Saturday, October 7, 2017

Dentists can harvest stem cells



  • Dr. Karl Kingsley and Dr. James Mah, research professors with the UNLV School of Dental Medicine.
  • Credit: Josh Hawkins/UNLV Creative Services

Stem cells. Few research discoveries hold as much promise of single-handedly expanding medical treatment options as they do. Miraculously able to act as transformers—either re-creating or morphing into a variety of cell types found within the organisms they originate from—stem cells offer humanity hope for new, more effective therapies against a number of chronic and terminal diseases. And finding them is surprisingly easy.
“Stem cells can be extracted from nearly any living tissue,” said Dr. James Mah, director of UNLV’s advanced education program in orthodontics, doctor of dental surgery, and dental researcher. “In fact, stem cells can even be found in tissues of the deceased.”
But in spite of all their potential, there’s a catch: “The biggest challenges with stem cells are gathering enough of them to work with and keeping them viable until they are needed,” Dr. Mah said.
He and UNLV biomedical sciences professor Karl Kingsley—along with a handful of undergraduate, graduate, and postdoctoral dental students—decided to take on this challenge, cutting their teeth in stem cell research by exploring those pearly whites in new ways. In the process, they developed a new method for extracting large numbers of stem cells they could then preserve from a surprisingly abundant source: wisdom teeth.
“More and more adults—approximately 5 million throughout the country—have their wisdom teeth, or third molars, removed,” Kingsley said. “Extracting teeth is relatively common among patients undergoing orthodontic treatments. And the majority of those teeth are healthy, containing viable tooth root pulp that offers opportunities for reproducing cells that have been damaged or destroyed by injuries or disease.”

A tough nut to crack

Tooth root pulp is home to two types of prized stem cells. The first, pluripotent stem cells, have the ability to become any cell in the organism from which they’re drawn. The second, multipotent stem cells, transform into specific types of cells within that organism.
Knowing where to find these cells was one thing. Recovering them, the researchers knew, would be another.
Common methods for extracting root pulp involve drilling into, removing the top of, or shattering the tooth. Each method has its detriments, Dr. Mah said, all of which lead to a low stem-cell recovery rate: damaging heat from drilling, corrosive elements in the water teeth are rinsed in, contaminating enamel particulates, and more. So the researchers sought to discover how to extract pulp in a manner that consistently produced a higher yield.
“Initially, the answer seemed simple: crack the tooth in half like a nut and remove the pulp,” Dr. Mah said.
Unfortunately, teeth have irregular surfaces and non-uniform shapes, so cracking teeth usually produces the same shattering effect as a hammer, thereby reducing the number of viable stem cells.
Happy Ghag, then a dental student working with Dr. Mah and Kingsley on the project, thought he might have solution to the dilemma. He approached Mohamed Trabia (UNLV Howard R. Hughes College of Engineering’s associate dean for research, graduate studies, and computing) and Brendan O’Toole (Mendenhall Innovation Program director and mechanical engineering researcher) to discuss fracture analysis.
“Happy had reviewed fracture mechanics literature and decided on a technique that scored the tooth to enable a clean break, similar to the process for custom-cut glass,” O’Toole said. After a few discussions, some of Engineering’s personnel helped Ghag fabricate the device.
The completed instrument, which the research team facetiously dubbed the “Tooth Cracker 5000,” uses a clamp to hold a tooth in position for a cutting tool to score the surface and a blade to crack it. The result: a perfectly halved tooth, with immediate access to undamaged and uncontaminated root pulp.
For O’Toole, this was just another successful collaboration between the two units, as Mechanical Engineering had been interacting with the School of Dental Medicine’s orthodontic program for a few years.
“Orthodontics, by definition, is a bioengineering topic,” O’Toole said. “They design and place mechanisms in people’s mouths that help move teeth into optimum position. The interaction between our departments makes a lot of sense.”
With the Tooth Cracker 5000 complete, Dr. Mah and Kingsley tested the fracture rate of 25 teeth, achieving a 100 percent rate of success. The fracture idea and design prototype had worked perfectly.

Excavating for success

Now that the researchers had cracked the challenge of accessing the root pulp, it was on to determining how many viable stem cells they could recover from the fractured teeth. Average pulp recovery rates employing common extraction methods (i.e., shattering, drilling, etc.) come in at around 20 percent, Dr. Mah noted.
It was time to test the mettle of their new fracture method. Dr. Mah and Kingsley dyed 31 fractured teeth pulp samples to highlight any viable stem cells the teeth contained. Dead cells would turn blue when exposed to the dye. Living cells would appear clear.
They looked under the microscope. Eighty percent of their extracted cells remained clear after the dye was introduced.
“Saying the test results were promising is a gross understatement,” Dr. Mah said. “We realized we’d invented an extraction process that produced four times the recovery success rate for viable stem cells. The potential application is enormous.”

Replicating for a rainy day

After mastering fracturing and extraction, it was time for the team to determine what kind of stem cells could be harvested and how best to store them.
Normal cells within the body typically die after 10 replications or passages, whereas stem cells can replicate indefinitely, Kingsley indicated. To isolate the stem cells from the rest of the root pulp, the researchers harvested cells from the pulp and cultured them on a petri dish. Once the cells covered the dish, they split the culture in half and repeated the process between 10 and 20 times.
By the end of the culturing, all nonstem cells had expired. Kingsley captured the remaining stem cells and collected their ribonucleic acid (RNA), which is converted into proteins that become biomarkers his team could use to characterize each stem cell type and its respective rate of replication.
“Scientists around the world are trying to figure out what type of stem cells can be coaxed into becoming new cells or different tissue types,” Kingsley said. “We already know some populations of dental pulp stem cells can be converted into neurons, which could become therapies for cognitive diseases such as Alzheimer’s or Parkinson’s.”
Kingsley noted that teams of scientists around the world are working with animal models to test using stem cells to treat neurological conditions. Early indications, he said, are positive. Although there is still a need for additional tests, Kingsley indicated that the next logical step in this research would be to test stem cells in humans to treat any number of chronic illnesses people face.
“There are potential applications of stem cells for multiple diseases, including cancer, arthritis, and lung disease,” Kingsley said. “The next challenge is reliably collecting the stem cells early enough and storing them successfully so they can be used when needed.”

Preserving the prize

According to multiple studies, the number of pluripotent stem cells found in teeth decrease dramatically after adults reach the age of 30, Kingsley said. However, people could donate stem cells found in their teeth much like they may donate their blood prior to a surgical procedure or preserve their umbilical cords. If people elected to have their wisdom teeth removed or were having a root canal performed, their stem cells could be harvested at that time and stored for future use.
Creating that possibility has led Dr. Mah and Kingsley to the next step in their research: the cryogenic process.
“There is no standard cryogenesis, or freezing process, for storing stem cells,” Kingsley said. “There are multiple organizations that collect and freeze teeth for future studies and use, but there is no evidence about the long-term effects of cryopreservation. We can’t answer yet just how long the cells will survive.”
In 2011 dental student Allison Tomlin studied different populations of stem cells and their viability after being thawed. Every year since, Kingsley and his team have thawed a portion of Tomlin’s sample and evaluated the viability of remaining stem cells. Initial findings—which Kingsley, Tomlin, and R. Michael Sanders (clinical sciences professor in the dental school) published in their Biomaterials and Biomechanics in Bioengineering article “The Effects of Cryopreservation on Human Dental Pulp-derived Mesenchymal Stem Cells”—indicate that rapidly dividing cells have higher rates of viability year after year compared to slower dividing cells. If these results remain constant, the stem cells could be sorted before the freezing process based on when they might be needed.
“The work Dr. Kingsley and I are doing is part of a paradigm shift,” Dr. Mah said. “Our fracturing process could hasten the collection and cryogenesis process, thereby preserving a high stem-cell count that furthers research into how using these cells can aid healing and potentially cure diseases.”

Friday, October 6, 2017

Antibiotics for dental procedures linked to superbug infection, study shows

                    

Antibiotics prescribed by dentists may contribute to the growing problem of Clostridium difficile (C. diff), a serious and potentially deadly infection that causes severe diarrhea, suggests research presented at IDWeek 2017. And many of those antibiotics are likely unnecessary, researchers note.

