Decision on dental amalgam secures an equity-focused, patient-centred approach

 

 A landmark decision was reached at the Sixth Conference of the Parties (COP6) to the Minamata Convention on Mercury, where Parties agreed to set 2034 as the global phase-out date after which the manufacture, import, or export of dental amalgam will no longer be permitted. This milestone marks a major win for oral and public health and underscores the power of unified, science-based advocacy led by FDI World Dental Federation (FDI) and the International Association for Dental, Oral, and Craniofacial Research (IADR).

The final decision reflects a balanced and equity-focused approach to phasing down dental amalgam use worldwide. Crucially, it includes a key exemption that supports the joint advocacy by FDI and IADR, which ensures that even after phase-out of dental amalgam it can be used “when its use is considered necessary by the dental practitioner based on the needs of the patient.” This provision ensures that patient care remains at the center of decision-making, safeguarding access to essential restorative treatments where alternatives are not yet available or viable.

FDI and IADR, with the support of the International Dental Manufacturers Association (IDM) and the American Dental Association (ADA), worked tirelessly to secure a balanced outcome by actively engaging in and influencing discussions throughout the negotiations. Coordinated advocacy efforts emphasized that while accelerating the phase down and eventually phasing out dental amalgam is essential, it must be achieved through an evidence-based, patient-centered, and equitable transition that is fair to all countries and considers their specific challenges and capacities.

“As we move toward the eventual phase-out of dental amalgam, it is essential that the needs of our members, and the patients they serve, remain at the heart of every decision,” said Mr Enzo Bondioni, Executive Director of FDI. “This outcome provides much-needed time and clarity for our members to plan, prepare, and implement the necessary national policies. It reinforces FDI’s commitment to supporting the global dental community in maintaining continuity of care and advancing oral health equity during this important transition”.

Over four days of intense deliberation, both organizations delivered individual and joint statements reinforcing the continued relevance of dental amalgam in restorative dentistry, while emphasizing the importance of prevention. They called for research into affordable, effective, and sustainable alternative materials and emphasized that waste management should be compulsory to reinforce the Convention’s broader objective of reducing environmental mercury exposure. These concerted efforts helped ensure that the final phase-out timeline was extended beyond 2030, the date originally proposed to 2034.

“Science and evidence must remain at the heart of every global health policy decision,” said Dr Christopher Fox, Chief Executive Officer of IADR. “This outcome reflects the progress we’ve made by investing in research into mercury-free alternatives, as called for in the text of the Minamata Convention, from both the public and private sectors. “IADR remains committed to supporting continued innovation and research that will further the rapid improvement of affordable, effective, and sustainable restorative materials, so no one is left behind in this transition”.

The decision gives Parties nine years to adapt their national strategies and healthcare systems to this new framework. This aligns closely with FDI and IADR’s long-standing position advocating for a coordinated and equity-focused phase-down that allows all countries, especially low- and middle-income nations, to strengthen capacity, build technical expertise, and ensure continuity of patient care during the transition.

By recognizing the diverse realities of healthcare delivery worldwide, the 2034 phase-out date and practitioner-based exemption together provide flexibility that avoids widening existing oral health inequalities. The Minamata Convention on Mercury, which entered into force in August 2017, now counts 153 Parties as of September 2025. The Seventh Conference of the Parties (COP7) will take place in June 2027, coinciding with the tenth anniversary of the Convention.

About FDI World Dental Federation (FDI)

FDI World Dental Federation is the leading global voice of the dental profession and envisions a world with optimal oral health. It serves as the principal representative body for over 1 million dentists worldwide. Its membership includes some 200 national dental associations and specialist groups in over 130 countries. www.fdiworlddental.org/

About International Association for Dental, Oral, and Craniofacial Research (IADR)

The International Association for Dental, Oral, and Craniofacial Research (IADR) is a nonprofit organization with a mission to drive dental, oral, and craniofacial research for health and well-being worldwide. IADR represents the individual scientists, clinician-scientists, dental professionals, and students based in academic, government, non-profit, and private-sector institutions who share our mission. Learn more at www.iadr.org.

Non-prescription pain meds work equally well for men and women after tooth extraction

 

Over-the-counter pain medications work as well or better than opioids after wisdom tooth extraction for both men and women, according to a Rutgers Health-led follow-up to a landmark paper on comparative pain relief.

