Reducing COVID-19 risk during dentist appointments

 

IMAGE: RESEARCHERS SIMULATED DENTAL TREATMENTS IN A REAL SURGERY USING A HARMLESS VIRUS TO TRACK THE SPREAD OF AEROSOLS IN THE AIR AND ON SURFACES view more 

CREDIT: UNIVERSITY OF LEEDS

Dentists could significantly increase the number of patients they see during the pandemic by switching the drills they use, according to new research. 

The study investigated whether different drill types increased or reduced the spread of aerosol spray in a dental surgery. Reducing aerosol spray results in a safer environment for patients and the dental team. 

The findings show that the time taken to prepare safe surgeries between appointments could be radically reduced by changing drills, potentially resulting in millions more treatments being carried out. 

The study, led by the University of Leeds, compared the aerosol patterns produced by dental drills rotated by air streams - that are most commonly used by UK dentists - to those produced by electric powered drills. 

Instead of simply mapping the spread of water spray during treatment, the research team instead introduced a virus that is similar in size and structure to the SARS-CoV-2 virus that causes COVID-19. 

Their results show that by replacing the high-speed air drills with lower speed electric drills, aerosol spray was virtually eliminated, creating a safer environment for both patients and the dental team. 

The research, funded by the British Endodontic Society, is published in the Journal of Dental Research. 

Lead clinical author Professor Brian Nattress, from Leeds’ School of Dentistry, said: “The issue for dentists during the coronavirus pandemic is that their routine work involves creating an aerosol spray in a confined space with an associated risk of airborne spread of COVID-19. 

“This is the first time the spread of a harmless COVID-19-like virus has been analysed during routine drilling procedures. 

“If the spread of that aerosol spray can be reduced or eradicated, that has enormous, positive implications for how dentists can go about their daily business not just during the coronavirus pandemic, but also during future virus outbreaks.” 

During the first national lockdown in England between March and June 2020, all dental surgeries were closed. 

Since reopening, because patients may be asymptomatic carriers of the SARS-CoV-2 virus when attending a dentist appointment, strict regulations have been introduced to ensure work areas are safe and prepared appropriately between appointments. Additional protective measures have been required for the dental team delivering patient care. This has led to much longer gaps between treating patients.  

Before the pandemic, about 18 million adults and children attended an NHS dental appointment each year in England. 

Reports by charity HealthWatch point to a growing backlog of patients waiting to see a dentist, with fears this could rise as the SARS-CoV-2 virus is expected to remain prevalent in the general population for many months more. 

Adjustments to the pandemic measures require high quality evidence to show how dentists can reduce the risk of spreading the SARS-CoV-2 virus when carrying out aerosol generating procedures (AGPs) during dental treatments. 

During the new research tests, use of the electric drill rather than an air drill led to a 99.98% reduction in aerosol spread of the virus into the air. 

When a dental suction tool was added, there was no detectable virus on surfaces or in air samples taken six to 10 minutes afterwards. 

The new research was carried out by the School of Dentistry, School of Civil Engineering and the Leeds Dental Institute. 

The research team set up simulated dental treatments in a real surgery scenario and - for the first time ever - used a harmless virus to track the spread of aerosols in the air and on surfaces. 

A dummy head and simulated saliva were used to measure the difference between the level of aerosols generated using a conventional air-driven dentist’s drill and a more modern electric hand piece. 

Professor David Wood, Director of Research and Innovation in the School of Dentistry, is co-author of the report. 

He said: “This robust scientific evidence addresses how the risks associated with the spread of the SARS-CoV-2 virus via dental drills can be successfully managed. 

“The recommendation we make in the report will help more people access the dental care they need, but haven’t been able to get since early 2020.” 

In light of the many restraints placed on dentists globally since the beginning of the pandemic, the research team is calling for further and essential studies to find different strategies to control the spread of dental aerosols and help to reduce the backlog of patients. 

Further information 

“Dental mitigation strategies to reduce aerosolization 1 of SARS-CoV-2”, is published in the Journal of Dental Research. 

DOI: https://doi.org/10.1177/00220345211032885 

Images and video copyright University of Leeds 

Image caption: Researchers simulated dental treatments in a real surgery using a harmless virus to track the spread of aerosols in the air and on surfaces 

Video caption: Difference in aerosol spray of a conventional air-driven dental handpiece (left) vs an electric handpiece (right) 

For further details, contact the University of Leeds press office via pressoffice@leeds.ac.uk. 

