Whiter teeth, without the burn

Peer-Reviewed Publication

AMERICAN CHEMICAL SOCIETY

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IMAGE: A NEW BLEACHING GEL WHITENED TOOTH SAMPLES BY SIX SHADES, USING A LOW LEVEL OF HYDROGEN PEROXIDE (12%). view more 

CREDIT: ADAPTED FROM ACS APPLIED MATERIALS & INTERFACES 2021, DOI: 10.1021/ACSAMI.1C06774

Most people would like to flash a smile of pearly whites, but over time teeth can become stained by foods, beverages and some medications. Unfortunately, the high levels of hydrogen peroxide in dentists’ bleaching treatments can damage enamel and cause tooth sensitivity and gum irritation. Now, researchers reporting in ACS Applied Materials & Interfaces have developed a gel that, when exposed to near infrared (NIR) light, safely whitens teeth without the burn.

The growing demand for selfie-ready smiles has made tooth whitening one of the most popular dental procedures. Treatments at a dentist’s office are effective, but they use high-concentration hydrogen peroxide (30–40%). Home bleaching products contain less peroxide (6–12%), but they usually require weeks of treatment and don’t work as well. When a bleaching gel is applied to teeth, hydrogen peroxide and peroxide-derived reactive oxygen species (mainly the hydroxyl radical) degrade pigments in stains. The hydroxyl radical is much better at doing this than hydrogen peroxide itself, so researchers have tried to improve the bleaching capacity of low-concentration hydrogen peroxide by boosting the generation of powerful hydroxyl radicals. Because previous approaches have had limitations, Xingyu Hu, Li Xie, Weidong Tian and colleagues wanted to develop a safe, effective whitening gel containing a catalyst that, when exposed to NIR light, would convert low levels of hydrogen peroxide into abundant hydroxyl radicals.

The researchers made oxygen-deficient titania nanoparticles that catalyzed hydroxyl radical production from hydrogen peroxide. Exposing the nanoparticles to NIR light increased their catalytic activity, allowing them to completely bleach tooth samples stained with orange dye, tea or red dye within 2 hours. Then, the researchers made a gel containing the nanoparticles, a carbomer gel and 12% hydrogen peroxide. They applied it to naturally stained tooth samples and treated them with NIR light for an hour. The gel bleached teeth just as well as a popular tooth whitening gel containing 40% hydrogen peroxide, with less damage to enamel. The nanoparticle system is highly promising for tooth bleaching and could also be extended to other biomedical applications, such as developing antibacterial materials, the researchers say.

The authors acknowledge funding from the National Natural Science Foundation of China, the National Key R&D Program of China and the Key Technologies R&D Program of Sichuan Province.

The abstract that accompanies this paper is available here.

Study: Dental implant surfaces play major role in tissue attachment, warding off unwanted bacteria

 

Research lays groundwork for improving the success of medical and dental implants

Peer-Reviewed Publication

 When dental implants are inserted, saliva or blood plasma immediately coat them. The implants adsorb a thin layer of proteins from these fluids that help gum tissue attach, but also allow microorganisms – including potentially harmful bacteria – to grow on the implant surface.

The surface of implants, as well as other medical devices, plays a significant role in the adsorption of oral proteins and the colonization by unwanted microorganisms (a process known as biofouling), according to a new study led by the University at Buffalo and the University of Regensburg.

The research, published in the Journal of Dental Research, sought to increase scientists’ understanding of this complex biological process by examining the makeup of the oral protein layer and how it can be controlled by chemically modifying the biomaterial surface. The findings lay the groundwork for improving the success of medical and dental implants, says co-lead investigator Stefan Ruhl, DDS, PhD, professor of oral biology in the UB School of Dental Medicine.

“It is often this protein layer, rather than the biomaterial surface, that is encountered by colonizing bacteria or attaching tissue cells. These proteins help determine the biological or pathological consequences that result in either long-term survival of the implant or its failure along with irreversible damage to the surrounding tissues from infection,” says Ruhl. “Therefore, it is important to determine how adsorption might be controlled through chemical modification of the biomaterial surface to achieve a desired outcome.”