Taking antibiotics can put patients at risk for developing C. diff and illustrates the importance of using the medications only when needed. The Minnesota Department of Health (MDH) tracked community-associated C. diff infections - meaning those in patients who did not have an overnight stay in a hospital or nursing home - in five counties in the state. During the six-year period, researchers determined 15 percent of those with the infection who had taken antibiotics had them prescribed for dental procedures.

But one-third of those patients' medical charts included no mention of receiving dental procedure-related antibiotics, researchers determined. An earlier survey conducted by the MDH found 36 percent of dentists prescribed antibiotics in situations that are generally not recommended by the American Dental Association (ADA) and reported challenges to making appropriate antibiotic prescribing decisions, including confusion about or perceived conflicts among prescribing guidelines.

"Dentists have been overlooked as a source of antibiotic prescribing, which can potentially delay treatment when doctors are trying to determine what is causing a patient's illness," said Stacy Holzbauer, DVM, MPH, lead author of the study and career epidemiology field officer for the CDC and MDH. "It's important to educate dentists about the potential complications of antibiotic prescribing, including C. diff. Dentists write more than 24.5 million prescriptions for antibiotics a year. It is essential that they be included in efforts to improve antibiotic prescribing."

Dentists appropriately prescribe antibiotics in certain situations, such as to treat infections stemming from a tooth abscess. However, some dentists prescribe antibiotics prophylactically before a dental procedure to prevent a heart infection in patients with heart conditions, or to prevent an infection of an artificial joint, such as a hip or knee replacement. The ADA no longer recommends preventive antibiotics in most of those cases, as it once did.

"It is possible some dentists aren't aware of the updated recommendations or are being asked by other healthcare providers to continue preventive antibiotics despite the change," said Dr. Holzbauer. Current recommendations note the risk of taking antibiotics - such as developing C. diff - is greater than the risk of an infection in those cases. Further, the inappropriate use of antibiotics helps fuel the creation of drug-resistant bacteria, which are very difficult to treat and are an increasing public health threat.

In the study, MDH researchers interviewed 1,626 people with community-associated C. diff between 2009 and 2015. Of those, 926 (57 percent) reported they had been prescribed antibiotics, 136 (15 percent) of those for dental procedures. The study found patients who were prescribed antibiotics for dental procedures tended to be older and more likely to receive clindamycin, an antibiotic that is associated with C. diff infection. Of those who had received antibiotics for a dental procedure, 34 percent had no mention of antibiotics in their medical charts, illustrating the disconnect between dental and medical care. During routine medical appointments, patients should bring up dental visits and medications, including antibiotics - they have taken. In addition, healthcare providers should ask patients about dental visits and medications taken for dental reasons.

Antibiotics kill bad and good bacteria in the gastrointestinal (GI) system. Wiping out the protective bacteria can allow the growth of C. diff bacteria, leading to severe and potentially deadly diarrhea. C. diff can occur after just one dose of antibiotics and is one of the top three most urgent antibiotic-resistant threats identified by the CDC. It caused almost half a million infections and led to 15,000 deaths in a single year, according to CDC estimates.

"Research has shown that reducing outpatient antibiotic prescribing by 10 percent could decrease C. diff rates outside of hospitals by 17 percent," said Dr. Holzbauer. "Limiting the use of inappropriate antibiotics in dentistry could also have a profound impact."

While the ADA has expressed a commitment to and is an active partner in antibiotic stewardship, a 2015 MDH survey of dentists found fewer than half were concerned about adverse drug effects, antibiotic resistance or C. diff as factors that influenced their prescribing decisions. That's likely because they are unaware when their patients develop C. diff, Dr. Holzbauer said. Better communication between dental and medical communities and improved history taking by all prescribers would help, she said.


Monday, September 25, 2017

Chronic migraine cases are amplified by jawbone disorder

                     


In a study, researchers at the University of São Paulo's Ribeirão Preto School of Medicine (FMRP-USP), in Brazil, finds that the more frequent the migraine attacks, the more severe will be the so-called temporomandibular disorder, or TMD. The temporomandibular joint acts like a sliding hinge connecting the jawbone to the skull, therefore the disorder's symptoms includes difficulty chewing and joint tension.
"Our study shows that patients with chronic migraine, meaning attacks occurring on more than 15 days per month, are three times as likely to report more severe symptoms of TMD than patients with episodic migraine," said Lidiane Florencio, the first author of the study, which is part of the Thematic Project "Association study of clinical, functional and neuroimaging in women with migraine", supported by the São Paulo Research Foundation - FAPESP.
Previous studies already indicated that migraine is somehow associated with pain in the chewing muscles. However, this research was the first to consider the frequency of migraine attacks when analyzing its connection with TMD: eighty-four women in their early to mid-thirties were assessed, being that 21 were chronic migraine patients, 32 had episodic migraine, while 32 with no history of migraine were included as controls - the results were published in the Journal of Manipulative and Physiological Therapeutics.
Signs and symptoms of TMD were observed in 54% of the control participants without migraine, 80% of participants with episodic migraine, and 100% of those with chronic migraine.
For Florencio, central sensitization may explain the association between the frequency of migraine attacks and the severity of TMD.
"The repetition of migraine attacks may increase sensitivity to pain," she said. "Our hypothesis is that migraine acts as a factor that predisposes patients to TMD. On the other hand, TMD can be considered a potential perpetuating factor for migraine because it acts as a constant nociceptive input that contributes to maintaining central sensitization and abnormal pain processes." Nociceptive pain is caused by a painful stimulus on special nerve endings called nociceptors.
Migraine and TMD have very similar pathological mechanisms. Migraine affects 15% of the general population, and progression to the chronic form is expected in about 2.5% of migraine sufferers. On the other hand TMD is stress-related as much as it has to do with muscle overload. Patients display joint symptoms - such as joint pain, reduced jaw movement, clicking or popping of the temporomandibular joint - but also develop a muscular condition, including muscle pain and fatigue, and/or radiating face and neck pain.
Which came first?
TMD and migraine are comorbidities. However, while people who suffer from migraine are predisposed to have TMD, people with TMD will not necessarily have migraine.
"Migraine patients are more likely to have signs and symptoms of TMD, but the reverse is not true. There are cases of patients with severe TMD who don't present with migraine," said Débora Grossi, the lead researcher for the study and principal investigator for the Thematic Project.
The researchers believe that TMD may increase the frequency and severity of migraine attacks, even though it does not directly cause migraine.
"We do know migraine isn't caused by TMD," Florencio said. "Migraine is a neurological disease with multifactorial causes, whereas TMD, like cervicalgia - neck pain - and other musculoskeletal disorders, is a series of factors that intensify the sensitivity of migraine sufferers. Having TMD may worsen one's migraine attacks in terms of both severity and frequency."
The journal article concludes that an examination of TMD signs and symptoms should be clinically conducted in patients with migraine.
"Our findings show the association with TMD exists but is less frequent in patients with rare or episodic migraine," Grossi said. "This information alone should change the way clinicians examine patients with migraine. If migraine sufferers tend to have more severe TMD, then health professionals should assess such patients specifically in terms of possible signs and symptoms of TMD."

Thursday, September 14, 2017

Don't blame your genes for your toothache, twin study shows

                     


For the first time, investigators have looked at the role that genes and the oral microbiome play in the formation of cavities and have found that your mother was right: The condition of your teeth depends on your dietary and oral hygiene habits. The study appears September 13 in Cell Host & Microbe.

"Limiting sugar consumption and acid buildup in the mouth have been part of the dogma of the dental community for some time," says senior author Karen Nelson, President of the J. Craig Venter Institute (JCVI). "This work introduces specific taxa of bacteria that can be acquired through the environment and that have the ability to induce cavities."

Since the early 20th century, dentists and other experts have known that Streptococcus bacteria in the mouth are linked to the formation of cavities. Now, with the ability to study studying the microbiome, the investigators were able to take a closer look at specific taxa that are important.

To separate the role of heritability versus the environment, Nelson and her team turned to a popular method for studying such interactions: identical and fraternal twins. Specifically, they profiled the oral microbiomes of 485 twin pairs between the ages of 5 and 11. There were 280 fraternal twins and 205 identical twins--and one set of triplets. The samples were obtained with mouth swabs.

