Flexible batteries a highlight for smart dental aids

IMAGE: Flexible lithium batteries have been incorporated into dental braces as part of efforts to increase the efficiency of corrective orthodontics. view more 

Credit: © 2017 KAUST

Smart 3D-printed braces that incorporate nontoxic batteries and lights could reduce the time and costs involved in realigning and straightening teeth.

The orthodontic system, conceptualized by researchers at KAUST, involves placing two near-infrared light-emitting diodes (LEDs) and one lithium-ion battery on every tooth in a semitransparent, 3D-printed dental brace.

The batteries provide energy to turn the near-infrared LEDs on and off, depending on how they are programmed by a dentist, to provide localized light therapy according to the needs of each tooth. Phototherapy enhances bone regeneration and can reduce the time and costs involved in corrective orthodontics. The brace would be removable to allow the batteries to be recharged.

"We started embedding flexible LEDs inside 3D-printed braces, but they needed a reliable power supply," explains Muhammad Hussain who led the study together with PhD student Arwa Kutbee. "After the incidents with the Samsung Galaxy 7 batteries exploding, we realized that traditional batteries in their current form and encapsulation don't serve our purpose. So we redesigned the state-of-the-art lithium-ion battery technology into a flexible battery, followed by biosafe encapsulation within the braces to make a smart dental brace."

The battery was redesigned using a dry-etching technique, which removes the silicon substrate normally found on its back. This process thinned the battery to 2.25mm x 1.7mm and made it flexible. Tests showed that the volumetric energy -- the ratio of energy to device size--of the redesigned batteries remained high even after many cycles of continuous operation.

Batteries were then encapsulated in biocompatible soft polymeric materials to prevent the possibility of leakage, making them safe to place in the mouth. As a testament to their biocompatibility, when human embryonic kidney cells were cultured on these batteries over a period of days, they thrived and proliferated. The batteries' electrochemical performance increased linearly with rising temperature, up to 90°C, making them stable.

Hussain says the system is a preliminary prototype, "which is more than a proof of concept." The next step, he says, is to conduct clinical trials.

Triclosan accumulates in toothbrushes, potentially prolonging users' exposure

In September, a ban on triclosan in over-the-counter antiseptic soaps, gels and wipes went into effect in the U.S. But the antibacterial ingredient is still allowed in toothpastes for its reported ability to reduce gum inflammation, plaque and cavities. Now a study in ACS' Environmental Science & Technology has found that triclosan accumulates in toothbrush bristles and elastomer parts, and is readily released when users switch toothpastes, potentially prolonging users' exposure to the compound.

Past research has demonstrated that triclosan has the potential to disrupt hormones in animals and humans, contribute to antibiotic resistance and cause acute toxicity to aquatic organisms. In light of the reported adverse effects and the lack of scientific evidence on its benefits over plain soap and water, the U.S. Food and Drug Administration banned triclosan in antiseptic washes. However, the ruling doesn't apply to toothpaste and other products, including clothing and cookware.

Jie Han, Wei Qiu, Baoshan Xing and colleagues suspected that triclosan might stick to materials commonly used on commercial toothbrush heads and get released in an uncontrolled manner, creating a hidden route of exposure and transport of the chemical that hadn't been previously considered.


The researchers simulated toothbrushing with a range of commercial brushes and pastes. Their testing showed that more than one third of the 22 toothbrushes tested, including two children's varieties, accumulated significant amounts of triclosan equivalent to seven to 12 doses of the amount used per brushing. Toothbrushes with "polishing cups" or "cheek/tongue cleaners," typically made of a class of materials called elastomers, absorbed the largest amounts.

When the researchers switched to triclosan-free toothpastes but continued to use the same brushes, triclosan was continuously released from the toothbrushes over the next two weeks. This release could lead to a user receiving prolonged exposure to triclosan, and potentially to other transformation products that previously hadn't been accounted for, even after switching toothpastes. Additionally, regular landfill disposal of used toothbrushes that have accumulated triclosan could result in the chemical leaching into the environment. The study also raises broader questions about the design of consumer products -- particularly those used for personal care -- with absorptive polymer components that are regularly exposed to chemicals during use.

Antimicrobial gel could improve root canal results

More than 15 million root canals are done each year, according to the American Association of Endodontists. During the procedure, the tooth's pulp and nerve are removed before the tooth is cleaned and sealed. If bacteria, viruses or yeasts contaminate the tooth, another root canal procedure or surgery must be done.

Now, the results of root canal treatments could improve because of an antimicrobial gel discovered and developed at the Indiana University School of Dentistry.

Ghaeth H. Yassen, a visiting assistant professor, has developed an injectable antimicrobial gel that could disinfect a tooth during a root canal procedure.

"I wanted to create a gel that provides sustained antimicrobial properties even when it is removed. I also wanted it to have minimal toxic effect on stem cells and not cause tooth discoloration," he said. "Creating an antimicrobial space is especially important during clinical regenerative endodontic procedures."

Yassen said the gel has advantages over traditional medications, including calcium hydroxide, widely used as an antibacterial agent.

"The gel offers extended and significantly longer residual antibacterial properties, which has been demonstrated in papers published in the Journal of Endodontics and the International Endodontic Journal," he said. "It is biocompatible, and it contains a low concentration of antimicrobial elements."
Yassen said the next steps include optimizing a version of the gel that is opaque to X-rays and other radiation, which will enable dental care professionals to track it within the root canal system.

Better food choices for healthier teeth

.A team of Montréal researchers, including Dr. Tracie Barnett of INRS, took a look at schools in Greater Montréal to see how oral health was being promoted and what incidence this had on cavity rates in children. Published in the American Journal of Preventive Medicine, this study concluded that prevention programs are important, but that school food environments play a leading role in the appearance of cavities in kids ages 8 to 10.

Food choices in and around schools vary greatly and affect the general health of children. It's an environment often carefully observed to understand its impact on obesity prevalence, but rarely in relation to cavities. The data gathered for the QUALITY study (family study on the prevention of cardiovascular disease and Type 2 diabetes in kids and teens) was ideal for verifying children's dental health.

Over a period of two years, the research team analyzed various factors affecting 330 students at 200 schools, including socioeconomic factors, school food environments, and cavity prevention programs. According to their findings, programs promoting healthy eating and good dental hygiene had a positive but relatively modest impact compared to children's food and socioeconomic environments.

Because cavities remain a public health concern, the researchers suggest making this component part of health promotion programs alongside obesity. Policies promoting healthy eating environments could have a greater impact on children's oral health than school programs run in isolation to encourage kids to take good care of their teeth.

Dentists can harvest stem cells

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• 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.”

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.