The study was also co-led by Rainer Müller, PhD, professor at the Institute of Physical and Theoretical Chemistry at the University of Regensburg.

Using silica beads designed in Müller’s lab with various chemically modified surfaces, the researchers found that the adsorption of proteins from blood plasma is more influenced by the amount of protein adsorbed than by the composition of the protein layer.

However, the adsorption of proteins from saliva was directly impacted by the biomaterial’s surface. Adsorption was lower on surfaces that had a negative electric charge or that repelled water, countering the findings of previous studies.

When examining complex biofluids such as saliva and blood, adsorption became unpredictable for the majority of proteins, says Ruhl.

“The interaction between the proteins contained in the biofluids may play an important, but still little understood, role in adsorption processes,” says Müller. “The ultimate goal to connect surface properties to protein adsorption so that optimal tissue compatibility will be achieved but microbial adhesion will be prevented, will likely not be as straightforward as expected.”

The model system of chemically modified silica surfaces developed by the researchers may serve as a platform to study the basic principles of protein adsorption from complex biofluids.

“To improve the design of implant surface coatings, future research should examine the adsorption of proteins that are known to either foster the attachment of tissue cells or colonizing bacteria, as well as explore the molecular structure of complex mixtures of blood plasma and saliva proteins,” says Ruhl.

Jutta Lehnfeld, doctoral candidate at the University of Regensburg, is the first author. Additional UB School of Dental Medicine investigators include alumnus Yegor Dukashin, DDS; alumna Janet Mark, DDS; Gregory White, DDS, volunteer clinical assistant professor; and alumna Stephanie Wu, DDS. University of Regensburg alumna Verena Katzur, PhD, is also an investigator.

Researchers identify oral bacteria as the major cause for periodontitis, a gum infection causing tooth loss

 

One of the major causes of tooth loss is the inflammation and weakening of the supporting structures of the teeth caused by bacterial infection, a condition commonly known as “periodontitis.” The oral cavity is home to a myriad of microorganisms, including bacteria that generally maintain a “symbiotic” (mutually beneficial) or neutral relationship with the host, but are also capable of initiating many diseases.

Aggregation of the bacterial community into “biofilms” is often associated with the development of infections, including periodontitis. With currently available treatment options often proving inadequate, there is a pressing need to understand the beginning and development of the disease better. Now, in a study published in International Journal of Environment and Public Health Research, a group of researchers led by Assistant Professor Naoki Toyama from Okayama University, Japan, reveal insightful findings that could provide new directions to the treatment strategies for periodontitis.

The physiology of an individual directly affects the development of infection. Genetic differences among hosts contribute to differences in susceptibility to specific pathogens and the chance of developing certain diseases. In their study, Dr. Toyama and colleagues focused on understanding the microbes associated with the presence of periodontitis and the host genetic factors that might facilitate the development of the conditions. Dr. Toyama explains the motivation behind their study, “Several studies on periodontitis have shown that the development of the disease is associated with the nature of the oral microbiome as well as with genetic ‘polymorphism,’ the most common type of genetic variation among people. However, there is no study that simultaneously assesses the importance of these two risk factors in developing the disease.”

Accordingly, the team conducted a cross-sectional study in which they genotypically analyzed 14,539 participants and conducted saliva sampling of 385 individuals. They finally retained 22 individuals for statistical analysis, and based on their periodontal status, divided them into “periodontitis” and “control” groups.

The team found that the “β-diversity” of the microbes, which refers to the ratio between regional and local species diversity, was significantly different between the periodontitis and control groups. Furthermore, they attributed the presence of the bacteria species, P. gingivalis and the bacterial families, Lactobacillaceae and Desulfobulbaceae, to periodontitis. In contrast, they found no relation between genetic polymorphism and periodontitis. Taking these inferences into account, the team concluded that our oral microbiome affects the status of periodontitis more than our genes.

