Coronavirus spread during dental procedures could be reduced with slower drill rotation

IMPERIAL COLLEGE LONDON

Research News

    SHARE

 PRINT  E-MAIL

Dental procedures can pose a high risk of viral transmission because the tools that are used often produce aerosols, which can contain high numbers SARS-CoV-2 virions, copies of the virus causing COVID-19.

The aerosols are generated when saliva mixes with water and air streams used in dental procedures. As a result, access to routine dentistry continues to be limited during the current COVID-19 pandemic.

Dental practices, which are now back in operation, have had to introduce new room decontamination processes and personal protective equipment measures which have dramatically reduced the number of patients that can be treated in a single day. In particular, dentists need to leave long intervals between treatments, leaving rooms unoccupied to allow aerosols to dissipate. This is limiting patient access and challenging financial feasibility for many dental practices worldwide.

Now, researchers at Imperial College London and King's College London have measured and analysed aerosol generation during dental procedures and suggested changes to prevent contamination in the first place to improve safety for both patients and the dental practice workforce.

They suggest that dentists avoid using dental drills that use a mixture of air and water as the abrasion coolants, and carefully select and control drill rotation speeds for those instruments that only use water as a coolant. Parameters have been identified that would allow some procedures such as dental fillings to be provided whilst producing 60 times fewer aerosol droplets than conventional instrumentation.

Lead author Dr Antonis Sergis of Imperial's Department of Mechanical Engineering said: "Aerosols are a known transmission route for the virus behind COVID-19, so, with our colleagues at King's, we have tested suggested solutions that reduce the amount of aerosols produced in the first place. These could help reduce the risk of transmission during dental procedures."

Co-author Professor Owen Addison of King's College London's Faculty of Dentistry, Oral & Craniofacial Sciences said: "This important work describes the basic mechanisms that lead to the features of dental aerosols that we currently consider to be high risk. This has enabled us to choose drill parameters to keep our patients and the dental team safe at this difficult time. Although we cannot provide every procedure, because slowing our drills is much less efficient, we now have the basis to do more than we have done in the last 6 months."

The results are published today in Journal of Dental Research and are already being included as evidence in guides for dental practices in the UK during the pandemic. The collaborative research used the engineering expertise at Imperial and clinical expertise at King's College London's Faculty of Dentistry, Oral & Craniofacial Sciences.

The researchers used dental clinical rooms at Guy's Hospital in London to test how aerosols are generated during procedures such as decay removal, applying and polishing fillings and adjusting prostheses. They measured the aerosol generation using high speed cameras and lasers. They then used these findings to suggest modifications.

They found that using air turbine drill types, which are the most common type of dental drill, creates dense clouds of aerosol droplets that spread as fast as 12 metres per second and can quickly contaminate an entire treatment room. Just one milliliter of saliva from infected patients contains up to 120 million copies of the virus, each having the capacity to infect.

They tested a different type of drill, known as high torque electric micromotor, with and without the use of water and air streams. They found that using this drill type at low speeds of less than 100,000 rpm without air streams produced 60 times fewer droplets than air turbine drill types.

In addition, they found that aerosol concentration and spread within a room is dependent on the positioning of the patient, presence of ventilation systems, and the room's size and geometry. It is also influenced by the initial direction and speed of the aerosol itself, which can be affected by the type of cutting instrument (burr), and the amount and type of cooling water used.

The researchers say that by understanding how to reduce the amount of aerosol generated in the first place, their suggestions could help dentists practice more and help patients get the treatment they need.

They also note that patients should still not attend dental appointments if they have symptoms of COVID-19.

Professor Owen Addison from King's said: "Because of the COVID-19 pandemic, dentistry has become a high-risk practice - but the need for treatments hasn't gone away. Our suggestions could help begin to open up dentistry to patients once again."