That first paper on the collective experience of more than 1,800 trial patients found that the combination of ibuprofen and acetaminophen provided better pain relief than hydrocodone with acetaminophen for the first two days after surgery and greater satisfaction over the post-operative period. The new subgroup analysis, published in JAMA Network Open, demonstrated that the results held for both male and female patients.

"We wanted to determine whether the pain medication’s effects were consistent in males and females separately," said Janine Fredericks Younger, an associate professor at Rutgers School of Dental Medicine and lead author of the analysis. "And what we found is that in both subgroups (males and females), the non-opioid was superior for that first day and night, and then no worse than the opioid for the rest of the post-op period."

The trial that produced both papers, funded by an $11 million grant from the National Institutes of Health, compared patients who received 400 milligrams of ibuprofen (Advil, Motrin) combined with 500 milligrams of acetaminophen (Tylenol) against those who got 5 milligrams of hydrocodone with acetaminophen. 

The gender-specific analysis was particularly important because women consistently report higher pain levels after surgery, raising questions about whether pain medications work differently for each sex. 

"There's obviously different biological mechanisms, different hormones involved," said Cecile Feldman, dean of Rutgers School of Dental Medicine and senior author of both studies. "But results confirm that the analgesic effect for both groups is the same."

The researchers deliberately enrolled equal numbers of men and women from the start, allowing them to conduct robust subgroup analyses. Patients across five universities tracked their pain twice daily for nine days using electronic diaries, rating not just pain but also sleep quality, ability to perform daily activities and overall satisfaction.

On every measure, the over-the-counter combination matched or beat the opioid. Patients taking the non-opioid medications reported better sleep quality and less interference with daily activities. Those who received opioids were twice as likely to call back requesting additional pain medication.

"The results actually came in even stronger than we thought they would," Feldman said. "We expected to find the non-opioid to be non-inferior, so that at least it was no worse than opioids. We were surprised to see that it was actually superior."

Dental procedures are a common entry point for opioid exposure. Dentists wrote more than 8.9 million opioid prescriptions in 2022, ranking among the nation's leading prescribers of the drugs.

"There are studies out there to show that when young people get introduced to opioids, as many have via wisdom tooth extraction, there's an increased likelihood that they'll eventually use them again, and then it can lead to addiction," said Fredericks Younger, noting that opioid overdoses kill more than 80,000 Americans annually.

The research focused on the extraction of impacted wisdom teeth, which requires cutting into gums and sometimes removing bone, making it one of the most painful dental procedures. The Food and Drug Administration uses this as a standard model for testing pain medications because it reliably produces moderate to severe pain for about 48 hours.

Feldman said the results, showing the superiority of the over-the-counter medication to opioids, likely apply to other dental procedures but cannot be automatically generalized to surgeries in other parts of the body. She would like to see similar studies conducted for a range of procedures, particularly those for orthopedic injuries, which frequently result in opioid prescriptions for high school and college athletes.

Despite mounting evidence, many dentists continue writing "just in case" opioid prescriptions for patients who are told to start with over-the-counter medications. The next phase of research will examine why these prescribing patterns persist.

"How can we now, with the evidence and the knowledge that we have, eliminate these prescriptions from being written?" Fredericks Younger said.

The findings align with American Dental Association recommendations to avoid opioids as first-line pain treatment. Feldman said the study's results leave little room for doubt.

"We feel pretty confident in saying that opioids should not be prescribed routinely for dental procedures," she said. "Our non-opioid combination really should be the analgesic choice."

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Journal

JAMA Network Open

DOI

10.1001/jamanetworkopen.2025.42467 

Scientists find cells that know when, where, and how to grow teeth

 Tooth development is a dynamic process that involves the stages of the bud, the cap, and the bell, followed by root development and subsequent tooth formation. Processes such as the bud-to-cap transition are mediated by epithelial-mesenchymal interactions. In addition, the position of a cell in a developing embryo determines its fate due to the relative differences in concentration of signaling molecules and growth factors.

Scientists have long known that a single tooth develops as a small bud of outer “epithelial” cells into the deeper “mesenchymal” cells. It then curves to form a cap shape and then folds in further to form the bell shape of a mature tooth, with surrounding bone and gums. Dr. Han-Sung Jung and his team at the Yonsei University College of Dentistry, Korea, extended these findings by examining how the position of young epithelial and mesenchymal dental cells would influence what they grow into and have published their findings in International Journal of Oral Science.

