A longitudinal study of dental caries and cariogenic microflora in a group of young adults from Göteborg.

Caries and cariogenic microorganisms were assessed in a group of young adults over a 3-year period. A 30% random sample comprising 101 individuals aged 18-19 years was re-examined under conditions consistent with the baseline survey 3 years earlier. The means for DFS prevalence and increment were 8.9 and 2, respectively. Continuing polarization of the disease was observed, with mean DFS score reaching 19.9 in the upper 15% of the frequency distribution. Highest caries activity was observed approximally where the increment of manifest and incipient lesions averaged 1.3 and 1.6 surfaces, respectively, as compared to 0.5/0.6 occlusally and 0.2/0.5 bucco-lingually. While the occlusal component continued to dominate DF score with 5.7 surfaces, the prevalence of approximal lesions increased by 48%, averaging 2.7 surfaces. Frequency distribution showed a shift to the right and increasing skewness. The proportion without manifest lesions/restorations had declined by 3%. While only 6% of the dentin lesions/restorations were found in the lowest quartile, 15% of the individuals with highest caries levels accounted for 40% of the total DFS and 58% of the D component. Among the 88 subjects who were saliva sampled, salivary mutans streptococci were detected in 89.7% and lactobacilli in 83%. Forty-one percent of the 18-19-year-olds had high numbers of mutans streptococci (> 5 x 10(5) cfu per ml) as compared to 33% at the age of 15-16-years, while high numbers of lactobacilli (> 10(5) cfu per ml) were recovered in 21.8% as compared to 14.3%. The stability within each range of microorganisms varied depending on the baseline level.(ABSTRACT TRUNCATED AT 250 WORDS)