Does a clinical evaluation of oral cleanliness correlate with caries incidence in preschool children? Findings from a cohort study.

The aim of this study was to assess whether a clinical evaluation of oral cleanliness reflects subsequent caries incidence. Oral examination of 180 children (1- to 4-year-olds) was carried out twice in a six-month period. Caries prevalence at baseline (dfs) in 1- to 2-year-olds (group A) and 3- to 4-year-olds (group B) correlated significantly with oral cleanliness as well as salivary mutans streptococci count (MS). Caries increment (delta(dfs)) correlated significantly with oral cleanliness in group A but not in group B, while delta(dfs) significantly correlated with MS in group B and slightly correlated with that in group A. ANCOVA revealed that dfs was significantly higher at the second examination than at baseline in group B, even after adjusting for oral cleanliness. This finding was confirmed by Wilcoxon test when group B was divided in three categories (low, middle and high) based on oral cleanliness. This suggests that the relationship between delta(dfs) and oral cleanliness decreased with age and that the significant positive correlation found in group B by our point-prevalence survey is derived from the remainder of the positive correlation that occurred at a younger age.