What does the DMFS index represent?

• A. The number of Decayed, Missing, and Filled Surfaces
• B. The number of Decayed, Missing, and Filled Teeth
• C. The number of Surfaces with any caries
• D. The number of decayed surfaces only

Answer: (A)

The key idea is how caries experience is quantified when we look at the mouth. The DMFS index tallies all tooth surfaces that have been affected by caries in some way: surfaces that are currently decayed, surfaces from which a tooth has been lost due to caries (missing), and surfaces that have been restored with fillings (filled). Since each tooth has multiple surfaces (for example, front teeth have several surfaces, and back teeth have even more), using surfaces as the unit gives a more detailed picture of caries experience than counting teeth alone.

This approach captures both active disease and past disease—decayed surfaces show current lesions, filled surfaces show past caries that have been treated, and missing surfaces reflect teeth lost to caries. That’s why the DMFS index is described as counting decayed, missing, and filled surfaces. It’s different from a measure that only counts active decay or only counts teeth, and it provides a fuller picture of a population’s caries burden.