Purpose: To analyse possible changes in the severity and distribution of dental caries within the dentition in five groups of 4-year-old children examined with the same methods and criteria between 1980 and 2002. Materials and Methods: The material consisted of retrospective caries recordings from cross-sectional studies performed in 1980, 1987, 1992, 1997 and 2002 in Umeň, Sweden. The distribution of dmfs within the dentition was analysed in the whole groups and in one third of each group with the highest dmfs-values (mSiC-index). Results: When comparing the whole groups, no statistically significant changes were found over the years concerning total dmfs, or dmfs in molars and canines or in occlusal surfaces (p > 0.05). There was a significant increase in dmfs-values in incisors observed between 1980 and 1987, while a similar reduction was observed between 1987 and 1992 (p < 0.05). When comparing subgroups constituting 33% of those with the highest dmfs-values for all teeth in each group, the mean values of dmfs for all teeth was higher in 2002 than in 1997 (6.0 compared with 5.3), but the rank sum test of dmfs-values displayed a non-significant difference (p > 0.05). There was, however, a statistically significant increase in the dmfs-values for molars and canines between 1997 and 2002 (p < 0.05). Between 1987 and 1992, a statistically significant decrease in dmfs-values in incisors (p < 0.01) was found, while the opposite trend occurred between 1992 and 1997 (p < 0.05). Conclusion: By analysing caries distribution within the dentition and in subgroups, trends can be detected over time that otherwise are obscured. The findings should be considered in future epidemiological studies, as even significant changes could be overlooked and disregarded.
Keywords: caries, children, significant caries, subgroups