TOOTH is a longitudinal cohort study involving over 1,000 participants aged 85 and older from central Tokyo, Japan. Participants were recruited between 2007 and 2008 through a random sample drawn from the basic city registry, followed by door-to-door recruitment, introduction letters, and home visits. The cohort consists of elderly individuals living in the Shinjuku, Minato, and the east half of Shibuya wards. The TOOTH study consisted of three waves: a baseline survey (Wave 1; 2008–2009) and two follow-up surveys for the remaining participants (Wave 2; 2010–2011 and Wave 3; 2014–2015). Follow-ups were conducted annually via telephone interviews and biennially through in-home interviews.