News Release

Setting the teeth on edge: Identifying the risk factors for tooth loss

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

Peer-Reviewed Publication

Okayama University

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.


About Okayama University, Japan
As one of the leading universities in Japan, Okayama University aims to create and establish a new paradigm for the sustainable development of the world. Okayama University offers a wide range of academic fields, which become the basis of the integrated graduate schools. This not only allows us to conduct the most advanced and up-to-date research, but also provides an enriching educational experience.

About Dr. Naoki Toyama from Okayama University, Japan
Dr. Naoki Toyama is an Assistant Professor at the Graduate School of Medicine, Okayama University, Japan. He is an active member of the research group of oral health science. His areas of interest include periodontitis, genetic association studies, and oral microbiome. As an expert in his field, Dr. Toyama has authored 13 research papers in reputed journals.


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