Their suggestions have been included in the evidence appraisal in dentistry document entitled "Rapid Review of Aerosol Generating Procedures in Dentistry", published by the Scottish Dental Clinical Effectiveness Programme (SDCEP). The results from the study have also been considered by an expert task force convened by the Faculty of General Dental Practice (FGDP (UK)) and the College of General Dentistry and published in their guide entitled "Implications of Covid-19 for the safe management of general dental practice."

Co-author Professor Yannis Hardalupas of Imperial's Department of Mechanical Engineering said: "The impact of the results is significant. For example, the risk categorisation for dental procedures included in the FGDP (UK) document was certainly influenced by our work."

The team's research is ongoing. They are currently better assessing the risk of infection by quantifying the amount of saliva mixed into the generated aerosols by dental instruments.

Alterations to oral microbiota reduce the cardiovascular benefits of sport

Research by the University of Plymouth in conjunction with the UOC assesses the factors that determine the composition of buccal bacteria

UNIVERSITAT OBERTA DE CATALUNYA (UOC)

Research News

    SHARE

 PRINT  E-MAIL

IMAGE: SPORTSMEN CONSUME A LOT OF DRINKS CONTAINING SUGAR AND ACID THAT CAN AFFECT ORAL HEALTH AND THE ABUNDANCE OF BACTERIAview more 

CREDIT: PHOTO: NIGEL MSIPA/UNSPLASH

Exercise plays a key role in maintaining good physical and mental health throughout life. There is an increasing amount of scientific evidence that some of the immune system and metabolism benefits provided by sport are related to the thousands of millions of bacteria that colonize the digestive tract, from the mouth to the intestines, known as microbiota. Although most studies in this field have traditionally focused on the microorganisms present in the intestine, in recent years it has been found that the bacteria in the mouth, the second most complex microbiome in the body, after the intestine, also play an important role.

Researchers from the University of Plymouth (United Kingdom) and the Universitat Oberta de Catalunya (UOC) have carried out research and assessed the scientific evidence available regarding the impact of physical exercise on the oral cavity, especially on saliva buccal microbiota, and they have published part of the results in the journal PharmaNutrition.

"The majority of bacteria in the mouth are essential for us to be healthy. Only a minority produce illnesses such as caries or periodontitis," the researchers point out in the study. "In fact, previous studies have shown that if you inhibit the activity of the bacteria in the mouth, the cardiovascular benefits of sport are reduced," said Raúl Bescós, professor of Physiology at the University of Plymouth and first author of the study.

"There were indications of the connection between sport and oral microbiota, but also a lot of gaps, which is why we wanted to review what impacted on oral microbiota and how that could affect the benefits of sport," he added.

Diet, a key factor

Recent studies have verified the relationship between the consumption of nitrates - present in leafy green vegetables such as rocket, broccoli and spinach, and also in beetroot - and sporting performance and cardiovascular health.

The study led by Bescós with the assistance of Patrícia Casas-Agustench, professor at the UOC Faculty of Health Sciences and associate researcher at the University of Plymouth, indicates that the nitrate is a molecule that we either consume in food or produce endogenously during physical activity. It acts as a nutrient for the bacteria in the mouth, which then convert it into nitrite. This nitrite can be used in the stomach and blood vessels, increasing the flow of blood to the muscles and reducing blood pressure.

This is why leading sports clubs such as FC Barcelona ensure that the diets of their players include foods rich in nitrates. Paradoxically observational studies suggested that the prevalence of oral disorders, including dental erosion, caries and periodontitis, among elite athletes is similar to or greater than it is among the general population. And it was felt that the reason could be related to diet and hydration.

"Sportsmen consume a lot of drinks containing sugar and acid that can affect oral health and the abundance of bacteria. They also consume a lot of carbohydrates, including products with a lot of sugar like energy bars and gel, that can alter the microbiota in the mouth," said Casas-Agustench, co-author of the study. The most notable results of these studies were presented during the #SportsTomorrow conferences organized by Barça Innovation Hub.

