Researchers at the University of Michigan (U-M) Medical School and School of Dentistry researchers have discovered a bacterium that they say is responsible for causing periodontitis (Cell Host and Microbe, May 15, 2013, Vol. 13:5, pp. 595-601).
Scientists and oral healthcare providers have known for decades that bacteria are responsible for periodontitis but did not know precisely which bacterium was to blame.
Using a mouse model, the researchers were able to isolate the bacterium NI1060 that normally lives in the oral cavity but triggers tooth-supporting bone loss that leads to periodontitis. They also discovered that a receptor that lines the oral cavity, Nod1, is activated by the NI1060 bacterium.
Scientists have known that periodontitis is caused by multiple bacteria and that some of them can damage the gingiva. But they also know that gingival damage is not sufficient to trigger bone loss and that unknown bacteria are responsible, explained Naohiro Inohara, PhD, an associate professor in the department of pathology.
Inohara and colleagues developed a way to induce damage to the gingiva between the molar teeth of mice. Over time, they discovered that the NI1060 bacterium accumulated at the damaged site. To prove NI1060 causes the disease, the bacterium was introduced into germ-free mice with gingival damage. This resulted in bone loss around the teeth, Inohara said.
Genomic sequencing revealed that NI1060 is a bacterium that is related to bacteria associated with the development of aggressive periodontitis in humans.
Nod1 is a part the mouth's protective mechanisms against bacterial infection and removes harmful bacteria during infection. However, in the case of periodontitis, accumulation of NI1060 stimulates Nod1 to trigger neutrophils and osteoclasts -- cells that destroy bone in the oral cavity.
However, it may take years for new therapies to be developed that dentists could use to help patients with periodontal disease, Inohara noted.
