What smoking does to oral bacteria

 

A study shows the effects of cigarette use and what happens when you stop

Peer-Reviewed Publication

EURAC RESEARCH

The father of Biotechnologist Giacomo Antonello, a dentist, sometimes amazed patients with his seemingly clairvoyant diagnostic abilities: one look in their mouth and he would advise them to see a specialist, because, he explained, they might have a problem with their heart or diabetes.  He often turned out to be correct. While his patients were always very impressed, for experts, the dentist’s diagnoses were justified: empirical studies show that there is often a connection between periodontitis and various cardiovascular diseases, even if the exact mechanisms are not fully understood.  Giacomo, who is currently conducting research for his PhD at the Institute of Biomedicine, has now just completed a study with colleagues at the Eurac Research Institute for Biomedicine that points to one possible factor: in people who smoke, the alteration of the healthy community of oral bacteria could contribute to the increased risk of these diseases. 

 

The study, which was conducted as part of the CHRIS study in Val Venosta, asks two central questions: What exactly happens to the bacterial community in the mouth, the so-called oral microbiome, when we smoke? And what effect does quitting have on these same communities? 

To find out, the research team in Bolzano, together with epidemiologist Betsy Foxman from the University of Michigan, analyzed saliva samples from more than 1600 people – a huge number of subjects for this research field, as bioinformatician Christian Fuchsberger, Giacomo’s doctoral advisor, emphasizes: “There are hardly any large studies on the salivary microbiome. This is a young research field in which a lot is happening right now and one in which not everything is conducted so clearly. Many of the current studies are working with very small numbers of cases, for example, which means their results are not broadly applicable.” 

 

Microbiome research is a fairly young field: just a few decades ago, the communities of trillions of microorganisms that live on and in humans – mostly in the digestive tract – were considered of little significance by scientists. Now, the microbiome is taking center stage and is recognized to be of massive importance to our development and health. The intestinal microbiome is the subject of intensive research with a major study currently underway at the Institute of Biomedicine (see box).  

Compared to the microbial density of the intestine, where thousands of strains of different bacteria live, our mouth is only sparsely populated. However, saliva has a particular advantage for studies: it is relatively easy to sample. Researchers can therefore acquire the data they need to investigate whether it is possible to identify changes in the oral flora (biomarkers) that indicate certain diseases, which, if found, could provide a valuable diagnostic tool that healthcare systems could easily employ. 

 

In the CHRIS Study’s examination, CHRIS participants were requested to spit 5 milliliters of saliva into a special collection tube. The participants were divided into groups according to whether they were current smokers, had stopped smoking, or had never started. Those who had quit were asked exactly when they had quit, and those who still smoked were asked about the number of cigarettes they smoked per day. To get a picture of the microbial community in each mouth – which species were represented and at what frequency – the research team employed a universally used technology for identifying bacteria, namely sequence analysis of the 16S rRNA gene, a gene which represents something like an “identity card” for each different species. 

 

Giacomo’s research using the microbiome data collected in the CHRIS Study showed clear results. People who have never smoked carry a significantly different microbial community in their mouths than people who still smoke or have recently given up. Cigarette consumption primarily affects the bacteria that need oxygen:aerobic bacteria. The number of these bacteria decreases continuously the more cigarettes one smokes; if one stops smoking, these aerobic bacteria gradually increase again. And the longer the smoke-free period, the more aerobic bacteria are found in the saliva. Only after five years of not smoking are former smokers indistinguishable, in terms of aerobic bacteria in their oral microbiome, from people who have never smoked. “We have observed that the effects of smoking persist for years,” Fuchsberger says. “So then, of course, it’s interesting to ask whether these effects are related to certain diseases.” 

 

Smokers are known to have an increased risk of both periodontitis and cardiovascular disease. Could the changes in the oral microbiome caused by cigarettes use play a role in this? This is where a function of the bacteria that live in the mouth comes into play, and like everything to do with our microbiome, it has been receiving increasing attention for some time – some of these bacteria, mainly aerobic ones, convert the nitrate we ingest with food into nitrite, which then become nitric oxide. Nitric oxide is an important substance for regulating blood pressure, among other things. If too little nitric oxide is available, this could contribute to poorly perfused gums and cardiovascular disease. Now, the study in the Venosta valley did not measure nitric oxide in saliva, but it did examine the microbes in it; all the research team can say, therefore, is that the more the subjects smoked, the fewer nitrate-reducing bacteria lived in their mouths. That this could be an additional explanation for why smokers have a higher risk of periodontal disease and cardiovascular disease is “a hypothesis that needs to be tested in further studies,” Giacomo emphasizes.  