As well as diet, other factors must be taken into account, such as dehydration or dryness of the mouth, occurring when athletes run or cycle, that can affect the diversity and abundance of oral microbiota and reduce protection for the teeth. "Some athletes often vomit as a result of the anxiety they feel before competing or during competitions because of the effort they are making, and that leads to alterations to the pH level in their mouths, erodes the enamel and alters the composition of the bacteria," she added.

Antibacterial mouthwash, only with a doctor's prescription

Another factor that has also been seen to have a negative effect on the composition and balance of oral microbiota is the use of antibacterial mouthwashes, like those containing chlorhexidine, when not prescribed by a doctor. "They inhibit the bacteria in the mouth and it has been observed that when chlorhexidine is used, the positive effects of exercise on blood pressure are drastically reduced," said Bescós, who reminded us that "oral microbiota is essential in the cardiovascular response to physical exercise. If the mouth is healthy, the bacteria help to break the nitrates down into nitrites. Otherwise, we lose much of the benefit of exercise".

The researchers also point out that there is a close relationship between oral and intestinal microbiomes, as detailed in various recent studies. We swallow nearly a litre of saliva every day and this contains a large amount of oral bacteria. Many are destroyed by the acids in the stomach but some can resist and reproduce there, a case in point being Helicobacter pylori, which causes stomach ulcers. Others can reach the colon, which they can colonize and where they will reproduce. As a result, according to Bescós and Casas-Agustench, oral health can affect intestinal health and vice versa.

The importance of chewing

"The best way to look after oral microbiota and improve sporting performance and cardiovascular health is to eat more vegetables that are rich in nitrates, but also to chew more. It helps you to salivate, and saliva is essential for regulating the pH in the mouth, and the composition and activity of bacteria in the mouth. So, products rich in fibre, like fruit, vegetables and nuts should be included in your diet," Bescós and Casas-Agustench advised.

How poor oral hygiene may result in metabolic syndrome

 

TOKYO MEDICAL AND DENTAL UNIVERSITY

Research News

    SHARE

 PRINT  E-MAIL

IMAGE: ANTI-PORPHYROMONAS GINGIVALIS ANTIBODY TITERS POSITIVELY CORRELATED WITH INTRAMUSCULAR ADIPOSE TISSUE CONTENT IN METABOLIC SYNDROME PATIENTS. ADMINISTRATION OF P. GINGIVALIS IMPAIRED GLUCOSE TOLERANCE AND INSULIN RESISTANCE, ALTERED THE GUT MICROBIOME. SKELETAL... view more 

CREDIT: DEPARTMENT OF PERIODONTOLOGY,TMDU

Researchers from Tokyo Medical and Dental University (TMDU) identify a novel mechanism by which periodontal disease may cause diabetes

Tokyo, Japan - Periodontal or gum disease is known to be a significant risk factor of metabolic syndrome, a group of conditions increasing the risk for heart disease and diabetes. In a new study, researchers from Tokyo Medical and Dental University (TMDU) discovered that infection with Porphyromonas gingivalis, the bacterium causing periodontal disease, causes skeletal muscle metabolic dysfunction, the precursor to metabolic syndrome, by altering the composition of the gut microbiome.

Periodontal bacteria have long been known to cause inflammation within the oral cavity, but also systemically increase inflammatory mediators. As a result, sustained infection with periodontal bacteria can lead to increases in body weight and lead to increased insulin resistance, a hallmark of type 2 diabetes. The function of insulin is to help shuttle glucose from the blood into tissues, most importantly to skeletal muscle, where one quarter of all glucose in stored. Unsurprisingly, insulin resistance plays a key role in the development of metabolic syndrome, a group of conditions including obesity, altered lipid metabolism, high blood pressure, high blood glucose levels, and systemic inflammation. Although skeletal muscle plays a key role in decreasing blood glucose levels, a direct connection between periodontal bacterial infection and the metabolic function of skeletal muscle has not been established yet.

