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.

Wednesday, May 10, 2017

Grape seed extract could extend life of resin fillings


A natural compound found in grape seed extract could be used to strengthen dentin -- the tissue beneath a tooth's enamel -- and increase the life of resin fillings, according to new research at the University of Illinois at Chicago College of Dentistry.

No filling lasts forever, whether it's composite-resin or amalgam. But dentists find amalgam -- a combination of mercury, silver, tin or other materials -- easier to use and less costly. Plus, it can last 10 to 15 years or more. Composite-resin fillings are more aesthetically pleasing because the mixture of plastic and fine glass particles can be colored to match a patient's teeth. However, the fillings typically last only five to seven years.

In research published in the Journal of Dental Research, Ana Bedran-Russo, associate professor of restorative dentistry, describes how grape seed extract can make composite-resin fillings stronger, allowing them to last longer. The extract, Bedran-Russo said, can increase the strength of the dentin, which comprises the majority of the calcified extracellular tissue of teeth, forming the layer just beneath the hard external enamel.

Dentin is mostly made of collagen, the main structural protein in skin and other connective tissues. Resins have to bind to the dentin, but the area between the two, or the interface, is a weak point, causing restorations to breakdown, Bedran-Russo said.

"When fillings fail, decay forms around it and the seal is lost. We want to reinforce the interface, which will make the resin bond better to the dentin," she said. "The interface can be changed through the use of new natural materials."

More than 90 percent of adults between the ages of 20 and 64 have cavities, according to a federal report. A cavity is a hole that forms in the tooth when acid produced by bacteria erodes the minerals faster than the tooth can repair itself. The dentist removes the decay, or caries, with a drill and seals the hole with a filling.

Secondary caries and margin breakdown are the most frequent causes of failed adhesive restorations, Bedran-Russo said. Despite numerous advances in dental restorative materials, degradation of the adhesive interface still occurs.

Bedran-Russo has discovered that damaged collagen can repair itself with a combination of plant-based oligomeric proanthocyanidins -- flavonoids found in most foods and vegetables -- and extracts from grape seeds. Interlocking the resin and collagen-rich dentin provides better adhesion and does not rely on moisture.

"The stability of the interface is key for the durability of such adhesive joints, and hence, the life of the restoration and minimizing tooth loss," Bedran-Russo said.

One of the possible benefits of using grape seed extract is that it prevents tooth decay, she said. She and Guido Pauli, professor of medicinal chemistry and pharmacognosy in the UIC College of Pharmacy, recently collaborated on another study that showed extract from the root bark of Chinese red pine trees has similar properties to the grape seed extract.

Wednesday, March 29, 2017

Gum disease, tooth loss may increase postmenopausal women's risk of death


Gum disease and tooth loss may be associated with a higher risk of death in postmenopausal women but not increased cardiovascular disease risk, according to new research in Journal of the American Heart Association, the open access journal of the American Heart Association/American Stroke Association.
Loss of all natural teeth also was linked with an increased risk of death in postmenopausal women, according to the study led by researchers at the University at Buffalo.
Periodontal disease, a chronic inflammatory disease of the gum and connective tissue surrounding the teeth, affects nearly two-thirds of U.S. adults 60 and older. The loss of all one's teeth, called edentulism, impacts about one-third of U.S. adults 60 and older and often results from periodontal disease.
"Beside their negative impact on oral function and dietary habits, these conditions are also thought to be related to chronic diseases of aging," said Michael J. LaMonte, PhD, study author and research associate professor of epidemiology and environmental health in UB's School of Public Health and Health Professions.
Researchers analyzed the health information from the Women's Health Initiative program -- a study of 57,001 women, 55 years and older.
"Previous studies included smaller sample sizes or had limited numbers of cardiovascular disease events for analysis. Ours is among the largest and focuses exclusively on postmenopausal women in whom periodontitis, total tooth loss and cardiovascular disease is high nationally," LaMonte said.
In 6.7-year follow up of postmenopausal women studied, they found:
  • There were 3,589 cardiovascular disease events and 3,816 deaths.
  • History of periodontal disease was associated with a 12 percent higher risk of death from any cause. 
  • Loss of all natural teeth was associated with a 17 percent higher risk of death from any cause. The risk of death associated with periodontal disease was comparable regardless of how often women saw their dentists.
  • Women who had lost their teeth were older, had more CVD risk factors, less education and visited the dentist less frequently compared to women with their teeth.
"Our findings suggest that older women may be at higher risk for death because of their periodontal condition and may benefit from more intensive oral screening measures," LaMonte said.
"However, studies of interventions aimed at improving periodontal health are needed to determine whether risk of death is lowered among those receiving the intervention compared to those who do not. Our study was not able to establish a direct cause and effect."

