Tooth loss increases the risk of diminished cognitive function

The International and American Associations for Dental Research (IADR/AADR) have published an article titled "Tooth Loss Increases the Risk of Diminished Cognitive Function: A Systematic Review and Meta-analysis" in the OnlineFirst portion of the JDR Clinical & Translational Research. In it, Cerutti-Kopplin et al systematically assessed the association between oral health and cognitive function in adult populations.

The increase of cognitive impairment and its pathologic correlates, such as dementia and Alzheimer's disease, in aging populations is progressing worldwide and creating a significant burden on health systems. Better insight into the nature and extent of the association between oral health and cognitive function is of great importance since it could lead to preventive interventions for cognitive performance. Therefore, the objective of this review was to systematically examine if tooth loss leads to cognitive impairment and its most prevalent pathologic correlate (dementia). 

Eligible study reports were identified by searching the MEDLINE (via Ovoid), EMBASE, PsycoINFO and Cochrane Library databases. Pooled hazard ratios with 95 percent confidence intervals were calculated with a random effects model. From 1,251 identified articles, 10 were included in the systematic review and eight in the meta-analysis. Random effects analysis showed, with statistically low heterogeneity, that individuals with less than 20 teeth were at a 20 percent higher risk for developing cognitive decline (hazard ratios equal 1.26, 95 percent confidence intervals equal 1.14 to 1.40) and dementia (hazard ratios equal 1.22, 95 percent confidence intervals equal 1.04 to 1.43) than those with greater than or equal to 20 teeth. 

Based on the published literature, the results of this study show that the risk for cognitive impairment and dementia increases with loss of teeth. This information suggests that oral health strategies aimed to preserve teeth may be important in reducing risk of systemic disease.

Postponing restorative intervention of occlusal dentin caries by non-invasive sealing

Today at the 45th Annual Meeting & Exhibition of the American Association for Dental Research, researcher Vibeke Qvist, University of Copenhagen, Denmark, will present a study titled "Postponing Restorative Intervention of Occlusal Dentin Caries by Non-Invasive Sealing." The AADR Annual Meeting is being held in conjunction with the 40th Annual Meeting of the Canadian Association for Dental Research.

In this study, reseachers investigated the possibility of postponing restorative intervention of manifest occlusal caries in the young permanent dentition by non-invasive sealing. This prospective, RCT-designed study included 521 occlusal caries lesions in 521 patients, aged 6-17 years. Based on clinical and radiographic assessment, all lesions were in need of restorative treatment. After randomization, 368 resin sealings and 153 composite-resin restorations were performed by 68 dentists from 2006 to 2009 in nine public dental health service locations. Treatments were annually controlled, clinically and radiographic, until patients were referred to private dentistry at age 18 years. Chi-square test, Kaplan-Meier survival-analyses and Cox regression-analyses were applied for statistical data-analyses.

After five to eight the dropout rate was eight percent and 54 percent of the treatments were completed due to age (50 percent) or primary caries (four percent). Thirty-one percent of the sealings were replaced by restorations and 12 percent were still functioning although some were repaired/renewed. Seven percent of the restorations were repaired/renewed and 20 percent were still functioning. No endodontics was performed. 

Survival of sealings was not influenced by eruption stage of tooth, nor by surface emineralization/cavitation. Notably, the results indicate the possibility of postponing restorative intervention of occlusal dentin caries lesions in young permanent teeth by non-invasive sealing. As expected, the restorations showed the best survival, but more than half of the sealed lesions were still not restored after the first seven years.

This is a summary of oral presentation #0043, "Postponing Restorative Intervention of Occlusal Dentin Caries by Non-Invasive Sealing," which will be presented on Wednesday March 16, 2016, 2:30 p.m. - 2:45 p.m. at the Los Angeles Convention Center, room #403A.

Antidepressants linked to tooth implant failure

Antidepressants, commonly used to treat anxiety, pain and other disorders, may play a role in dental implant failure, according to a new pilot study by University at Buffalo researchers.

The research found that the use of antidepressants increased the odds of implant failure by four times. Each year of antidepressant use doubled the odds of failure.

While these drugs are often used to manage mood and emotions, a side effect decreases the regulation of bone metabolism, which is crucial to the healing process.

For an implant to heal properly, new bone must form around it to secure it in place, says Sulochana Gurung, lead investigator and a doctor of dental surgery (DDS) candidate.

"Antidepressant medication may relieve depression symptoms and help millions of patients worldwide, however, their benefits must be weighed with the side effects. Patients should cooperate with their physician to reach the right balance," says Latifa Bairam, DDS, MS, an investigator on the study and clinical assistant professor in the Department of Restorative Dentistry in the UB School of Dental Medicine.