"Metabolic syndrome has become a widespread health problem in the developed world," says first author of the study Kazuki Watanabe. "The goal of our study was to investigate how periodontal bacterial infection might lead to metabolic alterations in skeletal muscle and thus to the development of metabolic syndrome."

To achieve their goal, the researchers first investigated antibody titers to Porphyromonas gingivalis in the blood of patients with metabolic syndrome and found a positive correlation between antibody titers and increased insulin resistance. These results showed that patients with metabolic syndrome were likely to have undergone infection with Porphyromonas gingivalis and thus have mounted an immune response yielding antibodies against the germ. To understand the mechanism behind the clinical observation, the researchers then turned to an animal model. When they gave mice that were fed a high-fat diet (a pre-requisite to developing metabolic syndrome) Porphyromonas gingivalis by mouth, the mice developed increased insulin resistance, and fat infiltration and lower glucose uptake in the skeletal muscle compared with mice that did not receive the bacteria.

But how was this bacterium capable of causing systemic inflammation and metabolic syndrome? To answer this question, the researchers focused on the gut microbiome, the network of bacteria present in the gut and with which the organism co-exists symbiotically. Intriguingly, the researchers found that in mice administered with Porphyromonas gingivalis the gut microbiome was significantly altered, which might decrease insulin sensitivity.

"These are striking results that provide a mechanism underlying the relationship between infection with the periodontal bacterium Porphyromonas gingivalis and the development of metabolic syndrome and metabolic dysfunction in skeletal muscle," says corresponding author of the study Professor Sayaka Katagiri.

Reversible stickiness is something to smile about

    SHARE

 PRINT  E-MAIL

IMAGE: TO FACILITATE THE DEBONDING OF DENTAL RESTORATIVE MATERIALS ADHERED ON TOOTH SURFACES, UV LIGHT-EMBRITTLED DENTAL RESIN CEMENT CONTAINING PHOTODEGRADABLE POLYROTACANE (PRX) CROSS-LINKERS WAS DEVELOPED. PRX IS A SUPRAMOLECULAR INTERLOCKED POLYMER... view more 

CREDIT: DEPARTMENT OF ORGANIC BIOMATERIALS,TMDU

Tokyo Medical and Dental University (TMDU) researchers report a cross-linker for dental cement that breaks down under UV light, making treatments easier to reverse.

Tokyo - Everyone who has had tooth cavities filled knows that the best dental materials stay where the dentist puts them. The adhesion of currently available dental materials to tooth surfaces continues to improve, but what about short-term treatments that are not supposed to adhere indefinitely? TMDU researchers have developed a method of making dental materials easier to remove; their findings are published in ACS Applied Polymer Materials.

The continual improvement of long-lasting caries treatments can be regarded a triumph of dental material research. However, there are dental procedures that require non-permanent adhesion to the tooth surface, such as the fixing of orthodontic brackets. Removing adhered materials after such procedures generally requires mechanical detachment that can damage tooth enamel.

Efforts to improve removal processes have produced materials that are weakened by triggers, such as heat or electric currents. However, approved sources of these stimuli are not readily available in standard dental clinics. The researchers therefore focused on UV light-responsive materials that can be triggered by the UV sources widely used by dentists to cure resin cements and composites.

The toughness of many dental cements is a result of mixing them with a cross-linker that locks the cement molecules to each other to form a stable network. The researchers have introduced a chemical 'switch' into a new cross-linker that opens when UV light is shined on it.

"The cross-linker structure resembles rings threaded onto a piece of string with bulky stoppers at each end," study lead author Atsushi Tamura explains. "We have added a section to the string--an o-nitrobenzyl ester group--that breaks under UV light causing the rings to slide off. This has a significant effect on the stability of the cement material the cross-linker is holding in place."

The researchers used their cross-linker to stabilize a commercially available resin cement that was used to stick two polymer blocks together, or to attach a polymer block to a bovine tooth. After shining UV light on the cross-linked cement for just 2 minutes, the cement showed a significant reduction in adhesion strength in both tests, meaning separation of the bonded materials was easier following UV treatment.