Lead author Dr. Jung said that his team “performed this study to identify how positional identity along the lingual-buccal axis determines distinct developmental fates of dental mesenchyme. This research has the potential to significantly impact our understanding of tooth development,” he says.

The investigators separated the mesenchymal cells on the lingual and buccal sides at both cap and bell stages of a developing mouse embryo and -compared their gene expression profiles through RNA-seq followed by Gene Ontology enrichment analysis to understand the differences with position and time. They then transplanted the cap-stage lingual and buccal cells separately under the kidney capsule of immunocompromised mice to see what each grew into. Analysis showed that cells on the lingual side were mainly geared toward making the tooth itself and shaping its structure, while cells on the buccal side were more focused on stem cell activity, forming surrounding tissues, and supporting tooth growth and repair. Not surprisingly, only the lingual cells in the mouse kidney grew into tooth enamel.

The researchers also reported haphazardly mixing up cap-stage, tagged buccal and lingual cells of genetically engineered mice. “We were curious to know if they could find their original place and reorganize when the fluorescently labled lingual and buccal mesenchymal cells were mixed randomly, which they not only did, but the lingual cells grew into dentin to form the tooth as before. This phenomenon is called cellular self-organization,” says first author Eun-Jung Kim.

Furthermore, they have extensively studied the signalling molecules in each group and found that WNT signalling and R-spondins (Rspo1/2/4) are enriched in lingual cells, along with high proliferation, low cell death, and higher migration rate, aiding tooth formation. On the other hand, buccal cells show increased expression of  BMP inhibitors, lower proliferation, higher apoptosis, and slower migration, favoring bone and surrounding tissue formation.

In conclusion, the authors proposed a model of dental cell positioning based on the lingual-buccal axis for tooth and surrounding tissue formation. The characteristics of dental mesenchymal cells were found to vary along this axis, and the fate of the tooth and surrounding tissue formation is determined by mesenchymal cells via WNT/BMP signaling. Deeper knowledge of the molecular nuances of tooth development will inspire further research in tissue engineering and regenerative medicine, which may ultimately lead to advancements in stem cell-based tooth regeneration and more effective therapeutic applications for dental restoration and repair.

 

***  
 

Reference
DOI: https://doi.org/10.1038/s41368-025-00391-7

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Journal

Gum disease and cavities linked to increased stroke risk

 

Highlights:

• A new study finds that having both gum disease and cavities is linked to an 86% increased risk of stroke compared to having a healthy mouth.
• Poor oral health was tied to a 36% higher risk of heart attacks and other cardiovascular events.
• People with regular dental visits were 81% less likely to have both gum disease and cavities.
• Researchers say improving oral health could be an important — and often overlooked — way to help reduce stroke risk.

MINNEAPOLIS – People with both cavities and gum disease may face a higher risk of ischemic stroke, according to a study published on October 22, 2025, in Neurology® Open Access, an official journal of the American Academy of Neurology. The study does not prove that poor oral health causes strokes; it only shows an association.

Ischemic strokes are the most common type of stroke and occur when a clot or blockage reduces blood flow to the brain, depriving it of oxygen and nutrients.

Cavities are holes in the tooth enamel caused by sugary or starchy foods or factors such as poor oral hygiene or genetics. Gum disease, usually caused by poor oral hygiene, is an inflammation or infection of the gums and jawbone. It can lead to tooth loss.

“We found that people with both cavities and gum disease had almost twice the risk of stroke when compared to people with good oral health, even after controlling for cardiovascular risk factors,” said study author Souvik Sen, MD, MS, MPH, of the University of South Carolina in Columbia. “These findings suggest that improving oral health may be an important part of stroke prevention efforts.”

Researchers analyzed data from 5,986 adults with an average age of 63 who had no prior history of stroke at the start of the study. All participants completed dental exams that assessed whether participants had gum disease, cavities or both. Participants were then placed in three groups: having a healthy mouth, gum disease only or gum disease with cavities.

Researchers followed them for two decades, using phone visits and medical records to determine which people had a stroke.

Of 1,640 people with healthy mouths, 4% had a stroke, of 3,151 people with gum disease only, 7% had a stroke and of 1,195 people with gum disease and cavities, 10% had a stroke.

