Home News

dentii | News

Investigators chart microbial ecology of gingivitis, periodontitis

Print PDF

the soft tissue of the gums and sometimes even destroys the bone supporting the teeth. An international team of researchers and clinicians has charted the microbial ecology of the mouth at all stages of this progression, in nearly 1,000 women in Malawi. This work is laying a foundation of knowledge that could lead to better oral health. The research is published inApplied and Environmental Microbiology, a journal of the American Society for Microbiology.

The investigators used high-throughput sequencing of the 16S ribosomal RNA (rRNA) gene to take the census of the oral microbiomes. Among much else, they found that a small number of species were associated with periodontitis, but not gingivitis, including members of the genera, Prevotella, Treponema, and Selemonas. "Our findings confirm that periodontitis cannot be considered simply an advanced stage of gingivitis, even when only considering supragingival plaque," said first author Liam Shaw, a PhD student at University College London, United Kingdom.

Periodontitis is diagnosed by measuring the depth of the pockets in the gums next to the teeth. "But diagnosing periodontitis visually is impossible and it doesn't usually give any symptoms until it has developed so far that teeth become mobile, which is very late for any treatment," said coauthor Ulla Harjunmaa, a dentist with a master's degree in international Health, who is a PhD student at the Center for Child Health Research, University of Tampere and Tampere University Hospital, Finland.

Diagnosis requires specially trained dental professionals and expensive equipment, which are seldom available in developing countries, said Harjunmaa. But among other things, in the future, this research may lead to an inexpensive and rapid point-of-care test, based on distinguishing the two conditions' microbiomes. "The research made it possible to tell which differences in bacteria were linked specifically to the deepening of dental pockets - which causes loss of teeth - rather than just to bleeding gums," explained Shaw.

"We're not the first to do this sort of research into periodontal disease, but our study is the largest to be done in such a setting," said Shaw. "There is a great need to find new solutions to prevent these problems everywhere, but especially in this kind of setting." He added that oral infections are very common in Malawi, since there is little awareness about oral health and prevention, and little treatment available.

Some of the techniques used in the research may have wide applications, said Shaw. "Where diseases can have multiple severities and clinical features that are also found in non-disease (like bleeding gums in periodontitis), this kind of modeling will be increasingly important in microbiome research."

Periodontal disease is a major public health problem associated with oral bacteria. In developed nations, approximately half of adults are thought to have moderate periodontal disease, with another 7-15 percent having advanced disease, according to the Centers for Disease Control and Prevention. Additionally, periodontal disease is thought to be a risk factor for cardiovascular disease, diabetes, and other chronic health conditions. Treating gum disease could reduce healthcare costs, as well as hospitalizations, according to a study published in the August, 2014 American Journal of Preventive Medicine.

"The best way to prevent periodontal disesases is by proper tooth brushing twice a day combined with flossing once a day," said Harjunmaa. For smokers, quitting is also critically important to prevention, she said.

 

Colorectal tumors exacerbated by mouth microbes

Print PDF

mouth microbes called fusobacteria may use the bloodstream to reach and worsen colorectal tumors through a special sugar-binding protein, study finds.

Colorectal cancer is the third leading cause of cancer-related deaths in the United States when men and women are considered separately, and the second leading cause when both sexes are combined.


While the death rate from colorectal cancer has decreased in both males and females - due to colorectal polyps being found by screening and removed before they can develop into cancer - not enough people are getting screened for colorectal cancer.


In 2014, 65.7 percent of U.S. adults were up-to-date with colorectal cancer screening; 7 percent had been screened, but were not up-to-date, and 27.3 percent had never been screened.


Previous studies by the Garrett Lab at the Harvard T.H. Chan School of Public Health in Boston, MA, have shown fusobacteria to promote the formation of colorectal tumors and exacerbate colorectal cancer in animals. Also, they found that fusobacteria are enriched in human colorectal tissue when compared with neighboring healthy tissue.


According to the Harvard researchers and scientists from the Hebrew University-Hadassah School of Dental Medicine in Israel, this is the first study to shed light on how the microbes from the mouth make their way to the gut, and how they localize to and become abundant in colorectal tumors.


The findings, published in Cell Host & Microbe, demonstrate that fusobacteria use a sugar-binding protein to stick to developing colorectal polyps and cancers, whereby they proliferate and subsequently accelerate the disease.


"As fusobacteria contribute to colon tumor development, revealing the mechanism that guides them to the tumor and why fusobacteria become abundant there might inform ways of blocking this," says co-senior author Wendy Garrett, of the Harvard T.H. Chan School of Public Health and the Dana-Farber Cancer Center.


