Modified Approximal Plaque Index 

Generally

Plaque is made visible with pigments (Relevators) in the form of Solutions. They contain food dyes (Erythrosine, patent blue V) that are stored in the plaque for a short time.
Erythrosine stains young plaque red. Patent blue V stains mature plaque blue.

• By staining, possible plaque in the approximal area is visible.
• Yes / No (positive/negative) evaluated
• The API should be evaluated in 1.+3. Quadrants orally, in 2.+4. Quadrants vestibular.

Evaluation

                                 ∑of positive plaque measurements
API =     ———————————————————————————       x 100

                                 ∑  of the measuring points

Results

• API 100-70% Insufficient oral hygiene
• API 69-40%    Moderate oral hygiene
• API 39-25%    Good oral hygiene
• API < 25%      Optimal  Mundhygiene 25%

References

Lange DE, Plagmann HC, Eenboom A, Promesberger A (1977): Clinical evaluation methods for objectifying oral hygiene. Dtsch Zahnärztl Z 32, 44-47.