Pulling wisdom teeth can improve long-term taste function

Penn Medicine study shows, for the first time, positive long-term effects of third molar extraction on taste

UNIVERSITY OF PENNSYLVANIA SCHOOL OF MEDICINE

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-Patients who had their wisdom teeth extracted had improved tasting abilities decades after having the surgery, a new Penn Medicine study published in the journal Chemical Senses found. The findings challenge the notion that removal of wisdom teeth, known as third molars, only has the potential for negative effects on taste, and represent one of the first studies to analyze the long-term effects of extraction on taste.

"Prior studies have only pointed to adverse effects on taste after extraction and it has been generally believed that those effects dissipate over time," said senior author Richard L. Doty, PhD, director of the Smell and Taste Center at the University of Pennsylvania. "This new study shows us that taste function can actually slightly improve between the time patients have surgery and up to 20 years later. It's a surprising but fascinating finding that deserves further investigation to better understand why it's enhanced and what it may mean clinically."

Doty and co-author Dane Kim, a third-year student in the University of Pennsylvania School of Dental Medicine, evaluated data from 1,255 patients who had undergone a chemosensory evaluation at Penn's Smell and Taste Center over the course of 20 years. Among that group, 891 patients had received third molar extractions and 364 had not.

The "whole-mouth identification" test incorporates five different concentrations of sucrose, sodium chloride, citric acid, and caffeine. Each solution is sipped, swished in the mouth, and then spit out. Subjects then indicate whether the solution tastes sweet, salty, sour, or bitter.

The extraction group outperformed the control group for each of the four tastes, and in all cases, women outperformed men. The study suggests, for the first time, that people who have received extractions in the distant past experience, on average, an enhancement (typically a three to 10 percent improvement) in their ability to taste.

"The study strongly suggests that extraction of the third molar has a positive long-term, albeit subtle, effect on the function of the lingual taste pathways of some people," Kim said.

Two possibilities, the authors said, could explain the enhancement. First, extraction damage to the nerves that innervate the taste buds on the front of the mouth can release inhibition on nerves that supply the taste buds at the rear of the mouth, increasing whole-mouth sensitivity. Second, hypersensitivity after peripheral nerve injury from a surgery like an extraction has been well documented in other contexts. There is evidence, for example, from animal studies that repetitive light touch, which might occur during chewing, gradually accentuates neural responses from irritated tissue that can lead to progressive long-term tactile hypersensitivity. Whether this occurs for taste, however, is not known.

"Further studies are needed to determine the mechanism or mechanisms behind the extraction-related improvement in taste function," Doty said. "The effects are subtle but may provide insight into how long-term improvement in neural function can result from altering the environment in which nerves propagate."

Predicting tooth loss

Machine-learning algorithms may help identify those at risk

HARVARD MEDICAL SCHOOL

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Tooth loss is often accepted as a natural part of aging, but what if there was a way to better identify those most susceptible without the need for a dental exam?

New research led by investigators at Harvard School of Dental Medicine suggests that machine learning tools can help identify those at greatest risk for tooth loss and refer them for further dental assessment in an effort to ensure early interventions to avert or delay the condition.

The study, published June 18 in PLOS ONE, compared five algorithms using a different combination of variables to screen for risk. The results showed those that factored medical characteristics and socioeconomic variables, such as race, education, arthritis, and diabetes, outperformed algorithms that relied on dental clinical indicators alone.

"Our analysis showed that while all machine-learning models can be useful predictors of risk, those that incorporate socioeconomic variables can be especially powerful screening tools to identify those at heightened risk for tooth loss," said study lead investigator Hawazin Elani, assistant professor of oral health policy and epidemiology at HSDM.

The approach could be used to screen people globally and in a variety of health care settings even by non-dental professionals, she added.

Tooth loss can be physically and psychologically debilitating. It can affect quality of life, well-being, nutrition, and social interactions. The process can be delayed, even prevented, if the earliest signs of dental disease are identified, and the condition treated promptly. Yet, many people with dental disease may not see a dentist until the process has advanced far beyond the point of saving a tooth. This is precisely where screening tools could help identify those at highest risk and refer them for further assessment, the team said.

In the study, the researchers used data comprising nearly 12,000 adults from the National Health and Nutrition Examination Survey to design and test five machine-learning algorithms and assess how well they predicted both complete and incremental tooth loss among adults based on socioeconomic, health, and medical characteristics.