He is already pursuing the next question based on the CHRIS samples. Namely, what are some of the other factors that influence our oral flora and to what extent? What role does genetics play, and what role do the people we share households with also play?  He will only be able to answer this question in about a year’s time, but one thing is already very clear: who we live with is very important. 

 

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JOURNAL

Scientific Reports

DOI

10.1038/s41598-023-42474-7 

The Second Plague Pandemic may have led to oral microbiomes that contribute to modern-day chronic disease

 

 The Second Plague Pandemic of the mid-14th century, also known as the Black Death, killed 30-60 percent of the European population and profoundly changed the course of European history. New research led by Penn State and the University of Adelaide suggests that this plague, potentially through resulting changes in diet and hygiene, may also be associated with a shift in the composition of the human oral microbiome toward one that contributes to chronic diseases in modern-day humans.  

“Modern microbiomes are linked to a wide range of chronic diseases, including obesity, cardiovascular disease, and poor mental health,” said Laura Weyrich, associate professor of anthropology, Penn State. “Uncovering the origins of these microbial communities may help in understanding and managing these diseases.” 

According to Weyrich, dietary changes are believed to have influenced oral microbiome evolution through time; however, few studies have directly examined the history of human oral microbiomes in a single population. Weyrich noted that some studies have used the microbiomes of living Indigenous people who practice traditional subsistence lifestyles as a proxy for the microbiomes of pre-industrialized peoples. Yet, this strategy is faulty, she said, because modern-day non-industrialized populations may not have microbes that accurately reflect those that existed in the ancestors of industrialized peoples.  

Additionally, she said, “This research places unnecessary responsibilities and obligations on Indigenous communities to participate in microbiome research, where the benefits of these studies may not directly serve Indigenous peoples.” 

A more accurate and ethically responsible method is to directly examine the oral microbiomes preserved within calcified dental plaque, known as calculus, from the ancestors of Industrialized people with the permission and collaboration of decedent populations and stakeholders. In the largest study to date of ancient dental calculus, Weyrich and her colleagues collected material from the teeth of 235 individuals who were buried across 27 archaeological sites in England and Scotland from about 2,200 B.C. to A.D. 1853.  

The findings published today (Nov. 29) in Nature Microbiology. 

The researchers processed the samples in an ultra-sterile, ancient DNA laboratory to minimize contamination. They identified 954 microbial species and determined that they fell within two distinct communities of bacteria — one dominated by the genus Streptococcus — which is common in the oral microbiomes of modern Industrialized peoples — and the other by the genus Methanobrevibacter — which is now largely considered extinct in healthy Industrialized people.  

Exploring the origins of these two communities, the team found that almost 11% of the total variation in microbiome species composition could be explained by temporal changes, including the arrival of the Second Plague Pandemic. But how could the Second Plague Pandemic contribute to changes in the oral microbiome? 

“We know that survivors of the Second Plague Pandemic earned higher incomes and could afford higher-calorie foods,” said Weyrich. “It’s possible that the pandemic triggered changes in people’s diets that, in turn, influenced the composition of their oral microbiomes.” 

The team used a novel approach to investigate whether a change in diet could have influenced the emergence of the Streptococcus group and the extinction of the Methanobrevibacter group. They assembled a list of functional differences among the bacteria in the two groups that could be linked to diet; for example, functions linked to high or low-dietary fiber digestion, carbohydrate metabolism and lactose — a sugar in milk — metabolism.  

The researchers found that the bacteria in the Streptococcus-dominated group had more functional traits that are significantly linked with low-fiber, high-carbohydrate diets, as well as dairy consumption — all of which characterize modern-day diets. By contrast, the Methanobrevibacter-dominated group were missing traits associated with dairy and sugar consumption, which characterized the diets of some ancient humans.  

The team further determined that the Streptococcus group was associated with the presence of periodontal disease, which is characterized by infections and inflammation of the gums and bones around the teeth. When this disease progresses, bacteria can enter the bloodstream through gum tissue and potentially cause respiratory disease, rheumatoid arthritis, coronary artery disease and blood sugar issues in diabetes. The Methanobrevibacter group, on the other hand, was associated with the presence of skeletal pathologies. 

