BackgroundTo date, a few studies have documented the detailed periodontal conditions of a Japanese population. It is important to know if the awareness of Japanese nationals and dentists regarding oral hygiene and prevention of periodontal disease have improved when compared with the past in Japan for the development of future scenarios regarding prevention. The aim of this study was to investigate the severity, prevalence, and extent of periodontal disease in the adult population of the city of Takahagi, Japan. Results were also compared with those of an epidemiological study performed in Japan in the 1980s.MethodsA total of 582 (aged 20 to 89 years) randomly sampled Takahagi residents answered a comprehensive questionnaire and participated in clinical examinations.ResultsThe mean percentages of tooth surfaces harboring plaque and exhibiting BOP were 59.5 ± 20.9% and 31.1 ± 21.1%, respectively. The mean PPD and CAL were 2.5 ± 0.5 mm and 2.9 ± 1.0 mm, respectively. Compared with results of the 1980s survey, the mean percentages of plaque and bleeding on probing were lower in the current population. The mean CAL and prevalence of attachment loss of ≥5 mm in some age groups were higher in the present study than in the 1980s study. There were no statistically significant differences with respect to mean probing depth between the 1980s and current age groups.ConclusionsPeriodontal disease was still prevalent in the current Japanese population, even though some improvement occurred. Proper public health programs therefore need to be established.