In clinical practice, the highest score in each sextant is identified after examining all the teeth whereas in epidemiological surveys, only index teeth are examined.  For adults, aged 20 years or more, only ten teeth, known as the 'Index Teeth’ are examined. These teeth have been identified as the best estimators of the worst periodontal condition of the mouth. The ten specified index teeth are 17/16 26/27 36/37 47/46 11 31.  For people upto 19 years, only six 'Index Teeth' are examined. The second molars are excluded at these ages because of the high frequency of false pockets (non inflammatory, associated with tooth eruption). The six index teeth selected are 16, 11, 26, 36, 31 and 46.