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JOURNAL

Journal of Dental Research

DOI

10.1177/00220345211032885 

Social isolation among older adults linked to having fewer teeth

Older adults who are socially isolated are more likely to have missing teeth—and to lose their teeth more quickly over time—than those with more social interaction, according to a new study of Chinese older adults led by researchers at NYU Rory Meyers College of Nursing. The findings are published in Community Dentistry and Oral Epidemiology. 

 

“Our study suggests that maintaining and improving social connections may benefit the oral health of older adults,” said Xiang Qi, a PhD student at NYU Meyers and the study’s first author. “The findings align with previous studies demonstrating that structural indicators of social disconnection can have powerful effects on indicators of health and well-being.”

 

Social isolation and loneliness in older adults are major public health concerns around the world and are risk factors for heart disease, mental health disorders, cognitive decline, and premature death. In some countries, including the United States and China, up to one in three older adults are lonely, according to the World Health Organization. The COVID-19 pandemic has exacerbated these issues among older adults, as many in-person interactions have been interrupted to protect older adults from infection.

 

Social isolation and loneliness are related but different. Social isolation is an objective measure defined as having few social relationships or infrequent social contact with others, while loneliness is the feeling created by a lack of social connection. 

 

“While social isolation and loneliness often go hand in hand, it’s possible to live alone and be socially isolated but to not feel lonely, or to be surrounded by people but still feel lonely,” said Bei Wu, Dean's Professor in Global Health at NYU Meyers and the study’s senior author.

 

Older adults are also at risk for another health concern: losing teeth. In China, older adults aged 65 to 74 have fewer than 23 teeth on average (adults typically have 32 teeth, or 28 if wisdom teeth have been removed) and 4.5% of this age group has lost all of their teeth. Gum disease, smoking, lack of access to dental care, and chronic illnesses like diabetes and heart disease increase the risks of tooth loss. Missing teeth can have a significant impact on one’s quality of life, affecting nutrition, speech, and self-esteem. 

 

To understand the relationship between social isolation, loneliness, and tooth loss in older adults in China, the researchers used the Chinese Longitudinal Healthy Longevity Survey to analyze data from 4,268 adults aged 65 and up. The participants completed surveys at three different timepoints (2011-12, 2014, and 2018), which captured measures of social isolation and loneliness, how many teeth people had and lost over the 7-year study, and other factors. More than a quarter (27.5%) of the study participants were socially isolated, and 26.5% reported feeling lonely.

 

The researchers found that higher levels of social isolation were associated with having fewer teeth and losing teeth more quickly over time, even when controlling for other factors such as oral hygiene, health status, smoking and drinking, and loneliness. Older adults who were socially isolated had, on average, 2.1 fewer natural teeth and 1.4 times the rate of losing their teeth than those with stronger social ties.

 

“Socially isolated older adults tend to be less engaged in social and health-promoting behaviors like physical activity, which could have a negative impact on their overall functioning and oral hygiene, as well as increase their risk for systemic inflammation,” said Wu. “This functional impairment seems to be a major pathway linking social isolation to tooth loss.”

 

Surprisingly, loneliness was not associated with the number of remaining teeth, nor with the rate of tooth loss.

 

“While social isolation can result in a lack of support that can affect health behaviors, for older adults who feel lonely, it’s possible that their social networks are still in place and can help them to keep up healthy behaviors,” said Qi.

 

The findings—which are relevant to countries beyond China, given that social isolation and tooth loss are global issues—highlight the importance of developing interventions to reduce social isolation. Programs could aim to foster intergenerational support within families and improve older adults' peer and social connections within their local communities. 

Feeding mode of newborns could influence oral bacteria makeup

After birth, the human mouth quickly becomes a hotbed of microbial variation. Streptococcus species largely dominate the oral cavity for the first 6 weeks of life, but the bacterial population diversifies with age and experience. Researchers study this early development, in part, to understand connections between the oral microbiota and associated diseases.