New research comes to terms with old ideas about canker sores


A burning pain sensation - and treatments that do not work. This is what daily life is like for many of those who suffer from recurrent aphthous stomatitis. Research from the Sahlgrenska Academy now sheds new light on the reasons behind this condition found in the mouth.
"There are many misconceptions regarding the reasons for the ulcers and the care of this patient category is hugely neglected despite the fact that many suffer a great deal from their symptoms. Patients may experience a general feeling of illness, and they have difficulties in eating and speaking and may not be able to go to school or work for several days due to the lesions," says Maria Bankvall, dentist and postdoctoral researcher in Odontology.
Mouth blisters, cold sores or apthae are words that are normally used to describe this specific type of lesion, which in medical terms is called recurrent aphthous stomatitis (RAS). The condition is considered one of the most common lesions of the oral mucosa found in the world today.
The lesions have a typical appearance with a red halo surrounding a whitish area, and they can appear anywhere in the non-keratinized mucosa, i.e., on the inside of the cheeks and lips, at the floor of the mouth, on the sides of the tongue and in the throat.
Lots of different causes
The lesions smart and burn and can be greatly disabling for anyone affected. Today there is no cure, instead treatment strategies are aimed at relieving the symptoms using none prescription and/or prescription drugs. 
"For a long time, it was believed that this condition was due to a virus, in the same way as mouth herpes, and many physicians and dentists treat aphthous stomatitis and herpes in the same way, also because it can be difficult to clinically distinguish the two conditions. The patient is often given anti-viral medication, which is a suitable treatment for herpes, but does not relieve aphthous stomatitis," says Maria Bankvall.
"RAS should probably not be regarded as a specific disease but as a general symptom of the body due to an imbalance similar to a headache or a fever," says Maria Bankvall. Her research points to the fact that there is great complexity and multiple interacting factors. 
Hereditary is an important factor as well as the bacterial flora in the mouth, our immune system and environmental factors. The thesis presents a theoretic frame for causality based on existing research and their own patient studies.
Genes and bacterial flora
A number of different genes have been identified as being of importance. The research also shows that the bacterial flora in the healthy oral mucosa seems to differ in people with RAS compared to healthy control subjects.
A certain sub-group of patients may also suffer from a food allergy, but we do not know that much about tolerance mechanisms in the mouth. The importance of the immune system in the oral cavity has also been studied in the thesis, initially with experiments on mice. 
"Today there is a great deal of knowledge regarding the two major conditions in the oral cavity, i.e., caries and periodontitis. However, there are still large information gaps when it comes to different types of oral mucosal lesions. Hopefully, our conclusions can contribute to increasing the knowledge regarding the most common lesions that affect this part of the mouth," says Maria Bankvall.