Notably, the algorithms were designed to assess risk without a dental exam. Anyone deemed at high risk for tooth loss, however, would still have to undergo an actual exam, the researchers added.

The results of the analysis point to the importance of socioeconomic factors that shape risk beyond traditional clinical indicators.

"Our findings suggest that the machine-learning algorithm models incorporating socioeconomic characteristics were better at predicting tooth loss than those relying on routine clinical dental indicators alone," Elani said. "This work highlights the importance of social determinants of health. Knowing the patient's education level, employment status, and income is just as relevant for predicting tooth loss as assessing their clinical dental status."

Indeed, it has long been known that low-income and marginalized populations experience a disproportionate share of the burden of tooth loss, likely due to lack of regular access to dental care, among other reasons, the team said.

"As oral health professionals, we know how critical early identification and prompt care are in preventing tooth loss, and these new findings point to an important new tool in achieving that," said Jane Barrow, associate dean for global and community health and executive director of the Initiative to Integrate Oral Health and Medicine at HSDM. "Dr. Elani and her research team shed new light on how we can most effectively target our prevention efforts and improve quality of life for our patients."

The research was done in collaboration with researchers at the Harvard T.H. Chan School of Public Health, the University of São Paolo in Brazil, and the University of Otago Faculty of Dentistry in New Zealand.

Co-investigators included André F. M. Batista, W. Murray Thomson, Ichiro Kawachi, and Alexandre D. P. Chiavegatto Filho.

This work was supported by the National Institute on Minority Health And Health Disparities (grant K99MD012253) and CNPq (grant 308731/2018-2).

Younger adults are taking medications that could affect long term oral health

Study shows dentists need to be aware of medication history even in younger patients

REGENSTRIEF INSTITUTE

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IMAGE: MEDICATIONS CAN PLAY A SIGNIFICANT ROLE IN ORAL HEALTH. A NEW STUDY FROM THE REGENSTRIEF INSTITUTE AND INDIANA UNIVERSITY SCHOOL OF DENTISTRY DEMONSTRATES THAT MANY YOUNGER ADULT DENTAL PATIENTS ARE... view more 

CREDIT: REGENSTRIEF INSTITUTE

INDIANAPOLIS -- A new study demonstrates that many younger adult dental patients are taking medications and highlights the importance of dental providers reviewing medication histories regardless of age.

The study from Regenstrief Institute and the Indiana University School of Dentistry looked at dental records from 11,220 dental patients over the age of 18. The results showed:

• 53 percent of all patients reported taking at least one medication
• 12 percent of those age 18-24 were taking at least one medication
• 20 percent of those age 25-34 were taking at least one medication

"The number of younger adults on medication really surprised us," said senior author Thankam Thyvalikakath, DMD, PhD, director of the Regenstrief and IU School of Dentistry Dental Informatics Program. "Often dentists will assume individuals this age aren't on medications, but these results underscore the importance of paying attention to medical histories of all patients, because medications can play a significant role in oral health."

Younger adults were most likely to be taking antidepressants, which can cause dry mouth, and opioids, which carry the risk of addiction.

"We need to be aware of these possibilities, because dry mouth increases risk for tooth decay and tooth loss, and dental professionals should be proactive with preventive measures," said Dr. Thyvalikakath. "In the same way, if someone is taking an opioid, we as dentists need to make sure we are not overprescribing these medications to that patient and possibly contributing to dependence or substance use disorder."

The study showed that older patients were more likely to be taking medications to treat chronic conditions like high cholesterol, hypertension and diabetes. Across all ages, white patients were more likely to be on a medication.

In the future, Dr. Thyvalikakath hopes to develop and test an intervention to alert dental care providers about medicines and medical history because a more complete picture of a person's health can lead to better care and prevention.

"Differences in medication usage of dental patients by age, gender, race/ethnicity and insurance status" was published online ahead of print in Technology and Health Care, the official journal of the European Society for Engineering and Medicine. This project was made possible by Dr. Thyvalikakath's start-up funds through the Indiana University School of Dentistry.

Complications following dental implant therapy are common

UNIVERSITY OF GOTHENBURG

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IMAGE: KAROLINA KARLSSON, PHD, DENTIST SPECIALIZED IN PERIODONTICS. view more 

CREDIT: PHOTO BY UNIVERSITY OF GOTHENBURG

More than four out of ten patients who received dental implants suffered complications within a nine-year period, these are the results of a thesis presented at the University of Gothenburg.

