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Tongue Microbiome Research Underscores Importance Of Dental Health

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Elderly individuals with fewer teeth, poor dental hygiene, and more cavities constantly ingest more dysbiotic microbiota, which could be harmful to their respiratory health, according to new research published in the journal mSphere. The findings come from a large, population-based study that identified variations in the tongue microbiota among community-dwelling elderly adults in Japan.

“Fewer teeth, poorer dental hygiene, and more dental caries (cavities) experience are closely related to dysbiotic shift in the tongue microbiota composition, which might be harmful to the respiratory health of elderly adults with swallowing problems,” said corresponding author Yoshihisa Yamashita, PhD, DDS, Section of Preventive and Public Health Dentistry, Division of Oral Health, Growth, and Development, Faculty of Dental Science, Kyushu University, Fukuoka.

Prior to this study, researchers knew that constant aspiration of saliva can lead to pneumonia, a major cause of death among elderly adults with swallowing impairments, and that tongue microbiota are a dominant source of oral microbial populations that are ingested with saliva. Previous research has also shown that in institutionalized frail elderly adults, the dysbiotic shift of indigenous tongue microbiota is associated with an increased risk of death from pneumonia.

In the new study, Dr. Yamashita and colleagues set out to understand the variations in tongue microbiota composition related to oral health conditions among community-dwelling elderly adults and to identify factors associated with the dysbiotic shift in the tongue microbiota. They investigated the tongue microbiota status and dental conditions of 506 adults aged 70 to 80 years living in the town of Hisayama, Japan who received a dental examination during a health examination of the town’s residents performed in 2016. The scientists collected the tongue microbiota from the center area of the tongue dorsum using a modified electric toothbrush as a sampling device, and used next-generation sequencing approaches to analyze the samples.

The researchers found that the total bacterial density was independent of the conditions of teeth surrounding the tongue, whereas the microbiota composition, especially the relative abundances of predominant commensals, showed an association with tooth conditions.

“Commensal microbiota composition, especially the relative abundances of predominant commensals, showed an association with tooth conditions,” said Dr. Yamashita.

“Two cohabiting groups of predominant commensals exist in the tongue microbiota; one of which was primarily composed of Prevotella histicola, Veillonella atypica, Streptococcus salivarius, and Streptococcus parasanguinis, which have been previously associated with an increased risk of mortality due to pneumonia in the frail elderly. This bacterial group was more predominant in the elderly with fewer teeth, a higher plaque index, and more dental caries-experienced teeth.”

The study highlights the importance of dental health.

“Careful attention should be given to the tongue microbiota status in elderly adults with poorer dental conditions,” said Dr. Yamashita.

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Novel Nanoparticle-Based Approach Detects And Treats Oral Plaque Without Drugs

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When the good and bad bacteria in our mouth become imbalanced, the bad bacteria form a biofilm (aka plaque), which can cause cavities, and if left untreated over time, can lead to cardiovascular and other inflammatory diseases like diabetes and bacterial pneumonia.

A team of researchers from the University of Illinois has recently devised a practical nanotechnology-based method for detecting and treating the harmful bacteria that cause plaque and lead to tooth decay and other detrimental conditions.

Bioengineering Associate Professor Dipanjan Pan (seated) and doctoral student Fatemeh Ostadhossein have demonstrated a drug-free, nanotechnology-based method for detecting and destroying the bacteria that causes dental plaque.

Oral plaque is invisible to the eye so dentists currently visualize it with disclosing agents, which they administer to patients in the form of a dissolvable tablet or brush-on swab. While useful in helping patients see the extent of their plaque, these methods are unable to identify the difference between good and bad bacteria.

“Presently in the clinic, detection of dental plaque is highly subjective and only depends on the dentist’s visual evaluation,” said Bioengineering Associate Professor Dipanjan Pan, head of the research team.

“We have demonstrated for the first time that early detection of dental plaque in the clinic is possible using the regular intraoral X-ray machine which can seek out harmful bacteria populations.”

In order to accomplish this, Fatemeh Ostadhossein, a Bioengineering graduate student in Pan’s group, developed a plaque detection probe that works in conjunction with common X-ray technology and which is capable of finding specific harmful bacteria known as Streptococcus mutans (S. mutans) in a complex biofilm network. Additionally, they also demonstrated that by tweaking the chemical composition of the probe, it can be used to target and destroy the S. mutans bacteria.

