SBI/API Index

Sulcus Bleeding Index (SBI) and Approximal Plaque Index (API)

Indices fulfill an important role in daily dental practice. They are used to identify high-risk patients and to monitor the patients’ oral hygiene, oral disease and/patient compliance over time.
Various indices are used in dental practice to register patient’s plaque control and gingival inflammation (Silness and Löe, 1943; Löe and Silness, 1963; Muhlemann & Son, 1971; Barnett et al. 1980, etc.).
Some of the indices were modified and adjusted for simple daily clinical practice (Lange 1977).
Sulcus Bleeding Index (SBI) and Approximal Plaque Index (API) are modified and simple options that record both presence of disclosed plaque (biofilm) and presence of bleeding in dichotomous manner. Both indices focus to interproximal areas that are in general plaque retentive and susceptible to inflammation.

Sulcus Bleeding Index (SBI)

Sulcus Bleeding Index (SBI) is determined by moving a WHO probe within the gingival sulcus towards the papilla from both sides, buccally in the first and third quadrants, and lingually in the second and fourth quadrants. After 10–30 seconds, the results should be recorded dichotomously as “+ if bleeding” and/or “- if not bleeding” for every interproximal area.

SBI clinical technique

SBI positive readings

Approximal plaque index (API)

Approximal plaque index (API) is determined dichotomously in the first and third quadrants lingually and in the second and fourth quadrants buccally. Teeth are rinsed with a spray of air and water to remove any loose food remnants and materia alba. Teeth are dried thoroughly and prepared for application of disclosing agent (mono-, di- or tri-tone). Following application of disclosing agent to proximal surfaces of adjacent teeth, the excess of the agent should be rinsed with water and teeth should be dried.

Api Technique

Both indices SBI and API are calculated and expressed as SBI (%) and API(%).

Method of calculation of SBI (%) & interpretation of results:
Number of sites positive to bleeding
SBI (%) = ——————————————————————————— x 100
Number of the measuring sites*
SBI>25% insufficient oral hygiene
SBI≤25% good oral hygiene
SBI≤15% very good oral hygiene

Method of calculation of SBI (%) & interpretation of results:

Number of sites positive to plaque (biofilm)
API (%) = ——————————————————————————— x 100
Number of the measuring sites*

API>35% insufficient oral hygiene
API≤35% good oral hygiene
API≤25% very good oral hygiene

SBA & API indices should be used to monitor patient’s compliance with oral hygiene measures and should be registered at every visit during periodontal treatment and maintenance.
Digital tool can be used for easy calculation of SBI and API Clinical Tools.
*In full dentition there are 28 reading sites (points).

References:
Lange DE, Plagmann HC, Eenboom A, Promesberger A (1977): Clinical evaluation methods for objectifying oral hygiene. Dtsch ZahnarztlZ 32, 44-47.
Muhlemann, H. (1971). Gingival sulcus bleeding-a leading symptom in initial gingivitis. Helv Odontol Acta, 15, 107-113.