So, how do these findings influence current clinical practices? Dr. Toyama surmises, “The fact that the prevalence of periodontitis is associated with the members of the microbiome rather than the genetic identity of the individual would motivate clinicians to pay more attention to microbiome composition than to host factors in the routine work of periodontal examination, and design customized treatment strategy for periodontitis.’’

As for us common folks, these findings further reinforce the importance of regular tooth cleaning in keeping periodontitis at bay.

Research finds ‘very low rates’ of dental fluoride varnish treatment for young children

 Affordable Care Act mandates insurance coverage for the service during well-child visits to medical provider

 Fewer than 5% of well-child visits for privately insured young children included a recommended dental fluoride varnish application, despite mandatory insurance coverage for this service, according to a University of Massachusetts Amherst study.

Fluoride varnish helps reduce tooth decay, which affects nearly 25% of 2- to 5-year-olds and more than half of 6- to 8-year-olds in the U.S., according to earlier studies. 

The new research, published Aug. 30 in JAMA Network Open, was the first to assess delivery of this evidence-based service recommended by the U.S. Preventive Task Force and the American Academy of Pediatrics for privately insured children. Previous research showed that fewer than 8% of 1- to 5-year-olds covered by Medicaid receive fluoride varnish in medical settings. 

While Medicaid in most states has paid for fluoride varnish applications for at least a decade, private insurance coverage was mandated in 2015 under the Affordable Care Act with no cost-share for families, explains lead author Kimberley Geissler, associate professor of health policy and management in the UMass Amherst School of Public Health and Health Sciences.

“Most kids are not getting fluoride varnish applications in the medical office,” Geissler says. “I wasn’t surprised due to the low rates we’ve seen in Medicaid-covered children, but I was disappointed that it wasn’t higher. Medical providers are not required to do this; it’s like a mammogram. It’s recommended and it’s good and they should do it, and the questions we were looking at were: do they do it and how often?”

Co-author and pediatrician Dr. Sarah Goff, associate professor of health policy and management at UMass Amherst, saysknowing that very low rates of fluoride varnish application are found in both Medicaid and commercially insured populations is important because it suggests that broader, system-level barriers exist. “As a health services researcher and primary care pediatrician, I am excited about our next steps of learning what sorts of things are presenting barriers to applying fluoride varnish and developing strategies for overcoming these barriers so all eligible children receive this important preventive intervention,” Goff says.

The JAMA study is part of a larger project in Massachusetts that will delve into more complex questions, such as whymedical providers aren’t applying fluoride varnish during well-child visits. The preventive treatment is especially critical in light of the statistic that fewer than one in three children under age 5 have an annual dentist visit, where this service also could be provided.

The research team, including senior author Ashley Kranz of the RAND Corporation, examined data from 2016-2018 for privately insured young children in Connecticut, Maine, New Hampshire and Rhode Island.

The sample included 328,661 well-child visits in the four states. Fluoride varnish application was more common among visits for younger children. A 2-year-old was nearly 8 percentage points more likely to receive fluoride varnish than a 5-year-old, an analysis of the data showed.

Fluoride varnish applications were most common in Rhode Island, with a regression-adjusted probability of 8.7%. New Hampshire had the lowest rate, with a regression-adjusted probability of 2.2%.

Geissler points to one “hopeful takeaway” from the study: the regression-adjusted probability of fluoride varnish application increased from 3.6% in 2016 to 5.8% in 2018. “That’s still really low,” she says, “but it did go up over time.”

The study concludes, “Although increases over time were encouraging, very low rates of fluoride varnish in medical settings suggest substantial expansion of this service in medical settings is critical for improving children’s oral health and overall well-being.” 

Gum disease linked with new onset heart disease

 

Reports and Proceedings

EUROPEAN SOCIETY OF CARDIOLOGY

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Sophia Antipolis, France – 25 Aug 2021:  Gum disease is associated with an increased risk of cardiovascular disease: the more severe the periodontitis, the higher the risk. The findings are presented at ESC Congress 2021.1 The association was particularly evident among patients who had experienced a heart attack in the past.