"We decided to focus on children because we hypothesized twow things--that the oral microbiome rapidly changes with age, and also that child twin pairs are likely to have a shared environment," Nelson says. "This allowed us to better control the influence of shared and unique environments."

Their results--driven with significant analysis input from co-authors Josh Espinoza (JCVI Engineer) and Chris Dupont (JCVI Associate Professor)--showed that identical twins had oral microbiomes that were more similar to each other than those of fraternal twins, indicating that there is genetic contribution to which kinds of bacteria are likely to be present in the mouth. However, the taxa that were linked most closely to heritability were not the ones that play a role in cavity formation. In addition, they found that the heritable strains of bacteria decrease in abundance as people get older, whereas the ones linked to the environment increase.

An important additional finding was the link between certain bacterial species and sugar consumption. Bacteria that were associated with fewer cavities were in lower abundance in twins who had a lot of added sugar in their food and drinks. In contrast, bacteria that are more common in children who consume a lot of sugar were associated with having more cavities.

The team plans to continue studying the twins over repeat visits to examine changing patterns in the oral microbiome. They are also looking at functional differences in the oral microbiomes of identical and fraternal twin pairs that have various states of oral health.
  

Friday, September 8, 2017

Many middle-aged adults report dental pain, embarrassment and poor prevention


The dental health of middle-aged Americans faces a lot of problems right now, and an uncertain future to come, according to new results from the University of Michigan National Poll on Healthy Aging.

One in three Americans between the ages of 50 and 64 say they're embarrassed by the condition of their teeth. A slightly larger percentage say dental problems have caused pain, difficulty with eating, missed work or other health problems in the past two years. Forty percent of those polled don't get regular cleanings or other preventive care that can help prevent dental problems.

Insurance coverage appears to have a lot to do with this lack of care. Overall, 28 percent of respondents said they don't have dental coverage. But that percentage was much higher -- 56 percent -- among those who say they only seek care for serious dental problems.

As for the future, 51 percent of those surveyed said they simply didn't know how they will get dental insurance coverage after they turn 65.

Another 13 percent of middle-aged adults expect to count on Medicare or Medicaid to cover their oral care needs after that age. Traditional Medicare does not cover routine dental care, and Medicaid dental coverage is often limited.

The poll, based on a nationally representative sample of older adults, was conducted by the U-M Institute for Healthcare Policy and Innovation with support from AARP and Michigan Medicine, U-M's academic medical center.

"Our findings highlight a stark divide among middle-aged Americans in terms of their oral health now, and a real uncertainty about how they will get and pay for care as they age," says associate poll director Erica Solway, Ph.D. "This is not out of disregard for the importance of preventive dental care - more than three-quarters of the people we polled agree that regular care is important to preventing problems later. But it does highlight opportunities to improve access to care and insurance options after age 65."

Solway and poll director Preeti Malani, M.D., a professor of internal medicine at the U-M Medical School, divided the poll respondents into three groups based on their responses about their use of dental care:
  • prevention-focused: about 60 percent of the sample, who got regular preventive care as well as getting attention for dental problems
  • inconsistent prevention: the 17 percent who sought preventive dental care occasionally
  • problem-only: the 23 percent who went to the dentist only for serious dental problems.
"We know that oral health is a critical factor in overall wellness, and this research helps us identify some key issues - such as affordability and coverage - that we can focus on to address those 40% who are not prevention-focused," stated Dr. Alison Bryant, Senior Vice President of Research for AARP.

A clear divide
Poll respondents who were female, white, had higher incomes or had insurance were much more likely than others to take a prevention-focused approach to dental care. Men, African Americans, Hispanics, those with lower income, or those without insurance were more likely to seek dental care for problems only.

The differences among the three groups was also apparent when the U-M team asked about how easy it was to get care, and why they might not have sought care.

Among those who were prevention-focused, only 13 percent said they had delayed or hadn't received dental care when they needed it in the last two years. But that jumped to 35 percent in the inconsistent-prevention group, and 56 percent in the problem-only group.

Why didn't poll respondents get needed dental care? Cost was the most commonly reported answer, given by 69 percent who said they did not get or delayed needed care. Respondents also reported they were afraid of the dentist, couldn't find time to go, or couldn't find a dentist. Of the people who didn't receive care they needed, one in five cited fear of the dentist as a major factor.

Uncertain future
Looking ahead to the years beyond their 65th birthday - an age when most Americans become eligible for Medicare- the poll respondents were uncertain about how they'd get dental insurance.
Some - 16 percent - said they counted on employer-based coverage or a retirement-based plan. Another 12 percent said they planned to buy supplemental dental insurance.

And in addition to the half of respondents who indicated that they didn't know whether they will have dental insurance at all after age 65, another eight percent said they'd just go without it.

But it's the remaining respondents - the 13 percent who expect Medicare or Medicaid to cover their dental care in their older years - that concern the poll leaders the most.

"Traditional Medicare does not cover dental care, and many states offer very limited or no dental coverage for adults with Medicaid," says Malani. "Even those who were diligent about seeing the dentist and had dental insurance throughout adulthood may find it harder to afford dental care as they get older and coverage options may be more limited."

The nationally representative sample included 1,066 people ages 50 to 64, who answered a wide range of questions online; laptops and Internet access were provided to those who did not already have it.
###
A full report of the findings and methodology is available at http://www.healthyagingpoll.org.

New dental imaging method uses squid ink to fish for gum disease



Squid ink might be a great ingredient to make black pasta, but it could also one day make getting checked for gum disease at the dentist less tedious and even painless. By combining squid ink with light and ultrasound, a team led by engineers at the University of California San Diego has developed a new dental imaging method to examine a patient's gums that is non-invasive, more comprehensive and more accurate than the state of the art.

"The last time I was at the dentist, I realized that the tools that are currently being used to image teeth and gums could use significant updating," said Jesse Jokerst, a nanoengineering professor at UC San Diego and senior author of the study.

The conventional method for dentists to assess gum health is to use an instrument called a periodontal probe -- a thin, hook-like metal tool that's marked like a tiny measuring stick and inserted in between the teeth and gums to see whether and how much the gums have shrunk back from the teeth, creating pockets. This method of measuring pocket depth is the gold standard used in dentistry. A pocket depth measuring one to two millimeters indicates healthy gums while three millimeters and deeper is a sign of gum disease. The deeper the pockets, the more severe the gum disease.

However, procedures using the periodontal probe are invasive, uncomfortable and sometimes painful for the patient. Measurements can also vary greatly between dentists, and the probe is only capable of measuring the pocket depth of one spot at a time.

In a paper published on Sept. 7 in the Journal of Dental Research, Jokerst and his team at UC San Diego introduced an innovative method that can image the entire pocket depth around the teeth consistently and accurately, without requiring any painful poking and prodding.

"Using the periodontal probe is like examining a dark room with just a flashlight and you can only see one area at a time. With our method, it's like flipping on all the light switches so you can see the entire room all at once," Jokerst said.

The method begins by rinsing the mouth with a paste made of commercially available food-grade squid ink mixed with water and cornstarch. The squid-ink-based rinse serves as a contrast agent for an imaging technique called photoacoustic ultrasound. This involves shining a light signal -- usually a short laser pulse -- onto a sample, which heats up and expands, generating an acoustic signal that researchers can analyze. "Light in, sound out," Jokerst said.

Squid ink naturally contains melanin nanoparticles, which absorb light. During the oral rinse, the melanin nanoparticles get trapped in the pockets between the teeth and gums. When researchers shine a laser light onto the area, the squid ink heats up and quickly swells, creating pressure differences in the gum pockets that can be detected using ultrasound. This method enables researchers to create a full map of the pocket depth around each tooth -- a significant improvement over the conventional method.

Researchers tested their photoacoustic imaging method in a pig model containing a mix of shallow and deep pockets in the gums. While their results closely matched measurements taken using a periodontal probe, they were also consistent across multiple tests. On the other hand, measurements with the periodontal probe varied significantly from one test to another.

"It's remarkable how reproducible this technique is compared to the gold standard," Jokerst said.
Moving forward, the team will be collaborating with dentists and testing their method in humans. Future work also includes minimizing the taste of the squid ink oral rinse -- it's salty and somewhat bitter -- and replacing laser lights with inexpensive, more portable light systems like LEDs. The team's ultimate goal is to create a mouthpiece that uses this technology to measure periodontal health.

