The Irreversible index measures a dental condition that cannot be reversed. Which of the following is an Irreversible index example?

• A. Dental caries index
• B. Plaque index
• C. Gingival index
• D. Caries risk assessment

Answer: (A)

In dental public health, an irreversible index records a condition that cannot be undone as part of the recorded data. A dental caries index does this by capturing caries experience—decayed, missing due to caries, and filled teeth. Those records reflect past disease and permanent changes to dentition, so they’re considered irreversible for surveillance purposes. Plaque and gingival indices, on the other hand, measure current plaque buildup and gingival inflammation, both of which can be reversed with proper hygiene and treatment. Caries risk assessment looks at factors that predict future caries but does not measure an existing irreversible condition, so it isn’t an irreversible index. Therefore, the caries index is the irreversible example.