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Significant Caries Index

A detailed analysis of the caries situation in many countries show that there is a skewed distribution of caries prevalence - meaning that a proportion of 12-year-olds still has high or even very high DMFT values even though a proportion is totally caries free. Clearly, the mean DMFT value does not accurately reflect this skewed distribution leading to incorrect conclusion that the caries situation for the whole population is controlled, while in reality, several individuals still have caries. A new index, the Significant Caries Index was introduced in order to bring attention to the individuals with the highest caries values in each population under investigation.

The Significant Caries Index calculation

  • Individuals are sorted according to their DMFT values
  • One third of the population with the highest caries scores is selected
  • The mean DMFT for this subgroup is calculated. This value is the SiC Index.


The graph shows caries data for a population, expressed as frequency distribution. In this example, about 45% are caries free (DMFT = 0). The mean DMFT is 1.91, and the Significant Caries Index is 4.61. Arrow and vertical line indicate the individuals that are included in the calculation of the index.

New goal for oral health

In 1981 the World Health Assembly of the WHO declared that the global goal for oral health by the year 2000 should be that the DMFT for the 12-year-olds should not exceed 3. Over a period of twenty years, nearly 70% of the countries in the world have succeeded in achieving this goal, or have never exceeded this borderline value - a great step towards "Health for All".

DMFT describes the amount - the prevalence - of dental caries in an individual and is obtained by calculating the number of Decayed (D), Missing (M) and Filled (F) teeth. The WHO goal thus indicate that a maximum of three teeth as a mean may be affected by caries at the age of 12. However, a low mean caries level such as '3' does not exclude a number of individuals with considerably higher DMFT values in the same population.

For those countries, who still have not reached the WHO/FDI global goal 3 DMFT, this goal is the first priority. As a following step, it has been proposed that the SiC Index for countries should be less than 3 DMFT in the 12-year-olds by the year 2015.


Focusing attention to the children with highest scores of DMFT with the SiC Index, will lead to significant gains for the society and for the person concerned as more specific targeted preventive actions can be implemented. Obviously, children with high caries prevalence will most likely to be those adults needing complex and expensive treatments in the future. Thus, the general concept is that first the country should reach the WHO goal of 3 or less DMFT for the whole population. The next step is SiC Index of 3 DMFT should be acheived for the one third of the highest caries scores for the population. When the SiC Index is reached for the whole country, one should target provinces, districts, cities and even schools where caries levels are still high - SiC Index is above 3 DMFT. This way, the concept of "Health for All" is strengthened.

SiC Index online

A manual that shows you how to calculate SiC Index with/without computer or on the Internet: 


An excel sheet to directly calculate the SiC Index for any given group: 

Calculation (English)

Calculation (Japanese)


1)      Bratthall D. Introducing the Significant Caries Index together with a proposal for a new oral health goal for 12-year-olds, Int Dent J 2000; 50: 378-384.

2)      Nishi M. et al. Caries experience of some countries and areas expressed by the Significant Caries Index. Community Dent Oral Epidemiol 2002; 30: 296-301.

Last updated by Marie Nordström