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 toot They scored calculus as follows [5]: 03 None present. calculus covering less than of the tooth surface 2 Supragingival calculus covering W or h of the tooth surface and small amounts of subgingival calculus present. Supragingival calculus covering more than h 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