Friday, March 24, 2017

New study identifies successful method to reduce dental implant failure


UNIVERSITY OF PLYMOUTH
IMAGE
IMAGE: NEW NANOCOATING SHOWS PROMISE IN DENTAL IMPLANT PROTECTION. view more 
CREDIT: UNIVERSITY OF PLYMOUTH
According to the American Academy of Implant Dentistry (AAID), 15 million Americans have crown or bridge replacements and three million have dental implants -- with this latter number rising by 500,000 a year. The AAID estimates that the value of the American and European market for dental implants will rise to $4.2 billion by 2022.
Dental implants are a successful form of treatment for patients, yet according to a study published in 2005, five to 10 per cent of all dental implants fail.
The reasons for this failure are several-fold - mechanical problems, poor connection to the bones in which they are implanted, infection or rejection. When failure occurs the dental implant must be removed.
The main reason for dental implant failure is peri-implantitis. This is the destructive inflammatory process affecting the soft and hard tissues surrounding dental implants. This occurs when pathogenic microbes in the mouth and oral cavity develop into biofilms, which protects them and encourages growth. Peri-implantitis is caused when the biofilms develop on dental implants.
A research team comprising scientists from the School of Biological Sciences, Peninsula Schools of Medicine and Dentistry and the School of Engineering at the University of Plymouth, have joined forces to develop and evaluate the effectiveness of a new nanocoating for dental implants to reduce the risk of peri-implantitis.
The results of their work are published in the journal Nanotoxicology.
In the study, the research team created a new approach using a combination of silver, titanium oxide and hydroxyapatite nanocoatings.
The application of the combination to the surface of titanium alloy implants successfully inhibited bacterial growth and reduced the formation of bacterial biofilm on the surface of the implants by 97.5 per cent.
Not only did the combination result in the effective eradication of infection, it created a surface with anti-biofilm properties which supported successful integration into surrounding bone and accelerated bone healing.
Professor Christopher Tredwin, Head of Plymouth University Peninsula School of Dentistry, commented: "In this cross-Faculty study we have identified the means to protect dental implants against the most common cause of their failure. The potential of our work for increased patient comfort and satisfaction, and reduced costs, is great and we look forward to translating our findings into clinical practice."
The University of Plymouth was the first university in the UK to secure Research Council Funding in Nanoscience and this project is the latest in a long line of projects investigating nanotechnology and human health.
Nanoscience activity at the University of Plymouth is led by Professor Richard Handy, who has represented the UK on matters relating to the Environmental Safety and Human Health of Nanomaterials at the Organisation for Economic Cooperation and Development (OECD). He commented: "As yet there are no nano-specific guidelines in dental or medical implant legislation and we are, with colleagues elsewhere, guiding the way in this area. The EU recognises that medical devices and implants must: perform as expected for its intended use, and be better than similar items in the market; be safe for the intended use or safer than an existing item, and; be biocompatible or have negligible toxicity."
He added: "Our work has been about proving these criteria which we have done in vitro. The next step would be to demonstrate the effectiveness of our discovery, perhaps with animal models and then human volunteers."
Dr Alexandros Besinis Lecturer in Mechanical Engineering at the School of Engineering, University of Plymouth, led the research team. He commented: "Current strategies to render the surface of dental implants antibacterial with the aim to prevent infection and peri-implantitis development, include application of antimicrobial coatings loaded with antibiotics or chlorhexidine. However, such approaches are usually effective only in the short-term, and the use of chlorhexidine has also been reported to be toxic to human cells. The significance of our new study is that we have successfully applied a dual-layered silver-hydroxyapatite nanocoating to titanium alloy medical implants which helps to overcome these risks."

Wednesday, March 8, 2017

Study links changes in oral microbiome with metabolic disease/risk for dental disease


A team of scientists from The Forsyth Institute and the Dasman Diabetes Institute in Kuwait have found that metabolic diseases, which are characterized by high blood pressure, high blood sugar, and obesity -- leads to changes in oral bacteria and puts people with the disease at a greater risk for poor oral health. This study of more than 8,000 ten year olds in Kuwait showed that metabolic diseases lead to increases in salivary glucose; alterations of the bacteria found in the mouth; and increased risk of cavities and gum disease. This work reinforces the need for preventive dental care and greater integration between medical and dental care. 



The study, titled, "The Salivary Microbiome is altered in the Presence of High Salivary Glucose," can be found on PLOS ONE. Over the past ten years, it has become clear that defining a "healthy" microbiome is a critical step for discovering how variations in the bacteria found in and on our body contribute to both disease and wellbeing. While scientists now know a great deal about what bacteria live in our mouth and throughout the body, it is still unclear whether differences in the human microbiome that are seen in many disease states are a symptom of the disease or part of the underlying cause. 
"The mouth represents a rich microbiome that is easily accessible," said Dr. Max Goodson, the study's lead author. "Our research is providing further evidence of the connections between the mouth and some of society's most costly and deadly systemic diseases--and of the importance of using the mouth as a tool for preventive health." 

Summary of Study
We measured the glucose concentration, bacterial counts, and relative frequencies of 42 bacterial species in whole saliva samples from 8,173 Kuwaiti adolescents (mean age 10.00 ± 0.67 years) using DNA probe analysis. In addition, clinical data related to obesity, dental caries, and gingivitis were collected. Data were compared between adolescents with high salivary glucose (HSG); glucose concentration and those with low salivary glucose. Investigators found that HSG was associated with dental caries and gingivitis in the study population. The overall salivary bacterial load in saliva decreased with increasing salivary glucose concentration. Under HSG conditions, the bacterial count for 35 (83%) of 42 species was significantly reduced, and relative bacterial frequencies in 27 species (64%) were altered, as compared with LSG conditions. These alterations were stronger predictors of high salivary glucose than measures of oral disease, obesity, sleep or fitness. These observations clearly indicate that metabolic diseases, such as diabetes, that produce elevated glucose in blood and saliva can significantly alter the oral microflora. 
Samples were obtain through the Forsyth Kuwait Healthy Life Study, is a longitudinal cohort investigation of more than 8,000 children. Forsyth has worked with The Dasman Diabetes Institute and the Kuwait/Forsyth School program to conduct a clinical investigation of the development of obesity, metabolic syndrome and type 2 diabetes in Kuwaiti children. During the five-year study, the body weight, height, blood pressure and fitness were measured, oral disease was evaluated, nutritional information was collected, questionnaires on sleep and medical history were answered and saliva was collected for analysis.