"Four of the many known side effects that are reported in the literature are a big concern to us as dentists in regard to oral and bone health."

Additional side effects of the drug include osteoporosis, a condition in which bones become weak and brittle; akathisia, a disorder characterized by the need to be in constant motion, including the head and jaw; bruxism, or teeth grinding; and dryness of the mouth, all of which affect the implant healing process, says Bairam.

The research, "A Pilot Study: Association between Antidepressant Use and Implant Failure," was funded by the Student Research Program through the SDM Dean's Vision Fund.

Gurung will present the findings at the 45th annual American Association for Dental Research conference on March 19. She also presented at the School of Dental Medicine's 2016 Student Research Day on Feb. 25.

She completed the study under the mentorship of Bairam, Sebastiano Andreana, DDS, MS, associate professor and director of implant dentistry, and Mine Tezal, PhD, DDS, clinical assistant professor in the Department of Oral Biology.

The research began to take shape after Bairam and Andreana, who have previously studied implant failure, noticed that a growing number of their patients reported use of antidepressant medication.

After analyzing data from the medical charts of UB Dental Clinic patients in 2014, the researchers found that of the few patients who experienced implant failures, 33 percent used antidepressants. For patients who did not experience failures, only 11 percent used the drug.

"We decided that the dental community and the world should be aware of this, and that triggered the preparation of the research," says Andreana. "The difference between 33 percent and 11 percent is quite remarkable and needs further in-depth analysis."

More than one in 10 Americans over the age of 12 use antidepressants, making it the second most prescribed type of drug in the U.S., according to data from the Centers for Disease Control and Prevention (CDC) and IMS Health.

And the rate is increasing. Antidepressant use has surged 400 percent between the periods 1988-94 and 2005-08, according to the CDC.

The researchers plan to build on the study by retesting their results on a larger scale. For now, they advise those using antidepressants to consult with their physician about the drug's side effects and alternative methods of managing depression, anxiety or pain.

Link between gum disease and cognitive decline in Alzheimer's

A new study jointly led by King's College London and the University of Southampton has found a link between gum disease and greater rates of cognitive decline in people with early stages of Alzheimer's Disease. 

Periodontitis or gum disease is common in older people and may become more common in Alzheimer's disease because of a reduced ability to take care of oral hygiene as the disease progresses. Higher levels of antibodies to periodontal bacteria are associated with an increase in levels of inflammatory molecules elsewhere in the body, which in turn has been linked to greater rates of cognitive decline in Alzheimer's disease in previous studies. 

The latest study, published in the journal PLOS ONE, set out to determine whether periodontitis or gum disease is associated with increased dementia severity and subsequent greater progression of cognitive decline in people with Alzheimer's disease. 

In the observational study, 59 participants with mild to moderate Alzheimer's Disease were cognitively assessed and a blood sample was taken to measure inflammatory markers in their blood. Participants' dental health was assessed by a dental hygienist who was blind to cognitive outcomes. The majority of participants (52) were followed-up at six months when all assessments were repeated. 

The presence of gum disease at baseline was associated with a six-fold increase in the rate of cognitive decline in participants over the six-month follow-up period of the study. Periodontitis at baseline was also associated with a relative increase in the pro-inflammatory state over the six-month follow-up period. The authors conclude that gum disease is associated with an increase in cognitive decline in Alzheimer's Disease, possibly via mechanisms linked to the body's inflammatory response. 

Limitations of the study included the small number of participants; the authors advise that the study should be replicated ideally with a larger cohort. The precise mechanisms by which gum disease may be linked to cognitive decline are not fully clear and other factors might also play a part in the decline seen in participants' cognition alongside their oral health. 

However, growing evidence from a number of studies links the body's inflammatory response to increased rates of cognitive decline, suggesting that it would be worth exploring whether the treatment of gum disease might also benefit the treatment of dementia and Alzheimer's Disease.

Professor Clive Holmes, senior author from the University of Southampton, says: "These are very interesting results which build on previous work we have done that shows that chronic inflammatory conditions have a detrimental effect on disease progression in people with Alzheimer's disease. Our study was small and lasted for six months so further trials need to be carried out to develop these results. However, if there is a direct relationship between periodontitis and cognitive decline, as this current study suggests, then treatment of gum disease might be a possible treatment option for Alzheimer's."

Dr Mark Ide, first author from the Dental Institute at King's College London says: "Gum disease is widespread in the UK and US, and in older age groups is thought to be a major cause of tooth loss. In the UK in 2009, around 80% of adults over 55 had evidence of gum disease, whilst 40% of adults aged over 65-74 (and 60% of those aged over 75) had less than 21 of their original 32 teeth, with half of them reporting gum disease before they lost teeth.

