular combination of bacteria in our mouths may be responsible for producing some very unpleasant smells. In a study published last month in mSystems, researchers from Osaka University revealed that the interaction between two common types of oral bacteria leads to the production of a chemical compound that is a major cause of bad breath.

Bad breath is caused by volatile compounds that are produced when bacteria in the mouth digest substances like blood and food particles. One of the worst smelling of these compounds is methyl mercaptan (CH3SH), which is produced by microbes that live around the teeth and on the surface of the tongue. However, little is known about which specific bacterial species are involved in this process.

Lead author of the study Takeshi Hara, said: “Most previous studies investigating CH3SH-producing oral bacteria have used isolated enzymes or relatively small culture volumes. In this study, we aimed to create a more realistic environment in which to investigate CH3SH production by major oral bacteria”.

To do this, the researchers developed a large-volume anaerobic co-culture system that enabled them to test interactions between multiple different types of bacteria that live in the mouth.

Masae Kuboniwa, senior author said: “The results were very intriguing. We found that Fusobacterium nucleatum produces large quantities of CH3SH in response to Streptococcus gordonii, another oral bacterium”.

Hara said: “Taken together, these findings suggest that CH3SH production in the mouth is driven by the interaction between S. gordonii and F. nucleatum”.

Understanding how these two bacterial species work together to cause bad breath could be helpful in developing ways to treat or even prevent bad breath.

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Bacteria in the mouth may play a role in survival from idiopathic pulmonary fibrosis (IPF), a serious chronic lung disease, finds a new study led by researchers from the University of Michigan (UM) and the University of Virginia (UV) in the United States.

The findings come from a larger analysis of the role of the lung microbiome and IPF.

Working under the hypothesis that treatment with antibiotics could improve outcomes in patients with the disease, the CleanUP-IPF study includes the collection of cheek swabs and other samples to examine changes in bacterial populations.

Dr David O’Dwyer of the Division of Pulmonary and Critical Care Medicine at UM Medical School, partnering with Drs John Kom and Imre Noth of UV, saw an opportunity to also study the role of the oral microbiome in lung disease, as it is now generally accepted that bacteria from the mouth and throat are a major contributor to the lung microbiome.

Using 16S rRNA analysis and other genetic techniques, the team extracted DNA from the cheek swabs to look for clues.

Surprisingly, they found that one bacterial species, Streptococcus mitis, tended to dominate in certain patients with IPF who were not treated with antibiotics. What’s more, those patients had better lung function and less severe disease – and ultimately, were more likely to survive. To date, research has shown that a more diverse set of bacteria in the lungs and the gut is reflective of better health. That does not hold true for the mouth, however, noted O’Dwyer. Streptococcus mitis tends to act as a gatekeeper toward other bacterial threats, including those that can cause periodontal disease, he said.

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A new report ‘Time to Put Your Money Where Your Mouth Is: Addressing Inequalities in Oral Health’ looks at the need for a joined-up approach between policy, public health initiatives and clinical practice to address the challenges facing oral health.

Published by the European Federation of Periodontology (EFP), in collaboration with Economist Impact, the report investigates the impact of gum disease and tooth decay, and the urgent need to address existing inequalities.

Dr Nigel Carter, Chief Executive of the Oral Health Foundation, was part of the editorial team for the report and believes the shift in understanding oral diseases as preventable non-communicable diseases (NCDs) is crucial: “Neglecting the impact of oral health and its shared risk factors with other NCDs is a missed opportunity for comprehensive healthcare planning. Urgent action is needed to boost public awareness on the relationship between oral health and overall well-being”.

Presented by the EFP in Brussels, the report also expressed concerns that clinical care for tooth decay remains largely focused on a “repair approach”. Analysis found that decades of oral care focus has been placed on reactive, not preventive, measures. It also revealed limited preventive training and inadequate incentives for health professionals.

The report also laid bare the economic burden of oral disease. Direct global treatment costs due to the three most common oral conditions (tooth decay, severe gum disease, and severe tooth loss) were estimated at €330 billion yearly, representing around 5% of worldwide health expenditure.

Economist Impact modelled the cost savings associated with preventive strategies. They found that implementing preventive interventions could reduce rates of tooth decay by as much as 30% while substantially cutting costs.

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Enamel, the hardest and most mineral-rich substance in the human body, covers and protects our teeth. But in one of every 10 people this layer appears defective, failing to protect the teeth properly. As a result, teeth become more sensitive to heat, cold and sour food, and they may decay faster. In most cases, the cause of the faulty enamel production is unknown.

Now, a study by Prof. Jakub Abramson and his team at the Weizmann Institute of Science, published recently in Nature, may shed light on this problem by revealing a new children’s autoimmune disorder that hinders proper tooth enamel development. The disorder is common in people with a rare genetic syndrome and in children with celiac disease. These findings could help develop strategies for early detection and prevention of the disorder.

A strange phenomenon was identified in people with a rare genetic disorder known as APS-1. Although the enamel layer of their milk teeth forms normally, something causes its faulty development in their permanent teeth. Since people with APS-1 suffer from a variety of autoimmune diseases, Abramson and his team hypothesised that the observed enamel defects may also be of an autoimmune nature – in other words, that their immune system could be attacking their own proteins or cells that are necessary for enamel formation.

