(IMAGE) Tokyo Medical and Dental University Caption The 16S rDNA sequencing revealed that the bacterial composition of Edo and modern samples with periodontitis were different. Interestingly, several bacteria observed in modern samples were not detected in the Edo samples. Credit Department of Periodontology, TMDU Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.