After adjusting for factors such as age, body mass index and smoking status, researchers found when compared to people with healthy mouths, those with both gum disease and cavities had an 86% higher risk of stroke. Those with gum disease alone had a 44% increased risk.

The study also looked more broadly and found that people with both gum disease and cavities had a 36% higher risk of experiencing a major cardiovascular event, such as a heart attack, fatal heart disease or stroke when compared to people with healthy mouths.

Participants who reported visiting the dentist regularly had 81% lower odds of having both gum disease and cavities and 29% lower odds of having gum disease alone.

“This study reinforces the idea that taking care of your teeth and gums isn’t just about your smile; it could help protect your brain,” said Sen. “People with signs of gum disease or cavities should seek treatment not just to preserve their teeth, but potentially to reduce stroke risk.”

A limitation of the study is that participants’ oral health was assessed only once at the start of the study, so changes in dental health over time weren’t captured. It’s also possible that other unmeasured health factors contributed to the findings.

Gum disease associated with changes in the brain

 Adults with gum disease may be more likely to have signs of damage to the brain’s white matter, called white matter hyperintensities, than people without gum disease, according to a new study published on October 22, 2025, in Neurology® Open Access, an official journal of the American Academy of Neurology.

White matter refers to nerve fibers that help different parts of the brain communicate. Damage to this tissue can affect memory, thinking, balance and coordination and has been linked to higher stroke risk.

White matter hyperintensities are bright spots that appear on brain scans that are thought to reflect damaged white matter tissue. While the study found an association, it does not prove that gum disease causes white matter damage.

“This study shows a link between gum disease and white matter hyperintensities suggesting oral health may play a role in brain health that we are only beginning to understand,” said study author Souvik Sen, MD, MS, MPH, of the University of South Carolina in Columbia. “While more research is needed to understand this relationship, these findings add to growing evidence that keeping your mouth healthy may support a healthier brain.”

The study included 1,143 adults with an average age of 77. Each person had a dental exam to check for gum disease. Of participants, 800 had gum disease and 343 did not.

Participants had brain scans to look for signs of cerebral small vessel disease, which is damage in the brain’s small blood vessels that can appear as white matter hyperintensities, cerebral microbleeds or lacunar infarcts. These brain changes become more common with age and are associated with increased risk of stroke, memory problems and mobility issues.

People with gum disease had more white matter hyperintensities, with an average volume of 2.83% of total brain volume compared to 2.52% for people without gum disease.

Researchers divided people into four groups based on white matter hyperintensity volume. Those in the highest group had a volume of more than 21.36 centimeters cubed (cm³) while those in the lowest group had a volume of less than 6.41 cm³.

Of people with gum disease, 28% were in the highest group compared to 19% of people without gum disease.

After adjusting for factors such as age, sex, race, high blood pressure, diabetes and smoking, people with gum disease had 56% higher odds of falling into the highest group of white matter hyperintensities than people without gum disease.

However, no links were found between gum disease and two other brain changes tied to small vessel disease, cerebral microbleeds and lacunar infarcts.

“Gum disease is preventable and treatable,” said Sen. “If future studies confirm this link, it could offer a new avenue for reducing cerebral small vessel disease by targeting oral inflammation. For now, it underscores how dental care may support long-term brain health.”A limitation of the study is that brain imaging and dental assessments were conducted only once, making it difficult to assess changes over time.

Researchers explore drill-free treatments for cavities in older adults

 A trip to the dentist isn’t something people usually look forward to.

“Because of all the drilling and injections, it’s not fun,” acknowledged Suchitra Nelson, an associate dean and professor at the Case Western Reserve University School of Dental Medicine.  

While discomfort can’t be entirely avoided in all dental procedures, Nelson is leading a new study to advance previous research that found two less-invasive options to treat and prevent cavities were equally effective.

The study focuses on older adults living in subsidized housing with limited access to dental care because of such barriers as dental insurance, transportation and their overall general health—especially mobility.

As with the previous study, the patients will be treated for cavities with two methods that don’t require a dental drill or anesthesia: Silver Diamine Fluoride (SDF) and Atraumatic Restorative Treatment (ART).

SDF, a liquid medication applied to cavities to stop them from progressing, is a quick and painless treatment that kills bacteria and strengthens the tooth’s surface, Nelson said. And ART involves removing decayed tissue with hand instruments and then applying a dental restorative material.