In Sweden, more than 30 000 patients receive implant-supported restorative therapy (treatment with dental implants to replace lost teeth) on an annual basis. Good long-time results have been reported, but different types of complications can occur. These complications may affect the tissues surrounding the implant, the implant itself or the implant-supported reconstruction.

Karolina Karlsson, a dentist specialized in periodontics and a Ph.D. at the Institute of Odontology at Sahlgrenska Academy, has in her thesis evaluated the frequency, consequences, and cost of such complications.

The research was part of a national project conducted as a population-based field study. It was based on randomly selected patients from the registry of the Swedish Social Insurance Agency. Initially, dental records and radiographs from 2 765 adult patients were assessed. Of these, 596 individuals were clinically examined, nine years after their treatment with dental implants.

The results showed that 42 percent of the patients suffered from at least one complication. The most common type was technical complications, which were mostly isolated phenomena. The strongest risk factor was the extent of the implant-supported reconstruction.

Peri-implantitis, a condition characterized by inflammation in the mucosa and bone loss around the implant, was the second most common complication. Treating peri-implantitis by non-surgical methods alone, in the form of professional cleaning and instructions on oral hygiene, proved to be insufficient. Additional surgical treatment however, was able to prevent further progression of the disease.

Implant loss was the type of complication resulting in the highest total cost.

Replacing lost teeth with dental implants is a common treatment option in dentistry. It is important for care-givers and patients to have a good understanding of the individual risk for complications in order to develop effective preventive strategies.

"The results provide dental professionals and patients with important information, enabling them to evaluate and reduce the risk for complications associated with implant-supported restorative therapy," Karlsson says.

###

Title: Implant-supported restorative therapy in a Swedish population: Complications and cost evaluations, http://hdl.handle.net/2077/68053

COVID-19 infection rates of dentists remain lower than other health professionals

AMERICAN DENTAL ASSOCIATION

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CHICAGO, May 24, 2021--More than a year after COVID-19 appeared in the U.S., dentists continue to have a lower infection rate than other front-line health professionals, such as nurses and physicians, according to a study published online ahead of the June print issue in the Journal of the American Dental Association. The study, "COVID19 among Dentists in the U.S. and Associated Infection Control: a six-month longitudinal study," is based on data collected June 9 - Nov. 13, 2020.

According to the study, based on the number of dentists with confirmed or probable COVID-19 infections over more than six months, the cumulative infection rate for U.S. dentists is 2.6%. The monthly incidence rate varied, ranging from 0.2% to 1.1% per month. By comparison, in June 2020, the cumulative COVID-19 prevalence rate for other U.S. health professionals ranged from 3.3% (Chicago-based hospital physicians) to 35.3% (U.S. based emergency medicine services).

"We're pleased to see that dentists have demonstrated continued low monthly incidence of disease despite several regional and national COVID-19 rate spikes during the study period," said American Dental Association (ADA) Science and Research Institute Chief Executive Officer Marcelo Araujo, D.D.S., M.S., Ph.D., the senior author of the report.

Dr. Araujo added, "This study shows high rates of pre-appointment screening of patients and appropriate infection control measures throughout the study period, demonstrating that adhering to very strict protocols for enhanced infection control helps protect their patients, their dental team and themselves."

In addition to Dr. Araujo, other authors of the report include researchers from the ADA Science and Research Institute and Health Policy Institute based in Chicago, as well as Maria L Geisinger, D.D.S., M.S. with University of Alabama at Birmingham in Birmingham, Ala., and Effie Ioannidou, D.D.S., M.D.S., with the University of Connecticut in Farmington, Conn., and a member of the ADA Council on Scientific Affairs.

This study is a continuation of the first large-scale report of incidence rates of COVID-19 among dentists in the U.S published in October 2020. The present six-month longitudinal study aimed to:

• Determine the cumulative prevalence rate of COVID-19 among dentists;

• Calculate the monthly incidence rate for the same population over the course of the study; and

• Assess the level of engagement in specific infection control practices among dentists over a six-month period of time.

The results of this present study, as well as the earlier study, show that prevalence and incidence rates among dentists continue to be very low when compared to the population as a whole and to other health care professionals.

"This study reinforces that the dental care sector is up and running safely," said Chief Economist and Vice President of the ADA Health Policy Institute Marko Vujicic, Ph.D. "Nowhere is this proof point more evident than by the fact that more than 90% of patients surveyed indicate they have already visited the dentist or soon will."