The probe is made up of nanoparticles made of hafnium oxide (HfO2), a non-toxic metal that is currently under clinical trial for internal use in humans. In their study, the team demonstrated the efficacy of the probe to identify biochemical markers present at the surface of the bacterial biofilm and simultaneously destroy S. mutans. They conducted their study on Sprague Dawley rats.

In practice, Pan envisions a dentist applying the probe on the patient’s teeth and using the X-ray machine to accurately visualize the extent of the biofilm plaque. If the plaque is deemed severe, then the dentist would follow up with the administering of the therapeutic HfO2 nanoparticles in the form of a dental paste.

In their study, the team compared the therapeutic ability of their nanoparticles with Chlorhexidine, a chemical currently used by dentists to eradicate biofilm. “Our HfO2 nanoparticles are far more efficient at killing the bacteria and reducing the biofilm burden both in cell cultures of bacteria and in [infected] rats,” said Ostadhossein, noting that their new technology is also much safer than conventional treatment.

The nanoparticles’ therapeutic effect is due, said Pan, to their unique surface chemistry, which provides a latch and kill mechanism.

“This mechanism sets our work apart from previously pursued nanoparticle-based approaches where the medicinal effect comes from anti-biotics encapsulated in the particles,” said Pan, also a faculty member of the Carle Illinois College of Medicine and the Beckman Institute for Advanced Science and Technology.

“This is good because our approach avoids anti-biotic resistance issues and it’s safe and highly scalable, making it well-suited for eventual clinical translation.”

In addition to Pan and Ostadhossein, other members of the research team include bioengineering post-doctoral researcher Santosh Misra, visiting scholar Indu Tripathi, undergraduate Valeriya Kravchuk, visiting scholar Gururaja Vulugundam; and Veterinary Medicine clinical assistant professor Denae LoBato and adjunct assistant professor Laura Selmic.

Their work is described in the paper, “Dual purpose hafnium oxide nanoparticles offer imaging Streptococcus mutans dental biofilm and fight it In vivo via a drug free approach,” published online on July 30, 2018, in the journal Biomaterials. The research was funded by the University of Illinois at Urbana-Champaign Children’s Discovery Institute and the American Heart Association.

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Unwise Opioids For Wisdom Teeth: Study Shows Link To Long-Term Use In Teens And Young Adults

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Getting wisdom teeth removed may be a rite of passage for many teens and young adults, but the opioid painkiller prescriptions that many of them receive could set them on a path to long-term opioid use, a new study finds.

Young people ages 13 to 30 who filled an opioid prescription immediately before or after they had their wisdom teeth out were nearly 2.7 times as likely as their peers to still be filling opioid prescriptions weeks or months later, according to new research from a University of Michigan team.

Those in their late teens and twenties had the highest odds of persistent opioid use, compared with those of middle school and high school age, the researchers report in a research letter in the new issue of JAMA.

Led by Calista Harbaugh, M.D., a U-M research fellow and surgical resident, the researchers used insurance data to focus on young people who were ‘opioid naïve’ — who hadn’t had an opioid prescription in the six months before their wisdom teeth came out, and who didn’t have any other procedures requiring anesthesia in the following year.

“Wisdom tooth extraction is performed 3.5 million times a year in the United States, and many dentists routinely prescribe opioids in case patients need it for post-procedure pain,” says Harbaugh, a National Clinician Scholar at the U-M Institute for Healthcare Policy and Innovation.

“Until now, we haven’t had data on the long-term risks of opioid use after wisdom tooth extraction. We now see that a sizable number go on to fill opioid prescriptions long after we would expect they would need for recovery, and the main predictor of persistent use is whether or not they fill that initial prescription.”

Other factors also predicted risk of long-term opioid use. Teens and young adults who had a history of mental health issues such as depression and anxiety, or chronic pain conditions, were more than others to go on to persistent use after filling their initial wisdom tooth-related prescription.

More about the study

In all, 1.3 percent of 56,686 wisdom tooth patients who filled their opioid prescription between 2009 and 2015 went on to persistent opioid use, defined as two or more prescriptions filled in the next year written by any provider for any reason. That’s compared with 0.5 percent of the 14,256 wisdom tooth patients who didn’t fill a prescription.

Though those numbers may seem small, the high number of wisdom teeth procedures every year mean a large number of young people are at risk, notes Harbaugh, a research fellow with the Michigan Opioid Prescribing and Engagement Network, or Michigan OPEN.