"Alternatively, and perhaps more importantly, if we know how fusobacteria localize and become enriched in colon tumors, hopefully, we can utilize the same or similar mechanisms to guide and deliver cancer therapeutics to colon tumors," she adds.


Injected oral microbes traveled to colorectal tumor site

Microbes have emerged as a key factor that influences the development and progression of colorectal cancer.


With co-senior author Gilad Bachrach, of the Hebrew University-Hadassah School of Dental Medicine, Garrett suspected that oral microbes might travel through the bloodstream to reach colorectal tumors.


The team examined two mouse models - with either precancerous or malignant colorectal tumors - and injected fusobacteria into their tail veins to test their hypothesis.


The fusobacteria became saturated in the colorectal tumors of both types of mice when compared with the adjacent normal tissue.


Metastatic cancer is cancer that spreads to other parts of the body. When colon cancer spreads, it often spreads to the liver. Like the mouse models, saturation of fusobacteria was also detected in secondary colorectal cancer samples of the liver, but it was not seen in samples taken from tumor-free liver biopsies.


Sugar-binding protein enables fusobacteria to attach to colorectal tumors

Additionally, the researchers discovered from using human samples and mouse models that the Fap2 protein that is located on the surface of fusobacteria recognizes a type of sugar, Gal-GalNac, which is abundant on the surface of colorectal tumor cells.


From experimenting, the researchers learned that Fap2 mediates fusobacterial colonization of colorectal cancer tumors and metastasis.


 

When paired with the knowledge from recent studies - that Fap2 protein impairs the ability of the host immune system to kill tumor cells - the findings suggest that fusobacteria reaches colorectal tumors through the bloodstream and uses their Fap2 protein to bind to host cells and proliferate tumors, thereby accelerating colorectal cancer.

 

Study: Recording selfies while brushing teeth can improve oral health care skills

Print PDF

Recording smart phone video "selfies" of tooth-brushing can help people learn to improve their oral health care techniques, according to a new study.

Using smart phones propped on stands, study participants filmed their brushing at home. Researchers saw an increase in the accuracy of brush strokes, an increase in number of strokes and an overall 8 percent improvement in tooth-brushing skill--but the length of time a person brushed did not change.

While most people have the ability, motivation and desire to brush their teeth properly, they often do not because of improper techniques--and opportunities to improve such skills can be few.

"Often, tooth-brushing is learned and practiced without proper supervision," said Lance T. Vernon, a senior instructor at the Case Western Reserve University School of Dental Medicine and co-author of the study. "Changing tooth brushing behaviors--which are ingrained habits tied to muscle memory--can take a lot of time and guidance."

"Our study suggests that, in the future, recording these selfies can help shift some of this time investment in improving brushing to technology," added Vernon. "Patients can then receive feedback from dental professionals."

The very act of recording a selfie may disrupt ingrained habits, making participants conscious of their brushing and reinforced staples of behavior change, including the process of memory formation, association and creating new muscle memory.

While the results of this small pilot study, published in the Indian Journal of Dental Research, are promising, researchers suggest that these findings are of more importance in proving the selfie concept is useful in a dental setting.

Video and picture selfies are increasingly used in medical fields to assess, monitor and determine the progression of diseases and effectiveness of treatment--a new area of gathering data known as mobile health, or "mHealth"--said Vernon.

"To our knowledge, this is the first report using selfies to study tooth-brushing behavior," he said. "It's a start at an mHealth strategy to create new habits, helping dentists and patients focus more on prevention, rather than on fixing problems once they occur--which can too often be the focus in dentistry."

The study

Before the study, participants' brushing habits were assessed and corrected until each were able to demonstrate proper technique. During the study, they were scored on time spent brushing and skill mastery, including brushing in a circular motion, obtaining a 45-degree angle while brushing facial surfaces of teeth and correct positioning of the arm.

Looking ahead, researchers envision a video-based monitoring app, which could record videos of patients brushing at home that are later reviewed by oral health professionals.

"The cost of an app could be minor, while potentially there could be major long-term benefits to a user's oral health and quality of life," Vernon said. "Dental care can be inaccessible because of cost and access. It's possible dental selfies and other 'mHealth' strategies on phones can become an important part of oral health prevention and diagnosis in the future."

Tooth-brushing helps avert preventable oral diseases, such as tooth decay and periodontal disease, although its effectiveness depends on brushing technique; currently, there is no standard brushing technique consistently recommended by dental organizations or even by oral health experts, Vernon said.

 
Page 2 of 58