Use of the Significant Caries Index in quantifying the changes in caries in Switzerland from 1964 to 2000

Objectives: To follow the changes in the Significant Caries Index (SiC) and the DMFT during the period 1964-2000 in children aged 12 and 15 in the Canton of Zurich. Methods: Examinations of random samples of children in 16 communities of the Canton were repeated every 4 years from 1964 onwards using the same standards for diagnosing caries. Results: In the 12-year-olds, the children in the low tertile had virtually no DMF-experience from 1980 on. On the contrary, the SiC, based on the children in the highest tertile, decreased until 1996. At the age of 15, the zero-average in the low tertile was reached in 1992 but the SiC continued to decrease until 2000. In the 12-year age group the reduction of the SiC from 1964 to 1996 was 81.3% and for the overall DMFT it was 89.7%. The corresponding reductions for the 15-year-olds, in this case from 1964 to 2000, were 77.0 and 88.4%, respectively. The DMFT-counts in the total samples had substantially higher coefficients of variation than those in the highest tertile. As a consequence, the SiC had relatively smaller confidence intervals than the average DMFT. Conclusions: The SiC is a very useful measure of dental caries experience. On the basis of the results in the 15-year-old group, the target of an SiC below 5.0 is proposed. The decline of the SiC demonstrates that even in the high-risk children caries experience has been reduced substantially.