The team used data from employer-based insurance plans, available through the Truven MarketScan database purchased for researchers’ use by IHPI. Chad Brummett, M.D., co-director of Michigan OPEN, is senior author of the new research, and the team includes U-M School of Dentistry professor Romesh Nalliah, D.D.S., MHCM.

The data show opioid prescriptions filled, but not actual use of opioid pills by patients. Leftover opioids pose a risk of their own, because they can be misused by the individual who received the prescription, or by a member of their household or a visitor. The researchers also couldn’t tell the reason for the later opioid prescription fills by those who went on to persistent use.

The authors suggest that dentists and oral surgeons should consider prescribing non-opioid painkillers before opioids to their wisdom tooth patients. If pain is acute, they should prescribe less than the seven-day opioid supply recently recommended by the American Dental Association for any acute dental pain.

“There are no prescribing recommendations specifically for wisdom tooth extraction,” says Harbaugh.

“With evidence that nonsteroidal anti-inflammatories may just as, if not more, effective, a seven-day opioid recommendation may still be too much.”

Brummett adds:

“These are some of the first data to the show long-term ill effects of routine opioid prescribing after tooth extractions. When taken together with the previous studies showing that opioids are not helpful in these cases, dentists and oral surgeons should stop routinely prescribing opioids for wisdom tooth extractions and likely other common dental procedures.”

Importance for patients and parents

Getting a prescription for an opioid painkiller around the time of a wisdom tooth procedure comes with many decision points, Harbaugh says.

“Patients must decide whether to fill the prescription and take the medication, and where to store and dispose of the unused pills. All of these decision points need to be discussed with patients,” she says.

“Patients should talk to their dentists about how to control pain without opioids first. If needed, opioids should only be used for breakthrough pain, as backup if the pain’s not controlled with other medications.”

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The Effectiveness Of Chlorhexidine Is Limited In Preventing Infections In Oral Procedures

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The human oral cavity is colonised by a huge variety of bacteria. When surgical procedures such as a tooth extraction are carried out, the bacteria can pass into the bloodstream causing bacteraemia that is generally transient. What is not yet clear is how significant this presence of bacteria in the blood is in terms of the origin and evolution of infectious processes such as endocarditis of the heart valves, prosthetic valves, hip and knee joint replacements generally, and in local infection.

Numerous studies have shown that a mouthwash containing chlorhexidine has a powerful antimicrobial effect on saliva microflora and bacterial plaque.

“On the basis of this hypothesis we can assume that antimicrobial mouthwashes used before the dental procedure should reduce the number of micro-organisms that pass into the patient’s bloodstream, yet this is a hotly debated issue,” said the members of the UPV/EHU’s research group.

In 1997 the American Heart Association (AHA) suggested that patients at risk of infectious endocarditis should use an antimicrobial mouthwash before a dental procedure. In 2006, the British Society for Antimicrobial Chemotherapy (BSAC) recommended a single mouthwash with 0.2% chlorhexidine (CHX) (10 ml for 1 minute) before the carrying out of dental procedures associated with bacteraemia in patients at risk. Yet in 2007 the AHA recommended against adopting any antiseptic prophylaxis protocol.

In an effort to shed scientific light on this issue, the UPV/EHU research group comprising Iciar Arteagoitia, Carlos Rodriguez-Andrés and Eva Ramos decided to conduct a systematic review and meta-analysis of random controlled trials (RCT), following the PRISMA Statement. The aim was to assess the effectiveness of chlorhexidine in preventing bacteraemia following a tooth extraction. The research was conducted in collaboration with the UPV/EHU’s Department of Epidemiology and was published in Plos One.

In the study that included 8 clinical trials with 523 patients there were 267 in the group treated with chlorhexidine, in which 145 cases of bacteraemia were recorded, and 256 in the control group, in which there were 156 cases of bacteraemia. The results of the research therefore indicate that the percentage of cases of bacteraemia that can be prevented if a population undergoes chlorhexidine-based prevention is 12%. The NNT, the number of patients that need to be treated to prevent bacteraemia, is 16.

The results point to the relative and not particularly significant effectiveness of the use of chlorhexidine when it comes to preventing the bacteria present in the mouth from passing into the bloodstream when dental extraction is carried out.

“Yet, given its low cost and the absence of adverse reactions and complications, we would recommend a mouthwash with chlorhexidine before a procedure of this type is carried out,” concluded the UPV/EHU’s research group.

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