Tuesday, August 22, 2017

A new dental restoration composite more durable than the conventional material



Fewer trips to the dentist may be in your future, and you have mussels to thank.

Inspired by the mechanisms mussels use to adhere to inhospitable surfaces, UC Santa Barbara researchers have developed a new type of dental composite that provides an extra layer of durability to treated teeth. The potential payoff? Longer lasting fillings, crowns, implants and other work.
"It's as hard as a typical dental restoration but less likely to crack," Kollbe Ahn, a materials scientist at UCSB's Marine Science Institute, said of the composite. The research is highlighted in the journal Advanced Materials. The paper, of which Ahn is the corresponding author, is the result of collaboration between research and industry.

On average, a dental restoration lasts five to 10 or so years before needing replacement. The time frame depends on the type of restoration and how well the patient cares for the treated tooth. However, the continual onslaught of chewing, acidic and hard foods, poor hygiene, nighttime tooth grinding, generally weak teeth and even inadequate dental work can contribute to a filling's early demise -- and another expensive and possibly less-than-pleasant experience in the dental chair.

According to Ahn, one of the primary reasons restorations fall out or crack is brittle failure of the bond with the surrounding tooth. "All dental composites have micro-particles to increase their rigidity and prevent their shrinkage during their curing process," he explained. "But there's a trade-off: When the composite gets harder, it gets more brittle."

With enough pressure or wear and tear, a crack forms, which then propagates throughout the entire restoration. Or, the gap between the tooth and the restoration results in restoration failures, including marginal tooth decay.

So Ahn and his colleagues looked to nature -- mussels, to be exact -- to find a way not only to maintain strength and hardness but also to add durability. Having perfected the art of adhering to irregular surfaces under the variable conditions of the intertidal zone -- evolving to resist pounding waves, the blazing heat of the sun and cycles of salt water immersion and windy dryness -- mussels presented the ideal model for more durable dental restoration materials. The byssal threads they use to affix to surfaces allow them to resist the forces that would tear them from their moorings.

"In nature, the soft collagenous core of the mussel's byssal threads is protected by a 5-to-10 micrometer thick, hard coating, which is also extensible and thus, tough," Ahn said. This durability and flexibility allow the mollusks to stick to wet mineral surfaces in harsh environments that involve repeated push-and-pull stress.

Key to this mechanism is what the scientists call dynamic or sacrificial bonding -- multiple reversible and weak bonds on the sub-nanoscopic molecular level that can dissipate energy without compromising the overall adhesion and mechanical properties of the load-bearing material.

"Say you have one strong bond," Ahn explained. "It may be strong but once it breaks, it breaks. If you have several weaker bonds, you would have to break them one by one." Breaking each weak bond, he continued, would dissipate energy, so the overall energy required to break the material would be greater than with a single strong bond.

This type of bonding occurs in many biological systems, including animal bone and tooth. The mussel's byssus contain a high number of unique chemical functional groups called catechols, which are used to prime and promote adhesion to wet mineral surfaces. The new study shows that using a catecholic coupling agent instead of the conventional silane coupling agent provides 10 times higher adhesion and a 50 percent increase in toughness compared to current dental restorative resin composites.

While research has proven this toughening mechanism in soft materials, this study is one of the first -- if not the first -- to prove it with rigid and load-bearing materials.

This proof-of-concept, which also demonstrates no cytotoxicity, could mean tougher, more durable dental fillings. And that, in the long run, could mean fewer dental visits. Because each replacement filling also requires the dentist to file the surrounding tooth to prime its surface, given enough replacements a tooth might need to be crowned or extracted; and if not replaced, the tooth loss could have adverse consequences for the individual's diet and health.

The next step, Ahn said, is to increase the material's durability even further.

"By changing the molecular design you could have even denser coupling agents that exist on the surface, and then we can have a stronger and more durable dental composite," he said, estimating a commercial product within a couple of years.

Thursday, August 17, 2017

Oral and Dental Problems That May Signal Child Abuse and Neglect


A report from the American Academy of Pediatrics and the American Academy of Pediatric Dentistry in the August 2017 Pediatrics (published online July 31) aims to help identify problems involving a child's teeth, gums and mouth that may be signs of physical or sexual abuse and neglect. According to the updated clinical report, "Oral and Dental Aspects of Child Abuse and Neglect," injuries and infections in and around the mouth appear often in children who are maltreated. These may occur when caregivers react violently during developmentally normal fussiness at mealtime or bedtime, for example.

Symptoms that may be signs of child abuse or neglect include:
  • bruises on the lips, gums, tongue, lips or soft tissue inside the mouth from eating utensils or a bottle during forced feeding;
  • burns or blisters from scalding liquids or fractures to teeth, facial or jaw bones or scars or blackened teeth from previous injuries;
  • skin irritation, bruising or scarring at the corners of the mouth, which could be from gags applied to the mouth in forceful attempts to quiet a child;
  • injuries to the back of the throat, sometimes intentionally inflicted to make a child cough up or vomit blood or create other symptoms that would require medical attention and care;
  • injuries and infections tied to forced oral sex, such as tears and other signs of trauma inside the mouth or sores or rashes caused by sexually transmitted disease.
  • bite marks inside the mouth from the child's own teeth, which sometimes are caused by physical or sexual abuse.
In cases of dental neglect, authors note, untreated cavities and gum disease interfere with a child's ability to eat, communicate, grow and develop properly. The report also describes the connection between bullying and dental health, citing research indicating that children with mouth or dental abnormalities are frequent targets of bullying and face increased risk of depression and suicidal thoughts or actions.

In addition, the estimated 100,000 U.S. children involved in sex trafficking or forced prostitution each year have oral and dental problems from abuse and from malnutrition, which can lead to poorly formed teeth, cavities, infections and tooth loss.

Tuesday, August 15, 2017

Chewing gum rapid test for inflammation

Dental implants occasionally entail complications: Six to fifteen percent of patients develop an inflammatory response in the years after receiving a dental implant. This is caused by bacteria destroying the soft tissue and the bone around the implant in the worst case.
In future, patients will benefit from a quick and affordable method assessing whether they carry such bacteria: using a chewing gum based diagnostic test developed by a pharmaceutical research team at the Julius-Maximilians-Universität (JMU) Würzburg in Bavaria, Germany.

In practice, the test works as follows: If there is an inflammation in the oral cavity, a bittering agent is released while chewing the gum. Patients can then visit their dentist who confirms the diagnosis and treats the disease. This type of early detection aims at preventing serious complications such as bone loss.

"Anyone can use this new diagnostic tool anywhere and anytime without any technical equipment," Professor Lorenz Meinel says; he is the head of the JMU Chair for Drug Formulation and Delivery. He developed the new diagnostic tool with Dr. Jennifer Ritzer and her team; the invention is currently featured in an article in the journal Nature Communications.

Enzymes release bitter taste
The scientific background: In the presence of inflammatory conditions, specific protein-degrading enzymes are activated in the mouth. In just five minutes, these enzymes also break down a special ingredient of the chewing gum, thereby releasing a bittering agent that could not be tasted before.
Meinel's team provided the proof that this principle actually works. First studies using the saliva of patients were conducted at Merli Dental Clinic in Rimini.

Company establishment planned
To launch the chewing gum into the market, Meinel's team plans to set up a company. The professor assumes that it will take two to three years until the gum is commercially available.
Chewing gum rapid tests for other medical applications are presently under development. "We hope to be able to diagnose other diseases with our "anyone, anywhere, anytime" diagnostics to identify and adress these diseases as early as possible," Meinel explains.

Monday, August 14, 2017

High sugar consumption gives rise to dental treatment costs in the billions



Worldwide, people are eating far too much sugar. This has negative consequences for their teeth and for their purses: seen at the global level, the costs of dental treatment are currently running at around 172 billion US dollars (128 billion euros). In Germany alone, these amount to 17.2 billion euros (23 billion US dollars) a year. These are the results of a joint study conducted by the Martin Luther University Halle-Wittenberg (MLU) and the Biotechnology Research and Information Network AG (BRAIN AG) published in the International Journal of Dental Research. The work was carried out within the strategic alliance NatLifE 2020 and was co-financed by the German Federal Ministry of Education and Research (BMBF).