"A number of studies have shown that having few teeth, possibly as a consequence of earlier gum disease, is associated with a greater risk of developing dementia. We also believe, based on various research findings, that the presence of teeth with active gum disease results in higher body-wide levels of the sorts of inflammatory molecules which have also been associated with an elevated risk of other outcomes such as cognitive decline or cardiovascular disease. Research has suggested that effective gum treatment can reduce the levels of these molecules closer to that seen in a healthy state. 

"Previous studies have also shown that patients with Alzheimer's Disease have poorer dental health than others of similar age and that the more severe the dementia the worse the dental health, most likely reflecting greater difficulties with taking care of oneself as dementia becomes more severe."

Fighting cavities could one day be as easy as taking a pill, research shows

University of Florida Health researchers have identified a new strain of bacteria in the mouth that may keep bad bacteria in check -- and could lead to a way to prevent cavities using probiotics.

The researchers say the findings could lead to the development of a supplement that patients could take orally to prevent cavities.

While developing an effective oral probiotic will require more research, a possible candidate organism has been identified: a previously unidentified strain of Streptococcus, currently called A12. Robert Burne, Ph.D., associate dean for research and chair of the UF College of Dentistry's department of oral biology, and Marcelle Nascimento, D.D.S., Ph.D., an associate professor in the UF College of Dentistry's department of restorative dental sciences, published the findings in late January in the journal Applied and Environmental Microbiology.

To maintain a healthy mouth, the oral environment must have a relatively neutral chemical makeup, or a neutral pH. When the environment in the mouth becomes more acidic, dental cavities or other disorders can develop, according to Burne.

"At that point, bacteria on the teeth make acid and acid dissolves the teeth. It's straightforward chemistry," Burne said. "We got interested in what activities keep the pH elevated."

Previous research by Burne, Nascimento and others found two main compounds that are broken down into ammonia, which helps neutralize acid in the mouth. These compounds are urea, which everyone secretes in the mouth, and arginine, an amino acid. Burne and Nascimento had also previously found that both adults and children with few or no cavities were better at breaking down arginine than people with cavities. Researchers knew bacteria were responsible for breaking down these compounds but needed to investigate which bacteria do this best, and how this inhibits cavities. Part of the answer is A12.

"Like a probiotic approach to the gut to promote health, what if a probiotic formulation could be developed from natural beneficial bacteria from humans who had a very high capacity to break down arginine?" said Burne. "You would implant this probiotic in a healthy child or adult who might be at risk for developing cavities. However many times you have to do that -- once in a lifetime or once a week, the idea is that you could prevent a decline in oral health by populating the patient with natural beneficial organisms."

A12 has a potent ability to battle a particularly harmful kind of streptococcal bacteria called Streptococcus mutans, which metabolizes sugar into lactic acid, contributing to acidic conditions in the mouth that form cavities. The UF researchers found that A12 not only helps neutralize acid by metabolizing arginine in the mouth, it also often kills Streptococcus mutans. 

"Also, if A12 doesn't kill Streptococcus mutans, A12 interferes with Streptococcus mutans' ability to carry out its normal processes that it needs to cause disease," Burne said. "If you grow them together, Streptococcus mutans does not grow very well or make biofilms, also known as dental plaque, properly."

Nascimento, a clinician, collected plaque samples for the study. Dental plaque is a mass of bacteria that grows on the surface of teeth and can contribute to the formation of cavities. She isolated more than 2,000 bacteria that the researchers then screened to find bacteria that fit the bill. 

"We then characterized 54 bacteria that metabolized arginine," Nascimento said. "Out of these, A12 stood out for having all of the properties we were looking for in a bacteria strain that could prevent cavities in a probiotic application."

The researchers sequenced the entire genome of A12 and plan to turn this discovery into a tool to screen for people who are at a higher risk for developing cavities, in combination with other factors such as a patient's diet and their oral hygiene habits.

"We may be able to use this as a risk assessment tool," Nascimento said. "If we get to the point where we can confirm that people who have more of this healthy type of bacteria in the mouth are at lower risk of cavities, compared to those who don't carry the beneficial bacteria and may be at high risk, this could be one of the factors that you measure for cavities risk."

Penn team reverses signs of naturally occurring chronic periodontitis

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IMAGE: A TOOTH BEFORE (TOP) AND AFTER (BELOW) SIX WEEKS OF TREATMENT SHOWS NOTICEABLE IMPROVEMENTS IN REDNESS AND INFLAMMATION. view more 

CREDIT: UNIVERSITY OF PENNSYLVANIA

Periodontitis, a gum disease present in nearly half of all adults in the United States, involves inflammation, bleeding and bone loss. In its severe form, it is associated with systemic inflammatory conditions such as atherosclerosis and rheumatoid arthritis. Few treatment options exist beyond dental scaling and root planing, done in an attempt to reduce plaque and inflammation.