Tooth loss linked to an increased risk of dementia


In a study of 1566 community-dwelling Japanese elderly who were followed for 5 years, the risk of developing dementia was elevated in individuals with fewer remaining teeth. 
Individuals with 10-19, 1-9, and no teeth had 62%, 81%, and 63% higher risks of dementia, respectively, than individuals with >20 teeth. Likewise, an inverse association was observed between the number of remaining teeth and the risk of developing Alzheimer's disease. 
"Our findings emphasize the clinical importance of dental care and treatment, especially in terms of maintenance of teeth from an early age for reducing the future risk of dementia," said Dr. Tomoyuki Ohara, co-author of the Journal of the American Geriatrics Society study.

Wednesday, February 22, 2017

Researchers find association between gum disease and ischemic stroke risk

Adults with gum, or periodontal, disease may be at greater ischemic stroke risk, according to research presented at the American Stroke Association's International Stroke Conference 2017.


Researchers assessed 6,711 adults, who had not had a stroke, for periodontal disease and categorized the adults according to whether they had mild, moderate or severe periodontal disease. They followed patients for 15 years for the incidence of stroke, also documenting the stroke subtype based on cause.
A total of 299 ischemic strokes occurred during the 15 years, including 47 percent that were thrombotic stroke, from a clot within the brain's blood vessels; 26 percent that were cardioembolic, when a blood clot forms in the heart; and 20 percent that were lacunar strokes, which occurs when there is a blockage of small arteries that supply blood to the brain.
They found:
Participants with mild periodontal disease were 1.9 times more likely to have an ischemic stroke than those without periodontal disease. Those with moderate periodontal disease had 2.1 times higher ischemic stroke risk and adults with severe gum disease were 2.2 times more likely to suffer an ischemic stroke than those who had no periodontal disease.
The association between increasing levels of periodontal disease and stroke risk was most pronounced in the cardioembolic and thrombotic stroke subtypes.
The graded association between the level of gum disease and incident ischemic stroke, supports a possible causal association between gum disease and ischemic stroke, researchers said.



Estrogen therapy shown effective in reducing tooth and gum diseases in postmenopausal women


Estrogen therapy has already been credited with helping women manage an array of menopause-related issues, including reducing hot flashes, improving heart health and bone density, and maintaining levels of sexual satisfaction. Now a new study suggests that the same estrogen therapy used to treat osteoporosis can actually lead to healthier teeth and gums. The study outcomes are being published online today in Menopause, the journal of The North American Menopause Society (NAMS).
As estrogen levels fall during menopause, women become more vulnerable to numerous health issues, including loss of bone mineral density which can lead to osteoporosis. Around the same time, changes in oral health also are common as teeth and gums become more susceptible to disease, which can lead to inflammation, pain, bleeding, and eventually loose or missing teeth.
In the Menopause article "Association between osteoporosis treatment and severe periodontitis in postmenopausal women," 492 postmenopausal Brazilian women aged 50 to 87 years, 113 in osteoporosis treatment and 379 not treated, were evaluated to determine whether osteoporosis treatment could help increase the bone mineral density in their jaws and, subsequently, improve overall oral health.
The study found that the rate of occurrence of severe periodontitis was 44% lower in the postmenopausal osteoporosis-treatment group than in the untreated group. Treatment consisted of systemic estrogen alone or estrogen plus progestin, as well as calcium and vitamin D supplements, for a minimum of six months.
"Osteoporosis can occur throughout the body, including the jaw, and lead to an increased risk of periodontal disease," says Dr. JoAnn Pinkerton, NAMS executive director. "This study demonstrates that estrogen therapy, which has proven to be effective in preventing bone loss, may also prevent the worsening of tooth and gum disease. All women, but especially those with low estrogen or on bisphosphonate treatment for osteoporosis, should make good dental care a part of their healthy lifestyles."

