Abstract
Indices are used in order to describe clinical variables used in the assessment of periodontal health and diseases. Indices may be divided into those that quantify variables, and those that simply annotate the presence or absence of variables. In this study, quantitative and binary (presence/absence) indices were compared in the evaluation of dental plaque and gingival bleeding. As the data were not directly comparable, they were transformed into percentage changes occurring between consecutive assessments. It was found that the differences between the two types of indices used to assess dental plaque and bleeding on gentle probing were marginal. Thus it was concluded that, the use of quantification indices may have little or no clinical benefit, and did not warrant the extra expenditure of time and effort required for their administration. However, in more detailed clinical and epidemiological trials designed to evaluate the distribution of clinical variables on different regions of tooth surfaces, the quantification indices are necessary. Therefore binary/dichotomous indices may be used effectively, especially in the daily clinical work without recourse to the more detailed and complex quantitative indices.