The authors plan future research projects on the barriers and facilitators to wearing Personal Protective Equipment (PPE) according to CDC recommendations, and levels of protection against COVID-19 provided by different levels of PPE use and infection control procedures.

A gentler strategy for avoiding childhood dental decay

By targeting the bonds between bacteria and yeast that can form a sticky dental plaque, a new therapeutic strategy could help wash away the build-up while sparing oral tissues, according to a new study by a team from the University of Pennsylvania

UNIVERSITY OF PENNSYLVANIA

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The combination of a carb-heavy diet and poor oral hygiene can leave children with early childhood caries (ECC), a severe form of dental decay that can have a lasting impact on their oral and overall health.

A few years ago, scientists from Penn's School of Dental Medicine found that the dental plaque that gives rise to ECC is composed of both a bacterial species, Streptococcus mutans, and a fungus, Candida albicans. The two form a sticky symbiosis, known scientifically as a biofilm, that becomes extremely virulent and difficult to displace from the tooth surface.

Now, a new study from the group offers a strategy for disrupting this biofilm by targeting the yeast-bacterial interactions that make ECC plaques so intractable. In contrast to some current treatments for ECC, which use antimicrobial agents that can have off-target effects, potentially harming healthy tissues, this treatment uses an enzyme specific to the bonds that exist between microbes.

"We thought this could be a new way of approaching the problem of ECCs that would intervene in the synergistic interaction between bacteria and yeast," says Geelsu Hwang, an assistant professor in Penn Dental Medicine and senior author on the study, published in the journal mBio. "This offers us another tool for disrupting this virulent biofilm."

The work builds off findings from a 2017 paper by Hwang and colleagues, including Hyun (Michel) Koo of Penn Dental Medicine, which found that molecules call mannans on the Candida cell wall bound tightly to an enzyme secreted by S. mutans, glycosyltransferases (Gftb). In addition to facilitating the cross-kingdom binding, Gftb also contributes to the stubbornness of dental biofilms by manufacturing gluelike polymers called glucans in the presence of sugars.

While some cases of ECC are treated with drugs that kill the microbes directly, potentially reducing the number of pathogens in the mouth, this doesn't always effectively break down the biofilm and can have off-target effects on "good" microbes as well as the soft tissues in the oral cavity.

Hwang and colleagues wanted to try a different approach that would directly target the insidious interaction between yeast and bacteria and opted to target the mannans in the Candida cell surface as a point of contact.

Using three different mannan-degrading enzymes, they applied each to a biofilm growing on a tooth-like surface in a human saliva medium and left it for five minutes. Following the treatment, they noted that the overall biofilm volume was reduced. Using powerful microscopy, they also observed drastic reductions in the biofilm thickness and interactions between bacteria and yeast. The pH of the surrounding medium was higher when exposed to the enzymes, indicating an environment that is not as acidic and thus less conducive to tooth decay.

They also measured how easy it was to break up the biofilm after treatment, using a device that applies a stress, akin to tooth brushing.

"The biofilm structure was more fragile after the enzyme treatment," Hwang says. "We were able to see that the biofilms were more easily removed."

To confirm the mechanism of their approach--that the mannan-degrading enzymes were weakening the binding between yeast and bacteria--the team used atomic-force microscopy to measure the bonds between Candida and Gftb. The therapy, they found, reduced this binding force by 15-fold.

Finally, they wanted to get a sense of how well-tolerated these enzymes would be when used in the oral cavity, especially since children would be the patient group targeted.

Applying the enzymes to human gingival cells in culture, they found no harmful impact, even when they used a concentrated form of the enzymes. In addition, they observed that the treatment didn't kill the bacteria or yeast, a sign that it could work even if the microbes developed mutations that would lend them resistance against other types of therapies.

The researchers kept the application time relatively short at five minutes though they hope to see activity in an even shorter time, like the two minutes that is recommended for tooth brushing. Hwang says they may consider a non-alcohol-based mouthwash with these enzymes added that could be used by children as a preventive measure against ECC.

The researchers hope to continue pursuing this possibility with additional follow up, including testing these enzymes in an animal model. With more successes, they aim to add another tool for fighting the public health threat of ECC.

Dental procedures during pandemic are no riskier than a drink of water

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 A new study's findings dispel the misconception that patients and providers are at high risk of catching COVID-19 at the dentist's office.