“Long-term evidence for these treatments is lacking,” Nelson said. “This long-term follow-up study can inform the best treatments for patients and providers to prevent and treat tooth decay.”

The study is being supported with a five-year, $5 million grant from the nonprofit Patient-Centered Outcomes Research Institute (PCORI).

Among older adults nationally, nearly 96% have had a cavity, and 33% of non-Hispanic Black, Hispanic and low-income older adults have teeth with decay that has gone untreated because of limited access to affordable dental care, according to according to the Centers for Disease Control’s National Center for Health Statistics.

Untreated tooth decay leads to painful toothaches, infection and tooth loss. But the related health concerns are much broader: Major dental issues can make heart and lung disease and diabetes worse.

In Nelson’s previous PCORI-funded study, 568 participants received either SDF or ART to prevent cavities. Participants received dental exams, treatments for cavities and completed surveys. The research found that the two treatments were equally effective in preventing cavities.

“We also found that dental hygienists can successfully deliver dental care at the housing facilities where older adults live,” Nelson said.

The new study will follow up with 480 of the patients living in 33 subsidized housing facilities in Northeast Ohio. The follow-up participants will be tracked for three visits over a year and receive the same treatments (SDF or ART) for any new cavities.

While the subject of the studies is older adults, Nelson said less invasive treatments could be used for patients of any age.

“Our stakeholder partners from local, state and national organizations have enthusiastically indicated that they would use the results of our work to make changes that improve access and clinical care, improve Medicaid policies for reimbursement and make the study’s results widely available,” she said.

Smartphone imaging system shows promise for early oral cancer detection in dental clinics

 

A smartphone-based system combines autofluorescence and white light imaging with machine learning for accurate identification of oral lesions that require referral to cancer specialists

Peer-Reviewed Publication

SPIE--International Society for Optics and Photonics

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image: 

Analysis of an anatomic site using the mobile Detection of Oral Cancer (mDOC) model involves multiple inputs: images of clinically relevant regions are masked, cropped, resized for analysis, and passed through the mDOC system, along with oral cancer risk factors. The output referral decision is “Refer” or “Do Not Refer” for oral cancer evaluation.

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Credit: R. Mitbander et al., doi 10.1117/1.BIOS.2.4.042307

Oral cancer remains a serious health concern, often diagnosed too late for effective treatment—even though the mouth is easily accessible for routine examination. Dentists and dental hygienists are frequently the first to spot suspicious lesions, but many lack the specialized training to distinguish between benign and potentially malignant conditions. To address this gap, researchers led by Rebecca Richards-Kortum at Rice University have developed and tested a low-cost, smartphone-based imaging system called mDOC (mobile Detection of Oral Cancer). Their recent study, published in Biophotonics Discovery, evaluates how well this system can help dental professionals decide when to refer patients to oral cancer specialists.

The mDOC device combines white light and autofluorescence imaging with machine learning to assess oral lesions. Autofluorescence imaging uses blue light to detect changes in tissue fluorescence, which can signal abnormal growth. However, this method alone can be misleading, as benign conditions like inflammation also reduce fluorescence. To improve accuracy, the mDOC system uses a deep learning algorithm that analyzes both image data and patient risk factors—such as age, smoking habits, and anatomic location—to make referral recommendations.

In this study, researchers collected data from 50 patients at two community dental clinics in Houston, Texas. Each patient underwent imaging of up to five oral sites using the mDOC device. The images were reviewed by expert clinicians, and their referral decisions served as the ground truth for training and testing the algorithm. The team used a rehearsal training method, combining new data with previously collected images from high-prevalence and healthy populations to improve the model’s performance in typical dental settings, where suspicious lesions are rare.

The final model was tested on a holdout dataset representing a low-prevalence population. It achieved an area under the ROC curve (AUC-ROC) of 0.778, with a sensitivity of 60 percent and specificity of 88 percent. This means the system correctly identified 60% of the sites that experts recommended for referral, while avoiding unnecessary referrals in most cases. Notably, the mDOC algorithm outperformed dental providers, who had 0% sensitivity and 100 percent specificity—missing all cases that required referral.

While the system misclassified two of five referral sites, those lesions had resolved by the time of the specialist visit, suggesting that mDOC may have correctly predicted that no further evaluation was needed. However, the algorithm also produced 21 false positives, indicating room for improvement in specificity.

