oral hygiene index (1960)
The oral hygiene was developed by Greene and Vermillion, and index (OHI) its original form was a combination of two indices: a calculus index and a debris index for every tooth.
They scored calculus as follows [5]:
0= None present.
1=Supragingival calculus covering less than 1/3 of the tooth surface.
2= Supragingival calculus covering 1/3 or 2/3 of the tooth surface and small amounts of subgingival calculus present.
3=Supragingival calculus covering more than 2/3 of the tooth surface or continuous bands of subgingival calculus.
The same scoring system was used for debris (plaque/food) and extrinsic staining. However, this index proved to be too complex and time-consuming for general use, and simplified it in facilitating its Greene use in wider population groups. The resulting simplified oral hygiene index (OHI-S) selected only six tooth surfaces from different areas as being repre- sentative of the whole mouth