For their work the researchers evaluated representative data on the prevalence of caries, inflammation of the gums (parodontitis) and tooth loss, corresponding costs of treatment and the disease burden, as well as data on sugar consumption, in 168 countries for the year 2010. On the basis of this data they calculated the share of total costs attributable to excessive consumption of sugar. In addition to white household sugar, the researchers also focused their attention, in the analysis, to "hidden" sugar that is contained in many processed products, such as soft drinks, ketchup, ice cream and frozen foods, as well as breads, cakes and pastries.

"The data shows a clear correlation between the consumption of sugar and the incidence of caries, parodontitis and, as a result, tooth loss," said the lead author of the study, Dr Toni Meier from the Institute of Agricultural and Nutritional Sciences at the MLU. "For every additional 25 grams of sugar consumed per person and day - which amounts to roughly eight sugar-cubes or a glass of sweetened lemonade - the costs of dental treatment in high-income countries increase on average by 100 US dollars (75 euros) per person and year."

In Germany, the average daily sugar consumption lies between 90 and 110 grams per person. The costs of treatment amount to 281 US dollars (210 euros) per person and year. This puts Germany in the group of countries with the highest costs of treatment per person and year. Other countries "in the group" are Switzerland (402 US dollars, 300 euros), Denmark (238 US dollars, 178 euros) and the USA (185 US dollars, 138 euros). "If the target of 50 grams of sugar per person and day set by the World Health Organization could be reached, this would result in savings in the costs of treatment within Germany of 150 euros (201 US dollars) per person and year. Extrapolating this figure to the federal level shows annual potential savings of approximately 12 billion euros, or 16 billion US dollars," added Meier. A low-sugar diet is becoming increasingly difficult, however, since almost all processed products in the supermarket contain large quantities of added sugars.

The highest levels of sugar-related dental illness were observed by the researchers in Guatemala, Mauretania and Mexico. "Newly industrialised countries such as India, Brazil and Mexico, but also Pakistan and Egypt, could avoid an excessive burden of illness and of health care costs by anchoring the topic in their health and nutritional policies at an early stage," said the co-author of the study and nutrition scientist, Professor Gabriele Stangl of the MLU. This objective could be achieved by way of educational campaigns or by special taxation on high-calorie food. Such a sugar tax was introduced in Mexico in 2014 and already after one year was proving to be effective: the consumption of sugar-sweetened beverages had decreased by five percent. In the second year this decrease even doubled to ten percent.

"To be able to reduce the burden of nutrition-related illnesses, a balanced mix of educational work and food-policy initiatives, along with innovative technological solutions, are needed," said the co-author of the study, Dr Katja Riedel, joint coordinator of the NatLifE 2020 innovative alliance and program manager of system-products nutrition at BRAIN AG. The alliance co-financed by the German Federal Ministry of Education and Research aims, with the help of biotechnology and the understanding of biological systems, to develop a new generation of sustainably produced and biological active substances for foods and cosmetics and thereby to make a contribution towards improving human nutrition, health and well-being.

Monday, August 7, 2017

Man loses feeling in legs after long-term denture fixative use


A 62-year-old man lost the feeling in both his legs after the regular long term use of a denture fixative containing zinc, reveal doctors writing in the online journal BMJ Case Reports.

The man was referred to a neurology clinic after developing numbness, pain and weakness in his legs. The symptoms, which had lasted for more than six months, stopped him from leaving the house.
An MRI (magnetic resonance imaging) scan revealed spinal cord abnormalities and after several tests he was diagnosed with copper deficiency myelopathy (CDM).

CMD is a neurological disorder which can cause loss of feeling and numbness in the arms and legs.
The man explained that he had been using 2-4 tubes of denture fixative that contained zinc every week for the past 15 years because of his ill-fitting false teeth.

Excess zinc intake can interfere with the absorption of copper, leading to neurological problems, in rare cases.

The man was advised to stop using the fixative and given copper supplements to treat his symptoms. But he didn't recover completely, and the doctors warn that irreversible nerve damage may be a consequence of a delayed diagnosis of CDM.

Wednesday, August 2, 2017

An end to cavities for people with sensitive teeth?


An ice cold drink is refreshing in the summer, but for people with sensitive teeth, it can cause a painful jolt in the mouth. This condition can be treated, but many current approaches don't last long. Now researchers report in the journal ACS Applied Materials & Interfaces the development of a new material with an extract from green tea that could fix this problem -- and help prevent cavities in these susceptible patients.  

Tooth sensitivity commonly occurs when the protective layers of teeth are worn away, revealing a bony tissue called dentin. This tissue contains microscopic hollow tubes that, when exposed, allow hot and cold liquids and food to contact the underlying nerve endings in the teeth, causing pain. Unprotected dentin is also vulnerable to cavity formation. Plugging these tubes with a mineral called nanohydroxyapatite is a long-standing approach to treating sensitivity. But the material doesn't stand up well to regular brushing, grinding, erosion or acid produced by cavity-causing bacteria. Cui Huang and colleagues wanted to tackle sensitivity and beat the bacteria at the same time.

The researchers encapsulated nanohydroxyapatite and a green tea polyphenol -- epigallocatechin-3-gallate, or EGCG -- in silica nanoparticles, which can stand up to acid and wear and tear. EGCG has been shown in previous studies to fight Streptococcus mutans, which forms biofilms that cause cavities. Testing on extracted wisdom teeth showed that the material plugged the dentin tubules, released EGCG for at least 96 hours, stood up to tooth erosion and brushing and prevented biofilm formation. It also showed low toxicity. Based on these findings, the researchers say the mate

Tuesday, August 1, 2017

History of gum disease increases cancer risk in older women


Postmenopausal women who have a history of gum disease also have a higher risk of cancer, according to a new study of more than 65,000 women.

The study, led by researchers at the University at Buffalo, is the first national study of its kind involving U.S. women, and the first to focus specifically on older women. It's also the first study to find an association between periodontal disease and gallbladder cancer risk in women or men. The findings were published today (Aug. 1) in the journal Cancer Epidemiology, Biomarkers & Prevention.

"This study is the first national study focused on women, particularly older women," said Jean Wactawski-Wende, the study's senior author.

"Our study was sufficiently large and detailed enough to examine not just overall risk of cancer among older women with periodontal disease, but also to provide useful information on a number of cancer-specific sites," added Wactawski-Wende, dean of UB's School of Public Health and Health Professions and a professor of epidemiology and environmental health.

The study included 65,869 postmenopausal women enrolled in the Women's Health Initiative, an ongoing national prospective study designed to investigate factors affecting disease and death risk in older American women. The average age of the participants was 68, and most were non-Hispanic white women.

As part of a follow-up health questionnaire, participants were asked "Has a dentist or dental hygienist ever told you that you had periodontal or gum disease?"

Women who reported a history of gum disease had a 14 percent increased risk of overall cancer. Of the 7,149 cancers that occurred in the study participants, the majority -- or 2,416 -- were breast cancer.

"There is increasing evidence that periodontal disease may be linked to an increased cancer risk and this association warrants further investigation," said the paper's first author, Ngozi Nwizu, who worked on the research while completing her residency in oral and maxillofacial pathology in UB's School of Dental Medicine and her doctorate in pathology (cancer epidemiology) at UB's Roswell Park Cancer Institute Graduate Division. Nwizu is now an assistant professor of oral and maxillofacial pathology at the University of Texas Health Science Center at Houston.

The risk associated with periodontal disease was highest for esophageal cancer, the researchers reported. "The esophagus is in close proximity to the oral cavity, and so periodontal pathogens may more easily gain access to and infect the esophageal mucosa and promote cancer risk at that site," Wactawski-Wende said.

Gallbladder cancer risk also was high in women who reported a history of gum disease. "Chronic inflammation has also been implicated in gallbladder cancer, but there has been no data on the association between periodontal disease and gallbladder risk. Ours is the first study to report on such an association," Nwizu said.

The esophageal and gallbladder cancer findings are significant, Nwizu said. "Esophageal cancer ranks among the most deadly cancers and its etiology is not well known, but chronic inflammation has been implicated," she said.

"Certain periodontal bacteria have been shown to promote inflammation even in tiny amounts, and these bacteria have been isolated from many organ systems and some cancers including esophageal cancers. It is important to establish if periodontal disease is an important risk of esophageal cancer, so that appropriate preventive measures can be promoted."