The study highlights the potential of mDOC to support early detection and referral decisions in dental clinics, especially where access to specialists is limited. With an average imaging time of just 3.5 minutes, the system fits easily into routine dental workflows. Future improvements may include collecting more detailed patient history and refining the algorithm to reduce false positives.

For details, see the original Gold Open Access article by R. Mitbander et al., “Optimization of a mobile imaging system to aid in evaluating patients with oral lesions in a dental care setting," Biophoton. Discovery 2(4), 042307 (2025), doi: 10.1117/1.BIOS.2.4.042307.

 

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Journal

Biophotonics Discovery

DOI

10.1117/1.BIOS.2.4.042307 

Dental shame stops people seeking help for oral health issues

Shame can lead people to avoid getting treatment for dental issues, potentially worsening oral health inequalities, a new study warns.

A better understanding of dental shame could encourage more people to seek help, researchers and practitioners have said.

It would alleviate some of the devastating consequences that oral health problems can have on overall health, disease and even risk of death.

Researchers warn that healthcare practitioners can incite shame in patients both intentionally and unintentionally. When shaming is used purposefully with the intention to attempt to motivate positive health behaviours, there is no guarantee this will result in beneficial change.

Those working in dentistry and other health care and social settings should be trained in shame competence. This approach includes addressing systemic barriers and designing empathetic and inclusive care environments.

Dental shame can stem directly from oral health issues or the aesthetic appearance of the teeth. It is often more found in those who are vulnerable because of deprivation, trauma or abuse. It is also found in relation to drinking, smoking or eating habits.

It can lead to lower self-worth, social isolation and unfavourable oral health care behaviours.

The study is by Louise Folker, Esben Boeskov Øzhayat and Astrid Pernille Jespersen from the University of Copenhagen, Luna Dolezal, from the University of Exeter, Lyndsey Withers, a community volunteer, Martha Paisi, from Peninsula Dental School, University of Plymouth, and Christina Worle, a dentist.

The academics from the University of Copenhagen are working on the project Lifelong Oral Health, which aims to identify barriers to oral health in Danish elderly care—and have identified dental shame as significant in elderly care settings. Professor Dolezal is leading the Shame and Medicine research project at the University of Exeter.

Professor Dolezal said: “Shame can help explain why some people don’t like to expose their teeth to dentists or tell them they smoke or have a poor diet.

“As the study explains, dental shame is both a consequence and a determinant of oral health issues. It is a consequence because oral health issues can cause shame, and it is a determinant because it can act as a barrier to both daily dental care and engagement with dentistry. This can turn dental shame into a self-reinforcing spiral, where shame about oral health can lead to unfortunate oral health behaviours, which can potentially intensify oral health issues and inequities, leading to more shame.

“Because our teeth are highly visible and central to our overall appearance and well-being, dental shame affects self-esteem, social interactions, access to the labour market, care systems and social services. This downward spiral concerns not only oral health but also various other aspects of life.”

“It is important to have non-judgmental environments where patients feel trustful and empowered to prioritise their oral health.”

The study says systemic inequities in dental care significantly contribute to dental shame and healthcare fee structures can increase dental shame.

Practitioners in oral health care and social settings should be trained in shame competence in order to be able to identify shame, to be aware of how it circulates between individuals and within institutional culture, to manage shame dynamics, identify shaming in policy and practice, and reduce the potentially damaging and anti-social effects of shame.

 

 

 

Afraid of the dentist? The cause may be something different from what you think

 

Between 8 – 20 per cent of children and adolescents are so afraid of dental treatment that they meet the criteria for being diagnosed with dental fear.

Young people who have experienced bullying, divorce, violence or abuse are significantly more likely to be anxious in the dentist’s chair. 

This angst may cause some people to avoid going to the dentist, while others feel an intense urge to flee once they are there.

A major risk factor is painful experiences at the dental clinic.

Between 8 – 20 per cent of children and adolescents are so afraid of dental treatment that they meet the criteria for being diagnosed with dental fear.

Now, new research shows that dental fear occurs more often in those who have been exposed to stressful childhood experiences.

In other words, painful experiences in life can affect how you feel in the dentist's chair.

