(IMAGE) Tokyo Medical and Dental University Caption Periodontal bone defects and dental calculus were observed in skeletons and several teeth from the Edo period, respectively. 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.