Study author Dr. Giulia Ferrannini of the Karolinska Institute, Stockholm, Sweden said: “Our study suggests that dental screening programmes including regular check-ups and education on proper dental hygiene may help to prevent first and subsequent heart events.”

The Swedish PAROKRANK study previously showed that periodontitis (gum disease) was significantly more common in first time heart attack patients compared to their healthy peers of the same age and sex and living in the same area.2

This long-term follow-up of PAROKRANK participants investigated whether the presence of gum disease, both in heart attack patients and their healthy peers, was related to an increased risk of new cardiovascular events over time.

The analysis included 1,587 participants with an average age of 62 years. Participants underwent a dental examination between 2010 and 2014: 985 were classified as healthy, 489 had moderate periodontitis, and 113 had severe periodontitis. Participants were followed up for the occurrence of cardiovascular events and death. The primary endpoint was a composite of all-cause death, non-fatal heart attack or stroke, or severe heart failure. Follow-up data were collected until the end of 2018 from Swedish national death and patient registries.

During an average follow up of 6.2 years, there were 205 primary endpoint events. In the overall cohort, participants with periodontitis at baseline had 49% higher odds of the primary endpoint compared to those with healthy gums. The probability of the primary endpoint rose with increasing severity of gum disease.

When heart attack patients and healthy controls were assessed separately, the graded relationship between gum disease severity and the primary endpoint was significant only for patients.

Dr. Ferrannini said: “The risk of experiencing a cardiovascular event during follow-up was higher in participants with periodontitis, increasing in parallel with the severity. This was particularly apparent in patients who had already experienced a myocardial infarction.”

She added: “We postulate that the damage of periodontal tissues in people with gum disease may facilitate the transfer of germs into the bloodstream. This could accelerate harmful changes to the blood vessels and/or enhance systemic inflammation that is harmful to the vessels.”

Dr. Ferrannini concluded: “It is important to underline that the quality of care in Sweden is high, as confirmed by the overall low number of total events during follow-up. Despite this, gum disease was linked with an elevated likelihood of cardiovascular disease or death.”

Dental mitigation strategies to reduce aerosolization of SARS-CoV-2

Peer-Reviewed Publication

INTERNATIONAL & AMERICAN ASSOCIATIONS FOR DENTAL RESEARCH

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Alexandria, Va., USA — Limiting infection transmission is central to the safety of all in dentistry, particularly during the current SARS-CoV-2 pandemic, yet many dental procedures unavoidably generate aerosols. In the study “Dental Mitigation Strategies to Reduce Aerosolization of SARS-CoV-2,” published in the Journal of Dental Research (JDR), researchers at the University of Leeds, England, UK used a ‘phantom head’ model to mimic dental procedures in a multifaceted approach to measure aerosol dispersal in a dental surgery setting and determine the potential of different mitigation strategies to reduce the infection risk to the dental team from bioaerosol exposure during routine dental procedures.

In a dental surgery setting, crown preparation and root canal access procedures were performed with an air turbine or high-speed contra-angle hand-piece (HSCAH) operated with water cooling, with mitigation via rubber dam or high-volume aspiration and a no mitigation control. A phantom head was used with a flow of artificial saliva infected with Φ6-bacteriophage, a surrogate virus for SARS-CoV-2. Bioaerosol dispersal was measured using agar settle plates lawned with the Φ6-bacteriophage host, Pseudomonas syringae. Viral air concentrations were assessed by active air sampling, and particle size and quantities were monitored using optical particle counters.

Bioaerosol levels were clearly diminished when using the HSCAH compared with the air turbine. Use of rubber dam or high volume evacuation were also effective in reducing bioaerosols and splatter.

While this model represents a worst-case scenario for possible SARS-CoV-2 dispersal, these data showed that the use of HSCAHs or other mitigation strategies can vastly reduce the risk of viral aerosolization, and suggests a prolonged clinic fallow time is not necessary.