Tuesday, February 21, 2017

Mapping a path to better oral health


Dentists aren't the only people who influence how we take care of our teeth; our friends and family play a big role, too. That is the conclusion of Brenda Heaton, an assistant professor of health policy and health services research at Boston University's Henry M. Goldman School of Dental Medicine, who is presenting her research on February 19, 2017, at the American Association for the Advancement of Science (AAAS) conference in Boston.
Heaton specializes in social epidemiology with a focus on oral health. In 2008, she, along with other members of BU's Center for Research to Evaluate & Eliminate Dental Disparities, began a new line of research, focused on understanding oral health and disease among residents in Boston public housing. The majority of the work to date has focused on whether or not "motivational interviewing" can influence how women care for their children's diet and oral health--specifically, the impact on kids with dental caries (also known as tooth decay). There is mounting evidence that one-on-one behavioral interventions, like motivational interviewing, may change short-term behavior, but the effects don't last long. "We started to get a sense that there may be more influences that we need to acknowledge beyond just the individual," says Heaton. She found that social networks--not Facebook and Twitter, but networks of friends, family, and acquaintances--may play an overlooked role in oral health care.
Some women Heaton interviewed "had been born and raised in the unit that they were living in, and were now raising their own child in that unit," she says, "so we had grandmother, mother, and child in one unit." Those close connections influenced how people behaved, and to make significant progress against diseases like tooth decay, Heaton had to tap into those networks herself.
That is not easy, but it is important, says Thomas Valente, a professor of preventive medicine at the University of Southern California and an expert in social networks in health care. People believe information more when it comes from someone they know or respect, and evidence suggests that people are more willing to trust people who are like them. All too often, says Valente, who was not involved in this study, health information is handed to a community by people on the outside, and it is less impactful. "It's like West Side Story," says Valente. "It's like being a Shark and having a Jet come up to you and tell you to do something. It is just not going to happen."
Heaton wants to spread resources about good oral health, not only to combat tooth decay but also because oral health is intertwined with other health concerns. "Sugar-sweetened beverage [consumption is] something that we are very interested in, not only because it is a huge risk factor for oral health outcomes, but it is also a huge risk factor for obesity and other obesity-related health conditions," she says.
To understand the connections that already existed within the community, Heaton needed to draw a social map. Since 2008, her team has interviewed close to 200 women living in Boston public housing and identified nearly 1,000 individuals who were influential. Heaton is using those network maps to find similarities about how information flows through these communities.
The ultimate goal, she says, is to use the map to introduce health information and resources into a community in ways that change long-term behaviors.
"You can't design those interventions until you actually have a really strong grasp of the network structure," says Heaton. For instance, if you want to make an impact, should you look for community members with the most personal connections or for people with large influence but fewer personal ties? Should you take advantage of existing connections or seed new ones?
The power of this approach is that it focuses on prevention rather than cures, says Heaton. It might take a village, but tooth decay "is an entirely preventable health outcome."

Wednesday, February 8, 2017

Genetic defects in tooth enamel conducive to development of caries


Why do some people develop caries even though they always brush their teeth carefully while others are less stringent regarding dental hygiene yet do not have any holes? Ultimately, both have bacteria on the surface of their teeth which can attack the enamel. Enamel forms via the mineralization of specific enamel proteins. If the outer layer of the teeth is defective, tooth decay can strike.
Researchers from the University of Zurich have now pinpointed a gene complex for the first time that is responsible for the formation of tooth enamel. Two teams from the Centre of Dental Medicine and the Institute of Molecular Life Sciences used mice with varying mutations of the enamel proteins involved in the so-called Wnt signaling pathway. Thanks to this transmission route, human and animal cells respond to external signals and specifically activate selected genes in the cell nucleus. The signaling pathway is essential for embryonal development and also plays a pivotal role in the development of cancer or physical malformations.
Mutations in proteins trigger defective tooth enamel
"All mice with mutations in these proteins exhibit teeth with enamel defects," explains Pierfrancesco Pagella, one of the study's two first authors. "Therefore, we demonstrated that there is a direct link between mutations in the genetic blueprints for these proteins and the development of tooth enamel defects." This genetic discovery goes a long way towards improving our understanding of the production of tooth enamel.
The team of researchers was the first in the world to use modern genetic, molecular and biochemical methods to study tooth enamel defects in detail. "We discovered that three particular proteins involved in the Wnt signaling pathway aren't just involved in the development of severe illnesses, but also in the qualitative refinement of highly developed tissue," says co-first author Claudio Cantù from the molecular biologist research group lead by Prof. Konrad Basler. "If the signal transmission isn't working properly, the structure of the tooth enamel can change."
Increased risk of caries with defective tooth enamel
The hardness and composition of the tooth enamel can affect the progression of caries. "We revealed that tooth decay isn't just linked to bacteria, but also the tooth's resistance," says Thimios Mitsiadis, Professor of Oral Biology at the Center of Dental Medicine. Bacteria and their toxic products can easily penetrate enamel with a less stable structure, which leads to carious lesions, even if oral hygiene is maintained.
Understanding the molecular-biological connections of tooth enamel development and the impact of mutations that lead to enamel defects opens up new possibilities for the prevention of caries. "New products that hinder the progress of tooth caries in the event of defective tooth enamel will enable us to improve the dental health of patients considerably," adds Mitsiadis.

