Abstract
Epidemiological analyses, with respect to periodontal disease prevalence according to signs and symptoms using the Ramfjord Calculus Index (CI) and Periodontal Disease Index (PDI), were performed on 881 mental retardates aged 15-48 who had one or more subject teeth. They were among a group of 1107 subjects admitted to the Niigata Prefectural Institute of Total Training for the Mentally Retarded, Colony Niigata Shiroiwa-no-Sato, during the years 1971-1988. It was found that the prevalence rate of disease increased, that of gingivitis and of calculus accummulation did not fluctuate, and the prevalence rate of periodontitis increased with age in 3 periods of admission, 1971-1975, 1976-1981 and 1982-1988. The admission periods, gender, IQ and the institutionalization did not appear to influence these rates. The prevalence rates of gingivitis and periodontitis were considered to be higher than in the standard Japanese population.
