Plaque regrowth studies: discriminatory power of plaque index compared to plaque area

A large number of plaque-scoring methods exist for the evaluation of plaque inhibition by oral hygiene agents, products or devices. The ability of suc h methods to discriminate between high and low plaque scores has not been c ompared. In this retrospective analysis, the F-ratios for differences betwe en treatments for plaque index and area were compared from 15, 4-day plaque regrowth studies. F-ratios favoured plaque index as having greater a discr iminatory power compared to plaque area in 2/3 of the studies considered. I t is concluded that, when appropriate, 2 scoring methods for plaque should be used, but if a choice is necessary, plaque index is likely to provide th e greater discriminatory power over plaque area.