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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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."

EPA Adopts The Dental Amalgam Rules

The U.S. Environmental Protection Agency issued last week its pretreatment standards to reduce discharges of mercury from dental offices into publicly owned treatment works (POTWs).

Dental offices discharge mercury present in amalgam used for fillings. According to the Agency, "amalgam separators are a practical, affordable and readily available technology for capturing mercury and other metals before they are discharged into sewers that drain to POTWs." EPA anticipates that once captured by a separator, mercury may be recycled.

Approximately fifty percent of dental amalgam is elemental mercury by weight. Dental amalgam is a dental filling material used to fill cavities caused by tooth decay. It has been used for more than 150 years in hundreds of millions of patients. EPA expects compliance with this final rule will annually reduce the discharge of mercury by 5.1 tons as well as 5.3 tons of other metals found in waste dental amalgam to POTWs.

EPA indicated that the rule will apply to offices, including large institutions such as dental schools and clinics, where dentistry is practiced that discharge to a POTW. "It does not apply to mobile units or offices where the practice of dentistry consists only of the following dental specialties: oral pathology, oral and maxillofacial radiology, oral and maxillofacial surgery, orthodontics, periodontics, or prosthodontics."

The final rule purports to ease administrative burdens from those initially proposed. "Administrative burden was a concern of many of the commenters on the 2014 proposed rule and EPA has greatly reduced that burden through streamlining the administrative requirements in this final rule." The Agency claims that to simplify implementation and compliance for the dental offices and the regulating authorities, the final rule establishes that dental dischargers are not Significant Industrial Users (SIUs) as defined in 40 CFR part 403, and are not Categorical Industrial Users (CIUs) or "industrial users subject to categorical pretreatment standards" as those terms and variations are used in the General Pretreatment Regulations, unless designated such by the Control Authority.

"While this rule establishes pretreatment standards that require dental offices to reduce dental amalgam discharges, the rule does not require Control Authorities to implement the traditional suite of oversight requirements in the General Pretreatment Regulations that become applicable upon the promulgation of categorical pretreatment standards for an industrial category." This, the EPA asserts, will significantly reduce the reporting requirements for dental dischargers that would otherwise apply by instead requiring them to demonstrate compliance with the performance standard and BMPs through a one-time compliance report to their Control Authority.


The approach will also eliminate additional oversight requirements for Control Authorities that are typically associated with SIUs, such as permitting and annual inspections of individual dental offices. "It also eliminates additional reporting requirements for the Control Authorities typically associated with CIUs, such as identification of CIUs in their annual pretreatment reports."

In its proposal EPA estimated that there approximately 160,000 dentists working in over 120,000 dental offices who use or remove amalgam in the United States – "almost all of whom discharge their wastewater exclusively to POTWs." According to the EPA news release at that time, "this is a common sense rule that calls for capturing mercury at a relatively low cost before it is dispersed into the POTW."

Specifically the rule requires dentists to cut their dental amalgam discharges to a level achievable through the use of the "best available technology," known as amalgam separators, and the use of other Best Management Practices. Amalgam separators are devices designed to remove amalgam waste particles from dental office wastewater.

In response to the proposed rule the American Dental Association said that it believes the "new federal regulation represents a fair and reasonable approach to the management of dental amalgam waste.... The rule includes reasonable exemptions, a phase-in period and considerations for dental practices that have already installed the devices."

The compliance date for existing facilities is three years from the rule publication in the Feedral Register.

Dental implants with antibacterial activity

The quest for surfaces capable of preventing bacterial colonisation and adhesion in the area surrounding the implant "is a subject of undoubted interest, borne out by the huge number of publications that have been developed in this field," explained Beatriz Palla, researcher in the Biomaterials Group of the UPV/EHU's Department of Polymer Science and Technology. The fact is that "about 10% of implants have to be removed due to osseointegration problems or to the onset of infections," she added.

When it comes to designing strategies to combat these problems, one has to bear in mind the challenge posed by providing the surface of titanium implants with antibacterial properties, and at the same time, by the tremendous resistance that bacterial strains are capable of developing to conventional therapies with antibiotics.

That was the challenge that the UPV/EHU group, which has for some time been developing materials geared towards dental implants, was keen to tackle. "We had already obtained coatings that facilitate the generating of bone around the implant and thus facilitate anchoring to the bone. In a bid to go a step further, we looked at how to turn these coatings into bactericides," said the researcher.

