The association between number of remaining teeth and maintenance of successful aging in Japanese older people: A 9-year longitudinal study

With population aging, an increasing attention has been paid to quality of life rather than mere longevity. Now, it is urgently needed to clarify predictors of well-being in later life, i.e., “successful aging (SA).” The aim of this study is to investigate whether the number of remaining teeth impacts on maintenance of SA among Japanese older people. The present study was conducted in Tsurugaya district, a suburban area of Sendai, in northern Japan, and included older people aged ≥ 70 years who had met the criteria for SA at a 2003 baseline survey. At the baseline survey, dentists obtained data for the number of remaining teeth. We obtained information about Long-term Care Insurance certification, including the dates of incident functional disability and death between 2003 and 2012. Data pertaining to health-related quality of life (HRQOL) were collected at the 2003 baseline survey and the 2012 follow-up survey. Maintenance of SA was defined in terms of survival, disability-free status and high HRQOL in both 2003 and 2012. Among 450 participants, 108 (24.0%) were considered to have maintained a state of SA. When participants were classified into three groups according to previous studies, in comparison with participants who retained 0-9 teeth, the multivariate prevalence ratios (95% confidence intervals) were 1.39 (0.81-2.36) for those who retained 10-19 teeth and 1.58 (1.002-2.50) for those who retained ≥ 20 teeth (p trend = 0.046). The present results suggest that retaining ≥ 20 teeth is associated with maintenance of SA among Japanese older people.