On longitudinal caries index data. A comparison study between cohort and cross-sectional attempts.

The aim of the present study was to compare registered data of caries prevalence and incidence from cross-sectional studies of specified age groups with the corresponding caries data from cohorts of individuals receiving dental health service from the same dental clinic during the years studied. The study covered two 15-19-year groups, who had been offered complete dental care from three years of age in the City of Göteborg for the time periods 1986/7-1990/1. When compared, the longitudinal cohort attempts often gave statistically significant different values to those of the cross-sectional year classes, which should be considered when presenting caries index mean values in dental health reviews. It is not indifferent to choose between longitudinal cohort and cross-sectional year class attempts when searching for dental health treatment effects. Due to the advantages of using longitudinal cohort study methods, and with regard to the differences of the study design used, as pointed out in the study, the use of longitudinal cohort patient material, extracted from cross-sectional epidemiological data bases, could favour analysis of the effects of different preventive dental care programs.