“Our research suggests that modern-day oral microbiomes may reflect past changes in diet, resulting from the Second Plague Pandemic,” said Weyrich. “Importantly, this work helps to inform our understanding of modern-day chronic, noncommunicable diseases.” 

Other Penn State authors of the paper include Abigail Gancz, graduate student; Michelle Nixon, assistant research professor of information sciences and technology; Sterling Wright, graduate student; Emily R. Davenport, assistant professor of biology; and Justin Silverman, assistant professor of information sciences and technology. Other co-authors include Andrew Farrer, graduate student, University of Adelaide; Luis Arriola, graduate student, University of Adelaide; C. Adler, senior lecturer, School of Dentistry, University of Sydney; Neville Gully, assistant dean learning and teaching, Adelaide Dental School, University of Adelaide; Alan Cooper; Kate Britton, professor of archaeology, University of Aberdeen; and Keith Dobney, head, School of Historical and Philosophical Inquiry, University of Sydney.  

The Australian Research Council, National Science Foundation and Penn State supported this research. 

A healthy mouth helps to maintain balanced metabolic profiles

An oral infections, periodontal diseases and caries, are associated with inflammatory metabolic profiles related to an increased risk of cardiometabolic diseases, a new study by an international team of researchers suggests. Oral infections also predicted future adverse changes in metabolic profiles.  

The association between oral infections and adverse metabolic profiles was observed in the Finnish Health 2000/2011 and Parogene study cohorts.

 “The observation is novel, since there are only few studies connecting extensive metabolic measures with oral infections, and no earlier prospective studies exist,” says Professor Pirkko Pussinen from the University of Eastern Finland. 

Published in Journal of Dental Research, the study also involved researchers from the University of Helsinki, Karolinska Institutet and Medical University of Graz.

Progressed oral infections and inflammations – endodontic lesions and periodontitis – are known to be associated with an increased risk of cardiometabolic diseases. Although the mechanisms behind these associations are partially unclear, poor oral health is probably sustaining systemic inflammation.

The present study comprised 452 middle-aged and elderly Parogene patients and 6,229 participants of the population-based Health-2000 survey. In 2011, 4,116 Health-2000 participants provided a follow-up serum sample. Serum concentrations of 157 metabolites reflecting the risk of chronic diseases, such as lipid and glucose metabolites, ketone bodies and amino acids, were determined with an NMR spectroscopy method.  

Parameters describing the oral health status were collected at baseline in clinical and radiographic examinations. They included those describing the periodontal status, such as bleeding on probing, periodontal probing depth and alveolar bone loss. Caries-related parameters included root canal fillings, apical rarefactions and caries lesions. The study composed of a cross-sectional part analysing the association between the metabolic measures with prevalent oral health, and of a prospective part examining whether oral infections predict the levels of metabolic measures in the follow-up.

Periodontitis especially linked to prevalent inflammatory metabolic profile, caries to future adverse metabolites

Among 157 metabolic measures, increased periodontal probing depth associated with 93, bleeding on probing with 88, and periodontal inflammation burden with 77 measures. Among the caries-related parameters, root canal fillings were associated with 47, inadequate root canal fillings with 27, and caries lesions with 8 metabolic measures. In the prospective analyses, caries was associated with 30 and bleeding on probing with 8 metabolites. These metabolic measures were typical of inflammation, thus showing positive associations with fatty acid saturation degree and very low density lipoprotein (VLDL) parameters, and negative associations with high density lipoprotein (HDL) parameters.

“Oral infections may partially explain unhealthy lipid profiles,” says Adjunct Professor Aino Salminen from the University of Helsinki.

Adjunct Professor Kåre Buhlin from Karolinska Institutet concludes: “Oral infections represent a significant risk factor for systemic health. Importantly, they are modifiable through early prevention and treatment.”

Soft drinks levy linked to fall in child hospital admissions for tooth extraction

2018 legislation may have saved more than 5,500 hospital admissions for tooth extractions

Peer-Reviewed Publication

BMJ

The UK soft drinks industry levy introduced in 2018 may have reduced the number of under 18s having a tooth removed due to tooth decay by 12%, suggests research published in the open access journal BMJ Nutrition, Prevention & Health. 