"We are very encouraged by the initial findings using our cross-linker," study corresponding author Nobuhiko Yui explains. "Although the UV wavelength used to disrupt the material was not clinically appropriate in this case, we intend to develop the chemistry of our internal switch so that it can provide a facile and readily accessible method of removing adhesives in the clinic."

The article, "Light-Embrittled Dental Resin Cements Containing Photodegradable Polyrotaxane Cross-Linkers for Attenuating Debonding Strength", was published in ACS Applied Polymer Materials (DOI: https://doi.org/10.1021/acsapm.0c01024).

At the same time, the article was selected to be featured as ACS (American Chemical Society) Editors' Choice (on 25th November, 2020) based on recommendations by ca. 70 ACS journals' editors due to its potential for broad public interest, an honor given to only one article from the entire ACS portfolio each day of the year.

Link between periodontitis and cardiovascular disease in individuals with rheumatoid arthritis

Rates of both periodontal disease and cardiovascular disease are elevated in individuals with rheumatoid arthritis. New research published in Arthritis & Rheumatology suggests that immune responses to certain bacteria that cause periodontal disease may play a role in patients' higher cardiovascular disease risk.

Among 197 patients with rheumatoid arthritis, those with antibody responses to common periodontal pathogens were more likely to also show signs of atherosclerosis.

"Evidence of exposure to a particular periodontal pathogen called Aggregatibacter actinomycetemcomitans had the strongest associations with atherosclerosis in the patients with rheumatoid arthritis that we studied," said lead author Jon T. Giles, MD MPH, of Columbia University. "Moreover, it was associated with measures of coronary, carotid, and peripheral atherosclerosis, over and above other risk factors for atherosclerosis. Further studies are needed to determine if eliminating exposure to this pathogen might modify the increase in cardiovascular disease known to be part of rheumatoid arthritis."

A reason for early deterioration of dental implants

 

    SHARE

 PRINT  E-MAIL

IMAGE: A TEAM OF DENTISTS FROM RUDN UNIVERSITY CONFIRMED THAT A CHANGE IN THE DOMINANT SIDE OF CHEWING IS A REASON FOR THE EARLY DETERIORATION OF DENTAL IMPLANTS. SUCH A CHANGE... view more 

CREDIT: RUDN UNIVERSITY

A team of dentists from RUDN University confirmed that a change in the dominant side of chewing is a reason for the early deterioration of dental implants. Such a change makes it more difficult for a patient to get accustomed to an implant and can lead to bone tissue abnormalities. The discovery can help dentists plan the recovery process after implantation surgeries. The results of the study were published in the European Journal of Dentistry.

Every year, around 2 mln dental implants with fixed dentures attached to them are installed all over the world. An implant is an effective way to restore a deformed or lost tooth without negatively affecting a patient's quality of life. Modern-day dental implants, usually made of titanium, are durable and quick to take in the bone tissue of a jaw. The only issue with them is their early deterioration in 4-5% of patients. Such deterioration is caused by microdamage that occurs when the load on the implant is calculated incorrectly before the surgery. Excessive load affects the junction between the metal and the bone, letting the bacteria in under the implant and causing inflammation. A team of dentists from RUDN University suggested that additional load on the implant might occur when a patient changes the dominant side of chewing in the first months after the surgery.

Most people don't chew symmetrically on both sides of the jaw but have a dominant side that accounts for up to 75% of chewing movements. However, such a side can be changed, for example, because of a sore tooth. It usually takes a patient 3 to 4 months to get accustomed to a dental implant and during this time the type of chewing and the load on the teeth can change. As a result, after the surgery, a patient can switch to a different side of chewing, and load calculations from before the surgery can become invalid. Until recently, the effect of this dramatic change in chewing habits on the state of dential implants remained understudied.