The method they used for this was sol-gel synthesis. Sol-gel synthesis is based on the preparation of a precursor solution (sol) that when left on its own for a while turns into a gel that can be used to coat the surface of the titanium screw, and after heat treatment at a high temperature in the kiln ends up finally being adhered to the screw that will be implanted. "We used silica as the precursor, because in many studies this compound has been shown to be osteoinductive, so it facilitates one of the objectives we wanted to achieve. What is more, to provide the materials with antibacterial characteristics, we added various antibacterial agents".

Three prototypes, one of them a trade secret

In the study carried out, Palla developed three types of coatings depending on the various antibacterial agents chosen; each one had a mechanism to tackle bacterial infections, either prophylactically by preventing the bacteria from becoming adhered initially and the subsequent infection, or else by eliminating it once it has developed.

What was needed in the case of prophylactic coatings was "a material with a very long degradation time so that it would remain adhered to the screw and work for as long as possible preventing bacteria from becoming adhered," said Palla. In the coatings designed to eradicate an infection that has already taken hold, however, "a rapidly degrading material is needed so that it can release the antibacterial agent as quickly as possible to attack the infection". What is more, one of the coatings developed for this purpose "is designed to be used in situ, at the dentist's surgery itself, on the infected screw without any need to extract the implant from the patient. This new material is in the process of being patented and remains a trade secret," pointed out the researcher.

In view of the results, Palla believes that "it is possible to confirm that coatings with an antibacterial capability and which do not affect the proper integration of the implant into the jawbone have been developed". She also admits, however, that there is still a long way to go until they can be applied and used at dentists' surgeries: "Apart from all the trials that remain to be carried out, it would also be advisable to pursue the research a little further to optimize the results more".

Training to become a scuba diver? Start at the dentist

Scuba divers may want to stop by their dentist's office before taking their next plunge. A new pilot study found that 41 percent of divers experienced dental symptoms in the water, according to new research from the University at Buffalo.

Due to the constant jaw clenching and fluctuations in the atmospheric pressure underwater, divers may experience symptoms that range from tooth, jaw and gum pain to loosened crowns and broken dental fillings.

Recreational divers should consider consulting with their dentist before diving if they recently received dental care, says Vinisha Ranna, BDS, lead author and a student in the UB School of Dental Medicine.

"Divers are required to meet a standard of medical fitness before certification, but there are no dental health prerequisites," says Ranna, who is also a certified stress and rescue scuba diver.
"Considering the air supply regulator is held in the mouth, any disorder in the oral cavity can potentially increase the diver's risk of injury. A dentist can look and see if diving is affecting a patient's oral health."
 
The study, "Prevalence of dental problems in recreational SCUBA divers," was published last month in the British Dental Journal.

The research was inspired by Ranna's first experience with scuba diving in 2013. Although she enjoyed being in the water, she couldn't help but notice a squeezing sensation in her teeth, a condition known as barodontalgia.

Published research on dental symptoms experienced while scuba diving is scarce or focuses largely on military divers, says Ranna, so she crafted her own study. She created an online survey that was distributed to 100 certified recreational divers. Those who were under 18-years-old, ill or taking decongestant medication were excluded.

Her goal was to identify the dental symptoms that divers experience and detect trends in how or when they occur.

Of the 41 participants who reported dental symptoms, 42 percent experienced barodontalgia, 24 percent described pain from holding the air regulator in their mouths too tightly and 22 percent reported jaw pain.

Another five percent noted that their crowns were loosened during their dive, and one person reported a broken dental filling.

"The potential for damage is high during scuba diving," says Ranna, who has completed 60 dives.
"The dry air and awkward position of the jaw while clenching down on the regulator is an interesting mix. An unhealthy tooth underwater would be much more obvious than on the surface. One hundred feet underwater is the last place you want to be with a fractured tooth."

The study also found that pain was most commonly reported in the molars and that dive instructors, who require the highest level of certification, experienced dental symptoms most frequently. This frequency is likely attributed to more time spent at shallower depths where the pressure fluctuations are the greatest, says Ranna.

The Professional Association of Diving Instructors has issued more than 24 million certifications around the world. As scuba diving gains popularity as a recreational sport, Ranna hopes to see oral health incorporated into the overall health assessments for certification.

Patients should ensure that dental decay and restorations are addressed before a dive, and mouthpiece design should be evaluated by manufacturers to prevent jaw discomfort, particularly when investigating symptoms of temporomandibular joint disorder in divers, says Ranna.