Periodontal disease also was associated with total cancer risk among former and current smokers.
The findings for this particular age group are significant because they offer a window into disease in a population of Americans that continues to increase as people live longer lives.

"The elderly are more disproportionately affected by periodontal disease than other age groups, and for most types of cancers, the process of carcinogenesis usually occurs over many years," said Nwizu. "So the adverse effects of periodontal disease are more likely to be seen among postmenopausal women, simply because of their older age."

Wednesday, July 12, 2017

Diabetes causes shift in oral microbiome that fosters periodontitis

A new study led by University of Pennsylvania researchers has found that the oral microbiome is affected by diabetes, causing a shift to increase its pathogenicity. The research, published in the journal Cell Host & Microbe this week, not only showed that the oral microbiome of mice with diabetes shifted but that the change was associated with increased inflammation and bone loss. 


"Up until now, there had been no concrete evidence that diabetes affects the oral microbiome," said Dana Graves, senior author on the new study and vice dean of scholarship and research at Penn's School of Dental Medicine. "But the studies that had been done were not rigorous."
Just four years ago, the European Federation of Periodontology and the American Academy of Periodontology issued a report stating there is no compelling evidence that diabetes is directly linked to changes in the oral microbiome. But Graves and colleagues were skeptical and decided to pursue the question, using a mouse model that mimics Type 2 diabetes.
"My argument was that the appropriate studies just hadn't been done, so I decided, We'll do the appropriate study," Graves said.
Graves co-authored the study with Kyle Bittinger of the Children's Hospital of Philadelphia, who assisted with microbiome analysis, along with E Xiao from Peking University, who was the first author, and co-authors from the University of São Paulo, Sichuan University, the Federal University of Minas Gerais and the University of Capinas. The authors consulted with Daniel Beiting of Penn Vet's Center for Host-Microbial Interactions and did the bone-loss measurements at the Penn Center for Musculoskeletal Diseases. 
The researchers began by characterizing the oral microbiome of diabetic mice compared to healthy mice. They found that the diabetic mice had a similar oral microbiome to their healthy counterparts when they were sampled prior to developing high blood sugar levels, or hyperglycemia. But, once the diabetic mice were hyperglycemic, their microbiome became distinct from their normal littermates, with a less diverse community of bacteria.
The diabetic mice also had periodontitis, including a loss of bone supporting the teeth, and increased levels of IL-17, a signaling molecule important in immune response and inflammation. Increased levels of IL-17 in humans are associated with periodontal disease.
"The diabetic mice behaved similar to humans that had periodontal bone loss and increased IL-17 caused by a genetic disease," Graves said.
The findings underscored an association between changes in the oral microbiome and periodontitis but didn't prove that the microbial changes were responsible for disease. To drill in on the connection, the researchers transferred microorganisms from the diabetic mice to normal germ-free mice, animals that have been raised without being exposed to any microbes. 
These recipient mice also developed bone loss. A micro-CT scan revealed they had 42 percent less bone than mice that had received a microbial transfer from normal mice. Markers of inflammation also went up in the recipients of the diabetic oral microbiome.
"We were able to induce the rapid bone loss characteristic of the diabetic group into a normal group of animals simply by transferring the oral microbiome," said Graves.
With the microbiome now implicated in causing the periodontitis, Graves and colleagues wanted to know how. Suspecting that inflammatory cytokines, and specifically IL-17, played a role, the researchers repeated the microbiome transfer experiments, this time injecting the diabetic donors with an anti-IL-17 antibody prior to the transfer. Mice that received microbiomes from the treated diabetic mice had much less severe bone loss compared to mice that received a microbiome transfer from untreated mice. 
The findings "demonstrate unequivocally" that diabetes-induced changes in the oral microbiome drive inflammatory changes that enhance bone loss in periodontitis, the authors wrote.
Though IL-17 treatment was effective at reducing bone loss in the mice, it is unlikely to be a reasonable therapeutic strategy in humans due to its key role in immune protection. But Graves noted that the study highlights the importance for people with diabetes of controlling blood sugar and practicing good oral hygiene.
"Diabetes is one of the systemic disease that is most closely linked to periodontal disease, but the risk is substantially ameliorated by good glycemic control," he said. "And good oral hygiene can take the risk even further down."

Friday, July 7, 2017

New dental materials developed to stop degradation of demineralized dentin



 
A: Demineralized dentin with a number of collagen fibres, that if not preserved and remineralized, these can be degraded by the action of the dentinal proteolytic enzymes. B: Dentin treated with resin with fluoride-containing bioactive glass, which presents mineral precipitations – signs of remineralization.
 
Credit: Image courtesy of Asociación RUVID
 
Salvatore Sauro, Professor of dental biomaterials and minimally invasive dentistry at CEU Cardenal Herrera University, in Spain, has collaborated with several researchers from Finland, Brazil, Belgium, Germany and the UK on the development of innovative dental biomaterials for the regeneration of dental hard tissues.

Bacterial plaque causes tooth decay due to acids produced by different bacteria species; this has trigged an intense research activity for the development of novel restorative biomaterials with protective and self-healing remineralizing properties. In this new study, Salvatore Sauro, a professor of CEU Cardenal Herrera University (Spain) specialized in the development of innovative dental biomaterials, has collaborated with several researchers from Finland, Brazil, Belgium, Germany and the United Kingdom in order to accomplish this target. Indeed, this international group of research generated two new dental restorative biomaterials containing bioactive glasses, and assessed their effectiveness in reducing the enzymatic auto-degradation of collagen fibres and evoking their remineralization.

The aim of the study was to evaluate the inhibition of endogenous proteolytic enzymes of dentin and the remineralization induced by two different innovative experimental resins containing bioactive glasses: one containing micro-particles of Bioglass 45S5 and the other one containing micro-particles of an experimental bioactive glass enriched with fluoride and high amount of phosphates. Their anti-degradation effects was evaluated on completely demineralized human dentin specimens after immersion in artificial saliva for a period of thirty days by means of an immunohistochemical process. The remineralization evoked by such experimental bioactive resins was also evaluated by means of infrared spectroscopy and scanning electron microscopy.

Greater effectiveness with fluoride and phosphates

According to Professor Salvatore Sauro and his co-authors, " the resin-based material containing the experimental bioactive glass enriched with fluoride and phosphates resulted to be more efficient in inhibiting the enzymatic-mediated degradation of demineralized dentine collagen, and more bioactive than the one containing Bioglass 45S5. This was mainly due to the fluoride ions as well as to the large amount of phosphates released by the material, which accelerated dentin remineralization and reduced the degradation of demineralized dentin collagen via inhibition of matrix metalloproteinases and cysteine cathepsins.

This type of experimental bioactive material would therefore be more suitable for the development of new restorative dental materials for the clinical treatment of the dental caries.

Publication in the Journal of Dental Research

Professor Sauro perform his research activity mainly at CEU Cardenal Herrera University, (Spain) as well as at King's College London (UK) where he has an honorary position as research senior lecturer. He spends most of his time in the development of minimally invasive treatments and therapeutic bioactive dental composites for the treatment and restoration of caries affected dentin, such as those tested in this study -- which seem to be able to prevent the degradation of dentin collagen and evoke the remineralization of demineralized dental tissues. In this study, Dr Salvatore Sauro collaborated with researchers from the Department of Restorative Dentistry of the University of Turku (Finland); the Faculty of Dentistry of the University of Fortaleza (Brazil); the Biomaterials Group of the University of Ghent (Belgium); the Friedrich Schiller University of Jena (Germany); and the Dental Institute of King's College London (United Kingdom), institution of which Salvatore Sauro is a Visiting Senior Lecturer.

The study is published in the Journal of Dental Research.

