Which of the following is an composite index:
Composite index is the one that measures both the reversible and irreversible nature of the diseases. The reversible index is the one that measures the reversible nature of the dental diseases like, the gingival index where the scores can be increased or decreased because when the etiologic agent is removed, then gingival inflammation will be reduced and reverted to a normal state. Other hand, irreversible index is the one where the score may remain the same or increase this is due to the nature of the diseases. Like in DMFT index an example of an irreversible index, even when the etiologic agent for causation of dental caries is removed tooth will never come back to its normal state.
There are some indices that measure both the reversible and irreversible nature of the dental diseases like Russell's periodontal index. In this index, both gingival and periodontal components are measured to assess the periodontal status of the individual and the community. Here, the gingival component is reversible whereas the periodontal component is irreversible. So, in composite index scores will fluctuate on either direction based on the disease process.