The fall in hospital admissions may have saved more than 5,500 hospital admissions for tooth decay alone and the largest reductions were in children aged up to nine years old.

Sugar-sweetened drinks account for around 30% of the added sugars in the diets of children aged one to three years and over 50% by late adolescence. In England, nearly 90% of all tooth extractions in young children are due to decay, resulting in around 60,000 missed school days a year. 

The World Health Organization has recommended a tax on sugar-sweetened drinks to reduce sugar consumption, which more than 50 countries have implemented.

In March 2016, the UK government announced a soft drinks industry levy or ‘sugar tax’, which aimed to reduce sugar intake by encouraging drinks manufacturers to reformulate their products. The levy was implemented in April 2018. 

While the relationship between sugar-sweetened drinks and tooth decay is well established, no studies have used real-world data to examine the relationship between the levy and dental health. 

To address this, the researchers analysed hospital admissions data for tooth extractions due to tooth decay in children aged 0 to 18 years old in England from January 2014 to February 2020, four years before to almost two years after the levy was introduced. They studied trends overall as well as broken down by neighbourhood deprivation and age groups. 

Overall, in children aged 18 and under, there was an absolute reduction in hospital admissions of 3.7 per 100,000 population per month compared to if the soft drinks levy had not happened. This equated to a relative reduction of 12% compared to if the levy was not introduced.

Based on a population of nearly 13,000,000 children aged 0–18 years in England in 2020, the researchers estimated that the reduction avoided 5,638 admissions for tooth decay. 

Reductions in hospital admissions were greatest in younger children aged 0–4 years and 5–9 years, with absolute reductions of 6.5 and 3.3 per 100,000 respectively. 

Dr Nina Rogers from the Medical Research Council (MRC) Epidemiology Unit at the University of Cambridge, the study’s first author, said: “This is an important finding given that children aged five to nine are the most likely to be admitted to hospital for tooth extractions under general anaesthesia.”

No significant changes in admission rates for tooth decay were seen in older age groups of 10–14 years and 15–18 years. However, reductions in hospital admissions were seen in children living in most areas regardless of deprivation. 

This is an observational study so causality can’t be established, and the researchers acknowledge there was no comparable control group so they could not fully attribute the changes in hospital admissions to the soft drinks levy. 

What’s more, they say other national interventions such as the sugar reduction programme and compulsory nutrition labels alongside the levy may have raised public awareness of sugar consumption and influenced buying habits. 

Nevertheless, they conclude that their study “provides evidence of possible benefits to children’s health from the UK soft drinks industry levy beyond obesity which it was initially developed to address.” 

*Professor David Conway, co-author, and professor of dental public health at University of Glasgow said: “Tooth extractions under general anaesthesia is among the most common reasons for children to be admitted to hospital across the UK. This study shows that ambitious public health policies such as a tax on sugary drinks can impact on improving child oral health.”

*Professor Sumantra Ray, Executive Director of the NNEdPro Global Centre for Nutrition & Health, said: “We welcome the publication of this research which attempts to draw the links between policy-level changes and the impact on early life oral/dental health outcomes which, if untoward, would produce a significant onward burden on dental services through the life course.” 

He added: “The economic effects of this are more pronounced given current challenges in the provision of far-reaching dental health coverage both in countries with nationalised healthcare systems as well as others. Whilst there are methodological limitations in this study in regard to causal inference, this paper provides the basis for the design of further policy sensitive research investigating these relationships in a manner that clearly links cause and effect.”

USPSTF statement on screening and preventive interventions for oral health in adults

 

 The U.S. Preventive Services Task Force (USPSTF) concludes that the current evidence is insufficient to assess the balance of benefits and harms of routine screening performed by primary care clinicians for oral health conditions, including dental caries or periodontal-related disease, in adults. The USPSTF also concludes that the current evidence is insufficient to assess the balance of benefits and harms of preventive interventions performed by primary care clinicians for oral health conditions, including dental caries or periodontal-related disease, in adults. Dental caries (cavities) and periodontal disease (gum disease) are common and often untreated oral health conditions that affect eating, speaking, learning, smiling, and employment potential. Untreated oral health conditions can lead to tooth loss, irreversible tooth damage, and other serious adverse health outcomes.