Tuesday, June 20, 2017

Blocking yeast-bacteria interaction may prevent severe biofilms that cause childhood tooth decay


Though most tooth decay can be blamed on bacteria, such as Streptococcus mutans, the fungus Candida albicans may be a joint culprit in an alarmingly common form of severe tooth decay affecting toddlers known as early childhood caries.
In earlier research, a team from the University of Pennsylvania School of Dental Medicine had found that C. albicans, a type of yeast, took advantage of an enzyme produced by S. mutans to form a particularly intractable biofilm. In a new study, the researchers have pinpointed the surface molecules on the fungus that interact with the bacterially-derived protein. Blocking that interaction impaired the ability of yeast to form a biofilm with S. mutans on the tooth surface, pointing to a novel therapeutic strategy.
"Instead of just targeting bacteria to treat early childhood caries, we may also want to target the fungi," said Hyun (Michel) Koo, senior author on the study and a professor in the Department of Orthodontics and Divisions of Pediatric Dentistry and Community Oral Health. "Our data provide hints that you might not need to use a broad spectrum antimicrobial and might be able to target the enzyme or cell wall of the fungi to disrupt the plaque biofilm formation."
Koo collaborated on the work with Penn Dental's Geelsu Hwang, the first author and a research assistant professor, as well as Yuan Liu, Dongyeop Kim and Yong Li. Damian J. Krysan of the University of Rochester was also a coauthor.
The research appears in the journal PLOS Pathogens.
Candida can't effectively form plaque biofilms on teeth on its own nor can it bind S. mutans, unless in the presence of sugar. Young children who consume sugary beverages and foods in excess are at risk of developing early childhood caries. Koo's team had previously discovered that an enzyme, GftB, secreted by S. mutans, uses sugar from the diet to manufacture glue-like polymers called glucans. Candida promotes this process, resulting in a sticky biofilm that allows the yeast to adhere to teeth and to bind to S. mutans.
The researchers suspected that the outer portion of the Candida cell wall, composed of molecules called mannans, might be involved in binding GftB. To gain a more detailed understanding of the interaction between the yeast and the enzyme, the researchers measured the binding strength between various mutant Candida strains and GtfB using biophysical methods. Such measurements were developed by Hwang, who has a background in engineering and is applying his unique expertise to advance dental science.
Koo, Hwang and colleagues found that the enzyme bound much more weakly to mutants that lacked components of the mannan layer than the wild-type Candida. The team next looked at the abilities of the mutant Candida to form biofilms with S. mutans in a laboratory assay. The mutants that had impaired binding with GftB were mostly unable to form biofilms with S. mutans, resulting in significantly fewer Candida cells and reduced production of the sticky glucans molecules.
Using another biophysical technique, the researchers tested how stable the biofilms were when attached to a tooth-like surface. While low-shear stress, roughly equivalent to the force generated by taking a drink of water, removed only a quarter of the wild-type biofilm, the same force removed 70 percent of the biofilms with mutant Candida. When the forces were increased to the equivalent of a vigorous mouth rinse, the mutant biofilms were almost completely dislodged.
To ensure their findings translated to in vivo conditions, they examined biofilm formation in a rodent model that can mimic the development of early childhood caries. When animals were infected with both S. mutans and either the wild type or defective mutant yeast strains, the researchers observed clear differences. While biofilm formation was abundant if the wild-type yeast was used, it was substantially reduced in animals infected with the mutant strain. A more precise analysis revealed that the these defective biofilms completely lacked viable Candida cells and S. mutans were reduced by more than five-fold.
The findings point to a new direction for treatment of early childhood caries. The current standard of care, beyond the use of fluoride as a preventive approach, is to target only the bacteria with antimicrobials, or to use surgical interventions if the tooth decay has become too severe.
"This disease affects 23 percent of children in the United States and even more worldwide," said Koo. "In addition to fluoride, we desperately need an agent that can target the disease-causing biofilms and in this case not only the bacterial component but also the Candida."
Koo and colleagues are now working on novel therapeutic approaches for targeted interventions, which can be potentially developed for clinical use.

Wednesday, June 14, 2017

Visiting virtual beach improves patient experiences during dental procedures


Imagine walking along a South Devon beach on a lovely day. The waves are lapping on the shore, rabbits are scurrying in the undergrowth, and the bells of the local church are mingling with the calls of the seagulls. Then, as you turn to continue along the coast path feeling calm and relaxed you suddenly hear your dentist say "Fine, all done, you can take the headset off now". For patients at one dental practice in Devon, England, such Virtual Reality encounters are resulting in demonstrably better experiences in the dentist's chair. 
A link to what the patient sees is here - https://youtu.be/n5kjETt8cZI.
In a study published today (Wednesday 14th June 2017) in the journal Environment & Behaviour, a team of researchers at the Universities of Plymouth, Exeter and Birmingham worked with Torrington Dental Practice in Devon to find out whether experiences like these could improve the patient's experience during routine dental procedures, such as fillings and tooth extractions. 
Patients, who had agreed to take part in the study were randomly allocated to one of three conditions: a) standard care (i.e. normal practice), b) a virtual walk around Wembury beach in Devon (using a headset and handheld controller), or c) a walk around an anonymous virtual reality city. Results found that those who 'walked' around Wembury were less anxious, experienced less pain, and had more positive recollections of their treatment a week later, than those in the standard care condition. These benefits were not found for those who walked around the virtual city. 
Dr. Karin Tanja-Dijkstra was the lead author of the study. She said: "The use of virtual reality in health care settings is on the rise but we need more rigorous evidence of whether it actually improves patient experiences. Our research demonstrates that under the right conditions, this technology can be used to help both patients and practitioners."
The authors of the research stress that the type of virtual reality environment the patient visits is important. Virtual Wembury was created by Professor Bob Stone and colleagues at the University of Birmingham, and the fact that only patients who visited Wembury, and not the virtual city, had better experiences than standard care is consistent with a growing body of work that shows that natural environments, and marine environments in particular, can help reduce stress and anxiety. 
Co-author Dr. Mathew White from the University of Exeter explained: "We have done a lot of work recently which suggests that people are happiest and most relaxed when they are at the seaside. So it seemed only natural to investigate whether we could "bottle" this experience and use it to help people in potentially stressful healthcare contexts." 
Dr Sabine Pahl, the project's coordinator at the University of Plymouth, added: "That walking around the virtual city did not improve outcomes shows that merely distracting the patients isn't enough, the environment for a patient's visit needs to be welcoming and relaxing. It would be interesting to apply this approach to other contexts in which people cannot easily access real nature such as the workplace or other healthcare situations."
The Torrington Practice dentist involved in the research, Melissa Auvray, agreed: "The level of positive feedback we got from patients visiting Virtual Wembury was fantastic. Of course, as dentists we do our very best to make the patient feel as comfortable as possible but we are always on the look out for new ways to improve their experiences." 
Professor David Moles from the University of Plymouth added "This research is one of a number of initiatives we at Plymouth University Peninsula School of Dentistry have been working on alongside the fabulous team at Torrington Dental Practice and it clearly demonstrates the benefits that can be achieved when academics work in partnership with clinicians in order to address problems that really matter to patients."
The team are hoping to now investigate whether Virtual Wembury can help patients in other medical contexts and whether certain additions to the virtual environment could make the experience even better.

Monday, June 12, 2017

Study: Use of prefabricated blood vessels may revolutionize root canals


While root canals are effective in saving a tooth that has become infected or decayed, this age-old procedure may cause teeth to become brittle and susceptible to fracture over time. Now researchers at OHSU in Portland, Oregon, have developed a process by which they can engineer new blood vessels in teeth, creating better long-term outcomes for patients and clinicians.
Their findings will publish online in the journal Scientific Reports on June 12, 2017. 
More than 15 million root canals are conducted annually in the United States. The current procedure involves removing infected dental tissues and replacing them with synthetic biomaterials covered by a protective crown. 
"This process eliminates the tooth's blood and nerve supply, rendering it lifeless and void of any biological response or defense mechanism. Without this functionality, adult teeth may be lost much sooner, which can result in much greater concerns, such as the need for dentures or dental implants," says principal investigator Luiz Bertassoni, D.D.S., Ph.D., assistant professor of restorative dentistry in the OHSU School of Dentistry, and assistant professor of biomedical engineering in the OHSU School of Medicine.
To address this issue, Bertassoni and colleagues used a 3D printing-inspired process -- based on their previous work fabricating artificial capillaries -- to create blood vessels in the lab. They placed a fiber mold made of sugar molecules across the root canal of extracted human teeth and injected a gel-like material, similar to proteins found in the body, filled with dental pulp cells. The researchers removed the fiber to make a long microchannel in the root canal and inserted endothelial cells isolated from the interior lining of blood vessels. After seven days, dentin-producing cells proliferated near the tooth walls and artificial blood vessels formed inside the tooth.
"This result proves that fabrication of artificial blood vessels can be a highly effective strategy for fully regenerating the function of teeth," says Bertassoni, who also serves as an honorary lecturer in Bioengineering at University of Sydney-School of Dentistry. "We believe that this finding may change the way that root canal treatments are done in the future."

