Effect on approximal caries in teenagers of interrupting a school-based weekly NaF mouthrinse program for 3 years

The aim of the present investigation was to follow the caries incidence in 126 13-yr-old children who experienced a 3-yr interruption of a supervised weekly mouthrinse program with 0.2% NaF solution (interrupted rinsing-, IR-group). 143 children, 13 yr old, who continuously participated in the NaF mouthrinse program, served as a comparison group (continuous rinsing-, CR-group). Dental caries and restorations were diagnosed on bitewing radiographs; thus only approximal tooth surfaces were considered. The caries incidence over the 3-yr period was 1.84 DFS in the IR- and 1.77 in the CR-group. The corresponding FS-values were 0.67 and 0.25, respectively. Two years later, i.e. when the children were 18-yr-old and the IR-group had had 2 yr back on the school-based mouthrinse program, they were examined again. The difference in caries incidence between 16 and 18 yr of age was still small, 1.32 DFS in the IR- and 1.22 in the CR-group. The corresponding FS-values were 0.63 and 0.49, respectively. Thus, this study showed that the 3-yr interruption of the NaF mouthrinse program resulted in a small, statistically non-significant increase in caries, mostly as regards the number of fillings, on approximal tooth surfaces.