Wednesday, January 18, 2017

New dental implant with built-in reservoir reduces risk of infections



A multidisciplinary team of researchers at KU Leuven (University of Leuven, Belgium) has developed a dental implant that gradually releases drugs from a built-in reservoir. This helps prevent and fight infections.

Our mouth contains many micro-organisms, including bacterial and fungal pathogens. On traditional dental implants, these pathogens can quickly form a so-called biofilm, which is resistant to antimicrobial drugs like antibiotics. As a result, these implants come with a significant risk of infections that may be difficult to treat.

KU Leuven researchers have now developed a new dental implant that reduces the risk of infections. "Our implant has a built-in reservoir underneath the crown of the tooth," explains lead author Kaat De Cremer. "A cover screw makes it easy to fill this reservoir with antimicrobial drugs.The implant is made of a porous composite material, so that the drugs gradually diffuse from the reservoir to the outside of the implant, which is in direct contact with the bone cells. As a result, the bacteria can no longer form a biofilm."

In the lab, the implant was subjected to various tests for use with chlorhexidine, a universal mouthwash with a powerful antimicrobial effect. The study shows that the Streptococcus mutans, a type of mouth bacteria that affect the teeth, can no longer form biofilms on the outside of the implant when the reservoir is filled with the mouthwash. Biofilms that were grown beforehand on the implant could be eliminated in the same way. This means that the implant is effective in terms of both preventing and curing infections.

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Tuesday, January 10, 2017

Natural tooth repair method, using Alzheimer's drug, could revolutionize dental treatments


A new method of stimulating the renewal of living stem cells in tooth pulp using an Alzheimer's drug has been discovered by a team of researchers at King's College London.

Following trauma or an infection, the inner, soft pulp of a tooth can become exposed and infected. In order to protect the tooth from infection, a thin band of dentine is naturally produced and this seals the tooth pulp, but it is insufficient to effectively repair large cavities.

Currently dentists use man-made cements or fillings, such as calcium and silicon-based products, to treat these larger cavities and fill holes in teeth. This cement remains in the tooth and fails to disintegrate, meaning that the normal mineral level of the tooth is never completely restored.

However, in a paper published today in Scientific Reports, scientists from the Dental Institute at King's College London have proven a way to stimulate the stem cells contained in the pulp of the tooth and generate new dentine - the mineralised material that protects the tooth - in large cavities, potentially reducing the need for fillings or cements.

The novel, biological approach could see teeth use their natural ability to repair large cavities rather than using cements or fillings, which are prone to infections and often need replacing a number of times. Indeed when fillings fail or infection occurs, dentists have to remove and fill an area that is larger than what is affected, and after multiple treatments the tooth may eventually need to be extracted.

As this new method encourages natural tooth repair, it could eliminate all of these issues, providing a more natural solution for patients.

Significantly, one of the small molecules used by the team to stimulate the renewal of the stem cells included Tideglusib, which has previously been used in clinical trials to treat neurological disorders including Alzheimer's disease. This presents a real opportunity to fast-track the treatment into practice.

Using biodegradable collagen sponges to deliver the treatment, the team applied low doses of small molecule glycogen synthase kinase (GSK-3) to the tooth. They found that the sponge degraded over time and that new dentine replaced it, leading to complete, natural repair. Collagen sponges are commercially-available and clinically-approved, again adding to the potential of the treatment's swift pick-up and use in dental clinics.

Lead author of the study, Professor Paul Sharpe from King's College London said: "The simplicity of our approach makes it ideal as a clinical dental product for the natural treatment of large cavities, by providing both pulp protection and restoring dentine.

"In addition, using a drug that has already been tested in clinical trials for Alzheimer's disease provides a real opportunity to get this dental treatment quickly into clinics."