Lying on your back can make you feel vulnerable

The study, with responses from more than 5800 adolescents aged 13 -17 years, shows that adolescents who have experienced stressful experiences during childhood, such as violence, divorce, abuse or bullying are significantly more likely to have dental fear than adolescents who do not have such experiences.

The study is based on data from HUNT, The Trøndelag Health Study, which is one of the largest health studies ever performed. It is a unique database of questionnaire data, clinical measurements and samples from a county’s inhabitants since 1984.

The more stressful experiences the young people had, the great was the likelihood that they would have dental fear. The study also shows that the association was stronger in girls than in boys.

"For many people who have experienced a lot of insecurity in childhood, dental treatment can be demanding. The patients lie on their backs in a vulnerable position while an authority figure works inside the mouth. It's no wonder that dental treatment can be difficult," says Lena Myran, a specialist in psychology. She works on a daily basis at the Competence Center Tannhelse Midt (TkMidt).

Not been to the dentist for 40 years

This centre includes several specialist services where dentists and psychologists work together in teams to help children and adults who have severe dental anxiety. Myran works with adult patients. She is also working on a doctoral thesis at the Norwegian University of Science and Technology (NTNU) on the connections between painful childhood experiences and health, related to the oral cavity and teeth.

"I have patients who haven't been to the dentist for 40 years," Myran said.

The study she recently published is only about young people and looks at the connections between painful childhood experiences and dental fear. The researchers looked at different types of stressors, but painful experiences at the dental clinic were not included in this material.

"It is also important to note that this is a cross-sectional study that does not provide a basis for saying what is cause or effect. We can only see if there is a connection," says Myran.

The study found a clear link between dental fear and various types of painful childhood experiences, including bullying.

Girls most at risk

"Bullying means being systematically rejected and ridiculed. If you have experienced bullying, you may have a hypersensitivity to other people's intentions. There may be periods during dental treatment where it is silent, and you do not quite know what the dentist is thinking. This may be similar to situations where these individuals have felt insecure. For people who have been bullied, saying what you think and feel may have felt dangerous," says Myran.

Myran was surprised that the correlation between painful childhood experiences and dental fear was stronger in girls than in boys.

"We know that dental fear is more common among girls and that more girls than boys have experienced sexual abuse. There are also more girls than boys who develop anxiety and depression in adolescence, but the fact that we found such a clear difference in our material was still surprising," Myran said.

She believes the findings should have consequences for how the dental health service treats young people.

"When dental professionals meet frightened patients, they can ask about the cause. Patients often find it safe for the dentist to ask. Patients know that the dentist is not a psychologist, so it does not have to be a long conversation. But by taking the patient’s experiences and fears into account, dental professionals can contribute to better dental health and safer patient experiences," says Myran.

Tell the dentist

Inspired by other initiatives in Norway, TkMidt established a service for children and adolescents who suffer from dental fear called “Trygge Barn i Tannbehandling” (Safe Children in Dental Treatment) (TBiT) eight years ago. This offer is now being rolled out nationally.

As part of the effort, training is being offered to dental professionals on how to deal with young patients who are afraid.

"It’s important to talk to your dentist or dental hygienist about how you feel. Just telling your dentist that you are afraid can help an incredible amount. Even a short sentence about your fears will lead many dentists to be more sensitive. The dentist is a good friend who should help, and you don't have to ask in any specific way, but just say that you are afraid," says Myran.

She emphasizes that many children may have had painful childhood experiences without developing dental fear, and that the anxiety about the dentist is generally greatest when you are a child, and that it often decreases as the child matures.

Children who have been in dental treatment a lot have an extra vulnerability to developing dental fear.

"Our study and other research show that, overall, there are many ways to develop intense fear of going to the dentist. Fortunately, there is good help available," says Myran.

It is possible for adult patients throughout Norway to seek help from one of Norway's Centres of Expertise in the Dental Health Service (in Norwegian).