SARS-CoV-2 spreads mainly through respiratory droplets, and dental procedures are known to produce an abundance of aerosols - leading to fears that flying saliva during a cleaning or a restorative procedure could make the dentist's chair a high-transmission location.

Ohio State University researchers set out to determine whether saliva is the main source of the spray, collecting samples from personnel, equipment and other surfaces reached by aerosols during a range of dental procedures.

By analyzing the genetic makeup of the organisms detected in those samples, the researchers determined that watery solution from irrigation tools, not saliva, was the main source of any bacteria or viruses present in the spatter and spurts from patients' mouths.

Even when low levels of the SARS-CoV-2 virus were detected in the saliva of asymptomatic patients, the aerosols generated during their procedures showed no signs of the coronavirus. In essence, from a microbial standpoint, the contents of the spray mirrored what was in the office environment.

"Getting your teeth cleaned does not increase your risk for COVID-19 infection any more than drinking a glass of water from the dentist's office does," said lead author Purnima Kumar, professor of periodontology at Ohio State.

"These findings should help us open up our practices, make ourselves feel safe about our environment and, for patients, get their oral and dental problems treated - there is so much evidence emerging that if you have poor oral health, you are more susceptible to COVID," Kumar said.

The study was published Wednesday, May 12, in the Journal of Dental Research.

Previous research has shown that dental-procedure aerosols tend to land on providers' faces and the patient's chest, and can travel as far as 11 feet. But the studies, catching the spray in petri dishes placed on people, equipment and around the room, found only that bacteria existed - they rarely identified the organisms and never determined where they came from. Saliva has been the presumptive source for a long time.

When saliva was considered potentially deadly at the start of the pandemic, Kumar decided a long-term answer was needed to settle the question of whether saliva is the source of dental aerosols.

For the study, the team enrolled 28 patients receiving dental implants and restorations using high-speed drills or ultrasonic scaling procedures in Ohio State's College of Dentistry between May 4 and July 10, 2020. Researchers collected samples of saliva and irrigant (the water-based cleaning solutions used to flush out the mouth) before each procedure and, 30 minutes after the procedure, aerosol remnants - condensate - from providers' face shields, the patient's bib and an area 6 feet away from the chair.

Kumar and colleagues then put genome sequencing technology to use that wasn't available in the petri-dish days. This allowed them to first characterize the microbial mix in pre-procedure saliva and irrigants, which they could then compare to organisms in the aerosol samples collected later.

With the analytical method they used, the researchers did not need to characterize the microbes - they instead looked for variations in sequences that provided enough information to identify the family of bacteria or viruses to which they belonged.

"Some species that live in your mouth can closely resemble those in water and the environment. Using this method, we don't even have to know the names of these organisms - you can tell whether they are exactly genetically identical or genetically different," Kumar said. "If you use this granular approach to see these very nuanced differences in the genetic code, you can very accurately identify where they're coming from."

No matter the procedure or where the condensate had landed, microbes from irrigants contributed to about 78% of the organisms in aerosols while saliva, if present, accounted for 0.1% to 1.2% of the microbes distributed around the room.

Salivary bacteria were detected in condensate from only eight cases and of those, five patients had not used a pre-procedural mouth rinse. The SARS-CoV-2 virus was identified in the saliva of 19 patients, but was undetectable in aerosols in any of the cases.

The findings are reassuring, but also make sense, Kumar said: Irrigant dilutes saliva - a "thick, viscous" substance - by an estimated 20- to 200-fold, and the research is validated by a 2020 study that reported a less than 1% COVID-19 positivity rate among dentists.

Kumar noted that dentistry has long been at the forefront of infection-control practices in health care. During the pandemic, new protocols have included strengthened ventilation systems, extra aerosol suction equipment, N95 masks and face shields on top of goggles, and extended downtime between patients. She is hopeful this study's findings will make practitioners and patients feel at ease about being in the dentist's office - with continued stringent protection in place.

"Dental surgeons and hygienists are always at the forefront of the war against bacteria in the mouth, and they of course did not feel safe because they are front-line workers surrounded by aerosol," said Kumar, who has a periodontology practice of her own and was one of the procedure operators in the study.

"Hopefully this will set their mind at rest because when you do procedures, it is the water from the ultrasonic equipment that's causing bacteria to be there. It's not saliva. So the risk of spreading infection is not high," she said. "However, we should not lose sight of the fact that this virus spreads through aerosol, and speaking, coughing or sneezing in the dental office can still carry a high risk of disease transmission."