The team monitored the course of rehabilitation of 64 patients with dental implants. The participants of the study were adults with implants installed only on one side of the jaw. Surgeries on both sides of the jaw were not included in the study as they would not allow for measuring the effect of dominant chewing side change. The team took X-ray images of the participants' teeth, measured the strength of their chewing muscles, and in some cases took CT images of the jaws. All these operations were conducted once before the surgery and twice within a year after it. To analyze the results of the treatment, the team asked the participants to fill in questionnaires.

40 patients (62.5%) reported changes in the dominant side of chewing after the surgery. According to the dentists, this might have happened because the patients returned to the chewing patterns they had been used to earlier, before losing a tooth. Having compared this group with the rest of the patients that reported no changes in their chewing habits, the team found out that a change of the dominant side of chewing leads to more bone tissue formation pathologies. In 4 patients with changed chewing habits, the first signs of issue deterioration around the implant were visible in X-ray images. As for the second group, these signs were identified in only one participant. Six months after the surgery the patients that changed their dominant side of chewing felt 22% less adapted to the implants than the patients with no changes in their chewing patterns.

"A change in the dominant side of chewing is an important factor in one's adaptation to dental implants. According to our study, it can also be the reason for pathological processes, eventually leading to the loss of an implant. Dentists need to be aware of the prevalence of such changes, consider them when developing postsurgical rehabilitation plants, and look for their signs during regular checkups," said Prof. Igor Voronov, MD, from the Department of Orthopedic Dentistry, RUDN University.

Most dentists have experienced aggression from patients

NYU study is first to describe rates of physical, verbal, and reputational aggression by patients toward practicing dentists

Roughly half of U.S. dentists experienced verbal or reputational aggression by patients in the past year, and nearly one in four endured physical aggression, according to a new study led by researchers at NYU College of Dentistry.

The study, published in the October issue of the Journal of the American Dental Association, is the first to document aggression toward dentists in the United States.

Workplace aggression toward health care professionals is common, with health care settings second only to law enforcement in the rate of violent incidents. However, there are no studies of aggression toward dentists in the U.S.--a workforce of 200,000--and only four studies have been conducted in other countries.

"Workplace violence toward health care professionals is both widespread and widely overlooked," said Kimberly Rhoades, a research scientist in the Family Translational Research Group at NYU College of Dentistry and the study's lead author. "The purpose of this study was to provide an initial estimate of rates of patient aggression in dental practices in the United States."

Rhoades and her colleagues surveyed 98 dentists practicing in the New York City metropolitan area; the dentists had been working an average of 17 years. Participants completed a confidential online survey assessing whether they had experienced any of 21 specific types of aggressive behaviors from their patients, including types of physical (e.g. being pushed or kicked), verbal (e.g. being insulted or sworn at), and reputational (e.g. threats of lawsuits or posting nasty comments on social media) aggression.

A substantial proportion of dentists reported experiencing aggression from patients in the past year, including physical (22.2%), verbal (55%), and reputational (44.4%) aggression. An even larger proportion of dentists surveyed were subjected to physical (45.5%), verbal (74%), and reputational (68.7%) aggression at some point during their career. These rates of patient aggression toward dentists are high and comparable with those reported in other health care settings.

Rates of aggression did not differ by dentists' sex, race, ethnicity, specialty, age, years practicing, or average number of patients treated per day.

The rates of physical and reputational aggression toward dentists were similar to those from a parallel study by NYU researchers of aggression toward dental students published earlier this year in the Journal of Dental Education. However, practicing dentists experienced less verbal aggression from patients than dental students (55% versus 86%), suggesting that additional experience may reduce the risk of verbal aggression.

"Dentistry is rife with situations that can elicit strong negative emotions, such as fear, pain, distrust, and anger. Many patients also experience high levels of anxiety and vulnerability, which may increase negative responses or aggression," said Rhoades. "Establishing that aggression toward dentists is a problem and how often it occurs can help us develop interventions to prevent aggression in dental practices."