Free access to the full-text article:

https://jamanetwork.com/journals/jama/fullarticle/10.1001/jama.2023.21409?guestAccessKey=08d18afc-2e75-4219-8eb4-2a18cd1e1d29&utm_source=For_The_Media&utm_mediu

Good news, bad news on dental pain care seen in new study

 

Patients are taking home far fewer opioid painkillers now than a few years ago, data show, but the pandemic slowed the decline greatly

Peer-Reviewed Publication

MICHIGAN MEDICINE - UNIVERSITY OF MICHIGAN

Americans who have a tooth pulled or another painful dental procedure in the United States today are far less likely to get opioid painkillers than they were just a few years ago, a new study shows.

That’s good news, since research shows that opioids are not necessary for most dental procedures.

But the COVID-19 pandemic seems to have thrown a wrench into the effort to reduce opioid use in dental care – and not just in the few months after dentists and oral surgeons started providing routine care again after a pause in spring 2020.

The decline in opioid prescriptions filled by dental patients was much faster in the pre-pandemic years 2016 through 2019, compared with the rate of decline from June 2020 to December 2022, the study shows.

In all, dental opioids dispensed to U.S. patients of all ages declined 45% from 2016 to the end of 2022, according to the new findings published in PLoS One by a team from the University of Michigan Medical School and School of Dentistry.

But even with the decline, 7.4 million dental patients of all ages filled opioid prescriptions in 2022.

Fortunately, opioid prescriptions to teens and young adults – who face especially high risks related to opioids – kept declining at a rapid rate after the pandemic pause in dental care, the study finds. But for other groups, the rate of decline slowed after June 2020. 

In all, the researchers estimate, 6.1 million more dental opioid prescriptions were dispensed between June 2020 and December 2022 than would have been if pre-pandemic trends had continued.

And American dentists and oral surgeons were still prescribing opioids in late 2022 at four times the rate that another study showed British dentists were in 2016.

“These data suggest the dental profession has made major strides in reducing opioid prescribing, but also suggest that progress is slowing,” said Kao-Ping Chua, M.D., Ph.D., the senior author of the new study and an assistant professor of pediatrics at U-M. He worked with first author and former U-M research assistant Jason Zhang, who is now in medical school at Northwestern University.

“We know from research that dental pain in most patients can be controlled with non-opioid medications, avoiding the risks of opioids,” said co-author Romesh Nalliah, D.D.S., M.H.C.M., professor and associate dean for clinical affairs at the U-M School of Dentistry. “While it’s reassuring that dental opioid prescribing is declining, the recent slowing in the decline suggests the dental profession must redouble its efforts to reduce unnecessary opioid prescribing.”

The researchers couldn’t determine the procedure that led to each opioid prescription, nor could they determine the exact reason for the slowing of the decline in dental opioid prescribing during the pandemic. However, there are some likely culprits.

“One reason for the slowing might be that dentists were more likely to prescribe opioids just in case they were necessary, out of concerns that patients couldn’t easily follow up with their dentist during the pandemic,” said Zhang.

Right-sizing prescribing

Chua, Nalliah and their colleagues have studied dental opioid prescribing multiple times, and worked with the Michigan Opioid Prescribing Engagement Network (OPEN) to develop prescribing guidelines for dental and oral surgery care available at michigan-open.org/dentistry.

Reducing the number of opioids dispensed to dental patients, especially young ones, is thought to reduce the risk of opioid misuse and diversion of pills to other people besides the patient.

Poisoning of others in the household, and interactions between opioids and other substances including alcohol and prescription drugs, are other reasons to focus on non-opioid dental pain care.

But no studies have examined dental opioid prescribing trends using pandemic-era data.

Differences by provider type, insurance type and region

The new study is based on data from a company called IQVIA that tracks prescriptions dispensed at 92% of U.S. pharmacies. The researchers excluded data from March through May of 2020, when routine dental care in the U.S. stopped temporarily.

The study revealed pandemic-associated changes in dental opioid prescribing varied widely. For instance, the rate of decline in opioid prescribing by oral and maxillofacial surgeons – who perform more complex procedures on people with advanced dental conditions – slowed during the pandemic to a lesser degree than for general dentists and dental subspecialists.  

For low-income patients covered by the Medicaid program, the number of dental opioid prescriptions during June 2020-December 2022 was 57% higher than predicted than if pre-pandemic trends had continued. For privately insured patients, this percentage was 30% higher than predicted.

