Interdental plaque

API Lange: plaque in interdental spaces

The Approximal Plaque Index reports the percentage of examined interdental spaces in which disclosed plaque is present.

Classical method

After disclosure, every accessible approximal site is scored as plaque present or absent. Plaque-positive sites are divided by all examined sites and multiplied by 100%.

Common interpretation

0–20%: optimal
>20–<40%: good
40–<70%: satisfactory
70–100%: unsatisfactory

API Lange calculator

Enter the number of examined interdental sites and the number where plaque was present.

API = plaque-positive sites ÷ all examined sites × 100%

Educational calculator. The result is not a diagnosis and must be interpreted with the clinical examination.

How Odonta Index AI uses it

AI identifies disclosed interdental regions visible in the submitted photos and creates a screening estimate. A classical API requires examination of all selected approximal sites; a clinician accounts for sites that are not visible in a photo.

Original publication

Lange et al., 1977 — Approximal Plaque Index

Try a preliminary analysis

Create an account and review the result before sharing it with a patient.

Try it free