“It is imperative to understand the inherent risks of viral dispersion associated with dental procedures and the efficacy of available mitigation strategies,” said JDR Editor-in-Chief Nicholas Jakubovics, Newcastle University, England. “To our knowledge, this study is the first to report the aerosolization in a simulated dental setting of bacteriophage, as a surrogate for SARS CoV2, as a marker for risk determination. The data described here present a clear picture of how risk of SARS-CoV-2 and similar biological hazards can be greatly attenuated using mitigation strategies including HSCAHs.”

Reducing COVID-19 risk during dentist appointments

Dentists could significantly increase the number of patients they see during the pandemic by switching the drills they use, according to new research. 

The study investigated whether different drill types increased or reduced the spread of aerosol spray in a dental surgery. Reducing aerosol spray results in a safer environment for patients and the dental team. 

The findings show that the time taken to prepare safe surgeries between appointments could be radically reduced by changing drills, potentially resulting in millions more treatments being carried out. 

The study, led by the University of Leeds, compared the aerosol patterns produced by dental drills rotated by air streams - that are most commonly used by UK dentists - to those produced by electric powered drills. 

Instead of simply mapping the spread of water spray during treatment, the research team instead introduced a virus that is similar in size and structure to the SARS-CoV-2 virus that causes COVID-19. 

Their results show that by replacing the high-speed air drills with lower speed electric drills, aerosol spray was virtually eliminated, creating a safer environment for both patients and the dental team. 

The research, funded by the British Endodontic Society, is published in the Journal of Dental Research. 

Lead clinical author Professor Brian Nattress, from Leeds’ School of Dentistry, said: “The issue for dentists during the coronavirus pandemic is that their routine work involves creating an aerosol spray in a confined space with an associated risk of airborne spread of COVID-19. 

“This is the first time the spread of a harmless COVID-19-like virus has been analysed during routine drilling procedures. 

“If the spread of that aerosol spray can be reduced or eradicated, that has enormous, positive implications for how dentists can go about their daily business not just during the coronavirus pandemic, but also during future virus outbreaks.” 

During the first national lockdown in England between March and June 2020, all dental surgeries were closed. 

Since reopening, because patients may be asymptomatic carriers of the SARS-CoV-2 virus when attending a dentist appointment, strict regulations have been introduced to ensure work areas are safe and prepared appropriately between appointments. Additional protective measures have been required for the dental team delivering patient care. This has led to much longer gaps between treating patients.  

Before the pandemic, about 18 million adults and children attended an NHS dental appointment each year in England. 

Reports by charity HealthWatch point to a growing backlog of patients waiting to see a dentist, with fears this could rise as the SARS-CoV-2 virus is expected to remain prevalent in the general population for many months more. 

Adjustments to the pandemic measures require high quality evidence to show how dentists can reduce the risk of spreading the SARS-CoV-2 virus when carrying out aerosol generating procedures (AGPs) during dental treatments. 

During the new research tests, use of the electric drill rather than an air drill led to a 99.98% reduction in aerosol spread of the virus into the air. 

When a dental suction tool was added, there was no detectable virus on surfaces or in air samples taken six to 10 minutes afterwards. 

The new research was carried out by the School of Dentistry, School of Civil Engineering and the Leeds Dental Institute. 

The research team set up simulated dental treatments in a real surgery scenario and - for the first time ever - used a harmless virus to track the spread of aerosols in the air and on surfaces. 

A dummy head and simulated saliva were used to measure the difference between the level of aerosols generated using a conventional air-driven dentist’s drill and a more modern electric hand piece. 

Professor David Wood, Director of Research and Innovation in the School of Dentistry, is co-author of the report. 

He said: “This robust scientific evidence addresses how the risks associated with the spread of the SARS-CoV-2 virus via dental drills can be successfully managed. 

“The recommendation we make in the report will help more people access the dental care they need, but haven’t been able to get since early 2020.” 

In light of the many restraints placed on dentists globally since the beginning of the pandemic, the research team is calling for further and essential studies to find different strategies to control the spread of dental aerosols and help to reduce the backlog of patients. 

Further information 

“Dental mitigation strategies to reduce aerosolization 1 of SARS-CoV-2”, is published on 2 August 2021 in the Journal of Dental Research. 

DOI: https://doi.org/10.1177/00220345211032885