The authors speculated that worsened access to dental care in Medicaid patients – who have already have poor access to begin with – may have increased the number of painful dental emergencies and the need for opioids.

People living in the Southern U.S. made up nearly 46% of all people with dental opioid prescriptions in 2022, higher than any other region. But the researchers found that the decline in dental opioid prescribing to people in the Northeast slowed to a greater degree than in other regions. This meant that by the end of 2022, dental opioid prescribing was 69% higher in the Northeast than it would have been if declines had continued at pre-pandemic rates, compared with 23.8% in the South.

Additional authors:

In addition to Chua, Zhang and Nalliah, the study’s authors include OPEN co-directors Jennifer Waljee, M.D., M.P.H., M.S. and Chad Brummett, M.D. All except Zhang are members of the U-M Institute for Healthcare Policy and Innovation, and Brummett co-directs the U-M Opioid Research Institute.

Chua is a member of the Susan B. Meister Child Health Evaluation and Research Center in the Department of Pediatrics, which also provided some of the funding for the study.

The study was also funded by the Benter Foundation and the Michigan Department of Health and Human Services.

Association Between the COVID-19 Outbreak and Opioid Prescribing by U.S. Dentists, PLOS ONE, DOI:10.1371/journal.pone.0293621

 

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JOURNAL

PLoS ONE

DOI

10.1371/journal.pone.0293621 

Increased risk of dental caries after bariatric surgery

 

IMAGE: 

NEGIN TAGHAT AND ANNA-LENA ÖSTBERG, SAHLGRENSKA ACADEMY AT THE UNIVERSITY OF GOTHENBURG.

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CREDIT: PHOTO: REGION VÄSTRA GÖTALAND

Those who have had surgical obesity treatment have a higher risk of dental caries than before surgery. They also often experience a general decline in oral health. This has been shown by a thesis at the University of Gothenburg.

The aim of the thesis was to study the oral health of individuals before and after treatment for severe obesity. The participants had a BMI of 40 or more, or 35 or more in combination with other medical conditions, such as diabetes. Treatment involved either surgery or medical treatment.

Medical treatment includes lifestyle advice, dietary treatment, possible drug treatment, and support with increased physical activity. However, surgery has proven more effective for weight loss, and with a growing obesity epidemic in many parts of the world, more and more people are having surgery.

“Around 5,000 cases of obesity surgery are performed each year in Sweden alone, and the trend is increasing,” says Negin Taghat, who has defended her doctoral thesis at the Institute of Odontology at the University of Gothenburg’s Sahlgrenska Academy, and who works as a dentist for the Swedish Public Dental Service in Region Västra Götaland. “We were therefore interested in seeing whether there is any change in the oral health of these patients after surgery.”

Increased caries risk after surgery

The group of 118 obese individuals followed in the thesis reveals a pattern whereby higher BMI is associated with higher caries risk according to a rising scale. At the highest BMI values, there was a doubled risk of caries and less regular dental care.

Two years after either surgical or medical treatment, a clear division emerged between the groups. Those who had undergone surgery had gone from an average of 15.0 caries lesions on the surface of the tooth enamel to 19.1. Within the group receiving medical treatment, however, enamel lesions had decreased.

Another example relates to deeper caries lesions in the dentine, with an average pre-treatment initial value of 4.3 lesions. Two years after treatment, individuals in the surgery group had an average of 6.4 such lesions while those in the medical treatment group had 4.9.

The associations were statistically significant, even when taking factors such as socioeconomic status and other medical conditions into account.

Important knowledge for healthcare

“Individuals who have undergone surgical obesity treatment may also experience a variety of oral symptoms and an impact on their oral quality of life,” continues Negin. “We saw that almost half of individuals experienced poorer oral health.”

Symptoms can include hypersensitive teeth and difficulties with chewing. The situation as a whole can also cause social discomfort.

“Health professionals and dental professionals meet these patient groups in their everyday work. It is extremely important for staff to be aware that oral health can be affected by both obesity and obesity treatment so that preventive measures can be planned.”

The group investigated within the thesis is part of the larger BAriatic surgery SUbstitution and Nutrition (BASUN) study, initiated by researchers at Sahlgrenska Academy to compare long-term outcomes of medical and surgical obesity treatment.

Title: On oral health before and after obesity treatment: Studies on clinical and patient-reported outcomes, https://hdl.handle.net/2077/76802