The researchers note that, while a larger, national study is needed to determine the true prevalence of aggression in U.S. dental settings, dental practices should consider implementing training that incorporates strategies for handling workplace violence. Training could address how to prevent patient aggression, and manage or de-escalate aggression when it does occur.

Mechanism linking gum disease to heart disease, other inflammatory conditions discovered

Researchers at the University of Toronto have found first evidence that neutrophil immune cell activity is the missing link connecting periodontal disease with heart disease, cancer, and other inflammatory conditions

UNIVERSITY OF TORONTO - FACULTY OF DENTISTRY

Research News

    SHARE

 PRINT  E-MAIL

IMAGE: NEUTROPHIL ACTIVATION IS NOW BELIEVED TO BE AT THE ROOT OF OVERACTIVE INFLAMMATORY RESPONSES, AND LINKS CONDITIONS SUCH AS PERIODONTAL DISEASE AND HEART DISEASE view more 

CREDIT: NOAH FINE

(TORONTO, ON) Oct. 20, 2020 -- The link between periodontal (gum) disease and other inflammatory conditions such as heart disease and diabetes has long been established, but the mechanism behind that association has, until now, remained a mystery. This month, a team of scientists and clinicians led by the University of Toronto's Faculty of Dentistry say they've found the reason why -- and it's related to the body's own hyperactive immune response. The findings were published in October in the Journal of Dental Research.

HYPERACTIVE STATE

Science has already established that state of your oral health is an important indicator of overall health. "There are statistically significant correlations between periodontitis (oral inflammatory disease) and systemic diseases ranging from diabetes to cardiovascular diseases," says Howard Tenenbaum, professor at the University of Toronto's Faculty of Dentistry, and chief dentist at Sinai Health Systems in Toronto, who is one of the authors of the study.

To find what links those conditions, the researchers focused on the behaviours of cells primarily activated by gum disease -- neutrophils, which are cells of the innate immune system. Through in vivo models, the researchers found that the immune system releases an abundance of these neutrophils to tackle the bacterial infections responsible for periodontitis, more commonly known as gum disease.

Activated to fight an oral infection, a systemic effect was noted: once periodontal inflammation was present, an overabundance of neutrophils circulated, 'primed' for attack. The hyper-vigilant immune system then responds with an excess of force to any secondary infection.

"It's almost as if these white blood cells are in second gear when should be in first," says Michael Glogauer, professor at the University of Toronto's Faculty of Dentistry and the study's senior author.

That's when the body becomes susceptible to damage from secondary inflammatory conditions. With the immune system already primed by the neutrophils for attack, a secondary event causes those immune cells to destroy affected tissues and organs.

"The [neutrophils] are much more likely to release cytokines much more quickly, leading to negative outcomes," adds Glogauer, who is also dentist-in-chief at the University Health Network and head of dental oncology at Toronto's Princess Margaret Cancer Centre.

Produced initially in in vivo models, the findings were confirmed through a controlled clinical experiment.

ORAL HEALTH KEY TO OVERALL HEALTH

The study's findings underscore the importance of oral health as a vital indicator of potential complications for other inflammatory conditions, as well as disease model outcomes.

"We believe this is the mechanism by which oral hygiene can impact vulnerability to unrelated secondary health challenges," says lead author Noah Fine, a postdoctoral fellow at the University of Toronto's Faculty of Dentistry. "Neutrophil (immune) priming throughout the body can connect these seemingly distinct conditions," he says.

The study also may have important ramifications for an inflammatory disease at the top of everyone's mind these days: COVID-19.

"There is evidence out there that patients with periodontal disease may be much more likely to have negative outcomes with COVID-19," explains Glogauer. The current study could provide some clues as to why: "Neutrophils are the cells that are at prime risk of causing cytokine storms. That's the exact cell we show is primed with people with periodontal disease," he explains.

Research into the relationship between neutrophils and inflammation is ongoing.