About this calculator
The O’Leary plaque control record is a practical way to document where disclosed plaque is present around the mouth. After plaque disclosure, each tooth surface is recorded as plaque-present or plaque-absent, then the plaque-positive surfaces are converted into a percentage.
This calculator is designed for dental hygiene teaching, periodontal maintenance notes, and chairside patient education. It is not a diagnosis of gum disease and should be interpreted with a full dental assessment.
O’Leary, Drake, and Naylor introduced the plaque control record in the Journal of Periodontology in 1972. This implementation calculates plaque-positive surfaces divided by available surfaces, expressed as a percentage, with optional four-surfaces-per-tooth counting.
Formula active — dental index, not diagnostic
Educational estimate only; not a diagnosis, prescription, or treatment plan.
Formula and method
Plaque index (%) = plaque-positive surfaces ÷ available surfaces × 100. In four-surface full-mouth recording, available surfaces can be estimated as teeth present × 4, minus any excluded or non-assessable surfaces.
Limitations and when not to rely on this result
- Educational estimate only; not a diagnosis, prescription, or treatment plan.
- Result depends on accurate inputs and may not apply to complex medical situations.
- Use clinician judgment, local guidance, and urgent care pathways when symptoms are severe.
Frequently asked questions
What is the O’Leary plaque index? +
It is a plaque control record that expresses the percentage of scored tooth surfaces where disclosed plaque is present. It is commonly used for oral hygiene instruction and monitoring improvement over time.
How is the plaque percentage calculated? +
Divide the number of plaque-positive surfaces by the number of available scored surfaces, then multiply by 100. A common full-mouth approach uses four surfaces per tooth.
What is a good O’Leary plaque score? +
Targets vary by clinic, course, and patient context. Some periodontal care workflows use plaque levels at or below 20%, or a large reduction from baseline, as a sign of improvement. Do not use the percentage alone to diagnose disease.
Should missing teeth be included? +
No. Missing teeth should not add available surfaces to the denominator. Exclude teeth or surfaces that were not assessed according to your charting protocol.
Can patients use this calculator at home? +
Patients can use it as an educational tracker after plaque disclosure, but the score is most useful when a dental professional shows how to identify plaque accurately and improve brushing or interdental cleaning.