In their new study, scientists from Abramson’s lab in Weizmann’s Immunology and Regenerative Biology Department, led by research student Yael Gruper, sought to work out how mutations in the Aire gene lead to deficient tooth enamel production.


Viking Age teeth from Varnhem bear witness to surprisingly advanced dentistry. This has been shown in a study carried out at the University of Gothenburg in Sweden. The study examined 3,293 teeth from 171 individuals among the Viking Age population of Varnhem in Västergötland, Sweden.

The site is known for extensive excavations of Viking and medieval environments, including tombs where skeletons and teeth have been preserved well in favorable soil conditions.

The research team from the University of Gothenburg’s Institute of Odontology worked with an osteologist from Västergötland’s Museum.

The teeth underwent clinical examinations using standard dentistry tools under bright light.

A number of X-ray examinations were also performed. The results, which have been published in PLOS ONE, show that 49% of the Viking population had one or more caries lesions. However, children with milk teeth – or with both milk and adult teeth – were entirely caries-free.

Tooth loss was also common among adults. The studied adults had lost an average of 6% of their teeth, excluding wisdom teeth, over their lifetimes. The findings suggest that caries, tooth infections, and toothache were common among the Viking population in Varnhem.

However, the study also reveals examples of attempts to look after teeth in various ways.

Carolina Bertilsson, a dentist and Associate Researcher, and the study’s corresponding author, said: “There were several signs that the Vikings had modified their teeth, including evidence of using toothpicks, filing front teeth, and even dental treatment of teeth with infections”.

One sign of more sophisticated procedures was molars with filed holes, from the crown of the tooth and into the pulp, probably in order to relieve pressure and alleviate severe toothache due to infection.

Carolina continues: “This study provides new insights into Viking oral health, and indicates that teeth were important in Varnhem’s Viking culture. It also suggests that dentistry in the Viking Age was probably more sophisticated than previously thought”.


A new study by investigators from Brigham and Women’s Hospital (BWH) in the US and Harvard Pilgrim Health Care Institute examined whether daily toothbrushing among hospitalised patients is associated with lower rates of hospital-acquired pneumonia and other outcomes. The team combined the results of 15 randomised clinical trials that included more than 2,700 patients and found that hospital-acquired pneumonia rates were lower among patients who received daily toothbrushing compared to those who did not. The results were especially compelling among patients on mechanical ventilation. Their results are published in JAMA Internal Medicine.

Corresponding author Michael Klompas, MD, MPH, hospital epidemiologist and an infectious disease physician in the Department of Medicine at BWH and Professor of Population Medicine at Harvard Pilgrim Health Care Institute, said: “The signal that we see here towards lower mortality is striking – it suggests that regular toothbrushing in the hospital may save lives. It’s rare in the world of hospital preventative medicine to find something like this that is both effective and cheap. Instead of a new device or drug, our study indicates that something as simple as brushing teeth can make a big difference”.

Hospital-acquired pneumonia occurs when bacteria in the mouth enter a patient’s airways and infect their lungs. Patients experiencing frailty or with a weakened immune system are particularly susceptible to developing hospital-acquired pneumonia.

However, adopting a daily toothbrushing regimen can decrease the amount of bacteria in the mouth, potentially lowering the risk of hospital-acquired pneumonia from occurring.

The team conducted a systematic review and meta-analysis to determine the association between daily toothbrushing and hospital-acquired pneumonia.


A study from the University of Minnesota School of Dentistry and published in Clinical Oral Investigations examined the patterns of splatter contamination created by rotary instruments and irrigation during oral surgery. This study is the first to examine rotary instrumentation splatter created during oral surgery procedures, and its findings provide several key suggestions for the future of oral surgery and improving safety measures for both providers and patients.

The study involved an experiment on manikins, otherwise known as patient simulators, in the University of Minnesota’s Oral and Maxillofacial Surgery operatories. Researchers simulated the surgical extraction of four molars in different quadrants with one operator and one assistant with four combinations of operations: saline with a self-irrigating drill; hydrogen peroxide with a self-irrigating drill; saline with hand irrigation; or, hydrogen peroxide with hand irrigation.

A total of 52 procedures were completed and splatter was collected on glass fibre prefilters, which were allowed to dry before being photographed under ultraviolet (UV) light. The study found that the most splatter occurred on the patient’s chest, followed by the assistant’s face shield. The operator’s face shield was also splattered, as were face masks and corners of the operatory. Also, the difference between assistant irrigation and self-irrigating drills was marginally significant, but found that using hydrogen peroxide to irrigate instead of saline increased the area of droplet splatter.

While hydrogen peroxide rinses were used throughout the Covid-19 pandemic as a pre-procedural rinse, this study is the first to report an enhancing effect of irrigation using hydrogen peroxide on the formation of splatter, and suggests that hydrogen peroxide actually increases the risk of spreading droplets when it’s used to irrigate.

The study also offers important insights for the use of personal protective equipment in oral surgery. Given the high level of splatter on the operator and assistant’s face shields, practitioners may consider continuing to use face shields.

The authors suggest further approaches could include additional studies of the effects of irrigants and irrigation methods on viral load and surface stability of viruses, and testing of frequently-touched locations.




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