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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.