Model for the study of the preeruptive effect of NaF tablets on caries in permanent teeth

The purpose of this study was to elaborate a model for estimating the caries-reducing effect of a preventive measure with due consideration of background factors. The material comprised 50 children, who had consumed NaF tablets regularly during preschool age, and 76 comparable children who had never consumed NaF tablets. They were all examined at 12 and 13 yr of age. Information on caries and, as confounding factors, dietary habits, oral hygiene and microbiologic variables, was obtained on both occasions. Correlations between the parameters and caries, their discriminating effects and interaction between them were studied. The results showed that correction for confounding diminished the crude caries-reducing effect of NaF tablets. Streptococcus mutans and lactobacilli turned out to be the strongest confounders to discriminate well as single variables and to behave logically in analyses of interaction. Therefore, these factors are recommended in the first place for inclusion in a correction model. If the material is sufficiently large for a further breakdown, oral hygiene (represented by bleeding on probing) could be added. The model will be used in future studies of the preeruptive effect of NaF tablets on caries in permanent teeth in the same population.