Children's oral health disparities persist despite equal dental care access

Oral health of children who receive dental care through Medicaid lags behind their privately insured peers, even though the children receive the same amount of dental care, according to a study from the Columbia University College of Dental Medicine.

The study was released in Health Affairs' December issue, and was discussed by Jaffer A Shariff, DDS, MPH, at a Washington, D.C., health policy briefing on December 7. 

"If poor and low-income children now enjoy equal access to dental care but do not have equal oral health, then the remedy should focus more tightly on the day-to-day factors that put them at higher risk for dental problems," said lead author Burton L. Edelstein, DDS, MPH, chair of the Section of Population Oral Health, professor of dental medicine at the College of Dental Medicine (CDM), and professor of health policy and management at Columbia's Mailman School of Public Health. "Low-income families often face income, housing, employment, and food insecurities that constrain their ability to engage in healthy eating and oral hygiene practices," he noted. 

The study considered data from the 2011-2012 National Survey of Children's Health, which included parent reports of oral health and use of dental care for 79,815 children and adolescents (age 1 to 17 years) of all social strata. No differences were found between Medicaid-insured and commercially-insured children in the odds of their having a dental visit, preventive or otherwise. However, parents of children enrolled in Medicaid were 25 percent more likely to report that their child did not have an "excellent or very good" dental condition and were 21 percent more likely to report that their child had a dental problem within the last year than were parents of commercially insured children.

"Because we found that low-income kids are seeing dentists at similar rates as privately insured children, we believe that other issues may negatively impact low income children's oral health. Addressing this would require attention from those currently outside the dental profession, such as social workers, health educators, nutritionists, and community health workers," said Jaffer A. Shariff, DDS, MPH, a research associate in the Section of Population Oral Health, a periodontal resident at CDM, and co-author of the study. "We need to develop an oral health promotion system that complements traditional dental care."

Medicaid's Equal Access Provision mandates that Medicaid beneficiaries have access to equivalent health services as the general population. While the study confirms that the mandate is being followed, it also shows that, "equal access to dental care does not ensure that low-income children obtain and maintain oral health at the same levels as other children," Dr. Edelstein said. 

Dentists need to "rethink the nature of oral health care by seeing it as part of a child's total health care and by treating tooth decay as the chronic disease that it is. We can't segregate oral health from overall health," Dr. Edelstein cautioned. "Evolving health systems that bring teams of providers together to promote healthy behaviors can address common risk factors that benefit a child's overall and oral health. But if you segregate dentistry, especially for Medicaid kids, then you lose that opportunity."

Periodontitis therapeutic vaccine trials could start in 2017

A world-first vaccine developed by Melbourne scientists, which could eliminate or at least reduce the need for surgery and antibiotics for severe gum disease, has been validated by research published this weekend in a leading international journal.

A team of dental scientists at the Oral Health CRC at the University of Melbourne has been working on a vaccine for chronic periodontitis for the past 15 years with industry partner CSL. Clinical trials on periodontitis patients could potentially begin in 2018.

Moderate to severe periodontitis affects one in three adults and more than 50 per cent of Australians over the age of 65. It is associated with diabetes, heart disease, rheumatoid arthritis, dementia and certain cancers. It is a chronic disease that destroys gum tissue and bone supporting teeth, leading to tooth loss.

The findings published in the journal NPJ Vaccines (part of the Nature series) represent analysis of the vaccine's effectiveness by collaborating groups based in Melbourne and at Cambridge, USA.

The vaccine targets enzymes produced by the bacterium Porphyromonas gingivalis, to trigger an immune response. This response produces antibodies that neutralise the pathogen's destructive toxins.

P. gingivalis is known as a keystone pathogen, which means it has the potential to distort the balance of microorganisms in dental plaque, causing disease.

CEO of the Oral Health CRC, Melbourne Laureate Professor Eric Reynolds AO, said it was hoped the vaccine would substantially reduce tissue destruction in patients harbouring P. gingivalis.

"We currently treat periodontitis with professional cleaning sometimes involving surgery and antibiotic regimes," Professor Reynolds said.

"These methods are helpful, but in many cases the bacterium re-establishes in the dental plaque causing a microbiological imbalance so the disease continues."

"Periodontitis is widespread and destructive. We hold high hopes for this vaccine to improve quality of life for millions of people.