Which of the following is NOT a commonly used periodontal index in periodontal studies of a population?

The O'leary Plaque Index (OPI) is indeed a plaque index, but it is not one of the commonly referenced indices specifically used in periodontal studies of a population. In periodontal research, indices like the Silness and Loe Plaque Index, the Periodontal Disease Index (PDI), and the Community Periodontal Index (CPI) have a more established presence and are widely recognized for assessing periodontal health and disease within populations.

The Silness and Loe Plaque Index evaluates plaque accumulation on tooth surfaces and is integral in clinical studies to assess oral hygiene. The Periodontal Disease Index (PDI) measures disease status in populations, focusing on both periodontal pockets and attachment loss, making it crucial for understanding the prevalence and severity of periodontal diseases in community settings. The CPI serves a similar function, providing a systematic method for assessing the extent and severity of periodontitis in populations, often used in epidemiological studies.

In contrast, while the O'leary Plaque Index can measure plaque presence, it is less frequently utilized as a standardized tool in evaluating population-level periodontal health compared to the other indices mentioned. Thus, identifying the O'leary Plaque Index as not commonly used in periodontal studies highlights the need to distinguish between more widely