Changes in periodontal disease indicators in 35-year-old Oslo citizens from 1973 to 1984.

Periodontal disease indicators were evaluated according to the periodontal treatment need system (PTNS) in random samples of 35-year-old citizens of Oslo in 1973 and 1984. The study indicated that although periodontal disease was a common finding in both samples, there was a significant reduction in score C (indicating need for complex periodontal treatment) in 1984 compared to 1973. Whereas 37.9% of the subjects showed inflamed pockets deeper than 5 mm (score C) in 1973, only 22.9% scored C in 1984 (non-Caucasians excluded). This reduction was most pronounced in females. The mean number of C-quadrants in subjects needing complex periodontal treatment was also reduced from 2.0 in 1973 to 1.7 in 1984. Further analyses of the 1984 sample showed that the mean number of C-quadrants was significantly lower in subjects with low OHI-S scores and in regular dental visitors, whereas sex, years at school, toothbrushing frequency, interdental cleaning habits, previous periodontal therapy, self-experienced need for treatment, health attitude or smoking habits, did not seem to influence the prevalence of score C.