Examples of where indices can be used Examples of data that can be gathered using indices include: Extent of caries how many in a population are affected? Extent of periodontal disease how widespread is it? Oral hygiene how effectively are people cleaning teeth? Presence of plaque (or debris) which surfaces are most commonly missed? Tooth loss at what age do people often loose teeth from gum disease? There are many indices (especially for plaque), although the CHE need only have knowledge of some of the simplest, which are used in conjunction with a disclosing solution to measure the extent of plaque on the teeth