References:
Myran, L., Sun, YQ., Dahllöf, G. et al.Associations of adverse childhood experiences with dental fear, and the mediating role of dental fear on caries experience: the Young-HUNT4 Survey. BMC Oral Health 25, 1141 (2025). https://doi.org/10.1186/s12903-025-06486-1

Laura Beaton, Ruth Freeman, Gerry Humphris; Why Are People Afraid of the Dentist? Observations and Explanations. Med Princ Pract 1 July 2014; 23 (4): 295–301. https://doi.org/10.1159/000357223

Raadal M, Strand GV, Amarante EC, Kvale G. Relationship between caries prevalence at 5 years of age and dental anxiety at 10. European Journal of Paediatric Dentistry. 2002 Mar;3(1):22-26. PMID: 12871013

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Journal

BMC Oral Health

DOI

10.1186/s12903-025-06486-1 

BMP9 regulates tooth root development

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Caption

(A) Construction of the Bmp9-KO mice. (B) Relative expression of Bmp9 in the liver of 8-week-old wild-type (WT) littermates and Bmp9-KO mice by quantitative PCR in vitro (n ≥ 3). (C) Western blots of BMP9 and β-actin in the liver of 8-week-old WT littermates and Bmp9-KO mice (n = 6). (D) Immunohistochemical staining of BMP9 on sections of mandibular first molars from WT littermates and Bmp9-KO mice at 2 weeks and 4 weeks old (n = 7). The boxes shown are insets at a lower magnification. Am, ameloblasts; Od, odontoblasts; D, dentin. (E) Quantitative analysis of BMP9 expression. Scale bars = 200 μm.

Credit

Chang Liu, Hongyan Yuan, Jindie Huang, Shidian Ran, Xiaorui Wei, Xingrui Yan, Linyu Xue, Tong-Chuan He, Yuxin Zhang, Mengqin Gu, Si Wu, Fugui Zhang, Wenping Luo, Hongmei Zhangng

The interaction between Hertwig's epithelial root sheath (HERS) and surrounding mesenchymal cells is crucial for root dentin formation. HERS influences tooth root development and odontoblast differentiation; however, further research is needed to elucidate its regulatory mechanisms.

A new study published in the Genes & Diseases journal by researchers from the Affiliated Hospital of Stomatology of Chongqing Medical University, the Chongqing Municipal Health Commission Key Laboratory of Oral Biomedical Engineering, Southwest University, and the University of Chicago Medical Center provides mechanistic insights into how Bmp9 signaling impacts tooth root development.

The authors have previously shown that Bmp9 is crucial for tooth and alveolar bone formation, and in this study report that Bmp9 signaling modulates tooth root development by regulating the development of odontoblasts and HERS.

The authors generated Bmp9-KO mice and, upon comparison with their wild-type (WT) mice, observed that BMP9 plays a critical role in molar root development, dentin mineralization, and root elongation during early odontogenesis. Knockdown of Bmp9 inhibited odontoblast differentiation and also impacted the normal development of the mandibular first molars, as evidenced by shorter molar roots, wider apical foramen, and reduced dentin thickness. Bmp9 ablation disrupted odontoblast polarization, affecting their secretory capacity and weakening DSPP secretion, resulting in delayed dentin mineralization, increased collagen type I deposition, and reduced root length.

Furthermore, knockdown of Bmp9 inhibited cell proliferation within the HERS, thereby affecting HERS elongation and bending, and formation of the root apical foramen, which resulted in shorter roots, thinner dentin, and an unclosed apical foramen in Bmp9-KO mandibular first molars. Additional experiments involving Bmp9 overexpression and knockdown in primary HERS cells showed that “Bmp9 signaling modulates both HERS cell proliferation and intercellular junctions, thereby contributing to the proper development of tooth roots.” 

Comparative transcriptomic profiling and pathway analysis (GO and KEGG) revealed that Bmp9 maintains HERS cell proliferation, junction homeostasis, and drives root morphogenesis by integrating a multidimensional regulatory network involving TGF-β and Wnt signaling and cell-cell connections.

In conclusion, this study is the first to report that BMP9 signaling influences root odontoblast function by regulating cell proliferation and intercellular junctions within HERS, thereby affecting the overall developmental trajectory of molar roots. The authors highlight the need for further research to identify specific binding sites and the mechanism of action of Bmp9 in regulating HERS proliferation and intercellular connectivity integrity.

Reference

Title of the original paper: Bmp9 modulates cell proliferation and intercellular junctions in HERS during tooth root development

Journal: Genes & Diseases

Genes & Diseases is a journal for molecular and translational medicine. The journal primarily focuses on publishing investigations on the molecular bases and experimental therapeutics of human diseases. Publication formats include full length research article, review article, short communication, correspondence, perspectives, commentary, views on news, and research watch

DOI: https://doi.org/10.1016/j.gendis.2025.101777