Common periodontal pathogen may interfere with conception in women


According to a study carried out at the University of Helsinki, Finland, a common periodontal pathogen may delay conception in young women. This finding is novel: previous studies have shown that periodontal diseases may be a risk for general health, but no data on the influence of periodontal bacteria on conception or becoming pregnant have been available.

"Our results encourage young women of fertile age to take care of their oral health and attend periodontal evaluations regularly", says periodontist and researcher Susanna Paju, University of Helsinki.

Study population comprised 256 healthy non-pregnant women (mean age 29.2 years, range 19 to 42) who had discontinued contraception in order to become pregnant. They were enrolled from the general community from Southern Finland. Clinical oral and gynecological examinations were performed. Detection of major periodontal pathogens in saliva and analysis of serum and saliva antibodies against major periodontal pathogens as well as a vaginal swab for the diagnosis of bacterial vaginosis at baseline were carried out.

Subjects were followed-up to establish whether they did or did not become pregnant during the observation period of 12 months.

Porphyromonas gingivalis, a bacterium associated with periodontal diseases, was significantly more frequently detected in the saliva among women who did not become pregnant during the one-year follow-up period than among those who did. The levels of salivary and serum antibodies against this pathogen were also significantly higher in women who did not become pregnant.

Statistical analysis showed that the finding was independent of other risk factors contributing to conception, such as age, current smoking, socioeconomic status, bacterial vaginosis, previous deliveries, or clinical periodontal disease.

Women who had P. gingivalis in the saliva and higher saliva or serum antibody concentrations against this bacterium had a 3-fold hazard for not becoming pregnant compared to their counterparts. Increased hazard was nearly to 4-fold if more than one of these qualities and clinical signs of periodontitis were present.

"Our study does not answer the question on possible reasons for infertility but it shows that periodontal bacteria may have a systemic effect even in lower amounts, and even before clear clinical signs of gum disease can be seen", says Dr. Paju. "More studies are needed to explain the mechanisms behind this association."

Infertility is a major concern, and increasing healthcare resources are needed for infertility treatments. More attention should be paid to the potential effects of common periodontal diseases on general health. Young women are encouraged to take care of their oral health and maintain good oral hygiene also when they are planning pregnancy, suggests Dr. Paju.

Wednesday, May 24, 2017

Recreational cannabis, used often, increases risk of gum disease


Columbia University dental researchers have found that frequent recreational use of cannabis--including marijuana, hashish, and hash oil--increases the risk of gum disease.
The study was published in the March issue of the Journal of Periodontology.
Periodontal (gum) disease is an inflammatory reaction to a bacterial infection below the gum line. Left untreated, gum disease can lead to receding gums and tooth loss. Longstanding periodontal disease has also been associated with a number of non-oral health issues, from preterm labor during pregnancy to heart disease.
Jaffer Shariff, DDS, MPH, a postdoctoral resident in periodontology at Columbia University School of Dental Medicine (CDM) and lead author, noticed a possible link between frequent recreational cannabis use and gum disease during his residency at a community-based dental clinic in Manhattan.
"It is well known that frequent tobacco use can increase the risk of periodontal disease, but it was surprising to see that recreational cannabis users may also be at risk," said Dr. Shariff. "The recent spate of new recreational and medical marijuana laws could spell the beginning of a growing oral public health problem."
Dr. Shariff and colleagues from CDM analyzed data from 1,938 U.S. adults who participated in the Centers for Disease Control's 2011-2012 National Health and Nutrition Examination Survey, administered in collaboration with the American Academy of Periodontology. Approximately 27 percent of the participants reported using cannabis one or more times for at least 12 months.
Periodontal exams focus on a patient's gum tissue and connection to the teeth. Among other assessments, periodontists look for plaque, inflammation, bleeding, and gum recession. The clinician uses a probe to measure the space between teeth and their surrounding gum tissue. 
Healthy gums fit a tooth snugly, with no more than one to three millimeters of space, known as pocket depth, between the tooth and surrounding gum tissue. Deeper pockets usually indicate presence of periodontitis. 
Among the study participants, frequent recreational cannabis users had more sites with pocket depths indicative of moderate to severe periodontal disease than less frequent users.
"Even controlling for other factors linked to gum disease, such as cigarette smoking, frequent recreational cannabis smokers are twice as likely as non-frequent users to have signs of periodontal disease," said Dr. Shariff. "While more research is needed to determine if medical marijuana has a similar impact on oral health, our study findings suggest that dental care providers should ask their patients about cannabis habits."
Commenting on the study, Dr. Terrence J. Griffin, president of the American Academy of Periodontology, said, "At a time when the legalization of recreational and medical marijuana is increasing its use in the United States, users should be made aware of the impact that any form of cannabis can have on the health of their gums."

Tuesday, May 23, 2017

Dentists in good compliance with American Heart Association guidelines, according to Rochester epidemiology project



In the first study examining dental records in the Rochester Epidemiology Project, results show that dentists and oral surgeons are in good compliance with guidelines issued by the American Heart Association (AHA) in 2007, describing prophylactic antibiotic use prior to invasive dental procedures.

The Rochester Epidemiology Project is a collaboration of medical and dental care providers in Minnesota and Wisconsin. With patient agreement, the organizations link medical, dental, surgical procedures, prescriptions, and other health care data for medical research.

Prior to 2007, the AHA guidelines recommended prophylactic antibiotics for patients with cardiac conditions who were at moderate or high risk of developing infective endocarditis -- a potentially deadly infection of the heart valve. After 2007, AHA recommended that only high-risk patients receive the antibiotics. This group represents a very small fraction of the individuals receiving antibiotics before 2007, says Daniel DeSimone, M.D., study lead author and infectious diseases and hospital internal medicine physician at Mayo Clinic. The study will be released May 23 online in Mayo Clinic Proceedings.

Earlier studies by Dr. DeSimone's team determined the incidence of infective endocarditis in Olmsted County before and after 2007, using Rochester Epidemiology Project data. They found no significant increase in cases of infective endocarditis following the introduction of updated AHA guidelines.

However, "the major limitation of these studies was the lack of access to dental records," says Dr. DeSimone.

"The inclusion of dental records in the Rochester Epidemiology Project provides a unique opportunity unlike any population health database in the United States," he says.

"The primary criticism of the earlier studies was, 'Are dentists actually following the 2007 AHA guidelines, or do patients continue to receive antibiotics when no longer indicated?'" reports Dr. DeSimone. "How could we prove that dentists were actually following the guidelines, rather than assuming they were? Now we can."

Dr. DeSimone also says, there are a number of health risks for patients when taking antibiotics. "Plus overuse of antibiotics can result in increased bacterial resistance, which is a widespread public health problem," he says.

In addition, while the cost to patients might only be a few dollars a dose, Dr. DeSimone says that when added up, this group of moderate-risk patients could spend well over $100 million per year.

"Using the Rochester Epidemiology Project, we have shown that the new guidelines were very helpful in reducing unnecessary antibiotic use and related issues, without an increase in new cases of infective endocarditis."

Although this was the first study using the newly linked dental records, it was just one of more than 2,600 medical research publications using the Rochester Epidemiology Project. Using medical and dental records, researchers can identify what causes diseases and how patients with certain diseases respond to surgery, medication or other interventions. They also can determine what the future holds for patients with specific diseases or medical conditions.


Friday, May 19, 2017

Extra weight may increase dental risks


Being overweight or obese was linked with an increased likelihood of having poor oral health in a recent study.

In the study of 160 participants, those with BMI ?23 had generally more severe periodontitis, total inflammatory dental diseases, and leukocyte counts than normal weight individuals. Patients who were obese (BMI ?25) had almost a 6-times increased risk for severe periodontitis compared with normal weight participants. Altered inflammatory molecules that are associated with obesity may play a role.

The results are published in Oral Diseases.