An infant’s mother is likely a major source—if not the most important one—of the early oral microbiota. This week in mBio, dental researchers in Japan report a new analysis of how new mothers share microbes with newborns. The researchers collected 892 tongue samples from 448 pairs of moms and babies (217 males, 231 females), collected when the children were 4 months old, to measure bacterial abundance and, more specifically, the abundance of single, unique DNA sequences, called amplicon sequence variants (ASV), shared between mother and child.
 
Shared ASVs in newborns ranged from almost none to almost 100%, said Yoshihisa Yamashita, Ph.D, at Kyushu University in Japan, senior author of the study. “The acquisition level of maternal oral bacteria varied widely among individuals,” he said. The median relative abundance of ASV that newborns shared with their mothers, however, was 9.7%, which the researchers noted was significantly higher than the abundance of ASVs newborns shared with other, unrelated mothers. The study was led by Shinya Kageyama, Ph.D, also at Kyushu University. 
 
Notably, the shared abundance and composition varied significantly by how the infant fed. Infants who breastfed exclusively shared fewer ASVs with their mothers than infants fed exclusively with formula or fed with some combination of breastfeeding and formula. Breastfed infants also had a bacterial composition most unrelated to the mother’s compared to other groups. The researchers found no difference in abundance linked to the age, sex, delivery mode, family smoking status or antibiotic use of the infants.

The researchers offered 2 hypotheses to explain the difference. “One is that protective factors of breast milk regulate mother-derived oral bacterial colonization,” said Yamashita. The second is that the different substrates provided by formula and breast milk influence the balance of bacteria in the mouth.

Unlike previous studies that have reported shared microbes between mothers and infants, the new work includes a full-length analysis of all 9 hypervariable regions in the 16s rRNA gene. In addition, the authors noted that the ASV approach allows for the identification of DNA sequences that differ by as little as a single nucleotide.

At Kyushu University, the researchers focus on connecting early-life oral microbiota to the risk of disease later in life. Previous studies have linked certain bacteria to cavities in the teeth and periodontitis. More recent research, however, has also reported that microbes usually found in the mouth show up in the gut in people with serious conditions ranging from liver cirrhosis to inflammatory bowel disease to colorectal cancer.

The new findings, said Yamashita, are “vital as a foundation for further studies.” The group plans to follow the same study population, with the next examination of the oral microbiota and clinical conditions set for the infants’ 3-year checkups. 

Bacteria that cause periodontal disease reduce oral defense and increase viral growth

Researchers from the University of Louisville School of Dentistry and their colleagues have discovered details of how proteins produced by oral epithelial cells protect humans against viruses entering the body through the mouth. They also found that oral bacteria can suppress the activity of these cells, increasing vulnerability to infection.

A family of proteins known as interferon lambdas produced by epithelial cells in the mouth serve to protect humans from viral infection, but the oral bacteria Porphyromonas gingivalis reduces the production and effectiveness of those important frontline defenders.

“Our studies identified certain pathogenic bacterial species, P. gingivalis, which cause periodontal disease, can completely suppress interferon production and severely enhance susceptibility to viral infection,” said Juhi Bagaitkar, assistant professor in the UofL Department of Oral Immunology and Infectious Disease. “These resident oral plaque bacteria play a key role in regulating anti-viral responses.”

Bagaitkar and Richard Lamont, professor and chair of the UofL Department of Oral Immunology and Infectious Disease, led the work, with first author Carlos J. Rodriguez-Hernandez and other colleagues at UofL and at Washington University in St. Louis. The findings were published in December in PNAS.

The mouth often is a gateway into the body for viruses that infect the gastrointestinal tract and lungs such as SARS-CoV-2, human immunodeficiency virus (HIV), herpes simplex and cancer-causing viruses such as human papillomavirus (HPV).

P. gingivalis, a common oral bacterium that causes periodontal disease, has been linked to numerous other diseases, including Alzheimer’s disease and rheumatoid arthritis. Recent clinical studies have shown that immune suppression in patients with periodontitis can enhance susceptibility to HIV, herpes simplex and HPV.

Improved understanding of how interferons provide broad antiviral protection and activate antiviral genes to protect people from viruses, as well as how P. gingivalis compromises their protection, may lead researchers to clinical approaches to increase that protection.

Research at UofL has revealed connections between P. gingivalis and multiple other diseases and conditions, including rheumatoid arthritis, Alzheimer’s disease and esophageal cancer.