Now, with findings from a study led by University of Pennsylvania researchers, there is new hope that the disease can be effectively reversed.

The work, which appears in the Journal of Clinical Periodontology, employed an inhibitor of a protein called C3, a component of the body's complement system, which is involved in immunity and inflammatory responses. Delivering this inhibitor, Cp40, to the periodontal tissue just once a week reversed naturally occurring chronic periodontitis inflammation in a preclinical model. 

George Hajishengallis, Thomas W. Evans Centennial Professor in Penn's School of Dental Medicine's Department of Biology, and John D. Lambris, Dr. Ralph and Sallie Weaver Professor of Research Medicine in the Perelman School of Medicine's Department of Pathology and Laboratory Medicine, were co-senior authors on the study, the result of years of collaboration.

"Even after one treatment, you could see a big difference in inflammation," said Hajishengallis. "After six weeks, we saw reversals in inflammation, both clinically and by looking at cellular and molecular measures of osteoclast formation and inflammatory cytokines."

"The results were so clean, so impressive," Lambris said. "The next step is to pursue Phase 1 trials in humans."

In addition to Hajishengallis and Lambris, the research team included lead author Tomoki Maekawa, Tetsuhiro Kajikawa and Evlambia Hajishengallis of Penn Dental Medicine; Sophia Koutsogiannaki and Daniel Ricklin of Penn Medicine; Ruel A. Briones and Cristina A. G. Garcia of Manila Central University and Ranillo R. G. Resuello and Joel V. Tuplano of the Simian Conservation Breeding and Research Center.

This study builds on earlier work by Hajishengallis, Lambris and colleagues which identified C3 as a promising target for treating periodontal disease. C3, or the third component of the complement system, is a key part of signaling cascades that trigger inflammation and activate the innate immune system. Their previous research, which used an inducible model of periodontal disease, found that Cp40 could reduce signs of the disease.

To get closer to a natural scenario, however, the current work was conducted on animals that naturally had developed chronic periodontitis. Initially the research team tried administering Cp40 three times a week, but after seeing significant reductions in inflammation, they tried giving it only once a week to a different group and saw the same good results.

"Statistically, giving the drug only once a week was indistinguishable from three times a week," Hajishengallis said.

This study delivered the drug via a local injection to avoid any potential systemic effects from inhibiting a component of the immune system. There were no adverse effects reported.

"Some people have been concerned that blocking complement would lead to more infections but that is not the case here," Lambris said. "We're stopping the inflammation in the gums and thereby killing the bacteria that need inflammatory tissue breakdown proteins to survive."

The researchers are even more encouraged that this treatment worked well as a stand-alone therapy; in humans, they said, it would be given in addition to the standard of care scaling and planing. They are planning to pursue a Phase 1 safety and efficacy study in human volunteers.

New research identifies role of tiny bubbles in teeth cleaning

Research into the science behind ultrasonic scalers, used by dental professionals to remove built up plaque, has identified that the formation of tiny bubbles around the head is key to the cleaning process.

The bubble formation, or cavitation, of water around the head of the scaler was observed using high speed cameras. Scalers of differing power, and head shape, were used and compared to quantify the patterns of cavitation.

The team believe that the methods developed in the study will help to test new instrument designs to maximise cavitation, with the aim of designing ultrasonic scalers that operate without touching the tooth surface. By doing so, the process of teeth cleaning at the dentist would become both less painful and more effective.

The findings, published in PLOS ONE, are the first to prove that cavitation takes place around the free end of ultrasonic scalers.

Professor Damien Walmsley, from the School of Dentistry at the University of Birmingham, explained, "Removing dental plaque and calculus, that is the build-up of what we know as tartar or hard plaque, is a big part of maintaining oral health and a regular occurrence in dental check-ups. These findings will help us to understand how to make the tools as effective as possible."

A Satelec ultrasonic scaler, operating at 29 kHz with three different shaped tips, was studied at medium and high operating power using high speed imaging at 15,000, 90,000 and 250,000 frames per second, and the tip displacement was recorded using scanning laser vibrometry. 

The team were not only able to show that cavitation occurred at the free end of the tip, but that it increases with power, and the area and width of the cavitation cloud varies for different shaped tips. 

Nina Vyas, lead author of the paper from the University of Birmingham, said, "Other studies we have done, using electron microscopy, have shown that removal of plaque biofilm is increased when cavitation is increased. Putting the pieces together, we can therefore say that altering the shape and power of these commonly used tools make them more effective, and hopefully, pain-free."